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Sample records for acetonitrile chromatographic separation

  1. Performance of short-chain alcohols versus acetonitrile in the surfactant-mediated reversed-phase liquid chromatographic separation of β-blockers.

    PubMed

    Ruiz-Ángel, M J; Torres-Lapasió, J R; Carda-Broch, S; García-Álvarez-Coque, M C

    2010-11-05

    Organic solvents are traditionally added to micellar mobile phases to achieve adequate retention times and peak profiles, in a chromatographic mode which has been called micellar liquid chromatography (MLC). The organic solvent content is limited to preserve the formation of micelles. However, at increasing organic solvent contents, the transition to a situation where micelles do not exist is gradual. Also, there is no reason to neglect the potentiality of mobile phases containing only surfactant monomers instead of micelles (high submicellar chromatography, HSC). This is demonstrated here for the analysis of β-blockers. The performance of four organic solvents (methanol, ethanol, 1-propanol, and acetonitrile) was compared in mobile phases containing the anionic surfactant sodium dodecyl sulphate in the MLC and HSC modes. The association of the organic solvent molecules with micelles gives rise to a significant loss in the elution strength of the organic solvent; whereas upon disruption of micelles, it tends to that observed in the hydro-organic mode. The elution behaviour of the β-blockers was modelled to predict the retention times. This allowed the detailed exploration of the selectivity and resolution of the chromatographic systems in relatively wide ranges of concentration of surfactant and organic solvent. The best performance in terms of resolution and analysis time was achieved using HSC with acetonitrile, being able to base-line resolve a mixture of eight β-blockers. Ethanol also provided a good separation performance, significantly improved with respect to methanol and 1-propanol. In contrast, the hydro-organic mode using acetonitrile or any of the short-chain alcohols could not succeed with the separation of the β-blockers, owing to the poorer selectivity and wider peaks.

  2. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  3. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  4. A validated liquid chromatographic method for the determination of polycyclic aromatic hydrocarbons in honey after homogeneous liquid-liquid extraction using hydrophilic acetonitrile and sodium chloride as mass separating agent.

    PubMed

    Koltsakidou, Anastasia; Zacharis, Constantinos K; Fytianos, Konstantinos

    2015-01-16

    In the present report, a simple and cost-effective method for the determination of twelve US EPA priority polycyclic aromatic hydrocarbons (PAHs) in honey samples after salting-assisted liquid-liquid extraction and UHPLC with fluorescence detection is proposed. The sample treatment is based on the usage of hydrophilic acetonitrile as extraction solvent and its phase separation under high salinity conditions. Due to the high sugar content of the samples the phase separation is promoted effortlessly. Several parameters affecting the extraction efficiency and method sensitivity including the concentration of the honey samples, the type and volume of the extraction solvent, the type and quantity of the inorganic salt, extraction time and centrifugation time was systematically investigated. The method was validated in-house according to the Commission Decision 2002/657/EC guidelines. The limit of detection (LOD) of the method lay between 0.02 and 0.04ngmL(-1) (corresponding to 0.08 and 0.16ngg(-1)) which are close to the quality criteria established by European Regulation (EC) 836/2011 concerning the PAHs in foodstuffs. The mean analytical bias (expressed as relative recoveries) in all spiking levels was acceptable being in the range of 54-118% while the relative standard deviation (RSD) was lower than 19%. The proposed method has been satisfactorily applied for the analysis of the selected PAHs residues in various honey samples obtained from Greek region.

  5. Acetonitrile

    Integrated Risk Information System (IRIS)

    TOXICOLOGICAL REVIEW OF ACETONITRILE ( CAS No . 75 - 05 - 8 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) January 1999 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed in accordance with U.S . Environmental Prot

  6. Acetone as a greener alternative to acetonitrile in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano Soleo; Carneiro, Renato Lajarim; Khandagale, Manish M; Cavalheiro, Alberto José; Hilder, Emily F

    2015-05-01

    A considerable amount of chemical waste from liquid chromatography analysis is generated worldwide. Acetonitrile is the most employed solvent in liquid chromatography analyses since it exhibits favorable physicochemical properties for separation and detection, but it is an unwelcome solvent from an environmental point of view. Acetone might be a much greener alternative to replace acetonitrile in reversed-phase liquid chromatography, since both share similar physicochemical properties, but its applicability with ultraviolet absorbance-based detectors is limited. In this work, a reference method using acetonitrile and high-performance liquid chromatography coupled to an ultraviolet photodiode array detector coupled to a corona charged aerosol detector system was developed to fingerprint a complex sample. The possibility of effectively substituting acetonitrile with acetone was investigated. Design of experiments was adopted to maximize the number of peaks acquired in both fingerprint developments. The methods with acetonitrile or acetone were successfully optimized and proved to be statistically similar when only the number of peaks or peak capacity was taken into consideration. However, the superiority of the latter was evidenced when parameters of separation and those related to greenness were heuristically combined. A green, comprehensive, time- and resource-saving approach is presented here, which is generic and applicable to other complex matrices. Furthermore, it is in line with environmental legislation and analytical trends.

  7. Chromatographic Separation of Glucose and Fructose

    NASA Astrophysics Data System (ADS)

    Kuptsevich, Yu E.; Larionov, Oleg G.; Stal'naya, I. D.; Nakhapetyan, L. A.; Pronin, A. Ya

    1987-03-01

    The structures, mutarotation, and the physicochemical properties of glucose and fructose as well as methods for their separation are examined. Their chromatographic separation on cation exchangers in the calcium-form is discussed in detail. A theory of the formation of complexes of carbohydrates with metal cations is described and the mechanism of the separation of glucose and fructose on cation exchangers in the calcium-form is discussed in detail. Factors influencing the chromatographic separation of glucose and fructose on sulphonic acid cation-exchange resins are also considered. The bibliography includes 138 references.

  8. Chromatographic separation and concentration of quercetin and (+)-catechin using mesoporous composites based on MCM-41

    NASA Astrophysics Data System (ADS)

    Karpov, S. I.; Belanova, N. A.; Korabel'nikova, E. O.; Nedosekina, I. V.; Roessner, F.; Selemenev, V. F.

    2015-05-01

    Data on chromatographic separation of quercetin and (+)-catechin-flavonoids with similar physicochemical (including sorption) properties—are presented. The highest efficiency of chromatographic process at high sorption capacity of the material with respect to quercetin and slightly lower capacity for (+)-catechin were observed when silylated composites of ordered MCM-41 type materials were used. The application of acetonitrile as a solvent increased the sorption capacity of the material and can be recommended for separation of related polyphenol substances and their determination using ordered MCM-41 modified with trimethylchlorosilane as a stationary phase in a chromatographic column.

  9. Liquid chromatographic method for determination of water in soils and the optimization of anion separations by capillary zone electrophoresis

    SciTech Connect

    Benz, N.

    1994-10-01

    A liquid chromatographic method for the determination of water in soil or clay samples is presented. In a separate study, the optimization of electrophoretic separation of alkylated phenolate ions was optimized by varying the pH and acetonitrile concentration of the buffer solutions.

  10. Reversed-phase liquid chromatographic separation and simultaneous profiling of steroidal glycoalkaloids and their aglycones.

    PubMed

    Kuronen, P; Väänänen, T; Pehu, E

    1999-11-19

    Improved and simplified reversed-phase liquid chromatographic conditions for the separation and simultaneous profiling of both steroidal glycoalkaloids and their aglycones, having solanidane- or spirosolane-type structures, are described. The most reproducible retention behavior for these ionizable compounds on C18 columns was achieved under isocratic and gradient elution conditions using acetonitrile in combination with triethylammonium phosphate buffer at pH 3.0, when basic functional groups of solutes and silanol groups on the silica are fully protonated minimizing ionic interactions. Gradient elution was the only feasible approach for the simultaneous separation of steroidal glycoalkaloids and their aglycones. A Zorbax SB C18 column, specially designed for low-pH separations, showed good performance in critical separations. The impurities of the commercial tomatine and tomatidine standards were studied and confirmed using mass spectrometric, liquid chromatographic and thin-layer chromatographic methods.

  11. Packed multi-channels for parallel chromatographic separations in microchips.

    PubMed

    Nagy, Andrea; Gaspar, Attila

    2013-08-23

    Here we report on a simple method to fabricate microfluidic chip incorporating multi-channel systems packed by conventional chromatographic particles without the use of frits. The retaining effectivities of different bottlenecks created in the channels were studied. For the parallel multi-channel chromatographic separations several channel patterns were designed. The obtained multipackings were applied for parallel separations of dyes. The implementation of several chromatographic separation units in microscopic size makes possible faster and high throughput separations.

  12. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    SciTech Connect

    Liu, Ying

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  13. Chromatographic Separation of Vitamin E Enantiomers.

    PubMed

    Fu, Ju-Yen; Htar, Thet-Thet; De Silva, Leanne; Tan, Doryn Meam-Yee; Chuah, Lay-Hong

    2017-02-04

    Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.

  14. Numerical Simulation of an Optical Chromatographic Separator

    DTIC Science & Technology

    2009-02-02

    its close relative, Bacillus thuringiensis ," Anal. Chem. 78, 3221-3225 (2006). 10. S. J. Hart, A. Terray, K. L. Kuhn, J. Arnold, and T. A. Leski...Terray, T. A. Leski, J. Arnold, and R. Stroud, "Discovery of a significant optical chromatographic difference between spores of Bacillus anthracis and

  15. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  16. A trade off between separation, detection and sustainability in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano S; Carneiro, Renato L; Cavalheiro, Alberto J; Hilder, Emily F

    2014-08-08

    It is now recognized that analytical chemistry must also be a target for green principles, in particular chromatographic methods which typically use relatively large volumes of hazardous organic solvents. More generally, high performance liquid chromatography (HPLC) is employed routinely for quality control of complex mixtures in various industries. Acetonitrile and methanol are the most commonly used organic solvents in HPLC, but they generate an impact on the environment and can have a negative effect on the health of analysts. Ethanol offers an exciting alternative as a less toxic, biodegradable solvent for HPLC. In this work we demonstrate that replacement of acetonitrile with ethanol as the organic modifier for HPLC can be achieved without significantly compromising analytical performance. This general approach is demonstrated through the specific example analysis of a complex plant extract. A benchmark method employing acetonitrile for the analysis of Bidens pilosa extract was statistically optimized using the Green Chromatographic Fingerprinting Response (GCFR) which includes factors relating to separation performance and environmental parameters. Methods employing ethanol at 30 and 80°C were developed and compared with the reference method regarding their performance of separation (GCFR) as well as by a new metric, Comprehensive Metric to Compare Liquid Chromatography Methods (CM). The fingerprint with ethanol at 80°C was similar to or better than that with MeCN according to GCFR and CM. This demonstrates that temperature may be used to replace harmful solvents with greener ones in HPLC, including for solvents with significantly different physiochemical properties and without loss in separation performance. This work offers a general approach for the chromatographic analysis of complex samples without compromising green analytical chemistry principles.

  17. Fast gas chromatographic separation of biodiesel.

    SciTech Connect

    Pauls, R. E.

    2011-05-01

    A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m x 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

  18. Optimizing Chromatographic Separation: An Experiment Using an HPLC Simulator

    ERIC Educational Resources Information Center

    Shalliker, R. A.; Kayillo, S.; Dennis, G. R.

    2008-01-01

    Optimization of a chromatographic separation within the time constraints of a laboratory session is practically impossible. However, by employing a HPLC simulator, experiments can be designed that allow students to develop an appreciation of the complexities involved in optimization procedures. In the present exercise, a HPLC simulator from "JCE…

  19. Cation exchange chromatographic elution and separation of rubidium

    SciTech Connect

    Mehta, V.P.; Khopkar, S.M.

    1982-01-01

    The systematic cation exchange chromatographic separation of rubidium on Dowex 50W-X8 was carried out with mineral acids and their salts as eluants.A selectivity scale for various eluants in terms of the elution constant was devised. Rubidium was separated from a large number of elements in binary mixtures by the process of gradient or selective elutions or selective sorption. The noteworthy feature of the method is the sequential separation of rubidium from alkali as well as alkaline earth elements.

  20. Rotating annular chromatograph for continuous metal separations and recovery

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. By continuously introducing the feed material to be separated at a stationary point at the top of the bed and eluent everywhere else around the annulus, elution chromatography occurs. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence, the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effect of annulus width and diameter has recently been studied using the same device with a 50.8-mm-wide annulus and another 0.6-m-long chromatograph with an 89-mm diameter and annulus widths of 6.4, 12.7, and 22.2 mm. These columns have been constructed of Plexiglas and typically operate at a gauge pressure of 175 kPa. To further study the effect of size and pressure, a new 445-mm-diam by 1-m-long column with a 31.8-mm-wide annulus has been fabricated. Its metal construction allows preparative-scale operation with a wide variety of liquids at pressures to 1.3 MPa. Three metal recovery systems have been explored: (1) separation of iron and aluminum in ammonium sulfate-sulfuric acid solutions; (2) separation of hafnium from zirconium in sulfuric acid solutions; and (3) the separation of copper, nickel, and cobalt in ammonium carbonate solutions. This last system simulates the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. It has been studied, using similar conditions, on each of the chromatographs, and the results demonstrate the effect of column dimensions on the quality and quantity of the separation. 8 figures, 1 table.

  1. Can enantiomers be separated in achiral chromatographic systems?

    NASA Astrophysics Data System (ADS)

    Davankov, V. A.

    2016-10-01

    Consideration of chromatography of a nonracemic mixture on an achiral sorbent from a stereochemical point of view allows the claim that partial separation of the excess enantiomer zone from the racemate zone is possible only with analytes capable of self-associating under the conditions of the chromatographic column. It is from these positions that features of this process can be explained and conditions for its maximal proceeding formulated.

  2. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Chromatographic separation material for clinical... Laboratory Instruments § 862.2230 Chromatographic separation material for clinical use. (a) Identification. A chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents,...

  3. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Chromatographic separation material for clinical... Laboratory Instruments § 862.2230 Chromatographic separation material for clinical use. (a) Identification. A chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents,...

  4. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium.

  5. Chromatographic separation of neodymium isotopes by using chemical exchange process.

    PubMed

    Ismail, I M; Ibrahim, M; Aly, H F; Nomura, M; Fujii, Y

    2011-05-20

    The neodymium isotope effects were investigated in Nd-malate ligand exchange system using the highly porous cation exchange resin SQS-6. The temperature of the chromatographic columns was kept constant at 50°C by temperature controlled water passed through the columns jackets. The separation coefficient of neodymium isotopes, ɛ's, was calculated from the isotopic ratios precisely measured by means of an ICP mass spectrometer equipped with nine collectors as ion detectors. The separation coefficient, ɛ×10(5), were calculated and found to be 1.4, 4.8, 5.4, 10.6, 16.8 and 20.2 for (143)Nd, (144)Nd, (145)Nd, (146)Nd, (148)Nd and (150)Nd, respectively.

  6. Mathematical model for multicomponent separations on the continuous annular chromatograph

    SciTech Connect

    Bratzler, R.L.; Begovich, J.M.

    1980-12-01

    A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally.

  7. Effect of Coriolis force on counter-current chromatographic separation by centrifugal partition chromatography.

    PubMed

    Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro

    2004-02-06

    The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.

  8. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E.P.; Chiarizia, R.; Dietz, M.L.

    1997-07-29

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support. 7 figs.

  9. Chromatographic Studies of Protein-Based Chiral Separations.

    PubMed

    Bi, Cong; Zheng, Xiwei; Azaria, Shiden; Beeram, Sandya; Li, Zhao; Hage, David S

    2016-09-01

    The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations.

  10. Chromatographic Studies of Protein-Based Chiral Separations

    PubMed Central

    Bi, Cong; Zheng, Xiwei; Azaria, Shiden; Beeram, Sandya; Li, Zhao; Hage, David S.

    2016-01-01

    The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations. PMID:28344977

  11. Improvement of the chromatographic separation of several 1,4-dihydropyridines calcium channel antagonist drugs by experimental design.

    PubMed

    Baranda, Ana B; Etxebarria, Nestor; Jiménez, Rosa M; Alonso, Rosa M

    2005-01-01

    A high-performance liquid chromatographic method with diode array detection has been developed and optimized for the separation of five calcium channel blockers belonging to the 1,4-dihydropyridine subgroup (nifedipine and related drugs). The possibility of the simultaneous drug analysis allows a decrease of time during the assay as well as a saving of reagents and solvents. In this work, the effect of four experimental parameters (organic modifier percentage, pH value, concentration of the buffer in the mobile phase, and column temperature) on the chromatographic resolution are investigated by experimental design in order to optimize the chromatographic separation of five 1,4-dihydropyridines (amlodipine, nitrendipine, felodipine, lacidipine, and lercanidipine). Fractional factorial design, central composite design, and finally the Multisimplex program are used to establish the optimal conditions in terms of resolution and minimum analysis time. Optimal separation of the five compounds under study is achieved in less than 12 min using a Sulpecosil LC-ABZ+Plus C18 column, a composition of mobile phase of acetonitrile-10mM acetic acid acetate buffer pH 5 (72:28, v/v) at a flow rate of 1 mL/min, a column temperature of 30 degrees C +/- 0.1 degrees C, and a detection wavelength of 238 nm.

  12. Liquid chromatographic separation of antidepressant drugs: I. Tricyclics.

    PubMed

    Beierle, F A; Hubbard, R W

    1983-01-01

    A simple normal-phase (silica), high-performance liquid chromatographic (HPLC) assay of amitriptyline (AMI), doxepin (DOX), imipramine (IMI), nortriptyline (NORT), desmethyldoxepin (DESDOX), desipramine (DESIP), and protriptyline (PRO) in serum with no coelution is described here. Trimipramine and promazine were used as internal standards. Extraction of the 1.0-ml serum samples (collected in plastic) was done with Bond-Elut C18 columns. The compounds of interest were eluted with 10 mM methanolic ammonium acetate. The eluates were evaporated at 56-58 degrees C and reconstituted with 200 microliters of the mobile phase. The mobile phase was absolute ethanol-acetonitrile-tert-butylamine (98:2:0.05, vol/vol/vol). Detection of eluted drugs was at 254 nm at 0.01 absorbance units full scale (AUFS), except for PRO, which was detected at 229 nm at 0.02 AUFS. Absolute recoveries were 87-97%. A 5-micron silica (4.6 X 250 mm) HPLC column was used; results with a 10-micron silica column (3.9 X 300 mm) are also presented. Peak height ratios with trimipramine were linear for each analyte between 25 and 1200 ng/ml. Peak height ratios with promazine as the internal standard were linear for each analyte between 25 and 600 ng/ml. Detection limits under the conditions described were 2 ng/ml for AMI, DOX, and IMI, 4 ng/ml for NORT, DESDOX, and DESIP, and 10 ng/ml for PRO. Coefficients of within-day and day-to-day variation at three concentration levels were less than 9.8% and less than 11.2%, respectively. The hydroxylated metabolites of IMI, DES, NORT, and the cis isomer of DOX are discussed. Steady-state daily dosages and corresponding serum levels are presented for 69 patients. The total assay time was less than 10 min for DESIP and 12 min for PRO. This assay can be used in correlating serum levels with clinical effects, compliancy, and pharmacokinetic studies.

  13. Chromatographic Separations Using Solid-Phase Extraction Cartridges: Separation of Wine Phenolics

    NASA Astrophysics Data System (ADS)

    Brenneman, Charles A.; Ebeler, Susan E.

    1999-12-01

    We describe a simple laboratory experiment that demonstrates the principles of chromatographic separation using solid-phase extraction columns and red wine. By adjusting pH and mobile phase composition, the wine is separated into three fractions of differing polarity. The content of each fraction can be monitored by UV-vis spectroscopy. When the experiment is combined with experiments involving HPLC or GC separations, students gain a greater appreciation for and understanding of the highly automated instrumental systems currently available. In addition, they learn about the chemistry of polyphenolic compounds, which are present in many foods and beverages and which are receiving much attention for their potentially beneficial health effects.

  14. Chromatographic Separation and NMR An Integrated Approach in Pharmaceutical Development.

    PubMed

    Gonnella, Nina C

    2012-01-01

    Over the past 10 years, major improvements in the performance of LC-NMR have been realized. The addition of postcolumn SPE, advances in probe technology including cryogenic probes and microcoil probes, improved solvent suppression pulse sequences, and shielded magnets with better homogeneity have all contributed to rapid advancements in this technology. Application of LC-NMR to problems in pharmaceutical development has had a major impact on structure elucidation studies. LC-NMR has been successfully applied to determine the structures of degradation products, impurities, mixtures of compounds, and metabolites. Use of stop flow techniques with LC-NMR experiments has been a critical means of identifying unstable compounds and studying conformational kinetics. The integration of SPE as an intermediate step between the LC unit and the NMR spectrometer has vastly improved the power of the hyphenated technique in trace analysis applications. Online postcolumn enrichment of chromatographic peaks by SPE dramatically reduces the NMR acquisition times by allowing repeated injections to be trapped onto the same cartridge or different cartridges. Because protonated solvents can be easily removed with a drying procedure, solvents and buffers may be freely chosen for maximizing chromatographic separation without compromising NMR spectral quality. The compound of interest may then be eluted from an SPE cartridge using deuterated organic solvent, which helps to reduce dynamic range issues. When combined with cryogenically cooled microcapillary probes, the sensitivity of the NMR signal increases about 10-fold over conventional room temperature probes, enabling full structure characterization at the microgram level. Heteronuclear experiments with concentrations previously only possible in a limited number of cases have now become standard experiments. The availability of HSQC and HMBC experiments and microcoil/cryogenic technology opens the possibility of using LC-(SPE) NMR for the

  15. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  16. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  17. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  18. HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF ORGANOPHOSPHORUS PESTICIDES ON POLYSACCHARIDE CHIRAL STATIONARY PHASES

    EPA Science Inventory

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiph...

  19. Techniques of preparing plant material for chromatographic separation and analysis.

    PubMed

    Romanik, G; Gilgenast, E; Przyjazny, A; Kamiński, M

    2007-03-10

    This paper discusses preparation techniques of samples of plant material for chromatographic analysis. Individual steps of the procedures used in sample preparation, including sample collection from the environment or from tissue cultures, drying, comminution, homogenization, leaching, extraction, distillation and condensation, analyte enrichment, and obtaining the final extracts for chromatographic analysis are discussed. The techniques most often used for isolation of analytes from homogenized plant material, i.e., Soxhlet extraction, ultrasonic solvent extraction (sonication), accelerated solvent extraction, microwave-assisted extraction, supercritical-fluid extraction, steam distillation, as well as membrane processes are emphasized. Sorptive methods of sample enrichment and removal of interferences, i.e., solid-phase extraction, and solid-phase micro-extraction are also discussed.

  20. Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

    PubMed

    Kučera, Lukáš; Fanali, Salvatore; Aturki, Zeineb; Pospíšil, Tomáš; Bednář, Petr

    2016-01-08

    Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace.

  1. Improved Chromatographic Separation of Sitagliptin Phosphate and Metformin Hydrochloride

    PubMed Central

    Hendy, Moataz S.

    2015-01-01

    New UPLC method was developed for determination of sitagliptin and metformin using Symmetry C18 column (100 mm × 2.1 mm, 2.2 μm) and isocratic elution (methanol 20%), pH (3.5) as a mobile phase. The ultraviolet detector was operated at 220 nm and the column temperature was 50°C. Linearity parameters were acceptable over the concentration ranges of 2-12 μgml-1 and 5-35 μgml-1 for sitagliptin and metformin, respectively. The variables were premeditated to adjust the chromatographic conditions using design of experiment. The proposed method was proved to be accurate for the quality control of the mentioned drugs in their pharmaceutical dosage form. PMID:26759536

  2. QbD-oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid-liquid extraction and chromatographic separation.

    PubMed

    Beg, Sarwar; Chaudhary, Vandna; Sharma, Gajanand; Garg, Babita; Panda, Sagar Suman; Singh, Bhupinder

    2016-06-01

    The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.

  3. High-performance liquid-chromatographic separation of subcomponents of antimycin-A

    USGS Publications Warehouse

    Abidi, S.L.

    1988-01-01

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  4. High-performance liquid chromatographic separation of subcomponents of antimycin A.

    PubMed

    Abidi, S L

    1988-08-05

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, A1a, A1b, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins A1, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpreted based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  5. Liquid chromatographic separation of the stereoisomers of thiazide diuretics.

    PubMed

    Hyun, M H; Pirkle, W H

    2000-04-21

    A number of racemic thiazide diuretics and analogues were resolved on two diastereomeric chiral stationary phases (CSPs) prepared from (S)- or (R)-alpha-[1-(6,7-dimethyl)naphthyl]-10-dodecenylamine and (S)-2-phenylpropanoic acid. Of the two diastereomeric CSPs, the (S,S) and the (R,S), the former is found to be better than the latter in separating the enantiomers of the racemic thiazide diuretics and their analogues with complete separation being observed on the (S,S)-CSP. Chiral recognition is controlled principally by the (R)- or (S)-alpha-[1-(6,7-dimethyl)naphthyl]-10-dodecenylamine portion of the CSPs. The second stereogenic center of the CSP provides but secondary effects on the chiral recognition presumably involving, in the case of the (S,S)-CSP, face-to-edge pi-pi interaction between the aromatic ring of the analytes and the phenyl on the second stereogenic center.

  6. Thin-Layer Chromatographic Separation of Phenols: An Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Kurth, Mark J.

    1986-01-01

    Background information, procedures used, and equipment needed are provided for an experiment in which a series of readily available, inexpensive, and relatively nontoxic phenols are separated using thin-layer chromatographic techniques. The experiment permits a discussion of how relative Rf values may be rationalized by considering a molecule's…

  7. Chiral porous organic frameworks for asymmetric heterogeneous catalysis and gas chromatographic separation.

    PubMed

    Dong, Jinqiao; Liu, Yan; Cui, Yong

    2014-12-11

    Three chiral robust diene-based porous organic frameworks (POFs) are prepared. POF- is shown to be an efficient heterogeneous catalyst after metallation for asymmetric conjugation addition with up to 93% ee, and it can also function as a new chiral stationary phase for gas chromatographic separation of racemates.

  8. [Chromatographic separation of activated proteases from human plasma].

    PubMed

    Lehmann, B; Taucher, M; Kühne, H; Scheuch, D W

    1988-01-01

    After separation of aceton and dextran sulfate activated human plasma by column chromatography on DEAE-cellulose three esterolytically and amidolytically active fractions, respectively, were obtained, which were assigned to the following species: plasma kallikrein (PK), PK.alpha-macroglobulin.HMW-Kininogen. Their percentage in the whole activity is variable. The proportion of free PK is low (0.11). For characterization of the products we studied inhibition by different polyvalent inhibitors. The Michaelis constant (Km) with p-toluene-sulfonyl-L-arginine methyl ester (TAME) were determined. For simulation of in vivo conditions dextran sulfate activated plasma was inactivated at 37 degrees C. The residual activity and the spontaneous activity in plasma from patients with shock are produced by different active protease inhibitor complexes.

  9. High-speed counter-current chromatographic separation of phytosterols.

    PubMed

    Schröder, Markus; Vetter, Walter

    2011-07-01

    Phytosterols are bioactive compounds which occur in low concentrations in plant oils. Due to their beneficial effects on human health, phytosterols have already been supplemented to food. Commercial phytosterol standards show insufficient purity and/or are very expensive. In this study, we developed a high-speed counter-current chromatography (HSCCC) method for the fractionation and analysis of a commercial crude β-sitosterol standard (purity ∼60% according to supplier). Different solvent systems were tested in shake-flask experiments, and the system n-hexane/methanol/aqueous silver nitrate solution (34/24/1, v/v/v) was finally used for HSCCC fractionation. About 50 mg phytosterols was injected and distributed into 57 fractions. Selected fractions were condensed and re-injected into the HSCCC system. This measure provided pure sitostanol (>99%) and β-sitosterol (∼99%), as well as a mixture of campesterol and stigmasterol without further phytosterols. An enriched HSCCC fraction facilitated the mass spectrometric analysis of further 11 minor phytosterols (after trimethylsilylation). It was also shown that the commercial product contained about 0.3% carotinoids which eluted without delay into an early HSCCC fraction and which were separated from the phytosterols.

  10. Chromatographic separation as selection process for prebiotic evolution and the origin of the genetic code.

    PubMed

    Lehmann, U

    1985-01-01

    A model for the evolution of a translation apparatus has been suggested where oligonucleotides in a hairpin conformation act as primordial adapters. Specifically activated amino acids are assumed to be attached to these hairpin molecules. For the specific activation, a chromatographic separation of, e.g. ala and CMP from gly and GMP can be accomplished on silica (e.g. of volcanic origin) with aqueous salt solutions. Other adsorbents like clays (kaolin, bentonite, montmorillonite), different silicates (florisil, magnesium trisilicate, calcium silicate, talc), hydroxyapatite, barium sulfate, calcium carbonate, calcium fluoride and titanoxide have been examined as model systems for the separation of nucleotides, nucleosides and amino acids on mineral surfaces. The possible role of chromatographic separation of amino acids for the formation of proteinoids, composed of selected amino acids, is also considered.

  11. Chromatographic enrichment and enantiomer separation of axially chiral polybrominated biphenyls in a technical mixture.

    PubMed

    Berger, Urs; Vetter, Walter; Götsch, Arntraut; Kallenborn, Roland

    2002-10-11

    The separation properties of different chromatographic methods regarding the enantioselective separation of axially chiral (atropisomeric) polybrominated biphenyls (PBB) were studied. For this purpose, the technical hexabromobiphenyl product Firemaster BP-6 was characterised by gas-chromatography coupled to electron capture detection (GC/ECD) and electron-capture negative ion mass spectrometry (GC/ECNI-MS) as well as by liquid chromatographic fractionating on active carbon and celite. Twelve individual PBBs including potential atropisomeric PBBs were isolated from Firemaster BP-6 by reversed-phase high-performance liquid chromatography (HPLC) on three serially coupled octadecylsilane columns. Six of the 12 isolated PBBs (three tri-ortho and di-ortho substituted PBBs, respectively) were separated into atropisomers on a HPLC column containing permethylated beta-cyclodextrin on silica. Moreover, the temperature dependency of the enantiomer separations is discussed. Gas chromatographic enantiomer separation of PBBs is a very demanding task due to high elution temperatures. However, the atropisomers of one tri-ortho substituted PBB congener (PBB 149) could be resolved on a column coated with randomly modified heptakis(6-O-tert.-butyldimethylsilyl-2,3-di-O-methyl)-beta-cyclodextrin in OV 1701.

  12. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column.

    PubMed

    Arai, Kaori; Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-04-01

    A combination of hydrophilic interaction chromatographic (HILIC) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography (IC). Firstly, the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions. The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10). When using tartaric acid as the eluent, the HILIC columns indicated strong retentions for anions, based on ion-pair interaction. Especially, HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I(-) > NO3(-) > Br(-) > Cl(-) > H2PO4(-). However, since HILIC-10 could not separate analyte cations, a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series. The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+, NH4+, K+, Mg2+, Ca2+, H2PO4(-), Cl(-), Br(-), NO3(-) and I(-)) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6. The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections. The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 micromol/L for the cations and 0.31 - 1.2 micromol/L for the anions. This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  13. Robust isocratic liquid chromatographic separation of functional poly(methyl methacrylate).

    PubMed

    Jiang, Xulin; Lima, Vincent; Schoenmakers, Peter J

    2003-11-07

    The separation of telechelic poly(methyl methacrylate) (PMMA) prepolymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column, which can interact with polar functional groups. The critical solvent compositions for non-functional, mono-functional and bi-functional PMMAs were determined in normal-phase LC using mixtures of acetonitrile and dichloromethane (DCM) of varying composition as the mobile phase. The telechelic prepolymers were successfully separated according to hydroxyl (OH) functionality (with zero, one, or two OH groups, respectively) under the critical conditions, in which fast (5 min), base-line separations were obtained independent of molecular weight. Changing the column temperature, flow rate, and mobile-phase composition within a certain range did not affect the functionality separation. Therefore this isocratic LC separation method is quite robust. Evaporative light-scattering detector (ELSD) calibration curves were used for the quantitative analysis of functional PMMA prepolymers.

  14. [Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

    PubMed

    Zhao, Yonggang; Chen, Xiaohong; Li, Xiaoping; Yao, Shanshan; Jin, Micong

    2011-10-01

    The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

  15. Advances in high-throughput and high-efficiency chiral liquid chromatographic separations.

    PubMed

    Patel, Darshan C; Wahab, M Farooq; Armstrong, Daniel W; Breitbach, Zachary S

    2016-10-07

    The need for improved liquid chromatographic chiral separations has led to the advancement of chiral screening techniques as well as the development of new, high efficiency chiral separation methods and stationary phases. This review covers these advancements, which primarily occurred over the last 15 years. High throughput techniques include multi-column screening units, multiple injection sequences, and fast gradient SFC screening. New separation methods and column technologies that aim at high efficiency chiral separations include the use of achiral UHPLC (i.e. sub-2μm) columns for separating derivatized chiral analytes or using chiral additives in the run buffer, UHPLC chiral stationary phases, and superficially porous particle based chiral stationary phases. Finally, the enhancement of chiral separations through these new technologies requires that certain instrumental considerations be made. Future directions in continuing to improve chiral separations are also discussed.

  16. Chromatographic separation of three monoclonal antibody variants using multicolumn countercurrent solvent gradient purification (MCSGP).

    PubMed

    Müller-Späth, Thomas; Aumann, Lars; Melter, Lena; Ströhlein, Guido; Morbidelli, Massimo

    2008-08-15

    Multicolumn countercurrent solvent gradient purification (MCSGP) is a continuous chromatographic process developed in recent years (Aumann and Morbidelli, 2007a; Aumann et al., 2007) that is particularly suited for applications in the field of bioseparations. Like batch chromatography, MCSGP is suitable for three-fraction chromatographic separations and able to perform solvent gradients but it is superior in terms of solvent consumption, yield, purity, and productivity due to the countercurrent movement of the liquid and the solid phases. In this work, the MCSGP process is applied to the separation of three monoclonal antibody variants on a conventional preparative cation exchange resin. The experimental process performance was compared to simulations based on a lumped kinetic model. Yield and purity values of the target variant of 93%, respectively were obtained experimentally. The batch reference process was clearly outperformed by the MCSGP process.

  17. Chromatographic separation of germanium and arsenic for the production of high purity (77)As.

    PubMed

    Gott, Matthew D; DeGraffenreid, Anthony J; Feng, Yutian; Phipps, Michael D; Wycoff, Donald E; Embree, Mary F; Cutler, Cathy S; Ketring, Alan R; Jurisson, Silvia S

    2016-04-08

    A simple column chromatographic method was developed to isolate (77)As (94±6% (EtOH/HCl); 74±11 (MeOH)) from germanium for potential use in radioimmunotherapy. The separation of arsenic from germanium was based on their relative affinities for different chromatographic materials in aqueous and organic environments. Using an organic or mixed mobile phase, germanium was selectively retained on a silica gel column as germanate, while arsenic was eluted from the column as arsenate. Subsequently, enriched (76)Ge (98±2) was recovered for reuse by elution with aqueous solution (neutral to basic). Greater than 98% radiolabeling yield of a (77)As-trithiol was observed from methanol separated [(77)As]arsenate [17].

  18. Intact protein separation by chromatographic and/or electrophoretic techniques for top-down proteomics.

    PubMed

    Capriotti, Anna Laura; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

    2011-12-09

    Mass spectrometry used in combination with a wide variety of separation methods is the principal methodology for proteomics. In bottom-up approach, proteins are cleaved with a specific proteolytic enzyme, followed by peptide separation and MS identification. In top-down approach intact proteins are introduced into the mass spectrometer. The ions generated by electrospray ionization are then subjected to gas-phase separation, fragmentation, fragment separation, and automated interpretation of mass spectrometric and chromatographic data yielding both the molecular weight of the intact protein and the protein fragmentation pattern. This approach requires high accuracy mass measurement analysers capable of separating the multi-charged isotopic cluster of proteins, such as hybrid ion trap-Fourier transform instruments (LTQ-FTICR, LTQ-Orbitrap). Front-end separation technologies tailored for proteins are of primary importance to implement top-down proteomics. This review intends to provide the state of art of protein chromatographic and electrophoretic separation methods suitable for MS coupling, and to illustrate both monodimensional and multidimensional approaches used for LC-MS top-down proteomics. In addition, some recent progresses in protein chromatography that may provide an alternative to those currently employed are also discussed.

  19. Application of Sigmoidal Transformation Functions in Optimization of Micellar Liquid Chromatographic Separation of Six Quinolone Antibiotics.

    PubMed

    Hadjmohammadi, Mohammadreza; Salary, Mina

    2016-03-01

    A chemometrics approach has been used to optimize the separation of six quinolone compounds by micellar liquid chromatography (MLC). A Derringer's desirability function, a multicriteria decision-making (MCDM) method, was tested for evaluation of two different measures of chromatographic performance (resolution and analysis time). The effect of three experimental parameters on a chromatographic response function (CRF) expressed as a product of two sigmoidal desirability functions was investigated. The sigmoidal functions were used to transform the optimization criteria, resolution and analysis time into the desirability values. The factors studied were the concentration of sodium dodecyl sulfate, butanol content and pH of the mobile phase. The experiments were done according to the face-centered cube central composite design, and the calculated CRF values were fitted to a polynomial model to correlate the CRF values with the variables and their interactions. The developed regression model showed good descriptive and predictive ability (R(2) = 0.815, F = 6.919, SE = 0.038, [Formula: see text]) and used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture. The efficiency of prediction of polynomial model was confirmed by performing the experiment under the optimal conditions.

  20. Liquid chromatographic separation in metal-organic framework MIL-101: a molecular simulation study.

    PubMed

    Hu, Zhongqiao; Chen, Yifei; Jiang, Jianwen

    2013-02-05

    A molecular simulation study is reported to investigate liquid chromatographic separation in metal-organic framework MIL-101. Two mixtures are considered: three amino acids (Arg, Phe, and Trp) in aqueous solution and three xylene isomers (p-, m-, and o-xylene) dissolved in hexane. For the first mixture, the elution order is found to be Arg > Phe > Trp. The hydrophilic Arg has the strongest interaction with the polar mobile phase (water) and the weakest interaction with the stationary phase (MIL-101), and thus transports at the fastest velocity. Furthermore, Arg forms the largest number of hydrogen bonds with water and possesses the largest hydrophilic solvent-accessible surface area. For the second mixture, the elution order is p-xylene > m-xylene > o-xylene, consistent with available experimental observation. With the largest polarity as compared to p- and m-xylenes, o-xylene interacts the most strongly with the stationary phase and exhibits the slowest transport velocity. For both mixtures, the underlying separation mechanism is elucidated from detailed energetic and structural analysis. It is revealed that the separation can be attributed to the cooperative solute-solvent and solute-framework interactions. This simulation study, for the first time, provides molecular insight into liquid chromatographic separation in a MOF and suggests that MIL-101 might be an interesting material for the separation of industrially important liquid mixtures.

  1. Superheated water as chromatographic eluent for parabens separation on octadecyl coated zirconia stationary phase.

    PubMed

    Dugo, Paola; Buonasera, Katia; Crupi, Maria Lucia; Cacciola, Francesco; Dugo, Giovanni; Mondello, Luigi

    2007-05-01

    In this study, the use of pure water at superheated temperatures, between 100 and 200 degrees C, as a mobile phase for RP separation is explored. Instrumental parameters, such as temperature, flow rate, preheating and cooling, have shown significant effects on the quality of the chromatographic peaks. The properties of superheated water as an eluent were investigated by observing the chromatographic behaviour of four parabens on a carbon-clad zirconia (ZR) phase with covalently bonded octadecyl groups. Results were compared with those obtained at 30 degrees C on a silica-based phase with octadecyl groups, using water and ACN as mobile phase. The optimized method was finally applied to analyse parabens in a commercial body cream.

  2. Chemometric approach for development, optimization, and validation of different chromatographic methods for separation of opium alkaloids.

    PubMed

    Acevska, J; Stefkov, G; Petkovska, R; Kulevanova, S; Dimitrovska, A

    2012-05-01

    The excessive and continuously growing interest in the simultaneous determination of poppy alkaloids imposes the development and optimization of convenient high-throughput methods for the assessment of the qualitative and quantitative profile of alkaloids in poppy straw. Systematic optimization of two chromatographic methods (gas chromatography (GC)/flame ionization detector (FID)/mass spectrometry (MS) and reversed-phase (RP)-high-performance liquid chromatography (HPLC)/diode array detector (DAD)) for the separation of alkaloids from Papaver somniferum L. (Papaveraceae) was carried out. The effects of various conditions on the predefined chromatographic descriptors were investigated using chemometrics. A full factorial linear design of experiments for determining the relationship between chromatographic conditions and the retention behavior of the analytes was used. Central composite circumscribed design was utilized for the final method optimization. By conducting the optimization of the methods in very rational manner, a great deal of excessive and unproductive laboratory research work was avoided. The developed chromatographic methods were validated and compared in line with the resolving power, sensitivity, accuracy, speed, cost, ecological aspects, and compatibility with the poppy straw extraction procedure. The separation of the opium alkaloids using the GC/FID/MS method was achieved within 10 min, avoiding any derivatization step. This method has a stronger resolving power, shorter analysis time, better cost/effectiveness factor than the RP-HPLC/DAD method and is in line with the "green trend" of the analysis. The RP-HPLC/DAD method on the other hand displayed better sensitivity for all tested alkaloids. The proposed methods provide both fast screening and an accurate content assessment of the six alkaloids in the poppy samples obtained from the selection program of Papaver strains.

  3. Liquid Chromatographic Separation and Thermodynamic Investigation of Mirabegron Enantiomers on a Chiralpak AY-H Column.

    PubMed

    Zhou, Fan; Zhou, Yuxia; Zou, Qiaogen; Sun, Lili; Wei, Ping

    2015-09-01

    Liquid chromatographic separation of mirabegron enantiomers on Chiralpak AY-H, a column coated with amylose tris-(5-chloro-2-methylphenylcarbamate) as a chiral stationary phase, was studied under normal phase conditions. The influence of ethanol content (30-45%) and column temperature (20-40°C) on retention, resolution and separation were evaluated. Apparent thermodynamic parameters deduced from Van't Hoff plots were used to understand chiral separation mechanisms, and the chiral separation was enthalpy driven. The optimized chromatographic conditions were using a mixture solution of n-hexane, ethanol and diethyl amine (55 : 45 : 0.1, v/v/v) as a mobile phase at a flow rate of 1.0 mL/min. The column temperature and UV detector were set at 35°C and 254 nm, respectively. The method was validated to be simple, accuracy, sensitive and robust according to the ICH guidelines, and it was suitable for the routine quality control of mirabegron enantiomers for pharmaceutical industries.

  4. LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF TRANS-CHLORDANE, CIS-CHLORDANE, HEPTACHLOR, HEPTACHLOR EPOXIDE AND ALPHA-HEXACHLOROCYCLOHEXANE WITH APPLICATION TO SMALL-SCALE PREPARATIVE SEPARATION

    EPA Science Inventory

    Analytical high-performance liquid chromatographic separations of the individual enantiomers of five polychlorinated compounds were obtained on polysaccharide stereoselective HPLC columns. The enantiomers of the pesticides trans-chlordane, cis-chlordane and heptachlor were separa...

  5. Gas Chromatographic Separation of an Acetylene Vinyl Fluoride-Difluoroethane Mixture on Triethylene Glycol and Silicone Oil,

    DTIC Science & Technology

    The purpose of the research was to study gas-chromatographic separation of impurities of acetylene and difluoroethane in vinyl fluoride obtained by...and difluoroethane . All the components are separated, and the criteria of separation of acetylene-vinyl fluoride and vinyl fluoride- difluoroethane

  6. [Development of online conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma].

    PubMed

    Huang, Zhi; Hong, Guangfeng; Gao, Mingxia; Zhang, Xiangmin

    2014-04-01

    Human plasma is one of the proteins-containing samples most difficult to characterize on account of the wide dynamic concentration range of its intact proteins. Herein, we developed a high-throughput conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma in online mode. In the system, a conventional strong-anion exchange chromatographic column was used as the first separation dimension and eight parallel conventional reversed-phase liquid chromatographic columns were integrated as the second separation dimension. The fractions from the first dimension were sequentially transferred into the corresponding reversed-phase liquid chromatographic precolumns for retention and enrichment using a 10-port electrically actuated multi-position valve. The second dimensional solvent flow was directly and identically split into 8 channels. The fractions were concurrently back-flushed from the precolumns into the 8 conventional RP columns and were separated simultaneously. An 8-channel fraction collector was refitted to collect the reversed-phase liquid chromatographic fractions for further investigation. Bicinchoninic acid (BCA) dyein solution was conveniently used for high-abundance protein location. Two separation dimensions were relatively independent parts, as well as each channel of the second dimensional array separation. Therefore, the new system could improve the separation throughput and total peak capacity. The system was successfully applied for the separation of human plasma intact proteins. The results indicated the established system is an effective method for removing high abundance proteins in plasma and in-depth research in plasma proteomics.

  7. Clickable Periodic Mesoporous Organosilica Monolith for Highly Efficient Capillary Chromatographic Separation.

    PubMed

    Wu, Ci; Liang, Yu; Yang, Kaiguang; Min, Yi; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

    2016-02-02

    A novel clickable periodic mesoporous organosilica monolith with the surface area up to 1707 m(2) g(-1) was in situ synthesized in the capillary by the one-step condensation of the organobridged-bonded alkoxysilane precursor bis(triethoxysilyl)ethylene. With Si-C bonds in the skeleton, the monolith possesses excellent chemical and mechanical stability. With vinyl groups highly loaded and homogeneously distributed throughout the structure, the monolith can be readily functionalized with functional groups by effective thiol-ene "click" chemistry reaction. Herein, with "click" modification of C18, the obtained monolith was successfully applied for capillary liquid chromatographic separation of small molecules and proteins. The column efficiency could reach 148,000 N/m, higher than most reported hybrid monoliths. Moreover, intact proteins could be separated well with good reproducibility, even after the monolithic column was exposed by basic mobile phase (pH 10.0) overnight, demonstrating the great promising of such monolith for capillary chromatographic separation.

  8. Extraction chromatographic separations of tantalum and tungsten from hafnium and complex matrix constituents.

    PubMed

    Snow, Mathew S; Finck, Martha R; Carney, Kevin P; Morrison, Samuel S

    2017-02-10

    Tantalum (Ta), hafnium (Hf), and tungsten (W) analyses from complex matrices require high purification of these analytes from each other and major/trace matrix constituents, however, current state-of-the-art Ta/Hf/W separations rely on traditional anion exchange approaches that show relatively similar distribution coefficient (Kd) values for each element. This work reports an assessment of three commercially available extraction chromatographic resins (TEVA, TRU, and UTEVA) for Ta/Hf/W separations. Batch contact studies show differences in Ta/Hf and Ta/W Kd values of up to 10(6) and 10(4) (respectively), representing an improvement of a factor of 100 and 300 in Ta/Hf and Ta/W Kd values (respectively) over AG1×4 resin. Variations in the Kd values as a function of HCl concentration for TRU resin show that this resin is well suited for Ta/Hf/W separations, with Ta/Hf, Ta/W, and W/Hf Kd value improvements of 10, 200, and 30 (respectively) over AG1×4 resin. Analyses of digested soil samples (NIST 2710a) using TRU resin and tandem TEVA-TRU columns demonstrate the ability to achieve extremely high purification (>99%) of Ta and W from each other and Hf, as well as enabling very high purification of Ta and W from the major and trace elemental constituents present in soils using a single chromatographic step.

  9. Electrochemical stabilization of transplutonium-element valence states under chromatographic separation conditions

    SciTech Connect

    Kosyakov, V.N.; Yakovlev, N.G.; Vlasov, M.M.

    1987-03-01

    The example of separating berkelium and trivalent transplutonium elements (TPE) is considered for an extraction-chromatographic system containing 4 mole/liter HNO/sub 3/ with D2EHPA, which demonstrates the scope for electrochemical stabilization of valency states. The carrier for the stationary organic phase was a corrosion-resistant conducting material of large surface area (ground vitrocarbon, graphitized carbon fiber, etc.), which at the same time was the working electrode in an electrochemical cell supplied with the appropriate potential. The method does not require the addition of oxidizing or reducing agents and allows remote control.

  10. Chromatographic separation of phenylpropanol enantiomers on a quinidine carbamate-type chiral stationary phase

    SciTech Connect

    Asnin, Leonid; Guiochon, Georges A

    2005-07-01

    The retention and the separation of the enantiomers of 1-phenylpropanol (1PP), 2-phenylpropanol (2PP), and 3-chloro-1-phenylpropanol (3CPP) on silica-bonded quinidine carbamate under normal phase HPLC conditions were investigated. A relatively high selectivity of the stationary phase for 3CPP and 1PP ({alpha} {approx} 1.07-1.09) was achieved with eluents containing ethyl acetate as the polar modifier. These mobile phases were examined in detail. Based on the set of chromatographic and thermodynamic data collected, conclusions regarding the mechanism of enantioselectivity and the structure of the selector chiral center are made.

  11. Extraction chromatographic separation of promethium from high active waste solutions of Purex origin

    SciTech Connect

    Ramanujam, A.; Achuthan, P.V.; Dhami, P.S.; Gopalakrishnan, V.; Kannan, R.; Mathur, J.N.

    1995-03-01

    An extraction chromatographic procedure for the separation of {sup 147}Pm from High Active Waste solutions of Purex process has been developed. Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide(CMPO) and 2-ethylhexyl-2-ethylhexylphosphonic acid (KSM-17), both sorbed separately on an inert support(chromosorb-102) have been sequentially employed for this purpose. In the CMPO column, the rare earths and the trivalent actinides are sorbed together with uranium, plutonium and traces of few other fission products. The elution of this column with 0.04 M HNO{sub 3} gives an eluate containing trivalent actinides and lanthanides. This solution, after adjusting the pH to 2.0, is used as feed for the second extraction chromatographic column based on KSM-17. All the trivalent metal ions are sorbed on the column leaving the trace impurities in the effluent. Fractional elution of the metal ions from this column is carried out with nitric acid of varying concentrations. At 0.09 M HNO{sub 3}, the pure beta emitting fraction of {sup 147}Pm has been obtained. 16 refs., 3 figs., 2 tabs.

  12. Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths.

    PubMed

    Teisseyre, Thomas Z; Urban, Jiri; Halpern-Manners, Nicholas W; Chambers, Stuart D; Bajaj, Vikram S; Svec, Frantisek; Pines, Alexander

    2011-08-01

    An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.

  13. Dried calcium alginate/magnetite spheres: a new support for chromatographic separations and enzyme immobilization

    SciTech Connect

    Burns, M.A.; Kvesitadze, G.I.; Graves, D.J.

    1985-02-01

    Dried spheres made from an alginate solution containing magnetite particles have excellent potential as a support for enzyme immobilization and chromatographic applications. The beads were found to be much stronger than gels such as polyacrylamide and dextran, indicating that high flow rates and pressures could be used in column separations. The support withstood not only temperatures of up to 120/sup 0/C, but also most pH values and common solvents. While some solutions, such as phosphate buffers, dissolved the spheres, stabilization with Tyzor TE eliminated this problem. The physical properties of the beads include a glasslike density of 2.2 g/mL, excellent sphericity, low porosity, and a narrow size distribution. The magnetite present in the support allows the beads to be used for magnetic separations such as high gradient magnetic filtration. Their high degree of microroughness provides a large exposed surface area for enzyme and ligand binding. Mixed Actinomyces fradiae proteases and Aspergillus niger ..cap alpha..-amylase, two enzymes representative of classes which attack large substrates, were immobilized on the bead's surface with high activity and stability. A cyanuric dye which can be used in chromatographic applications (Cibacron Blue F3GA) was also readily coupled to the surface of this support with good yield.

  14. Novel behavior of the chromatographic separation of linear and cyclic polymers

    PubMed Central

    Montenegro-Burke, J. Rafael; Bennett, Jackson M.; McLean, John A.; Hercules, David M.

    2016-01-01

    In various polymerization processes, the formation of a wide variety of chains, not only in length but also in chemical composition, broadly complicates comprehensive polymer characterization. In this communication, we compare different stationary and mobile phases for the analysis of complex polymer mixtures via size-exclusion chromatography-mass spectrometry (SEC-MS). To the best of our knowledge, we report novel chromatographic effects for the separation of linear and cyclic oligomers for polyesters (PE) and polyurethanes (PUR). A complete separation for the different structures was achieved for both polymer types with a single solvent system (ACN) and without extensive optimization. Additionally, cyclic species were found to show an inverse elution profile compared to their linear counterparts, suggesting distinct physical properties between species. PMID:26637218

  15. Ion chromatographic separation and determination of phosphate and arsenate in water and hair.

    PubMed

    Antony, P J; Karthikeyan, S; Iyer, C S P

    2002-02-15

    A simple and sensitive method for the sequential determination of phosphate and arsenate was developed based on initial ion chromatographic separation followed by detection as the ion-association complex formed by heteropolymolybdophosphate and arsenate with bismuth. With 200 microl sample injection and separation on a AS4A-SC column using an eluent of 3.5 mM sodium hydrogen carbonate-10.0 mM sodium hydroxide, the detection limits which are calculated as the concentration equivalent to twice the baseline noise, were found to be 0.8 microg/l and 4.2 microg/l for P and As, respectively. Spiked samples were analyzed and recoveries were found to be satisfactory in the range of 95-105% for phosphate and 90-105% for arsenate. Samples of water and hair were analyzed by the proposed method.

  16. Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR.

    PubMed

    Huang, Shaohua; Wu, Rui; Bai, Zhengwu; Yang, Ying; Li, Suying; Dou, Xiaowei

    2014-09-01

    Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p-xylene, benzyl alcohol, and p-methylphenol by the chromatographic NMR technique. The effects of concentration and weight-average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity-higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p-xylene and benzyl alcohol gradually increased, and the one between p-xylene and p-methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient.

  17. Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger.

    PubMed

    Fritz, J S; Topping, J J

    1971-09-01

    In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.

  18. Greener bioanalytical approach for LC/MS-MS assay of enalapril and enalaprilat in human plasma with total replacement of acetonitrile throughout all analytical stages.

    PubMed

    Cheregi, Mihaela; Albu, Florin; Udrescu, Ştefan; Răducanu, Nicoleta; Medvedovici, Andrei

    2013-05-15

    Green bioanalytical approaches are oriented toward minimization or elimination of hazardous chemicals associated to bioanalytical applications. LC/MS-MS assay of enalapril and enalaprilat in human plasma was achieved by elimination of acetonitrile from both sample preparation and chromatographic separation stages. Protein precipitation (PP) by acetonitrile addition was replaced by liquid-liquid extraction (LLE) in 1-octanol followed by direct large volume injection of the organic layer in the chromatographic column operated under reversed phase (RP) separation mechanism. At the mean time, acetonitrile used as organic modifier in the mobile phase was successfully replaced by a mixture of propylene carbonate/ethanol (7/3, v/v). Three analytical alternatives ((I) acetonitrile PP+acetonitrile based chromatographic elution; (II) 1-octanol LLE+acetonitrile based chromatographic elution; (III) 1-octanol LLE+propylene carbonate/ethanol based chromatographic elution) were validated and the quality characteristics were compared. Comparison between these alternative analytical approaches was also based on results obtained on incurred samples taken during a bioequivalence study, through application of the Bland-Altman procedure.

  19. Graphitic carbon nitride as high-resolution stationary phase for gas chromatographic separations.

    PubMed

    Zheng, Yunzhong; Qi, Meiling; Fu, Ruonong

    2016-07-08

    This work presents the first example of utilization of graphitic carbon nitride (g-C3N4) as stationary phase for capillary gas chromatographic (GC) separations. The statically coated g-C3N4 column showed the column efficiencies of 3760 plates/m and weak polarity. Its resolving capability and retention behaviours were investigated by using the Grob test mixture, and mixtures of diverse types of analytes, and structural and positional isomers. The results showed superior separation performance of the g-C3N4 stationary phase for some critical analytes and preferential retention for aromatic analytes. Specifically, it exhibited high-resolution capability for aromatic and aliphatic isomers such as methylnaphthalenes and dimethylnaphthalenes, phenanthrene and anthracene and alkane isomers. In addition, g-C3N4 column showed excellent thermal stability up to 280°C and good repeatability with relative standard deviation (RSD) values less than 0.09% for intra-day, below 0.23% for inter-day and in the range of 1.9-8.4% for between-column, respectively. The advantageous separation performance shows the potential of g-C3N4 and related materials as stationary phase in GC and other separation technologies.

  20. Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions.

    PubMed

    Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-12-28

    We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were separated using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H(+) concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary phase column but smaller than that of an anion-exchange column. The separation of anions using the diol-column was strongly affected by the interaction of H(+) ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good separation was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n=5) of 0.04-0.07% for the retention time and 0.4-2.0% for the peak areas. This method was successfully applied to the determination of H(2)PO(4)(-), Cl(-), and NO(3)(-) in a liquid fertilizer sample.

  1. Thin-layer chromatographic (TLC) separations and bioassays of plant extracts to identify antimicrobial compounds.

    PubMed

    Kagan, Isabelle A; Flythe, Michael D

    2014-03-27

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions. This paper describes standard protocols for TLC and contact bioautography with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light. Zones are cut out and incubated face down onto agar inoculated with the test microorganism. Inhibitory bands are visualized by staining the agar plates with tetrazolium red. The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen. The TLC methods apply to many types of plant extracts and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

  2. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds

    PubMed Central

    Freire, Carmen S. R.; Coutinho, João A. P.; Silvestre, Armando J. D.; Freire, Mara G.

    2016-01-01

    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction–separation processes using IL aqueous solutions are suggested within a green chemistry perspective. PMID:27667965

  3. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds.

    PubMed

    Soares, Belinda; Passos, Helena; Freire, Carmen S R; Coutinho, João A P; Silvestre, Armando J D; Freire, Mara G

    2016-09-07

    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction-separation processes using IL aqueous solutions are suggested within a green chemistry perspective.

  4. Kinetics and equilibria of the chromatographic separation of maltose and trehalose.

    PubMed

    He, Dengjun; Zhou, Jiachun; Xia, Quanming; Jiang, Lihua; Qiu, Yongjun; Zhao, Liming

    2015-07-01

    Trehalose, a nonreducing disaccharide, has been extensively applied to food, cosmetics, and pharmaceutical goods. The resultant solution of trehalose prepared by enzymatic methods includes high amounts of maltose. However, it is quite difficult to separate maltose and trehalose on an industrial scale because of their similar properties. In this paper, a high-performance resin was selected as a stationary phase to separate trehalose and maltose, and the resolution of these sugars was 0.59. The potential of a cation exchange resin was investigated as the stationary phase in separating trehalose and maltose using deionized water as the mobile phase. Based on the equilibrium dispersive model, the axial dispersion coefficients and overall mass transfer coefficients of maltose and trehalose were determined by moment analysis at two different temperatures, 50 and 70°C. Other parameters, including the column void and the adsorption isotherms, were also determined and applied to simulate the elution curves of trehalose and maltose. The simulated results matched the experimental data, validating the parameters. The optimized parameters are critical to the chromatographic separation of trehalose and maltose on an industrial scale.

  5. Separative analyses of a chromatographic column packed with a core-shell adsorbent for lithium isotope separation

    SciTech Connect

    Sugiyama, T.; Sugura, K.; Enokida, Y.; Yamamoto, I.

    2015-03-15

    Lithium-6 is used as a blanket material for sufficient tritium production in DT fueled fusion reactors. A core-shell type adsorbent was proposed for lithium isotope separation by chromatography. The mass transfer model in a chromatographic column consisted of 4 steps, such as convection and dispersion in the column, transfer through liquid films, intra-particle diffusion and and adsorption or desorption at the local adsorption sites. A model was developed and concentration profiles and time variation in the column were numerically simulated. It became clear that core-shell type adsorbents with thin porous shell were saturated rapidly relatively to fully porous one and established a sharp edge of adsorption band. This is very important feature because lithium isotope separation requires long-distance development of adsorption band. The values of HETP (Height Equivalent of a Theoretical Plate) for core-shell adsorbent packed column were estimated by statistical moments of the step response curve. The value of HETP decreased with the thickness of the porous shell. A core-shell type adsorbent is, then, useful for lithium isotope separation. (authors)

  6. Evolutionary multi-objective optimization based comparison of multi-column chromatographic separation processes for a ternary separation.

    PubMed

    Heinonen, Jari; Kukkonen, Saku; Sainio, Tuomo

    2014-09-05

    Performance characteristics of two advanced multi-column chromatographic separation processes with discontinuous feed, Multi-Column Recycling Chromatogrphy (MCRC) and Japan Organo (JO), were investigated for a ternary separation using multi-objective optimization with an evolutionary algorithm. Conventional batch process was used as a reference. Fractionation of a concentrated acid hydrolysate of wood biomass into sulfuric acid, monosaccharide, and acetic acid fractions was used as a model system. Comparison of the separation processes was based on selected performance parameters in their optimized states. Flow rates and step durations were taken as decision variables whereas the column configuration and dimensions were fixed. The MCRC process was found to be considerably more efficient than the other processes with respect to eluent consumption. The batch process gave the highest productivity and the JO process the lowest. Both of the multi-column processes gave significantly higher monosaccharide yield than the batch process. When eluent consumption and monosaccharide yield are taken into account together with productivity, the MCRC process was found to be the most efficient in the studied case.

  7. Chromatographic cation exchange separation of decigram quantities of californium and other transplutonium elements

    SciTech Connect

    Benker, D.E.; Chattin, F.R.; Collins, E.D.; Knauer, J.B.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1981-01-01

    Decigram quantities of highly radioactive transplutonium elements are routinely partitioned at TRU by chromatographic elution from cation resin using AHIB eluents. Batch runs containing up to 200 mg of /sup 252/Cf can be made in about 5 h (2 h to load the feed and 3 h for the elution), with two high-pressure ion exchange columns, a small one for the initial loading of the feed and a large one for the elution. The separations achieved in the column are preserved by routing the column effluent through an alpha detector and using the response from the detector to select appropriate product fractions. The high-pressure ion exchange process has been reliable and relatively easy to operate; therefore it will continue to be used for partitioning transplutonium elements at TRU. 3 figures, 1 table.

  8. Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology

    NASA Astrophysics Data System (ADS)

    Kuo, C.-Y.; Chen, P.-S.; Chen, H.-T.; Lu, C.-J.; Tian, W.-C.

    2017-03-01

    In this study, a simple process for fabricating a novel micromachined preconcentrator (μPCT) and a gas chromatographic separation column (μSC) for use in a micro gas chromatograph (μGC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μPCT and μSC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μPCT and μSC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μPCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s‑1. Repeatable thermal heating responses for μPCTs were achieved; good linearity (R 2  >  0.9997) was attained at three heating rates for the temperature programme for the μSC (0.2, 0.5 and 1 °C s‑1). The volatile organic compounds (VOCs) toluene and m-xylene were concentrated over the μPCT by rapid thermal desorption (peak width of half height (PWHH)  <1.5 s) preconcentration factors for both VOCs are  >7900. The VOCs acetone, benzene, toluene, m-xylene and 1,3,5-trimethylbenzene were also separated on the μSC as evidenced by their different retention times (47–184 s).

  9. Retention behavior of phenols, anilines, and alkylbenzenes in liquid chromatographic separations using subcritical water as the mobile phase.

    PubMed

    Yang, Y; Jones, A D; Eaton, C D

    1999-09-01

    The unique characteristic of subcritical water is its widely tunable physical properties. For example, the polarity (measured by dielectric constant) of water is significantly decreased by raising water temperature. At temperatures of 200-250 °C (under moderate pressure to keep water in the liquid state), the polarity of pure water is similar to that of pure methanol or acetonitrile at ambient conditions. Therefore, pure subcritical water may be able to serve as the mobile phase for reversed-phase separations. To investigate the retention behavior in subcritical water separation, the retention factors of BTEX (benzene, toluene, ethylbenzene, and m-xylene), phenol, aniline, and their derivatives have been determined using subcritical water, methanol/water, and acetonitrile/water systems. Subcritical water separations were also performed using alumina, silica-bonded C18, and poly(styrene-divinylbenzene) columns to study the influence of the stationary phase on analyte retention under subcritical water conditions.

  10. [Optimization of two-dimensional high performance liquid chromatographic columns for highly efficient separation of intact proteins].

    PubMed

    Hong, Guangfeng; Gao, Mingxia; Yan, Guoquan; Guan, Xia; Tao, Qian; Zhang, Xiangmin

    2010-02-01

    In order to optimize two-dimensional liquid chromatographic (2D-LC) columns for highly efficient separation of proteins, several liquid chromatographic columns were investigated and evaluated. Weak anion-exchange (WAX) column was chosen as the first dimension because of its extensive protein separation power. By comparison of different WAX chromatographic columns for human liver protein separation, TSKgel DEAE-5PW column was selected as the first dimension of a 2D-LC system. For the second dimension, ten typical reversed-phase (RP) LC columns (250 mm x 4.6 mm, 5 microm, 30 nm) were investigated and evaluated. Their silica based RP stationary phases were butyl (C4), octyl (C8) or octadecyl (C18). To evaluate the retention behavior and non-specific protein adsorption ability of these ten columns, four neutral compounds (uracil, nitrobenzene, naphthalene and fluorene) and three standard proteins (cytochrome C, myoglobin and albumin from chicken egg white) were adopted and separated by RPLC. Meantime, WAX fractions were used to investigate the separation ability of different alkyl-bonded silica stationary phase columns for complex protein samples. By comparison of column separation efficiency, adsorption of intact proteins and sample analysis, Jupiter 300 C4 column was finally employed for its excellent separation ability. Optimization of WAX and RPLC columns offers reliable foundation for the construction of 2D-LC protein separation systems.

  11. Comprehensive two-dimensional gas chromatographic separations with a microfabricated thermal modulator.

    PubMed

    Serrano, Gustavo; Paul, Dibyadeep; Kim, Sung-Jin; Kurabayashi, Katsuo; Zellers, Edward T

    2012-08-21

    Rapid, comprehensive two-dimensional gas chromatographic (GC × GC) separations by use of a microfabricated midpoint thermal modulator (μTM) are demonstrated, and the effects of various μTM design and operating parameters on performance are characterized. The two-stage μTM chip consists of two interconnected spiral etched-Si microchannels (4.2 and 2.8 cm long) with a cross section of 250 × 140 μm(2), an anodically bonded Pyrex cap, and a cross-linked wall coating of poly(dimethylsiloxane) (PDMS). Integrated heaters provide rapid, sequential heating of each μTM stage, while a proximate, underlying thermoelectric cooler provides continual cooling. The first-dimension column used for GC × GC separations was a 6 m long, 250 μm i.d. capillary with a PDMS stationary phase, and the second-dimension column was a 0.5 m long, 100 μm i.d. capillary with a poly(ethylene glycol) phase. Using sets of five to seven volatile test compounds (boiling point ≤174 °C), the effects of the minimum (T(min)) and maximum (T(max)) modulation temperature, stage heating lag/offset (O(s)), modulation period (P(M)), and volumetric flow rate (F) on the quality of the separations were evaluated with respect to several performance metrics. Best results were obtained with a T(min) = -20 °C, T(max) = 210 °C, O(s) = 600 ms, P(M) = 6 s, and F = 0.9 mL/min. Replicate modulated peak areas and retention times were reproducible to <5%. A structured nine-component GC × GC chromatogram was produced, and a 21 component separation was achieved in <3 min. The potential for creating portable μGC × μGC systems is discussed.

  12. Anion exchange chromatographic separation of inositol phosphates and their quantification by gas chromatography.

    PubMed

    Heathers, G P; Juehne, T; Rubin, L J; Corr, P B; Evers, A S

    1989-01-01

    The direct measurement of mass of inositol trisphosphate from biologic samples is described. Separation of inositol monophosphate, bisphosphate, trisphosphate, and inositol tetrakisphosphate was achieved using anion exchange chromatography with a sodium sulfate gradient. In addition, separation of the isomers of each inositol phosphate was performed using HPLC procedures. The individual inositol phosphate fractions were subsequently dephosphorylated and desalted. The myo-inositol from each fraction was then derivatized to the hexatrimethylsilyl derivative and the myo-inositol derivatives were quantified by a novel gas chromatographic analysis using the hexatrimethylsilyl derivative of chiro-inositol as an internal concentration reference. This method is a reproducible and relatively rapid procedure for the direct quantification of inositol phosphate mass which overcomes many of the problems associated with the use of radiolabeled precursors. The method is a significant improvement over existing procedures for the quantitative determination of the mass of inositol phosphate by virtue of improved recovery, sensitivity, and technical simplicity. The applicability of this method is illustrated by the quantitative determination of inositol trisphosphate in response to norepinephrine stimulation of adult canine myocytes and cerebral cortical brain slices and by measurement of the isomers of inositol trisphosphate in isolated myocytes.

  13. A novel and effective chromatographic approach to the separation of isoflavone derivatives from Pueraria lobata.

    PubMed

    Fu, Jiang; Jing, Wenguang; Wang, Weihao; Chen, Sha; Zhang, Jun; Liu, An

    2015-03-05

    A novel and effective chromatographic approach to the separation and purification of isoflavone compounds from Pueraria lobata is described. The method is based on flash chromatography (FC), coupled to preparative high performance liquid chromatography (prep-HPLC) via a six-way valve. The FC step comprised tandem reversed phase columns, pre-packed with MCI gel (Mitsubishi Chemical Corp., Tokyo, Japan) and C18 (Fuji Silysia Chemical Ltd, Osaka, Japan) resin, respectively, and was designed to separate a crude Pueraria lobata extract into several preliminary fractions. Fractions containing the target compounds were then directly injected via the six-way valve into prep-HPLC columns, without further treatment, for final isolation and purification. Nine isoflavonoids were successfully isolated, three through an online mode and the other six through an offline mode. The purities of all compounds exceeded 95.0%, as determined by HPLC with an UV-vis photodiode array detector. The convenience, low solvent consumption, and time-saving advantages of this method offer an attractive and promising approach to the isolation of natural products.

  14. Facile room-temperature solution-phase synthesis of a spherical covalent organic framework for high-resolution chromatographic separation.

    PubMed

    Yang, Cheng-Xiong; Liu, Chang; Cao, Yi-Meng; Yan, Xiu-Ping

    2015-08-07

    A simple and facile room-temperature solution-phase synthesis was developed to fabricate a spherical covalent organic framework with large surface area, good solvent stability and high thermostability for high-resolution chromatographic separation of diverse important industrial analytes including alkanes, cyclohexane and benzene, α-pinene and β-pinene, and alcohols with high column efficiency and good precision.

  15. Replacement of acetonitrile by ethanol as solvent in reversed phase chromatography of biomolecules.

    PubMed

    Brettschneider, F; Jankowski, V; Günthner, T; Salem, S; Nierhaus, M; Schulz, A; Zidek, W; Jankowski, J

    2010-03-15

    Acetonitrile, which is a by-product of acrylonitrile synthesis, is the commonly used solvent in ion-pair reversed phase chromatography. In consequence of the decreasing demand for acrylonitrile due to the financial crisis, a worldwide shortage of acetonitrile is observed. Therefore, the aim of this study was to establish ion-pair reversed phase chromatographic assays using alternative eluents for acetonitrile and to decrease costs incurred hereby. We compared the performance of ion-pair reversed phase chromatography using acetonitrile with the alternative eluents methanol, ethanol and n-propanol, using monolithic reversed phase C5 as well as C18 chromatography columns. We used triethylammonium acetate (TEAA) and tetrabutylammonium sulfate (TBA) as representative cationic ion-pair reagents and trifluoroacetic acid (TFA) as representative anionic ion-pair reagent. For covering a large field of applications, we fractionated representative low, middle and high-molecular weight biomolecules, in particular dinucleoside polyphosphates, peptides, proteins and tryptic digested human serum albumin. Whereas the chromatographic characteristics of both methanol and n-propanol were partly insufficient, ethanol was characterised equally or partly even better in the matter of elution strength and separation quality compared to the eluent water-acetonitrile. In conclusion, ethanol is an appropriate alternative for acetonitrile in ion-pair reversed phase chromatography of biomolecules.

  16. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories

    ERIC Educational Resources Information Center

    Brunauer, Linda S.; Caslavka, Katelyn E.; Van Groningen, Karinne

    2014-01-01

    A multiday laboratory exercise is described that is suitable for first-year undergraduate chemistry, biochemistry, or biotechnology students. Students gain experience in performing chromatographic separations of biomolecules, in both a column and thin layer chromatography (TLC) format. Students chromatographically separate amino acids (AA) in an…

  17. Novel chromatographic separation and carbon solid-phase extraction of acetanilide herbicide degradation products.

    PubMed

    Shoemaker, Jody A

    2002-01-01

    One acetamide and 5 acetanilide herbicides are currently registered for use in the United States. Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of these acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. Alachlor ESA and other acetanilide degradation products are listed on the U.S. Environmental Protection Agency's (EPA) 1998 Drinking Water Contaminant Candidate List. Consequently, EPA is interested in obtaining national occurrence data for these contaminants in drinking water. EPA currently does not have a method for determining these acetanilide degradation products in drinking water; therefore, a research method is being developed using liquid chromatography/negative ion electrospray/mass spectrometry with solid-phase extraction (SPE). A novel chromatographic separation of the acetochlor/alachlor ESA and OA structural isomers was developed which uses an ammonium acetate-methanol gradient combined with heating the analytical column to 70 degrees C. Twelve acetanilide degradates were extracted by SPE from 100 mL water samples using carbon cartridges with mean recoveries >90% and relative standard deviations < or =16%.

  18. Using precipitation by polyamines as an alternative to chromatographic separation in antibody purification processes.

    PubMed

    Ma, Junfen; Hoang, Hai; Myint, Thomas; Peram, Thanmaya; Fahrner, Robert; Chou, Judy H

    2010-03-15

    Polyamine precipitation conditions for removing host cell protein impurities from the cell culture fluid containing monoclonal antibody were studied. We examined the impact of polyamine concentration, size, structure, cell culture fluid pH and ionic strength. A 96-well microtiter plate based high throughput screening method was developed and used for evaluating different polyamines. Polyallylamine, polyvinylamine, branched polyethyleneimine and poly(dimethylamine-co-epichlorohydrin-ethylenediamine) were identified as efficient precipitants in removing host cell protein impurities. Leveraging from the screening results, we incorporated a polyamine precipitation step into a monoclonal antibody purification process to replace the Protein A chromatography step. The optimization of the overall purification process was performed by taking the mechanisms of both precipitation and chromatographic separation into account. The precipitation-containing process removed a similar amount of process-related impurities, including host cell proteins, DNA, insulin and gentamicin and maintained similar product quality in respect of size and charge variants to chromatography based purification. Overall recovery yield was comparable to the typical Protein A affinity chromatography based antibody purification process.

  19. Surface-modified polystyrene beads as photografting imprinted polymer matrix for chromatographic separation of proteins.

    PubMed

    Qin, Lei; He, Xi-Wen; Zhang, Wei; Li, Wen-You; Zhang, Yu-Kui

    2009-01-30

    A new and facile fabricating method for lysozyme molecularly imprinted polymer beads (lysozyme-MIP beads) in aqueous media was presented. Mesoporous chloromethylated polystyrene beads (MCP beads) containing dithiocarbamate iniferter (initiator transfer agent terminator) were used as supports for the grafting of lysozyme imprinted copolymers with acrylamide and N,N'-methylenebisacrylamide through surface initiated living-radical polymerization (SIP). After the polymerization, a layer of lysozyme-MIP was formed on the MCP beads. The SIP allowed an efficient control of the grafting process and suppressed solution propagation. Therefore, the obtained lysozyme-MIP beads had a large quantity of well-distributed pores on the surface without any visible gel formation in solution and were more advantageous comparing with traditional MIPs which were prepared by traditionally initiated radical polymerization. The obtained composites were characterized by Fourier transform infrared spectroscopy, elemental analysis, nitrogen sorption analysis and scanning electron microscopy. Chromatographic behaviors of the column packed with lysozyme-MIP beads exhibited ability in separating lysozyme from competitive protein (bovine hemoglobin, bovine serum albumin, ovalbumin or cytochrome c) in aqueous mobile phase.

  20. Optimisation of temperature-programmed gas chromatographic separation of organochloride pesticides by response surface methodology.

    PubMed

    D'Archivio, Angelo Antonio; Maggi, Maria Anna; Marinelli, Cristina; Ruggieri, Fabrizio; Stecca, Fabrizio

    2015-12-04

    A response surface methodology (RSM) approach is applied to optimise the temperature-programme gas-chromatographic separation of 16 organochloride pesticides, including 12 compounds identified as highly toxic chemicals by the Stockholm Convention on Persistent Organic Pollutants. A three-parameter relationship describing both linear and curve temperature programmes is derived adapting a model previously used in literature to describe concentration gradients in liquid chromatography with binary eluents. To investigate the influence of the three temperature profile descriptors (the starting temperature, the gradient duration and a shape parameter), a three-level full-factorial design of experiments is used to identify suitable combinations of the above variables spanning over a useful domain. Resolutions of adjacent peaks are the responses modelled by RSM using two alternative methods: a multi-layer artificial network (ANN) and usual polynomial regression. The proposed ANN-based approach permits to model simultaneously the resolutions of all the consecutive analyte pairs as a function of the temperature profile descriptors. Four critical pairs giving partially overlapped peaks are identified and multiresponse optimisation is carried out by analysing the surface plot of a global resolution defined as the average of the resolutions of the critical pairs. Descriptive/predictive performance and applicability of the ANN and polynomial RSM methods are compared and discussed.

  1. Development and assessment of a miniaturised centrifugal chromatograph for reversed-phase separations in micro-channels.

    PubMed

    Penrose, Andrew; Myers, Peter; Bartle, Keith; McCrossen, Sean

    2004-08-01

    This paper describes the micro-fabrication and preliminary assessment of a miniature polydimethylsiloxane (PDMS) device for performing rapid, parallel liquid phase chromatographic separations driven by centrifugal force in microchannels. Device components include a main separating channel, into which a high performance liquid chromatography (HPLC) particulate stationary phase was packed under pressure by application of centrifugal force, in addition to solvent and sample reservoirs. Also described are methods for sealing such devices based upon partial polymerisation of PDMS. The mobile phase flow rate through a typical device was measured and several important chromatographic parameters determined from a test separation. An expression describing mobile phase flow through packed channels was also developed, based upon work on liquid flow in open micro-channels. Good agreement between predicted and measured flow rates were observed. Some predictions for potential uses of such devices and possibilities for further miniaturisation are discussed.

  2. Separation and identification of various vulcanization agents and antioxidants in two types of rubber by chromatographic and spectrometric methods.

    PubMed

    Chauveau, S; Hamon, M; Leleu, E

    1991-11-01

    The aim of this study was to separate and identify by chromatographic and spectrometric methods, the various allergenic vulcanization agents and antioxidants used in the manufacture of industrial rubber. Specimens of elastomers were manufactured specially for this study. The specificity of the gas chromatographic method developed allows separation of all the manufacturing additives in the selected rubber types after one injection only, even though they belong to extremely varied chemical categories. The GLC method was coupled with mass spectrometry, which permitted identification of the peaks obtained and the study of the fragmentation of the 4 reference products under various conditions. Separation by TLC was performed in parallel on the same extracts, allowing rapid identification of the products tested for, and showed new spots after vulcanization.

  3. Separation studies of As(III), Sb(III) and Bi(III) by reversed-phase paper chromatographic technique

    SciTech Connect

    Raman, B.; Shinde, V.M.

    1987-07-01

    Reversed-phase paper chromatographic separations of As(III), Sb(III) and Bi(III) have been carried out on Whatman No 1 filter paper impregnated with triphenylphosphine oxide as stationary phase and using organic complexing agents such as sodium acetate, sodium succinate and sodium malonate solutions as active mobile phases. Results for the separation of binary and ternary mixtures are reported and the method has been successfully applied to the separation and detection of these elements present in real samples and at ppm level concentration.

  4. Stable hydrogen isotopic analysis of nanomolar molecular hydrogen by automatic multi-step gas chromatographic separation.

    PubMed

    Komatsu, Daisuke D; Tsunogai, Urumu; Kamimura, Kanae; Konno, Uta; Ishimura, Toyoho; Nakagawa, Fumiko

    2011-11-15

    We have developed a new automated analytical system that employs a continuous flow isotope ratio mass spectrometer to determine the stable hydrogen isotopic composition (δD) of nanomolar quantities of molecular hydrogen (H(2)) in an air sample. This method improves previous methods to attain simpler and lower-cost analyses, especially by avoiding the use of expensive or special devices, such as a Toepler pump, a cryogenic refrigerator, and a special evacuation system to keep the temperature of a coolant under reduced pressure. Instead, the system allows H(2) purification from the air matrix via automatic multi-step gas chromatographic separation using the coolants of both liquid nitrogen (77 K) and liquid nitrogen + ethanol (158 K) under 1 atm pressure. The analytical precision of the δD determination using the developed method was better than 4‰ for >5 nmol injections (250 mL STP for 500 ppbv air sample) and better than 15‰ for 1 nmol injections, regardless of the δD value, within 1 h for one sample analysis. Using the developed system, the δD values of H(2) can be quantified for atmospheric samples as well as samples of representative sources and sinks including those containing small quantities of H(2) , such as H(2) in soil pores or aqueous environments, for which there is currently little δD data available. As an example of such trace H(2) analyses, we report here the isotope fractionations during H(2) uptake by soils in a static chamber. The δD values of H(2) in these H(2)-depleted environments can be useful in constraining the budgets of atmospheric H(2) by applying an isotope mass balance model.

  5. Experimental Confirmation of Isotope Fractionation in Thiomolybdates Using Ion Chromatographic Separation and Detection by Multicollector ICPMS.

    PubMed

    Kerl, Carolin F; Lohmayer, Regina; Bura-Nakić, Elvira; Vance, Derek; Planer-Friedrich, Britta

    2017-03-07

    Molybdenum (98)Mo/(95)Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO4(2-)) is quantitatively transformed to tetrathiomolybdate (MoS4(2-)) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Using commercially available MoO4(2-) and MoS4(2-) standards, the method was evaluated and excellent reproducibility and accuracy were obtained. For species with longer retention times, complete chromatographic peaks had to be collected to avoid isotope fractionation within peaks. Isotope fractionation during formation of thiomolybdates could be experimentally proven for the first time in the reaction of MoO4(2-) with 20-fold or 50-fold excess of sulfide. The previously calculated isotope fractionation for MoS4(2-) was confirmed, and the result for MoO2S2(2-) was in the predicted range. Isotopic fractionation during MoS4(2-) transformation with pressurized air was dominated by kinetic fractionation. Further optimization and online-coupling of the HPLC-MC-ICPMS approach for determination of low concentrations in natural samples will greatly help to obtain more accurate species-selective isotope information.

  6. High-performance reversed-phase ion-pair chromatographic study of myo-inositol phosphates. Separation of myo-inositol phosphates, some common nucleotides and sugar phosphates.

    PubMed

    Patthy, M; Balla, T; Arányi, P

    1990-12-07

    A detailed study of all the major chromatographic variables affecting the retention behaviour and separation of myo-inositol phosphates in reversed-phase ion-pair chromatographic systems was carried out. The parameters studied included the eluent concentration of the pairing ion, the eluent concentration of the organic modifier and the buffer salt, the pH of the eluent, the minimum column plate count necessary for the separation of the inositol trisphosphate isomers and isocratic and gradient modes of separation. The retention behaviour of some common nucleotides and sugar phosphates was also investigated as these phosphates present chromatographic interference problems in biochemical studies based on the cellular incorporation of [32P]Pi. The separation methods developed appear to be superior to established anion-exchange separation techniques in terms of separation speed and "mildness" of the chromatographic conditions.

  7. A theoretical model for the separation of glucose and fructose mixtures by using a semicontinuous chromatographic refiner

    SciTech Connect

    Lee, Kwang Nam; Lee, Won Kook )

    1992-03-01

    The separation of a glucose and fructose mixture was experimentally performed by using a semicontinuous chromatographic refiner (SCCR) packed with Ca{sup 2+} ion in the form of DOWEX 50W 12X resin. The plug flow model with velocity-dependent mass transfer resistance was resistance was presented for calculating both products and on-concentrations in the SCCR unit, and the validity of the model was experimentally confirmed.

  8. Bioanalytical solutions to acetonitrile shortages.

    PubMed

    Gao, Hong; Williams, John; Carrier, Scott; Brummel, Christopher L

    2010-09-01

    The acetonitrile shortage during 2008 to 2009 challenged bioanalytical scientists due to the ubiquitous role that acetonitrile plays in sample preparation and analysis. Replacement, reduction and reuse of acetonitrile were the core tenants behind each approach used to tackle the shortage. Sample preparation of biological matrices can be accomplished by protein precipitation using a variety of solvents; methanol is usually the best substitute for acetonitrile. The potential liabilities in using methanol can be handled with appropriate modifications. Often methanol is superior to acetonitrile for both protein precipitation and chromatography if phospholipid interference is a problem. Solvent consumption can be minimized by reducing column dimensions and particle size. Separations can be achieved at greatly reduced run times using sub-2-μm and fused-core particle columns. Emerging technologies, such as desorption ESI, direct analysis in real time and laser diode thermal desorption, eliminate the need for chromatography and achieve significant solvent and time savings. Acetonitrile recyclers can purify HPLC waste for reuse.

  9. Acetonitrile in the air over Europe

    SciTech Connect

    Hamm, S.; Helas, G.; Warneck, P.

    1989-06-01

    A gas chromatographic technique was developed to measure acetonitrile mixing ratios in air samples collected during three aircraft flights over Europe. Uniform mixing ratios were observed in the troposphere independent of altitude, with an average of 144+-26 pptv for the first two flights, and 194+-7 pptv for the third. /copyright/ American Geophysical Union 1989

  10. [Contamination mechanism and regeneration strategies of chromatographic resin in separation process for expression product from mammary gland bioreactor].

    PubMed

    Sun, Xiyan; Zhang, Yan; Li, Yan; Luo, Jian; Qin, Peiyong; Su, Zhiguo

    2011-11-01

    This study focused on the contamination mechanism and regeneration strategies of sulfopropyl ion exchange resin (SP Sepharose FF) during the separation of recombinant human lactoferrin from transgenic bovine milk. We analyzed primary constituents' contents in chromatorgraphic material and fractions. The results showed that the lipid in milk can clog the column or adhere to the resin through hydrophobic interaction, leading to an increase in column pressure. Some casein molecules were found to adsorb onto the resin through electrostatic interaction, therefore the adsorption capacity was decreased. There was no direct interaction between lactose and the resin in the chromatorgraphic process. Increased continuous chromatographic cycles and prolonged time interval between protein purification and column regeneration could enhance the undesirable interaction between the contaminants and resin, thus lowering the regeneration efficiency. NaOH was found to be effective in the removal of lipid and casein molecules from the column. Furthermore, normal microstructure and chromatographic performance of the ion exchanger was recovered after this cleaning procedure.

  11. Liquid-chromatographic separation and determination of process-related impurities, including a regio-specific isomer of celecoxib on reversed-phase C18 column dynamically coated with hexamethyldisilazane.

    PubMed

    Rao, R Nageswara; Meena, S; Nagaraju, D; Rao, A Raghuram; Ravikanth, S

    2006-09-01

    A simple and rapid reversed-phase high-performance liquid-chromatographic method for the separation and determination of process-related impurities of celecoxib (CXB) in bulk drugs and pharmaceuticals was developed. The separation of impurities viz., 4-methylacetophenone (I), 1-(4-methylphenyl)-4,4,4-trifluorobutane-1,3-dione (II), 4-hydrazinobenzene sulfonamide (III) and a regio-specific isomer [3-(4-methylphenyl)-5-trifluoromethyl-1H-pyrazole-1-yl]-benzenesulfonamide (IV), was accomplished on an Inertsil ODS-3 column dynamically coated with 0.1% hexamethyldisilazane (HMDS) in acetonitrile:water (55:45 v/v) as a mobile phase and detection at 242 nm using PDA at ambient temperature. The chromatographic conditions were optimized by studying the effects of HMDS, an organic modifier, time of silanization and column temperature. The method was validated and found to be suitable not only for monitoring the synthetic reactions, but also to evaluate the quality of CXB.

  12. Thin-layer chromatographic specification and separation of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations.

    PubMed

    Savasci, Sahin; Akçay, Mehmet; Ergül, Soner

    2010-07-01

    The M(PyDTC)(2) (M: Cu, Co, or Ni) and CuPyDTC complexes, prepared by reactions of ammonium pyrrolidinedithiocarbamate with metal nitrates, are examined for qualitative analysis, speciation, and mutual separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated and non-activated thin layers of silica gel 60GF(254) (Si-60GF(254)) with a 250-microm thickness. Toluene-dichloromethane mixtures (4:1, 1:1, 1:4 v/v) are used as mobile phases for running of the complexes. All of these chromatographic systems are successfully used for speciation of Cu(2+) and Cu(1+) cations. The best analytical separation for the qualitative analysis of corresponding metal cations and mutual separation of components in M(PyDTC)(2) and CuPyDTC complexes are obtained when using pure toluene-dichloromethane (1:1 v/v) on the activated layer. This study shows that it is possible to qualitatively analyze and satisfactorily separate a mixture of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations on cited chromatographic systems. These results may be also said for the adaptability or validity on column chromatography.

  13. Chromatographic separation of platinum group metals from simulated high level liquid waste using macroporous silica-based adsorbents.

    PubMed

    Xu, Yuanlai; Kim, Seong-Yun; Ito, Tatsuya; Tokuda, Haruki; Hitomi, Keitaro; Ishii, Keizo

    2013-10-18

    To separate platinum group metals (PGMs) from high level liquid waste, three novel macroporous silica-based adsorbents, namely, (Crea+Dodec)/SiO2-P, (Crea+TOA)/SiO2-P and (MOTDGA+TOA)/SiO2-P, were synthesized by introducing extractants Crea (N',N'-di-n-hexyl-thiodiglycolamide), TOA (Tri-n-octylamine), MOTDGA (N,N'-dimethyl-N,N'-di-n-octyl-thiodiglycolamide) along with theirs modifier, Dodec (n-dodecyl alcohol), into 50μm diameter SiO2-P particles by impregnation. Chromatographic separation of PGMs from simulated high level liquid waste was investigated by column method. It was found that 100% of Pd(II) and Re(VII) could be eluted out from simulate HLLW in 3.0M HNO3 solution using three adsorbents. For Ru(III) and Rh(III), high temperature has distinct effect on the adsorption rate and a further study for Ru(III) and Rh(III) is necessary to separate them from HLLW completely. In all six column experiments, a relatively satisfactory chromatographic separation operating for PGMs from simulated HLLW was obtained using (Crea+TOA)/SiO2-P adsorbent packed column at 323K.

  14. Persistence of acetonitrile bilayers at the interface of acetonitrile/water mixtures with silica.

    PubMed

    Rivera, Christopher A; Bender, John S; Manfred, Katherine; Fourkas, John T

    2013-11-21

    Previous experiments and simulations have shown that acetonitrile organizes into a lipid-like bilayer at the liquid/silica interface. Recent simulations have further suggested that this bilayer structure persists in mixtures of acetonitrile with water, even at low acetonitrile concentrations. This behavior is indicative of microscopic phase separation of these liquids near silica interfaces and may have important ramifications for the use of acetonitrile in chromatography and heterogeneous catalysis. To explore this phenomenon, we have used vibrational sum-frequency-generation spectroscopy to probe acetonitrile/water mixtures at a silica interface. Our spectra provide evidence that acetonitrile partitions to the hydrated silica interface even when the mole fraction of acetonitrile is as low as 10%. A blue shift is observed in the spectrum of the methyl symmetric stretch upon increasing water mole fraction, in agreement with vibrational spectra of bulk mixtures. Line shape analysis suggests that acetonitrile may exist in the form of bilayer patches at high water mole fractions.

  15. Kinetic optimisation of the reversed phase liquid chromatographic separation of rooibos tea (Aspalathus linearis) phenolics on conventional high performance liquid chromatographic instrumentation.

    PubMed

    Beelders, Theresa; Sigge, Gunnar O; Joubert, Elizabeth; de Beer, Dalene; de Villiers, André

    2012-01-06

    Rooibos tea, produced from the endemic South African shrub Aspalathus linearis, has various health-promoting benefits which are attributed to its phenolic composition. Generating reliable, quantitative data on these phenolic constituents is the first step towards documenting the protective effects associated with rooibos tea consumption. Reversed phase liquid chromatographic (RP-LC) methods currently employed in the quantitative analysis of rooibos are, however, hampered by limited resolution and/or excessive analysis times. In order to overcome these limitations, a systematic approach towards optimising the RP-LC separation of the 15 principal rooibos tea phenolics on a 1.8 μm phase using conventional HPLC instrumentation was adopted. Kinetic plots were used to obtain the optimal configuration for the separation of the target analytes within reasonable analysis times. Simultaneous optimisation of temperature and gradient conditions provided complete separation of these rooibos phenolics on a 1.8 μm C18 phase within 37 min. The optimised HPLC-DAD method was validated and successfully applied in the quantitative analysis of aqueous infusions of unfermented and fermented rooibos. Major phenolic constituents of fermented rooibos were found to be a phenylpropanoid phenylpyruvic acid glucoside (PPAG), the dihydrochalcone C-glycoside aspalathin, the flavones isoorientin and orientin, and a flavonol O-diglycoside tentatively identified as quercetin-3-O-robinobioside. Content values for PPAG, ferulic acid and quercetin-3-O-robinobioside in rooibos are reported here for the first time. Mass spectrometric (MS) and tandem MS detection were used to tentatively identify 13 additional phenolic compounds in rooibos infusions, including a new luteolin-6-C-pentoside-8-C-hexoside and a novel C-8-hexosyl derivative of aspalathin reported here for the first time.

  16. Cyclotriveratrylene as a new-type stationary phase for gas chromatographic separations of halogenated compounds and isomers.

    PubMed

    Lv, Qing; Zhang, Qing; Qi, Meiling; Bai, Hua; Ma, Qiang; Meng, Xianshuang; Fu, Ruonong

    2015-07-24

    Cyclotriveratrylene (CTV) is reported here for the first time as stationary phase for capillary gas chromatographic (GC) separations. CTV stationary phase showed weak polarity comparable to the conventional 5% phenyl polysiloxane stationary phase but exhibited different retention behaviours and higher resolution for some of the indicated analytes. Most importantly, CTV stationary phase exhibited preferential selectivity for halogenated compounds, positional and geometrical isomers. Effect of column temperature on retention and thermal stability of CTV column were also investigated. Moreover, CTV capillary column showed good repeatability in terms of run-to-run, day-to-day and column-to-column. The unique physicochemical features and efficient separation ability for analytes of close properties show the potential of CTV as a new-type stationary phase in GC as well as separation science.

  17. How to compare separation selectivity of high-performance liquid chromatographic columns properly?

    PubMed

    Andrić, Filip; Héberger, Károly

    2017-03-10

    Comparison and selection of chromatographic columns is an important part of development as well as validation of analytical methods. Presently there is abundant number of methods for selection of the most similar and orthogonal columns, based on the application of limited number of test compounds as well as quantitative structure retention relationship models (QSRR), from among Snyder's hydrophobic-subtraction model (HSM) have been most extensively used. Chromatographic data of 67 compounds were evaluated using principal component analysis (PCA), hierarchical cluster analysis (HCA), non-parametric ranking methods as sum of ranking differences (SRD) and generalized pairwise correlation method (GPCM), both applied as a consensus driven comparison, and complemented by the comparison with one variable at a time (COVAT) approach. The aim was to compare the ability of the HSM approach and the approach based on primary retention data of test solutes (logk values) to differentiate among ten highly similar C18 columns. The ranking (clustering) pattern of chromatographic columns based on primary retention data and HSM parameters gave different results in all instances. Patterns based on retention coefficients were in accordance with expectations based on columns' physicochemical parameters, while HSM parameters provided a different clustering. Similarity indices calculated from the following dissimilarity measures: SRD, GPCM Fisher's conditional exact probability weighted (CEPW) scores; Euclidian, Manhattan, Chebyshev, and cosine distances; Pearson's, Spearman's, and Kendall's, correlation coefficients have been ranked by the consensus based SRD. Analysis of variance confirmed that the HSM model produced statistically significant increases of SRD values for the majority of similarity indices, i.e. HS transformation of original retention data yields significant loss of information, and finally results in lower performance of HSM methodology. The best similarity measures were

  18. Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.

    PubMed

    Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping

    2015-05-01

    Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences.

  19. Countercurrent Chromatographic Separation of Proteins Using an Eccentric Coiled Column with Synchronous and Nonsynchronous Type-J Planetary Motions

    PubMed Central

    SHINOMIYA, Kazufusa; YOSHIDA, Kazunori; TOKURA, Koji; TSUKIDATE, Etsuhiro; YANAGIDAIRA, Kazuhiro; ITO, Yoichiro

    2015-01-01

    Protein separation was performed using the high-speed counter-current chromatograph (HSCCC) at both synchronous and nonsynchronous type-J planetary motions. The partition efficiency was evaluated with two different column configurations, eccentric coil and toroidal coil, on the separation of a set of stable protein samples including cytochrome C, myoglobin and lysozyme with a polymer phase system composed of 12.5% (w/w) polyethylene glycol 1000 and 12.5% (w/w) dibasic potassium phosphate. Better peak resolution was obtained by the eccentric coil than by the toroidal coil using either lower or upper phase as the mobile phase. The peak resolution was further improved using the eccentric coil by the nonsynchronous type-J planetary motion with the combination of 1066 rpm of column rotation and 1000 rpm of revolution. PMID:25765276

  20. Liquid chromatographic enantiomer separation of 1-naphthylamides of chiral acids using several amylose- and cellulose-derived chiral stationary phases.

    PubMed

    Islam, Md F; Adhikari, Suraj; Paik, Man-Jeong; Lee, Wonjae

    2017-03-01

    The liquid chromatographic enantiomer separation of various chiral acids as 1-naphthylamides was performed using several chiral stationary phases (CSPs). The CSPs used in this study were six covalently bonded and four coated type CSPs derived from amylose and cellulose derivatives as chiral selectors. The degree of enantioseparation is affected by the structure of chiral acids and the CSPs used, which have different chiral selectors and types of immobilization. For the enantiomer resolution of chiral acids as 1-naphthylamide derivatives, the performance of the coated type Lux Cellulose-1 was superior to those of the other CSPs, except for 2-aryloxypropionic acid derivatives. Owing to the strong ultraviolet absorbance of the 1-naphthyl group, the convenient analytical method developed and validated in this study could be expected to be very useful for the enantiomer separation of various chiral acids as 1-naphthylamide derivatives using polysaccharide-derived CSPs.

  1. Gas chromatographic separation of diastereomeric isoprenoids as molecular markers of oil pollution.

    PubMed

    Berthou, F; Friovourt, M P

    1981-12-18

    By means of high-performance glass capillary gas chromatography (GC), diastereomeric isoprenoids were resolved into double peaks. The retention indices on three liquid phases and the mass spectra of the diastereoisomers were almost similar. The leading GC peaks represent the isoprenoids of fossil origin, while the rear peaks correspond to those of recent origin. Computerized gas chromatography-mass spectrometry was used for fingerprinting isoprenoids in different samples. The mass fragmentation patterns were characteristic of the branched alkanes. Hydrocarbon mixtures from four crude oil spills in the sea and from polluted and oil-free oyster tissues were investigated. The relative ratios of n-alkanes/pristane or phytane were shown to be strongly dependent on the chromatographic resolution of the isoprenoid peaks. It is suggested that the double GC peaks in the isoprenoid series are an unmistakable sign of oil pollution.

  2. Statistical learning of peptide retention behavior in chromatographic separations: a new kernel-based approach for computational proteomics

    PubMed Central

    Pfeifer, Nico; Leinenbach, Andreas; Huber, Christian G; Kohlbacher, Oliver

    2007-01-01

    Background High-throughput peptide and protein identification technologies have benefited tremendously from strategies based on tandem mass spectrometry (MS/MS) in combination with database searching algorithms. A major problem with existing methods lies within the significant number of false positive and false negative annotations. So far, standard algorithms for protein identification do not use the information gained from separation processes usually involved in peptide analysis, such as retention time information, which are readily available from chromatographic separation of the sample. Identification can thus be improved by comparing measured retention times to predicted retention times. Current prediction models are derived from a set of measured test analytes but they usually require large amounts of training data. Results We introduce a new kernel function which can be applied in combination with support vector machines to a wide range of computational proteomics problems. We show the performance of this new approach by applying it to the prediction of peptide adsorption/elution behavior in strong anion-exchange solid-phase extraction (SAX-SPE) and ion-pair reversed-phase high-performance liquid chromatography (IP-RP-HPLC). Furthermore, the predicted retention times are used to improve spectrum identifications by a p-value-based filtering approach. The approach was tested on a number of different datasets and shows excellent performance while requiring only very small training sets (about 40 peptides instead of thousands). Using the retention time predictor in our retention time filter improves the fraction of correctly identified peptide mass spectra significantly. Conclusion The proposed kernel function is well-suited for the prediction of chromatographic separation in computational proteomics and requires only a limited amount of training data. The performance of this new method is demonstrated by applying it to peptide retention time prediction in IP

  3. Comprehensive multi-dimensional liquid chromatographic separation in biomedical and pharmaceutical analysis: a review.

    PubMed

    Dixon, Steven P; Pitfield, Ian D; Perrett, David

    2006-01-01

    'Multi-dimensional' liquid separations have a history almost as long as chromatography. In multi-dimensional chromatography the sample is subjected to more than one separation mechanism; each mechanism is considered an independent separation dimension. The separations can be carried out either offline via fraction collection, or directly coupled online. Early multi-dimensional separations using combinations of paper chromatography, electrophoresis and gels, in both planar and columnar modes are reviewed. Developments in HPLC have increased the number of measurable analytes in ever more complex matrices, and this has led to the concept of 'global metabolite profiling'. This review focuses on the theory and practice of modern 'comprehensive' multi-dimensional liquid chromatography when applied to biomedical and pharmaceutical analysis.

  4. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals.

    PubMed

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf

    2014-09-19

    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  5. Design of chiral monochloro-s-triazine reagents for the liquid chromatographic separation of amino acid enantiomers.

    PubMed

    Brückner, H; Wachsmann, M

    2003-05-23

    A series of chiral derivatizing reagents (CDRs) was synthesized by nucleophilic replacement of one chlorine atom in cyanuric chloride (2,4,6-trichloro-1,3,5-triazine; s-triazine) by alkoxy (methoxy, butoxy, 1,1,1-trifluoroethoxy) or aryloxy groups (phenoxy, nitrophenoxy, phenylphenoxy, 4-methylcoumaryloxy), and displacement of a second chlorine by L-alanine amide, L-phenylalanine amide, L-proline tert.-butyl ester, or Boc-L-lysine tert.-butyl ester. Further, CDRs were investigated in which two chlorine atoms in cyanuric chloride were substituted consecutively by L-valine amide and L-phenylalanine amide. The resulting CDRs having a remaining reactive chlorine were tested for their capability of derivatizing DL-amino acids followed by liquid chromatographic separation of the resulting diastereomers.

  6. Single-walled carbon nanotubes as stationary phase in gas chromatographic separation and determination of argon, carbon dioxide and hydrogen.

    PubMed

    Safavi, Afsaneh; Maleki, Norooz; Doroodmand, Mohammad Mahdi

    2010-08-24

    A chromatographic technique is introduced based on single-walled carbon nanotubes (SWCNTs) as stationary phase for separation of Ar, CO(2) and H(2) at parts per million (ppm) levels. The efficiency of SWCNTs was compared with solid materials such as molecular sieve, charcoal, multi-walled carbon nanotubes and carbon nanofibers. The morphology of SWCNTs was optimized for maximum adsorption of H(2), CO(2) and Ar and minimum adsorption of gases such as N(2), O(2), CO and H(2)O vapour. To control temperature of the gas chromatography column, peltier cooler was used. Mixtures of Ar, CO(2) and H(2) were separated according to column temperature program. Relative standard deviation for nine replicate analyses of 0.2 mL H(2) containing 10 microL of each Ar or CO(2) was 2.5% for Ar, 2.8% for CO(2) and 3.6% for H(2). The interfering effects of CO, and O(2) were investigated. Working ranges were evaluated as 40-600 ppm for Ar, 30-850 ppm for CO(2) and 10-1200 ppm for H(2). Significant sensitivity, small relative standard deviation (RSD) and acceptable limit of detection (LOD) were obtained for each analyte, showing capability of SWCNTs for gas separation and determination processes. Finally, the method was used to evaluate the contents of CO(2) in air sample.

  7. Application of chiral derivatizing agents in the high-performance liquid chromatographic separation of amino acid enantiomers: a review.

    PubMed

    Ilisz, István; Berkecz, Robert; Péter, Antal

    2008-05-12

    The past 20 years has seen an explosive growth in the field of chirality, as illustrated by the rapid progress in the various facets of this intriguing field. The impetus for advances in chiral separation has been highest in the past decade and this still continues to be an area of high focus. This paper reviews indirect separation approaches, i.e. derivatization reactions aimed at creating the basis for the chromatographic resolution of biologically and pharmaceutically important enantiomers, with emphasis on the literature published in the last 12 years. The main aspects of the chiral derivatization of amino acids are discussed, i.e. derivatization on the amino group, transforming the molecules into covalently bonded diastereomeric derivatives through the use of homochiral derivatizing agents. The diastereomers formed (amides, urethanes, urea, thiourea derivatives, etc.) can be separated on achiral stationary phases. The applications are considered, and in some cases different derivatizing agents for the resolution of complex mixtures of proteinogenic d,l-amino acids, non-proteinogenic amino acids and peptides/amino acids from peptide syntheses or microorganisms are compared.

  8. Chromatographic separation of arsenic species with pentafluorophenyl column and application to rice.

    PubMed

    Baba, Koji; Arao, Tomohito; Yamaguchi, Noriko; Watanabe, Eiki; Eun, Heesoo; Ishizaka, Masumi

    2014-08-08

    Arsenic species, including arsenous acid, arsenic acid, methylarsonic acid, and dimethylarsinic acid, were determined using HPLC-ICPMS. The species were separated with a Discovery HS F5 column and a simple, volatile, and isocratic mobile phase of 0.1% (v/v) formic acid and 1% (v/v) methanol. The Discovery HS F5 column with a pentafluorophenyl (PFP) stationary phase gave sharp peaks and full separation of the arsenic species in 5min, and other PFP columns showed lower performance. This separation method was applied to arsenic species analysis in rice. The extraction of arsenic from rice samples was performed using 0.15M nitric acid. The methodology was validated by use of certified reference materials, NMIJ CRM 7503-a and NIST SRM 1568a, and extremely low arsenic rice samples as blank samples.

  9. Chromatographic separation of selenium and arsenic: A potential (72)Se/(72)As generator.

    PubMed

    Wycoff, Donald E; Gott, Matthew D; DeGraffenreid, Anthony J; Morrow, Ryan P; Sisay, Nebiat; Embree, Mary F; Ballard, Beau; Fassbender, Michael E; Cutler, Cathy S; Ketring, Alan R; Jurisson, Silvia S

    2014-05-02

    An anion exchange method was developed to separate selenium and arsenic for potential utility in a (72)Se/(72)As generator. The separation of the daughter (72)As from the (72)Se parent is based on the relative acid-base behavior of the two oxo-anions in their highest oxidation states. At pH 1.5, selenate is retained on strongly basic anion exchange resin as HSeO4(-) and SeO4(2-), while neutral arsenic acid, H3AsO4, is eluted.

  10. Chromatographic Separation of Selenium and Arsenic: A Potential 72Se/72As Generator

    PubMed Central

    Wycoff, Donald E.; Gott, Matthew D.; DeGraffenreid, Anthony J.; Morrow, Ryan P.; Sisay, Nebiat; Embree, Mary F.; Ballard, Beau; Fassbender, Michael E.; Cutler, Cathy S.; Ketring, Alan R.; Jurisson, Silvia S.

    2014-01-01

    Summary An anion exchange method was developed to separate selenium and arsenic for potential utility in a 72Se/72As generator. The separation of the daughter 72As from the 72Se parent is based on the relative acid-base behavior of the two oxo-anions in their highest oxidation states. At pH 1.5, selenate is retained on strongly basic anion exchange resin as HSeO4− and SeO42−, while neutral arsenic acid, H3AsO4, is eluted. PMID:24679827

  11. Thin-layer chromatographic (TLC) separations and bioassays of plant extracts to identify antimicrobial compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungal spores in nutrient solution or bacteria in liquefied agar), allowing time for the microbes to gr...

  12. Ion-exchange chromatographic separation of einsteinium from irradiated californium targets

    SciTech Connect

    Elesin, A.A.; Nikolaev, V.M.; Shalimov, V.V.; Popov, Yu.S.; Kovantsev, V.N.; Tselishchev, I.V.; Filimonov, V.T.; Mishenev, V.B.; Yadovin, A.A.; Golosovskii, L.S.; Chetverikov, A.P.

    1987-07-01

    Einsteinium was obtained by preparing two experimental californium targets and subjecting them to neutron irradiation in a high-flux reactor. The einsteinium was separated from the bombarded targets on a column packed with KU-2U sulfonated cation-exchange resin (20-50 ..mu..m) and eluted at room temperature with an ammonium ..cap alpha..-hydroxyisobutyrate solution. Three successive separation cycles removed californium to produce einsteinium in 68% yield with a decontamination factor of 5.3 x 10/sup 6/. About 20% of the einsteinium was used up by analysis and 11% remained in intermediate fractions. The method developed yielded pure einsteinium with little fission products present. The contribution of the fission products to the total einsteinium gamma-irradiation dose rate was no greater than 81%, due primarily to the radioisotope terbium-160.

  13. Electrochemically modulated liquid chromatographic separation of triazines and the effect of pH on retention.

    PubMed

    Yakes, Betsy Jean; Keller, David W; Porter, Marc D

    2010-06-25

    Electrochemically modulated liquid chromatography (EMLC) manipulates analyte retention by changing the potential applied (E(app)) to a conductive stationary phase. This paper applies EMLC to the separation of a set of seven triazines which are commonly used but environmentally hazardous herbicides. Experiments herein examine the influence of E(app) and the pH of the mobile phase on triazine retention. The results are discussed in terms of: (1) retention of triazines of dissimilar acid strengths and by correlations with the pH of the mobile phase; (2) how changes in E(app) and acid-base equilibria modulate elution; (3) qualitative insights into EMLC-based retention; and (4) potential merits of EMLC in realizing the rapid separation of the seven-component triazine mixture.

  14. A Novel Micellar Electrokinetic Chromatographic Method for Separation of Metal-DDTC Complexes

    PubMed Central

    Mallah, Arfana; Memon, Saima Q.; Solangi, Amber R.; Memon, Najma; Abbassi, Kulsoom; Khuhawar, Muhammad Yar

    2012-01-01

    Micellar electrokinetic chromatography (MEKC) was examined for the separation and determination of Mo(VI), Cr(VI), Ni(II), Pd(II), and Co(III) as diethyl dithiocarbamate (DDTC) chelates. The separation was achieved from fused silica capillary (52 cm × 75 μm id) with effective length 40 cm, background electrolyte (BGE) borate buffer pH 9.1 (25 mM), CTAB 30% (100 mM), and 1% butanol in methanol (70 : 30 : 5 v/v/v) with applied voltage of −10 kV using reverse polarity. The photodiode array detection was achieved at 225 nm. The linear calibration for each of the element was obtained within 0.16–10 μg/mL with a limit of detection (LOD) 0.005–0.0167 μg/mL. The separation and determination was repeatable with relative standard deviation (RSD) within 2.4–3.3% (n = 4) in terms of migration time and peak height/peak area. The method was applied for the determination of Mo(VI) from potatoes and almond, Ni(II) from hydrogenated vegetable oil, and Co(III) from pharmaceutical preparations with RSD within 3.9%. The results obtained were checked by standard addition and rechecked by atomic absorption spectrometry. PMID:22649320

  15. Liquid-chromatographic separation and on-line bioluminescence detection of creatine kinase isoenzymes

    SciTech Connect

    Bostick, W.D.; Denton, M.S.; Dinsmore, S.R.

    1980-01-01

    Isoenzymes of creatine kinase were separated by anion-exchange chromatography, with use of an elution gradient containing lithium acetate (0.1 to 0.6 mol/L). A stream splitter was used to divert a 5% side stream of column effluent, which was subsequently mixed with the reagents necessary for bioluminescence assay of the separated isoenzymes. The use of the stream splitter greatly decreased the rate of consumption of reagent and, when combined with a peristaltic pumping system, permitted independent control of the side-stream flow rate. Thus both the residence interval in a delay coil in which the ATP reaction product is formed and the bioluminescence emission was monitored in a flow-through fluorometer without use of an external light source or filters. Separation and detection of the isoenzymes of creatine kinase were rapid, sensitive, and highly selective. The incremental decrease of bioluminescence response owing to inhibition by the ions in the eluent was less than 31% across the entire gradient.

  16. Triticonazole enantiomers: Separation by supercritical fluid chromatography and the effect of the chromatographic conditions.

    PubMed

    He, Jianfeng; Fan, Jun; Yan, Yilun; Chen, Xiaodong; Wang, Tai; Zhang, Yaomou; Zhang, Weiguang

    2016-11-01

    Enantiomeric pairs of triticonazole have been successfully separated by supercritical fluid chromatography coupled with a tris(3,5-dimethylphenylcarbamoyl) cellulose-coated chiral stationary phase in this work. The effects of co-solvent, dissolution solvent, flow rate, backpressure, and column temperature have been studied in detail with respect to retention, selectivity, and resolution of triticonazole. As indicated, the co-solvents mostly affected the retention factors and resolution, due to the different molecular structure and polarity. In addition, the dissolution solvents, namely, chloromethanes and alcohols, have been also important for enantioseparation because of the different interaction with stationary phase. Higher flow rate and backpressure led to faster elution of the triticonazole molecules, and the change of column temperature showed slight effect on the resolution of triticonazole racemate. Moreover, a comparative separation experiment between supercritical fluid chromatography and high performance liquid chromatography revealed that chiral supercritical fluid chromatography gave the 3.5 times value of Rs /tR2 than high performance liquid chromatography, which demonstrated that supercritical fluid chromatography had much higher separation efficiency.

  17. Simultaneous separation and sensitive detection of naringin and naringenin in nanoparticles by chromatographic method indicating stability and photodegradation kinetics.

    PubMed

    Cordenonsi, Leticia Malgarim; Bromberger, Nathany Genro; Raffin, Renata Platcheck; Scherman, Elfrides Eva

    2016-02-01

    A simple, sensitive, precise and linear method by liquid chromatography was established for simultaneous determination and quantification of naringin and naringenin in polymeric nanoparticles. The method results in excellent separation in <11 min and with a peak purity of both flavonoids. The analyses were performed using a C18 column (4.6 × 150 mm, 5 µm), at a 1 mL/min flow rate. The mobile phase consisted of a gradient of acetonitrile-water (pH 4.0; v/v) at a temperature of 25°C. The nanoparticles were prepared according to the method of interfacial deposition of a pre-formed polymer. The method were validated in compliance with guidelines, and was found to be linear in the 1-40 µg/mL concentration range for both naringin and naringenin (r > 0.99). Repeatability was determined at three concentration levels, obtaining an RSD (%) <0.9%, and the accuracy of the method was >98%. The photodegradation kinetics was determined for naringin; the coefficient that best represents degradation was of first order and naringenin presented a zero-order kinetics. To our knowledge, a rapid and sensitive method for naringin and naringenin in polymeric nanoparticles has not been published elsewhere and this method is applicable to simultaneous evaluation of flavonoids.

  18. Optimization to eliminate the interference of migration isomers for measuring 1-O-beta-acyl glucuronide without extensive chromatographic separation.

    PubMed

    Xue, Y-J; Akinsanya, J Billy; Raghavan, Nirmala; Zhang, Donglu

    2008-01-01

    A highly selected reaction monitoring (SRM) method has been investigated for the determination of muraglitazar 1-O-beta-acyl glucuronide in animal and human plasma without chromatographic separation of this naturally formed acyl glucuronide from its migration isomers. In the ion source or the collision cell, glucuronides are often prone to lose the dehydrated glucuronic acid (176 Da) and convert back into the parent drug (aglycone). The extent of loss of the glucuronide moiety can differ among glucuronides. For the naturally occurring muraglitazar 1-O-beta-acyl glucuronide, or its synthetic anomer 1-O-alpha-glucuronide, the loss of the glucuronide moiety was a major fragment ion. The loss of the glucuronide moiety was greater for the 1-O-beta-acyl glucuronide than the 1-O-alpha-anomer. In addition, the loss of the glucuronide moiety was insignificant (less than 0.01%) with the other glucuronide isomers (2-, 3- or 4-O, alpha or beta). Given the fact that the 1-O-alpha-anomer was a minor impurity in the muraglitazar 1-O-beta-acyl glucuronide reference standard, and not either a conversion product of 1-O-beta-acyl glucuronide or endogenously formed, the SRM transition corresponding to the loss of the glucuronide moiety was very specific for 1-O-beta-acyl glucuronide, and practically free from interference of the other isomers under optimized collision-cell conditions. As a result, extensive chromatographic separation of 1-O-beta-acyl glucuronide from its migration isomers was not required. The use of this specific SRM transition effectively reduced the separation time from 12.0 min of a long-column high-performance liquid chromatography (HPLC) method to 2.5 min by use of a shorter column. The standard curve performance and analysis results of 1-O-beta-acyl glucuronide incubation samples showed that the short-column method could produce equivalent results to the long-column method but with a 4.5-fold improvement in sample throughput. This approach may be useful for

  19. Determination of mercurial species in fish by inductively coupled plasma mass spectrometry with anion exchange chromatographic separation.

    PubMed

    Chen, Xiaopan; Han, Chao; Cheng, Heyong; Liu, Jinhua; Xu, Zigang; Yin, Xuefeng

    2013-09-24

    This work demonstrated the feasibility of mercury speciation analysis by anion exchange chromatographic separation with inductively coupled plasma mass spectrometry detection. For the first time, by complexing with the mobile phase containing 3-mercapto-1-propanesulfonate into negatively charged complexes, fast separation of inorganic mercury (Hg(2+)), monomethylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) was achieved within 5 min on a 12.5-mm strong anion exchange column. The detection limits for Hg(2+), MeHg, EtHg and PhHg were 0.008, 0.024, 0.029 and 0.034 μg L(-1), respectively. The relative standard deviations of peak height and peak area (5.0 μg L(-1) for each Hg species) were all below 3%. The determined contents of Hg(2+), MeHg and total Hg in a certified reference material of fish tissue by the proposed method were in good accordance with the certified values with satisfactory recoveries. The relative errors for determining MeHg and total mercury were -2.4% and -1.2%, respectively, with an acceptable range for spike recoveries of 94-101%. Mercury speciation in 11 fish samples were then analyzed after the pretreated procedure. The mercury contents in all fish samples analyzed were found compliant with the criteria of the National Standards of China.

  20. A low-power pressure-and temperature-programmed separation system for a micro gas chromatograph.

    SciTech Connect

    Sacks, Richard D. (University of Michigan, Ann Arbor, MI); Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Lambertus, Gordon R. (University of Michigan, Ann Arbor, MI); Potkay, Joseph A. (University of Michigan, Ann Arbor, MI); Wise, Kensall D. (University of Michigan, Ann Arbor, MI)

    2006-10-01

    This thesis presents the theory, design, fabrication and testing of the microvalves and columns necessary in a pressure- and temperature-programmed micro gas chromatograph ({micro}GC). Two microcolumn designs are investigated: a bonded Si-glass column having a rectangular cross section and a vapor-deposited silicon oxynitride (Sion) column having a roughly circular cross section. Both microcolumns contain integrated heaters and sensors for rapid, controlled heating. The 3.2 cm x 3.2 cm, 3 m-long silicon-glass column, coated with a non-polar polydimethylsiloxane (PDMS) stationary phase, separates 30 volatile organic compounds (VOCs) in less than 6 min. This is the most efficient micromachined column reported to date, producing greater than 4000 plates/m. The 2.7 mm x 1.4 mm Sion column eliminates the glass sealing plate and silicon substrate using deposited dielectrics and is the lowest power and fastest GC column reported to date; it requires only 11 mW to raise the column temperature by 100 C and has a response time of 11s and natural temperature ramp rate of 580 C/min. A 1 m-long PDMS-coated Sion microcolumn separates 10 VOCs in 52s. A system-based design approach was used for both columns.

  1. Discovery of active components in herbs using chromatographic separation coupled with online bioassay.

    PubMed

    De-Qiang, Li; Zhao, Jing; Wu, Dong; Shao-Ping, Li

    2016-05-15

    Discovery of bioactive compounds from complex mixtures is a challenge. In past decades, several strategies were developed and implemented for rapid and effective screening and characterization of bioactive components in complex matrices. This review mainly focused on the online strategies, which integrated the separation science, mass spectrometry, and bioactivity screening in a single platform, allowing simultaneous screening and characterization of active compounds from complex matrices, especially from the herbs. The online screening methodologies, including pre-column affinity-based screening and post-column bioassay, were discussed and their applied examples were also presented to illustrate the strengths and limitations of these approaches.

  2. Comprehensive two-dimensional gas chromatographic separations with a temperature programmed microfabricated thermal modulator.

    PubMed

    Collin, William R; Nuñovero, Nicolas; Paul, Dibyadeep; Kurabayashi, Katsuo; Zellers, Edward T

    2016-04-29

    Comprehensive two-dimensional gas chromatography (GC×GC) with a temperature-programmed microfabricated thermal modulator (μTM) is demonstrated. The 0.78 cm(2), 2-stage μTM chip with integrated heaters and a PDMS coated microchannel was placed in thermal contact with a solid-state thermoelectric cooler and mounted on top of a bench scale GC. It was fluidically coupled through heated interconnects to an upstream first-dimension ((1)D) PDMS-coated capillary column and a downstream uncoated capillary or second-dimension ((2)D) PEG-coated capillary. A mixture of n-alkanes C6-C10 was separated isothermally and the full-width-at-half-maximum (fwhm) values of the modulated peaks were assessed as a function of the computer-controlled minimum and maximum stage temperatures of μTM, Tmin and Tmax, respectively. With Tmin and Tmax fixed at -25 and 100°C, respectively, modulated peaks of C6 and C7 had fwhm values<53 ms while the modulated peaks of C10 had a fwhm value of 1.3s, due to inefficient re-mobilization. With Tmin and Tmax fixed at 0 and 210°C, respectively, the fwhm value for the modulated C10 peaks decreased to 67 ms, but C6 and C7 exhibited massive breakthrough. By programming Tmin from -25 to 0°C and Tmax from 100 to 220°C, the C6 and C7 peaks had fwhm values≤50 ms, and the fwhm for C10 peaks remained<95 ms. Using the latter conditions for the GC×GC separation of a sample of unleaded gasoline yielded resolution similar to that reported with a commercial thermal modulator. Replacing the PDMS phase in the μTM with a trigonal-tricationic room temperature ionic liquid eliminated the bleed observed with the PDMS, but also reduced the capacity for several test compounds. Regardless, the demonstrated capability to independently temperature program this low resource μTM enhances its versatility and its promise for use in bench-scale GC×GC systems.

  3. Evaluation of two approaches to characterise liquid chromatographic columns using pharmaceutical separations.

    PubMed

    Dragovic, Sanja; Haghedooren, Erik; Németh, Tamás; Palabiyik, I Murat; Hoogmartens, Jos; Adams, Erwin

    2009-04-10

    In this paper a comparison of two column characterisation systems is reported: the method based on the hydrophobic-subtraction model of Dolan and Snyder (HS method) versus the method developed at the Katholieke Universiteit Leuven (KUL method). Comparison was done for seven different pharmaceutical separations (fluoxetine, gemcitabine, erythromycin, tetracycline, tetracaine, amlodipine and bisacodyl), using a set of 59 columns. A ranking was built based on an F value (KUL) or F(s) value (HS) versus a (virtual) reference column. Both methods showed similar probabilities of ranking patterns. Correlation of the respective test parameters of both approaches was poor. Both methods are not perfect and do not match well, but anyhow yield results which allow, with a relatively high certainty, the selection of similar or dissimilar columns as compared to a reference column. An analyst that uses either of the two methods will end up with a similar probability to choose an adequate column. From a practical point of view, it must be noted that the KUL method is easier to use.

  4. Preparation of weak cation exchange packings for chromatographic separation of proteins using "click chemistry''.

    PubMed

    Zhao, Kailou; Bai, Quan; Song, Chao; Wang, Fei; Yang, Fan

    2012-04-01

    "Click chemistry" is defined as a class of robust and selective chemical reactions affording high yields and is tolerant to a variety of solvents (including water), functional groups, and air. In this study, click chemistry was used as an effective strategy for coupling three alkyne-carboxylic acids onto the azide-silica to obtain three novel stationary phases of weak cation exchange chromatography, which were characterized with FTIR and elemental analysis. Six kinds of standard proteins, such as myoglobin, RNase A, RNase B, cytochrome C, α-chymotrypsin A, and lysozyme, were separated completely with the three novel weak cation exchange chromatography stationary phases. Compared with commercial weak cation exchange chromatography columns, the three kinds of novel weak cation exchange chromatography packings prepared by click chemistry approach have better resolution and selectivity. The mass recovery of more than 97% was obtained for all the tested proteins, and the bioactivity recovery of lysozyme on the prepared column was determined to be 96%. In addition, lysozyme was purified successfully from egg white with the novel weak cation exchange chromatography column by one step. The purity was more than 97% and a high specific activity was achieved to be 81 435 U/mg. The results illustrate the potential of click chemistry for preparing stationary phase for ion-exchange chromatography.

  5. An analytical method with a single extraction procedure and two separate high performance liquid chromatographic systems for the determination of artesunate, dihydroartemisinin and mefloquine in human plasma for application in clinical pharmacological studies of the drug combination.

    PubMed

    Lai, Choon-Sheen; Nair, N K; Mansor, S M; Olliaro, P L; Navaratnam, V

    2007-10-01

    The combination of two sensitive, selective and reproducible reversed phase liquid chromatographic (RP-HPLC) methods was developed for the determination of artesunate (AS), its active metabolite dihydroartemisinin (DHA) and mefloquine (MQ) in human plasma. Solid phase extraction (SPE) of the plasma samples was carried out on Supelclean LC-18 extraction cartridges. Chromatographic separation of AS, DHA and the internal standard, artemisinin (QHS) was obtained on a Hypersil C4 column with mobile phase consisting of acetonitrile-0.05 M acetic acid adjusted to pH 5.2 with 1.0M NaOH (42:58, v/v) at the flow rate of 1.50 ml/min. The analytes were detected using an electrochemical detector operating in the reductive mode. Chromatography of MQ and the internal standard, chlorpromazine hydrochloride (CPM) was carried out on an Inertsil C8-3 column using methanol-acetonitrile-0.05 M potassium dihydrogen phosphate adjusted to pH 3.9 with 0.5% orthophosphoric acid (50:8:42, v/v/v) at a flow rate of 1.00 ml/min with ultraviolet detection at 284 nm. The mean recoveries of AS and DHA over a concentration range of 30-750 ng/0.5 ml plasma and MQ over a concentration of 75-1500 ng/0.5 ml plasma were above 80% and the accuracy ranged from 91.1 to 103.5%. The within-day coefficients of variation were 1.0-1.4% for AS, 0.4-3.4% for DHA and 0.7-1.5% for MQ. The day-to-day coefficients of variation were 1.3-7.6%, 1.8-7.8% and 2.0-3.4%, respectively. Both the lower limit of quantifications for AS and DHA were at 10 ng/0.5 ml and the lower limit of quantification for MQ was at 25 ng/0.5 ml. The limit of detections were 4 ng/0.5 ml for AS and DHA and 15 ng/0.5 ml for MQ. The method was found to be suitable for use in clinical pharmacological studies.

  6. Quantitative Mass Spectrometric Analysis of Ropivacaine and Bupivacaine in Authentic, Pharmaceutical and Spiked Human Plasma without Chromatographic Separation

    PubMed Central

    Salama, Nahla N.; Wang, Shudong

    2009-01-01

    The present study employs time of flight mass and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL−1 for both drugs. The correlation coefficient was ≥0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%–102.75% was obtained. The method is accurate (% RE < 5%) and reproducible with intra- and inter-assay precision (RSD% < 8.0%). The quantification limit is 23.8 ng mL−1 for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs. PMID:19652756

  7. Quantitative mass spectrometric analysis of ropivacaine and bupivacaine in authentic, pharmaceutical and spiked human plasma without chromatographic separation.

    PubMed

    Salama, Nahla N; Wang, Shudong

    2008-05-28

    The present study employs time of flight mass and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL(-1) for both drugs. The correlation coefficient was >or=0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%-102.75% was obtained. The method is accurate (% RE < 5%) and reproducible with intra- and inter-assay precision (RSD% < 8.0%). The quantification limit is 23.8 ng mL(-1) for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs.

  8. High-performance liquid chromatographic separation of paclitaxel intermediate phenylisoserine derivatives on macrocyclic glycopeptide and cyclofructan-based chiral stationary phases.

    PubMed

    Ilisz, István; Grecsó, Nóra; Forró, Enikő; Fülöp, Ferenc; Armstrong, Daniel W; Péter, Antal

    2015-10-10

    High-performance liquid chromatographic methods were developed for the separation of enantiomers of four unnatural paclitaxel precursor phenylisoserine analogs on chiral stationary phases containing macrocyclic glycopeptides and cyclofructans as chiral selectors. The effects of the mobile phase composition, the nature and concentration of different mobile phase additives (alcohols, amines and acids) in different chromatographic modes, temperature and the structures of the analytes on the separations were investigated. Separations were carried out at constant mobile phase compositions in the temperature range 10-50°C on macrocyclic antibiotic-based and 5-35°C on cyclofructan-based columns and the changes in enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°), were calculated. The elution sequence was determined in most cases; no general rule could be observed.

  9. Gas chromatographic separation of fatty acid esters of cholesterol and phytosterols on an ionic liquid capillary column.

    PubMed

    Hammann, Simon; Vetter, Walter

    2015-12-15

    Steryl esters are high molecular weight compounds (600-700g/mol) regularly present as a minor lipid class in animal and plant lipids. Different sterol backbones (e.g., cholesterol, β-sitosterol and brassicasterol) which can be esterified with various fatty acids can result in highly complex steryl ester patterns in food samples. The gas chromatographic (GC) analysis of intact steryl esters is challenging, since high elution temperatures are required for their elution. On nonpolar GC phases, steryl esters with fatty acids with differing degree of unsaturation (e.g., oleate and linoleate) cannot be separated and there are only few polar columns available with sufficient temperature stability. In this study, we used gas chromatography with mass spectrometry (GC/MS) and analyzed intact steryl esters on a commercial room temperature ionic liquid (RTIL) column which was shortened to a length of 12m. The column separated the steryl esters both by total carbon number and by degree of unsaturation of the fatty acid. For instance, cholesteryl esters with stearic acid (18:0), oleic acid (18:1n-9), linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3) could be resolved (R≥1.3) from each other. By analysis of synthesized standard substances, the elution orders for different steryl backbones and different fatty acids on a given sterol backbone could be determined. Analysis of spreads and plant oils allowed to determine retention times for 37 steryl esters, although a few co-elutions were observed. The ionic liquid column proved to be well-suited for the analysis of intact steryl esters.

  10. Sorption characteristics and chromatographic separation of gold (I and III) from silver and base metal ions using polyurethane foams.

    PubMed

    Farag, A B; Soliman, M H; Abdel-Rasoul, O S; el-Shahawi, M S

    2007-10-10

    The influence of different parameters on the sorption profiles of trace and ultra traces of gold (I) species from the aqueous cyanide media onto the solid sorbents ion exchange polyurethane foams (IEPUFs) and commercial unloaded polyurethane foams (PUFs) based polyether type has been investigated. The retention of gold (I) species onto the investigated solid sorbents followed a first-order rate equation with an overall rate constant k in the range 2.2-2.8+/-0.2 s(-1). The sorption data of gold (I) followed Freundlich and Langmuir isotherm models. Thus, the a dual-mode of sorption mechanism involving absorption related to "weak base anion exchanger" and an added component for "surface adsorption" seems the most likely proposed dual mechanism for retention profile of gold (I) by the IEPUFs and PUFs solid sorbents. The capacity of the IEPUFs and PUFs towards gold (I) sorption calculated from the sorption isotherms was found to be 11.21+/-1.8 and 5.29+/-0.9 mg g(-1), respectively. The chromatographic separation of the spiked inorganic gold (I) from de ionized water at concentrations 5-15 microg mL(-1) onto the developed IEPUFs and PUFs packed columns at 10 mL min(-1) flow rate was successfully achieved. The retained gold (I) species were then recovered quantitatively from the IEPUFs (98.4+/-2.4%, n=5) and PUFs (95.4+/-3.4%, n=5) packed columns using perchloric acid (60 mL, 1.0 mol L(-1)) as a proper eluting agent. Thiourea (1.0 mol L(-1))-H2SO4 (0.1 mol L(-1)) system was also used as eluting agent for the recovery of gold (I) from IEPUFS (95.4+/-5.4%, n=3) and also PUFs (93.4+/-4.4%, n=3) packed columns. The performance of the IEPUFs and PUFs packed columns in terms of the height equivalent to the theoretical plates (HETP), number of plates (N), and critical and breakthrough capacities towards gold (I) species were evaluated. The developed IEPUFs packed column was applied successfully for complete retention and recovery (98.5+/-2.7) of gold (III) species spiked onto

  11. Identification and separation of the organic compounds in coal-gasification condensate waters. [5,5 dimethyl hydantoin, dihydroxy benzenes, acetonitrile

    SciTech Connect

    Mohr, D.H. Jr.; King, C.J.

    1983-08-01

    A substantial fraction of the organic solutes in condensate waters from low-temperature coal-gasification processes are not identified by commonly employed analytical techniques, have low distriution coefficients (K/sub C/) into diisopropyl ether (DIPE) or methyl isobutyl ketone (MIBK), and are resistant to biological oxidation. These compounds represent an important wastewater-treatment problem. Analytical techniques were developed to detect these polar compounds, and the liquid-liquid phase equilibria were measured with several solvents. A high-performance liquid - chromatography (HPLC) technique was employed to analyze four condensate-water samples from a slagging fixed-bed gasifier. A novel sample-preparation technique, consisting of an azeotropic distillation with isopropanol, allowed identification of compounds in the HPLC eluant by combined gas chromatography and mass spectrometry. 5,5-dimethyl hydantoin and related compounds were identified in condensate waters for the first time, and they account for 1 to 6% of the chemical oxygen demand (COD). Dimethyl hydatoin has a K/sub D/ of 2.6 into tributyl phosphate (TBP) and much lower K/sub D/ values into six other solvents. It is also resistant to biological oxidation. Phenols (59 to 76% of the COD), dihydroxy benzenes (0.02 to 9.5% of the COD), and methanol, acetonitrile, and acetone (15% of the COD in one sample) were also detected. Extraction with MIBK removed about 90% of the COD. MIBK has much higher K/sub D/ values than DIPE for dihydroxy benzenes. Chemical reactions occurred during storage of condensate-water samples. The reaction products had low K/sub D/ values into MIBK. About 10% of the COD had a K/sub D/ of nearly zero into MIBK. These compounds were not extracted by MIBK over a wide range of pH. 73 references, 6 figures, 35 tables.

  12. Continuous countercurrent chromatographic separator for the purification of sugars from biomass hydrolyzate. Final project report, July 1, 1996--September 30, 1997

    SciTech Connect

    Wooley, R J

    1997-12-01

    Production of pure sugars is required to enable production of fuels and chemicals from biomass feedstocks. Hydrolysis of cellulose and hemicellulose (principal constituents of biomass) produces sugars that can be utilized in various fermentation process to produce valuable chemicals. Unfortunately, the hydrolysis process also liberates chemicals from the biomass that can be toxic to the fermenting organisms. The two primary toxic components of biomass hydrolyzate are sulfuric acid (catalyst used in the hydrolysis) and acetic acid (a component of the feed biomass). In the standard batch chromatographic separation of these three components, sugar elutes in the middle. Batch chromatographic separations are not practical on a commercial scale, because of excess dilution and high capital costs. Because sugar is the {open_quotes}center product,{close_quotes} a continuous separation would require two costly binary separators. However, a single, slightly larger separator, configured to produce three products, would be more economical. This FIRST project develops a cost-effective method for purifying biomass hydrolyzate into fermentable sugars using a single continuous countercurrent separator to separate this ternary mixture.

  13. High-resolution hydrodynamic chromatographic separation of large DNA using narrow, bare open capillaries: a rapid and economical alternative technology to pulsed-field gel electrophoresis?

    PubMed

    Liu, Lei; Veerappan, Vijaykumar; Pu, Qiaosheng; Cheng, Chang; Wang, Xiayan; Lu, Liping; Allen, Randy D; Guo, Guangsheng

    2014-01-07

    A high-resolution, rapid, and economical hydrodynamic chromatographic (HDC) method for large DNA separations in free solution was developed using narrow (5 μm diameter), bare open capillaries. Size-based separation was achieved in a chromatographic format with larger DNA molecules being eluting faster than smaller ones. Lambda DNA Mono Cut Mix was baseline-separated with the percentage resolutions generally less than 9.0% for all DNA fragments (1.5 to 48.5 kbp) tested in this work. High efficiencies were achieved for large DNA from this chromatographic technique, and the number of theoretical plates reached 3.6 × 10(5) plates for the longest (48.5 kbp) and 3.7 × 10(5) plates for the shortest (1.5 kbp) fragments. HDC parameters and performances were also discussed. The method was further applied for fractionating large DNA fragments from real-world samples (SacII digested Arabidopsis plant bacterial artificial chromosome (BAC) DNA and PmeI digested Rice BAC DNA) to demonstrate its feasibility for BAC DNA finger printing. Rapid separation of PmeI digested Rice BAC DNA covering from 0.44 to 119.041 kbp was achieved in less than 26 min. All DNA fragments of these samples were baseline separated in narrow bare open capillaries, while the smallest fragment (0.44 kbp) was missing in pulsed-field gel electrophoresis (PFGE) separation mode. It is demonstrated that narrow bare open capillary chromatography can realize a rapid separation for a wide size range of DNA mixtures that contain both small and large DNA fragments in a single run.

  14. [Development of an automatic vacuum liquid chromatographic device and its application in the separation of the components from Schisandra chinensis (Turz) Baill].

    PubMed

    Zhu, Jingbo; Liu, Baoyue; Shan, Shibo; Ding, Yanl; Kou, Zinong; Xiao, Wei

    2015-08-01

    In order to meet the needs of efficient purification of products from natural resources, this paper developed an automatic vacuum liquid chromatographic device (AUTO-VLC) and applied it to the component separation of petroleum ether extracts of Schisandra chinensis (Turcz) Baill. The device was comprised of a solvent system, a 10-position distribution valve, a 3-position changes valve, dynamic axis compress chromatographic columns with three diameters, and a 10-position fraction valve. The programmable logic controller (PLC) S7- 200 was adopted to realize the automatic control and monitoring of the mobile phase changing, column selection, separation time setting and fraction collection. The separation results showed that six fractions (S1-S6) of different chemical components from 100 g Schisandra chinensis (Turcz) Baill. petroleum ether phase were obtained by the AUTO-VLC with 150 mm diameter dynamic axis compress chromatographic column. A new method used for the VLC separation parameters screened by using multiple development TLC was developed and confirmed. The initial mobile phase of AUTO-VLC was selected by taking Rf of all the target compounds ranging from 0 to 0.45 for fist development on the TLC; gradient elution ratio was selected according to k value (the slope of the linear function of Rf value and development times on the TLC) and the resolution of target compounds; elution times (n) were calculated by the formula n ≈ ΔRf/k. A total of four compounds with the purity more than 85% and 13 other components were separated from S5 under the selected conditions for only 17 h. Therefore, the development of the automatic VLC and its method are significant to the automatic and systematic separation of traditional Chinese medicines.

  15. Refined separation of combined Fe–Hf from rock matrices for isotope analyses using AG-MP-1M and Ln-Spec chromatographic extraction resins

    PubMed Central

    Cheng, Ting; Nebel, Oliver; Sossi, Paolo A.; Chen, Fukun

    2014-01-01

    A combined procedure for separating Fe and Hf from a single rock digestion is presented. In a two-stage chromatographic extraction process, a purified Fe fraction is first quantitatively separated from the rock matrix using AG-MP-1M resin in HCl. Hafnium is subsequently isolated using a modified version of a commonly applied method using Eichrom LN-Spec resin. Our combined method includes:•Purification of Fe from the rock matrix using HCl, ready for mass spectrometric analysis.•Direct loading of the matrix onto the resin that is used for Hf purification.•Collection of a Fe-free Hf fraction. PMID:26150946

  16. Poly(triallyl isocyanurate-co-ethylene dimethacrylate-co-alkyl methacrylate) stationary phases in the chromatographic separation of hydrophilic solutes.

    PubMed

    Lin, Cheng-Lan; Singco, Brenda; Wu, Ching-Yi; Liang, Pei-Zhu; Cheng, Yi-Jie; Huang, Hsi-Ya

    2013-01-11

    This study describes the ability of triallyl isocyanurate (TAIC)-co-methacrylate ester polymer monoliths as stationary phases for the separation of hydrophilic compounds (phenolic acids, amino acids and catecholamines) in capillary electrochromatography (CEC) and ultra high pressure liquid chromatography (UHPLC). Several TAIC-co-methacrylate ester polymer monoliths prepared by single-step in situ copolymerization of TAIC, ethylene dimethacrylate (EDMA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), with or without alkyl methacrylates were characterized by examining the SEM image, surface area, contact angle, and the thermal decomposition temperature. Compared to the conventional methacrylate ester-based monoliths, these proposed monoliths possessed hydrophilic character thus increased wettability which improved chromatographic separation selectivity of polar phenolic acids. Among the proposed TAIC-co-methacrylate monoliths, poly(TAIC-co-EDMA-AMPS-co-stearyl methacrylate (SMA)) showed separation selectivity with an increased analyte resolution from 0.0 to 0.92 for 4-hydroxybenzoic acid and vanillic acid, which were consistently difficult to resolve in the reversed-phase chromatographic mechanism of these monoliths in aqueous mobile phases. Moreover, stable ionization efficiencies were observed when this monolith was combined with ESI-MS detector possibly because an organic solvent-rich sheath liquid was used in the CEC-MS. This study demonstrates the potentiality of novel TAIC-co-methacrylate polymer monoliths in hydrophilic solute separation either in CEC or UHPLC mode.

  17. Modified normal-phase ion-pair chromatographic methods for the facile separation and purification of imidazolium-based ionic compounds

    SciTech Connect

    Urban, ND; Schenkel, MR; Robertson, LA; Noble, RD; Gin, DL

    2012-07-04

    lmidazolium- and oligo(imidazolium)-based ionic organic compounds are important in the design of room-temperature ionic liquid materials; however, the chromatographic analysis and separation of such compounds are often difficult. A convenient and inexpensive method for effective thin-layer chromatography (TLC) analysis and column chromatography separation of imidazolium-based ionic compounds is presented. Normal-phase ion-pair TLC is used to effectively analyze homologous mixtures of these ionic compounds. Subsequent separation of the mixtures is performed using ion-pair flash chromatography on normal-phase silica gel, yielding high levels of recovery. This method also results in a complete exchange of the counter anion on the imidazolium compounds to the anion of the ion-pair reagent. (C) 2012 Elsevier Ltd. All rights reserved.

  18. Separation of the fatty acids in menhaden oil as methyl esters with a highly polar ionic liquid gas chromatographic column and identification by time of flight mass spectrometry.

    PubMed

    Fardin-Kia, Ali Reza; Delmonte, Pierluigi; Kramer, John K G; Jahreis, Gerhard; Kuhnt, Katrin; Santercole, Viviana; Rader, Jeanne I

    2013-12-01

    The fatty acids contained in marine oils or products are traditionally analyzed by gas chromatography using capillary columns coated with polyethylene glycol phases. Recent reports indicate that 100 % cyanopropyl siloxane phases should also be used when the analyzed samples contain trans fatty acids. We investigated the separation of the fatty acid methyl esters prepared from menhaden oil using the more polar SLB-IL111 (200 m × 0.25 mm) ionic liquid capillary column and the chromatographic conditions previously optimized for the separation of the complex mixture of fatty acid methyl esters prepared from milk fat. Identifications of fatty acids were achieved by applying Ag(+)-HPLC fractionation and GC-TOF/MS analysis in CI(+) mode with isobutane as the ionization reagent. Calculation of equivalent chain lengths confirmed the assignment of double bond positions. This methodology allowed the identification of 125 fatty acids in menhaden oil, including isoprenoid and furanoid fatty acids, and the novel 7-methyl-6-hexadecenoic and 7-methyl-6-octadecenoic fatty acids. The chromatographic conditions applied in this study showed the potential of separating in a single 90-min analysis, among others, the short chain and trans fatty acids contained in dairy products, and the polyunsaturated fatty acids contained in marine products.

  19. Catalyst assisted synthesis of initiator attached silica monolith particles via isocyanate-hydroxyl reaction for production of polystyrene bound chromatographic stationary phase of excellent separation efficiency.

    PubMed

    Ali, Faiz; Kim, Yune Sung; Lee, Jin Wook; Cheong, Won Jo

    2014-01-10

    Dibutyltin dichloride (DBTDC) was used as a catalyst to chemically bind 4-chloromehtylphenylisocynate (4-CPI) to porous monolithic silica particles via isocyanate-hydroxyl reaction, and the reaction product was reacted with sodium diethyldithiocarbamate (SDDC) to yield initiator attached silica monolith particles. Reversible addition-fragmentation transfer (RAFT) polymerization was taken place on them to result in polystyrene attached silica particles that showed excellent separation efficiency when packed in a chromatographic column (1.0 mm × 300 mm). The numbers of theoretical plates (N) of 56,500 is better than those of any commercially available HPLC or UHPLC column yet.

  20. Direct quantitative gas chromatographic separation of C2-C6 fatty acids, methanol, and ethyl alcohol in aqueous microbial fermentation media.

    PubMed

    Rogosa, M; Love, L L

    1968-02-01

    A method is described for the direct quantitative gas chromatographic separation of C(2)-C(6) lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 muliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C(2)-C(6) acids added to culture supernatant fluids were obtained.

  1. Direct Quantitative Gas Chromatographic Separation of C2-C6 Fatty Acids, Methanol, and Ethyl Alcohol in Aqueous Microbial Fermentation Media

    PubMed Central

    Rogosa, M.; Love, L. L.

    1968-01-01

    A method is described for the direct quantitative gas chromatographic separation of C2-C6 lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 μliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C2-C6 acids added to culture supernatant fluids were obtained. PMID:5645415

  2. Liquid chromatographic determination of melamine in beverages.

    PubMed

    Ishiwata, H; Inoue, T; Yamazaki, T; Yoshihira, K

    1987-01-01

    A liquid chromatographic method is described for the determination of melamine in beverages. Melamine is separated by column chromatography using cation and anion exchange resin and determined by ion-pair liquid chromatography using an ODS column and a mixture of acetonitrile and 0.05M phosphate buffer (pH 3.0) containing 0.005M sodium 1-laurylsulfate (1 + 4, v/v) as mobile phase. Recoveries of melamine ranged between 90.3 +/- 7.8 and 102.1 +/- 5.6% at levels of 0.6 to 2.4 ppm in 4 kinds of beverages. The quantitation limit was 2.5 micrograms melamine in 50 mL beverage. The method was applied to the migration test of melamine from melamine-formaldehyde resin products to the beverages.

  3. Polar Aprotic Modifiers for Chromatographic Separation and Back-Exchange Reduction for Protein Hydrogen/Deuterium Exchange Monitored by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Valeja, Santosh G.; Emmett, Mark R.; Marshall, Alan G.

    2012-04-01

    Hydrogen/deuterium exchange monitored by mass spectrometry is an important non-perturbing tool to study protein structure and protein-protein interactions. However, water in the reversed-phase liquid chromatography mobile phase leads to back-exchange of D for H during chromatographic separation of proteolytic peptides following H/D exchange, resulting in incorrect identification of fast-exchanging hydrogens as unexchanged hydrogens. Previously, fast high-performance liquid chromatography (HPLC) and supercritical fluid chromatography have been shown to decrease back-exchange. Here, we show that replacement of up to 40% of the water in the LC mobile phase by the modifiers, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) (i.e., polar organic modifiers that lack rapid exchanging hydrogens), significantly reduces back-exchange. On-line LC micro-ESI FT-ICR MS resolves overlapped proteolytic peptide isotopic distributions, allowing for quantitative determination of the extent of back-exchange. The DMF modified solvent composition also improves chromatographic separation while reducing back-exchange relative to conventional solvent.

  4. Importance of MS selectivity and chromatographic separation in LC-MS/MS-based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study.

    PubMed

    Ibáñez, M; Gracia-Lor, E; Sancho, J V; Hernández, F

    2012-08-01

    Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking-water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high-resolution MS data using a hybrid quadrupole time-of-flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co-eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC-MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected.

  5. Set-up of large laboratory-scale chromatographic separations of poly(ethylene glycol) derivatives of the growth hormone-releasing factor 1-29 analogue.

    PubMed

    Piquet, G; Gatti, M; Barbero, L; Traversa, S; Caccia, P; Esposito, P

    2002-01-25

    In this paper we report the scale-up of the purification of poly(ethylene glycol) (PEG) derivatives of the growth hormone-releasing factor 1-29, from laboratory scale (100 mg of bulk starting material) to larger scale (3 g of bulk), through the use of a cation-exchange TSK-SP-5PW chromatographic column. A one-step purification process capable of purifying large amounts of mono-PEGylated GRF species from the crude reaction mixture was developed. A simple, straightforward stepwise gradient elution separation was developed at laboratory scale and then scaled up with a larger column packed with a chromatographic resin with the same chemistry which maintained the laboratory-scale separation profile. Active material recovery and material purity remained constant through the scale-up from the 13-microm stationary phase to the 25-microm larger column. Overall, the gram GRF equivalent/batch process scale showed to be quite reproducible, and could be considered as a good platform for scale up to production scale.

  6. Polar Aprotic Modifiers for Chromatographic Separation and Back-Exchange Reduction for Protein Hydrogen/Deuterium Exchange Monitored by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    PubMed Central

    Valeja, Santosh G.; Emmett, Mark R.; Marshall, Alan G.

    2013-01-01

    Hydrogen/deuterium exchange monitored by mass spectrometry is an important non-perturbing tool to study protein structure and protein–protein interactions. However, water in the reversed-phase liquid chromatography mobile phase leads to back-exchange of D for H during chromatographic separation of proteolytic peptides following H/D exchange, resulting in incorrect identification of fast-exchanging hydrogens as unexchanged hydrogens. Previously, fast high-performance liquid chromatography (HPLC) and supercritical fluid chromatography have been shown to decrease back-exchange. Here, we show that replacement of up to 40% of the water in the LC mobile phase by the modifiers, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) (i.e., polar organic modifiers that lack rapid exchanging hydrogens), significantly reduces back-exchange. On-line LC micro-ESI FT-ICR MS resolves overlapped proteolytic peptide isotopic distributions, allowing for quantitative determination of the extent of back-exchange. The DMF modified solvent composition also improves chromatographic separation while reducing back-exchange relative to conventional solvent. PMID:22298288

  7. On-line continuous sampling dynamic microwave-assisted extraction coupled with high performance liquid chromatographic separation for the determination of lignans in Wuweizi and naphthoquinones in Zicao.

    PubMed

    Gao, Shiqian; You, Jingyan; Wang, Ying; Zhang, Rui; Zhang, Hanqi

    2012-03-01

    The on-line continuous sampling dynamic microwave-assisted extraction (on-line CSDMAE) coupled with high-performance liquid chromatographic separation and determination of the lignans in Wuweizi and naphthoquinones in Zicao was developed. The extraction, separation and determination of target analytes were simultaneously carried out. The experimental parameters, including type of extraction solvent, microwave extraction power, solvent flow rate, amount of sample and particle size of the sample, were evaluated by the univariate method and orthogonal screening. The detection limits for schisandrin A, schisantherin A, deoxyschizandrin, shikonin and β,β'-dimethylacrylshikonin are 0.86, 0.90, 0.27, 0.42 and 0.92 μg mL⁻¹, respectively. Compared with the conventional extraction methods, such as off-line continuous microwave-assisted extraction, ultrasound-assisted extraction and Soxhlet extraction, the proposed method is quicker and more effective.

  8. Improved separation of fluorogenic derivatized intact proteins with high resolution and efficiency using a reversed-phase liquid chromatographic system.

    PubMed

    Ichibangase, Tomoko; Nakata, Katsunori; Imai, Kazuhiro

    2014-06-01

    Although the efficient separation of intact protein mixtures is extremely difficult, reversed-phase chromatography is an important technique for performing quantitative, accurate and reproducible proteomics analyses. Here, we show that, despite the operating constraints of conventional high-performance liquid chromatography, such as column temperature, operating pressure and separation time, comprehensive separation of fluorogenic derivatized intact proteins could be achieved with high resolution and separation efficiency. First, amylin was chosen as a model peptide and used to estimate the separation efficiency with respect to column temperature and flow rate, as indicated by peak capacity. Then, an extract of human primary hepatocytes was used to model complex component mixtures and the separation conditions were optimized. The effects of mobile-phase pH, the separation time and the column length were also investigated. Consequently, more than 890 peaks could be separated efficiently in the extract, which is 1.5-fold greater than when using conventional conditions. Finally, it was demonstrated that both longer separation time and column length contributed greatly to the effective separation of the protein mixture. These results are expected to provide insights into the separation of intact proteins.

  9. Purification method development for chiral separation in supercritical fluid chromatography with the solubilities in supercritical fluid chromatographic mobile phases.

    PubMed

    Gahm, Kyung H; Tan, Helming; Liu, Jodi; Barnhart, Wesley; Eschelbach, John; Notari, Steve; Thomas, Samuel; Semin, David; Cheetham, Janet

    2008-04-14

    A comprehensive approach was applied to develop a chiral purification method for an analyte that was found to be unusually difficult to scale-up in supercritical fluid chromatography (SFC). This was performed by studying major factors such as the solubility of an analyte in SFC mobile phases, impurity profiles, and cycle time. For this case study, the solubility in SFC mobile phase was measured by a packed column technique, coupled with a novel trapping mechanism to enhance measurement precision in SFC conditions. The solubility studies in SFC mobile phases suggested a couple of possible SFC mobile phases, in which the analyte would potentially be most soluble. The SFC methods were developed to purify a sample containing 15% of an impurity, after considering impurity profiles and cycle times of several potential methods in addition to SFC mobile phase solubility. An equal volume mixture of acetonitrile and ethanol was chosen for the final purification method, since this mixture demonstrated the relatively high SFC solubility among all solvent combinations with enhanced resolution between the analyte and the impurity as well as the shortest run time. The solubility of the compound was also determined in various organic solvents using a high throughput solubility screening system to better understand relative change of solubility from neat solution to SFC mobile phases.

  10. Enantioselective nano liquid chromatographic separation of racemic pharmaceuticals: a facile one-pot in situ preparation of lipase-based polymer monoliths in capillary format.

    PubMed

    Ahmed, Marwa; Ghanem, Ashraf

    2014-11-01

    New affinity monolithic capillary columns of 150 µm internal diameter were prepared in situ fused glass capillary via either immobilization or encapsulation of Candida antarctica lipase B (CALB) on or within polymer monoliths, respectively. The immobilized lipase-based monoliths were prepared via copolymerization of 19.1% monomers (8.9% MMA and 10.2% GMA), 19.8% EDMA, and 61.1% porogens (54.2% formamide and 6.9% 1-propanol) w/w or 20% GMA, 20% EDMA, and 60% porogens (51.6% cyclohexanol and 8.4% 1-dodecanol) in the presence of AIBN (1%) as a radical initiator. This was followed by pumping a solution of lipase through the capillaries and rinsing with potassium phosphate buffer. On the other hand, the encapsulated lipase-based monoliths were prepared via copolymerization of 20% monomers (GMA), 20% EDMA, and 60% porogens (48% 1-propanol, 6% 1,4-butanediol) or 16.4% monomers (16% BuMA, 0.4% SPMA), 23.6% EDMA, and 60% porogens (36% 1-propanol, 18% 1,4-butanediol along with 6% lipase aqueous solution in potassium phosphate buffer. The prepared capillary columns were investigated for the enantioselective nano liquid chromatographic separation of a set of different classes of racemic pharmaceuticals, namely, α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs, and antiarrhythmic drugs. Run-to-run repeatability was quite satisfactory. The encapsulated lipase-based capillary monolith showed better enantioselective separations of most of the investigated compounds. Baseline separation was achieved for alprenolol, atenolol, bromoglutithimide, carbuterol, chloropheneramine, cizolertine carbinol, 4-hydroxy-3-methoxymandelic acid, desmethylcizolertine, nomifensine, normetanephrine, and sulconazole under reversed phase chromatographic conditions. A speculation about the understanding of the chiral recognition mechanism of

  11. Optimization of liquid chromatographic method for the separation of nine hydrophilic and hydrophobic components in Salviae miltiorrhizae Radix et Rhizoma (Danshen) using microemulsion as eluent.

    PubMed

    Huang, Hongzhang; Xuan, Xueyi; Xu, Liyuan; Yang, Jianrui; Gao, Chongkai; Li, Ning

    2014-04-01

    In this study, we have proposed and developed a novel, environmental-friendly and simple method for separation of nine hydrophilic and hydrophobic components in Danshen using microemulsion liquid chromatography. The proposed method was optimized via the preliminary screening experiment and the experimental design. The following factors were investigated in preliminary screening experiment: pH of mobile phase, column type, the nature of surfactant, the nature of oil phase and additives. In order to simultaneously optimize resolution and analysis time, the chromatographic optimization function (COF) was adopted to evaluate chromatograms. The central composite design (CCD) was used to create the matrix of experiments for mapping the chromatographic response surface. Finally, the COF values were fitted into a second order polynomial model and the response surface methodology (RSM) was employed to find the optimal eluent constituents. The reliability of the established model was confirmed by the good agreement obtained between experimental data and predictive values. Based on the results from the preliminary screening experiment and the CCD optimization, the optimal mobile phase was identified as a solution consisting of 6.68% (w/w) polyoxyethylene lauryl ether (Brij35), 0.84% (w/w) cyclohexane, 6.92% (w/w) n-butanol, 85.56% (w/w) phosphate buffer (pH 6.60) and 8mM cetyltrimethyl ammonium bromide (CTAB).

  12. Synthesis and characterization of novel stationary phases for small scale liquid chromatographic separations of proteins and nanoparticles

    NASA Astrophysics Data System (ADS)

    Hutanu, Daniela

    The emerging field of nanotechnology strictly requires the micro-scaling of the available separation technology and the design of novel devices for separations of molecules of interest. The separation of proteins and nanoparticles is challenging due to their relatively large size, non-specific adherence to surfaces and instability in many solvents. This dissertation presents the synthesis and characterization of novel stationary phases for use in separations of proteins or nanoparticles in both capillary and microchip formats. In order to separate blood proteins with high specificity, a DNA aptamer selected for alpha-thrombin was employed as an affinity component of the stationary phases. Silica surfaces and organic monoliths were modified with the aptamer via an azlactone linkage and have demonstrated highly efficient separations of thrombin from a mixture in the microscale. The high efficiency of the protein separation (HETP = 276 mum, RS = 1.7) is comparable with macroscale results using antibodies as the affinity factor. Novel hybrid inorganic-organic polysilsesquioxane stationary phases were synthesized by way of surfactant templated polymerization of bridged alcoxy-silyl ethane monomers, in presence of sodium hydroxide. The novel materials were successful in size exclusion separation of polystyrene standards with molecular diameters of 0.3-2.4 nm. A hybrid inorganic-organic polysilsesquioxane sorbent also proved useful for small scale separations of triphenyl phosphine protected gold nanoparticles, based on a sorptive mechanism instead of a size exclusion mechanism. Polysilsesquioxanes were easily synthesized in-situ inside fused silica capillary columns and PMMA microchip channels in order to facilitate integration with a micro-reactor. The novel stationary phases proved efficient for separation of proteins and nanoparticles in the micro-scale format and can further be utilized for online purification and separation of these difficult compounds.

  13. High performance liquid chromatographic separations of gas oil samples and their hydrotreated products using commercial normal phases.

    PubMed

    Oro, Nicole E; Lucy, Charles A

    2011-10-28

    Three commercially available high performance liquid chromatography columns are used in normal phase or quasi-normal phase mode for the separation of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for separations of petroleum samples and their ability to separate the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl phase, and a Chromegabond "DNAP" column from ES Industries. The HGN column separates gas oils based on both ring structure and heteroatom, while the biphenyl phase has low retention of most compounds studied in quasi-normal phase mode. The "DNAP" column is selective for nitrogen-containing compounds, separating them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns.

  14. Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.

    PubMed

    Kifle, Dejene; Wibetoe, Grethe

    2013-09-13

    One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III.

  15. Fabrication of zeolitic imidazolate framework-8-methacrylate monolith composite capillary columns for fast gas chromatographic separation of small molecules.

    PubMed

    Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

    2015-08-07

    A composite zeolitic imidazolate framework-8 (ZIF-8) with a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.) was fabricated to enhance the separation efficiency of methacrylate monoliths toward small molecules using conventional low-pressure gas chromatography in comparison with a neat butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.). The addition of 10mgmL(-1) ZIF-8 micro-particles increased the BET surface area of BuMA-co-EDMA by 3.4-fold. A fast separation of five linear alkanes in 36s with high resolution (Rs≥1.3) was performed using temperature program. Isothermal separation of the same sample also showed a high efficiency (3315platesm(-1) for octane) at 0.89min. Moreover, the column was able to separate skeletal isomers, such as iso-octane/octane and 2-methyl octane/nonane. In addition, an iso-butane/iso-butylene gas mixture was separated at ambient temperature. Comparison with an open tubular TR-5MS column (30m long×250μm i.d.) revealed the superiority of the composite column in separating the five-membered linear alkane mixture with 4-5 times increase in efficiency and a total separation time of 0.89min instead of 4.67min. A paint thinner sample was fully separated using the composite column in 2.43min with a good resolution (Rs≥0.89). The perfect combination between the polymeric monolith, with its high permeability, and ZIF-8, with its high surface area and flexible 0.34nm pore openings, led to the fast separation of small molecules with high efficiency and opened a new horizon in GC applications.

  16. Gas chromatographic separation of stereoisomers of non-protein amino acids on modified γ-cyclodextrin stationary phase.

    PubMed

    Fox, Stefan; Strasdeit, Henry; Haasmann, Stephan; Brückner, Hans

    2015-09-11

    Stereoisomers (enantiomers and diastereoisomers) of synthetic, non-protein amino acids comprising α-, β-, and γ-amino acids, including α,α-dialkyl amino acids, were converted into the respective N-trifluoroacetyl-O-methyl esters and analyzed and resolved by gas chromatography (GC) on a commercial fused silica capillary column coated with the chiral stationary phase octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. This column is marketed under the trade name Lipodex(®) E. Chromatograms, retention times, and a chart displaying the retention times of approximately 40 stereoisomers of amino acids are presented. With few exceptions, baseline or almost baseline resolution was achieved for enantiomers and diastereoisomers. The chromatographic method presented is considered to be highly suitable for the elucidation of the stereochemistry of non-protein amino acids, for example in natural products, and for evaluating the enantiopurity of genetically non-coded amino acids used for the synthesis and design of conformationally tailored peptides. The method is applicable to extraterrestrial materials or can be used in experimental work related to abiotic syntheses or enantioselective destruction and amplification of amino acids.

  17. Gas chromatographic separation of nitrogen, oxygen, argon, and carbon monoxide using custom-made porous polymers from high purity divinylbenzene

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Ohara, D.; Hollis, O. L.

    1984-01-01

    Existing porous polymers were surveyed for their ability to separate the subject gases. Certain products that showed more promise than others were synthesized and the existing synthetic procedures studied and modified to produce new polymers with enhanced ability to separate the subject gases. Evaluation of the porous polymers was carried out practically by gas chromatography at ambient temperature. The modified synthetic procedures were somewhat simpler than the originals. The new porous polymers made with high purity divinylbenzene enabled use of shorter columns to obtain the separations desired.

  18. Separation of short-chain fatty acids on a gas chromatographic column coated with oxidized lubricating oil.

    PubMed

    Moustafa, Nagy Emam

    2007-07-01

    The oxidized lubricating naphthenic base oil was used as a stationary phase for the separation of short-chain free fatty acids (SFFA) either as a pure sample or an aqueous solution containing 0.9-1.2 mg/L of each acid. It is found that the oil oxidation for 20 h improved the separation of SFFA in these two sample forms. This separation improvement represents not only the increase in retention volume intervals and peak symmetries in case of the pure sample but also in acid peak areas in case of the aqueous solution sample.

  19. Improving accuracy and precision of ice core δD(CH4) analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

    NASA Astrophysics Data System (ADS)

    Bock, M.; Schmitt, J.; Beck, J.; Schneider, R.; Fischer, H.

    2014-07-01

    Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4) or δ2H(CH4)) 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4) measurements in (ice core) air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping), both on a carbon-PLOT capillary at -196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL - at standard temperature and pressure (STP) - of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.

  20. Improving accuracy and precision of ice core δD (CH4) analyses using methane pre- and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

    NASA Astrophysics Data System (ADS)

    Bock, M.; Schmitt, J.; Beck, J.; Schneider, R.; Fischer, H.

    2013-12-01

    Firn and polar ice cores offer the only direct paleoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD (CH4)) 0.5 to 1.5 kg of ice was previously necessary to achieve the required precision. Here we present a method to improve precision and reduce the sample amount for δD (CH4) measurements on (ice core) air. Pre-concentrated methane is focused before a high temperature oven (pre pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post pyrolysis trapping), both on a carbon-PLOT capillary at -196 °C. A small amount of methane and krypton are trapped together with H2 and must be separated using a short second chromatographic column to ensure accurate results. Pre and post pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods we estimate a precision of 2.2‰ for 350 g of ice (or roughly 30 mL (at standard temperature and pressure (STP)) of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.

  1. Performance comparison of three types of high-speed counter-current chromatographs for the separation of components of hydrophilic and hydrophobic color additives.

    PubMed

    Weisz, Adrian; Ito, Yoichiro

    2011-09-09

    The performance of three types of high-speed counter-current chromatography (HSCCC) instruments was assessed for their use in separating components in hydrophilic and hydrophobic dye mixtures. The HSCCC instruments compared were: (i) a J-type coil planet centrifuge (CPC) system with a conventional multilayer-coil column, (ii) a J-type CPC system with a spiral-tube assembly-coil column, and (iii) a cross-axis CPC system with a multilayer-coil column. The hydrophilic dye mixture consisted of a sample of FD&C Blue No. 2 that contained mainly two isomeric components, 5,5'- and 5,7'-disulfonated indigo, in the ratio of ∼7:1. The hydrophobic dye mixture consisted of a sample of D&C Red No. 17 (mainly Sudan III) and Sudan II in the ratio of ∼4:1. The two-phase solvent systems used for these separations were 1-butanol/1.3M HCl and hexane/acetonitrile. Each of the three instruments was used in two experiments for the hydrophilic dye mixture and two for the hydrophobic dye mixture, for a total of 12 experiments. In one set of experiments, the lower phase was used as the mobile phase, and in the second set of experiments, the upper phase was used as the mobile phase. The results suggest that: (a) use of a J-type instrument with either a multilayer-coil column or a spiral-tube assembly column, applying the lower phase as the mobile phase, is preferable for separating the hydrophilic components of FD&C Blue No. 2; and (b) use of a J-type instrument with multilayer-coil column, while applying either the upper phase or the lower phase as the mobile phase, is preferable for separating the hydrophobic dye mixture of D&C Red No. 17 and Sudan II.

  2. Chromatographic Separation of Cd from Plants via Anion-Exchange Resin for an Isotope Determination by Multiple Collector ICP-MS.

    PubMed

    Wei, Rongfei; Guo, Qingjun; Wen, Hanjie; Peters, Marc; Yang, Junxing; Tian, Liyan; Han, Xiaokun

    2017-01-01

    In this study, key factors affecting the chromatographic separation of Cd from plants, such as the resin column, digestion and purification procedures, were experimentally investigated. A technique for separating Cd from plant samples based on single ion-exchange chromatography has been developed, which is suitable for the high-precision analysis of Cd isotopes by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The robustness of the technique was assessed by replicate analyses of Cd standard solutions and plant samples. The Cd yields of the whole separation process were higher than 95%, and the (114/110)Cd values of three Cd second standard solutions (Münster Cd, Spex Cd, Spex-1 Cd solutions) relative to the NIST SRM 3108 were measured accurately, which enabled the comparisons of Cd isotope results obtained in other laboratories. Hence, stable Cd isotope analyses represent a powerful tool for fingerprinting specific Cd sources and/or examining biogeochemical reactions in ecological and environmental systems.

  3. Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.

    PubMed

    Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

    2012-01-06

    The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column.

  4. Gradient HPLC separation of dehydroepiandrosterone (DHEA) from its metabolites and biological congeners: role of tetrahydrofuran in the chromatographic mechanism.

    PubMed

    Gergely, András; Horváth, Péter; Szász, György; Veress, Gábor

    2009-08-01

    A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7alphaOH-DHEA, 7betaOH-DHEA, 7-keto-DHEA), and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.

  5. Chromatographic separation of certain metal ions using a bifunctional quaternary ammonium-sulfonate mixed bed ion-exchanger.

    PubMed

    Lasheen, Y F; Seliman, A F; Abdel-Rassoul, A A

    2006-12-15

    The separation behaviour of Pb(2+), Cu(2+), Cd(2+), Co(2+), Zn(2+) and Ni(2+) on bifunctional quaternary ammonium-sulfonate mixed ion-exchangers (Dionex, IonPac CS5 and CG5) was studied using different eluents including solutions of oxalic acid, potassium oxalate, sodium oxalate and ammonium oxalate. Separated metal ions were followed by using 4-(2-pyridylazo) resorcinol (PAR) as post-colouring complex. The retention factors of different ions proved to be dependent on the pH, concentration, nature of each complexing agent, and to less extent on eluent flow rate. The retention behaviour and separation mechanism of complexed metal analytes are discussed in the light of the stability of metal complexes and the ligand complexing ability of used eluent. Comparison between various mobile phases is evaluated, and both sodium and potassium oxalate can be used successfully for simultaneous separation of studied metals with good resolution within short elution periods. The method can be used in different applications including analysis of bottled water from different resources.

  6. Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection.

    PubMed

    Rozmarić, Martina; Ivsić, Astrid Gojmerac; Grahek, Zeljko

    2009-11-15

    The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding strength increases proportionally to increase the concentration of acids. Uranium and thorium bind rather strongly to TRU resin from the nitric acid in concentration ranging from 0.5 to 5 mol L(-1), while large quantities of other ions present in the sample do not influence on the binding strength. Due to the difference in binding strength in HCl and HNO(3) respectively, uranium and thorium can be easily separated from each other on the columns filled with TRU resin. Furthermore, thorium binds to anion exchanger in nitrate form from alcohol solutions of nitric acid very strongly, while uranium does not, so they can be easily separated. Based on these results, we have created the procedures of preconcentration and separation of uranium and thorium from the soil, drinking water and seawater samples by using TRU and UTEVA resins and strong base anion exchangers in nitrate form. In one of the procedures, uranium and thorium bind directly from the samples of drinking water and seawater on the column filled with TRU resin from 0.5 mol L(-1) HNO(3) in a water sample. After binding, thorium is separated from uranium with 0.5 mol L(-1) HCl, and uranium is eluted with deionised water. By applying the described procedure, it is possible to achieve the concentration factor of over 1000 for the column filled with 1g of resin and splashed with 2L of the sample. Spectrophotometric determination with Arsenazo III, with this concentration factor results in detection limits below 1 microg L(-1) for uranium and thorium. In the second procedure, uranium and thorium are isolated from the soil samples with TRU

  7. Modification of the murakami retention model in reversed-phase high-performance liquid chromatography for micellar chromatographic separations

    NASA Astrophysics Data System (ADS)

    Loginova, L. P.; Boichenko, A. P.; Kulikov, A. Yu.

    2008-09-01

    A retention model for micellar liquid chromatography was tested based on the data of separation of three benzodiazepins and six β-blockers. The model was obtained by analyzing changes in the microenvironment of a sorbate in transferring from the mobile to stationary phase. It can be used to describe the retention of benzodiazepins, which are neutral under the separation conditions, and the positively charged β-blockers. The calculated model coefficients are indicative of an increase in the number of 1-pentanol molecules and sodium dodecyl sulfate monomers in the microenvironment of the sorbates in transferring from the mobile to stationary phase. The solvation of the positive β-blockers by anionic surfactant monomers was higher than that of neutral benzodiazepins.

  8. Effects of ammonioalkyl sulfonate internal salts on electrokinetic micropump performance and reversed-phase high-performance liquid chromatographic separations.

    PubMed

    Reichmuth, David S; Kirby, Brian J

    2003-09-26

    Ammonioalkyl sulfonate internal salts are explored owing to their potential for improving electrokinetic pumps used to perform miniaturized HPLC separations. The internal salts investigated can be added at high molarity since they are net-neutral, and furthermore show potential for increasing electroosmotic pumping owing to their large positive dielectric increment. Streaming potential measurements of buffered aqueous systems with varying concentrations of ammonioalkyl sulfonate internal salts have been used to measure these dielectric increments, which increase with the length of the alkyl linker. Due to their positive dielectric increments and their decremental effect on solution conductivity, all of the measured species are predicted to improve the pressure generation (up to 85%) and efficiency performance (up to 140%) of electrokinetic pumps when added at 1 M concentration. RP-HPLC separations with an ammonioalkyl sulfonate (TMAPS) have been performed and indicate that separation performance is essentially unaffected by these species. These results indicate the potential for a variety of ammonioalkyl sulfonates to be used to improve electrokinetic pump performance for miniaturized HPLC.

  9. Chromatographic separation and detection of contaminants from whole milk powder using a chitosan-modified silver nanoparticles surface-enhanced Raman scattering device.

    PubMed

    Li, Dan; Lv, Di Y; Zhu, Qing X; Li, Hao; Chen, Hui; Wu, Mian M; Chai, Yi F; Lu, Feng

    2017-06-01

    Methods for the on-site analysis of food contaminants are in high demand. Although portable Raman spectroscopy is commonly used to test food on-site, it can be challenge to achieve this goal with rapid detection and inexpensive substrate. In this study, we detected trace food contaminants in samples of whole milk powder using the methods that combined chromatography with surface-enhanced Raman scattering detection (SERS). We developed a simple and efficient technique to fabricate the paper with chitosan-modified silver nanoparticles as a SERS-active substrate. The soaking time of paper and the concentration of chitosan solution were optimized for chromatographic separation and SERS detection. We then studied the separation properties for real applications including complex sample matrices, and detected melamine at 1mg/L, dicyandiamide at 100mg/L and sodium sulfocyanate at 10mg/L in whole milk powder. As such, our methods have great potential for field-based detection of milk contaminants.

  10. Retention of ionisable compounds on high-performance liquid chromatography XVIII: pH variation in mobile phases containing formic acid, piperazine, tris, boric acid or carbonate as buffering systems and acetonitrile as organic modifier.

    PubMed

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

    2009-03-20

    In the present work dissociation constants of commonly used buffering species, formic acid, piperazine, tris(hydroxymethyl)-aminomethane, boric acid and carbonate, have been determined for several acetonitrile-water mixtures. From these pK(a) values a previous model has been successfully evaluated to estimate pH values in acetonitrile-aqueous buffer mobile phases from the aqueous pH and concentration of the above mentioned buffers up to 60% of acetonitrile, and aqueous buffer concentrations between 0.005 (0.001 mol L(-1) for formic acid-formate) and 0.1 mol L(-1). The relationships derived for the presently studied buffers, together with those established for previously considered buffering systems, allow a general prediction of the pH variation of the most commonly used HPLC buffers when the composition of the acetonitrile-water mobile phase changes during the chromatographic process, such as in gradient elution. Thus, they are an interesting tool that can be easily implemented in general retention models to predict retention of acid-base analytes and optimize chromatographic separations.

  11. High-pressure liquid chromatographic separation of the naturally occurring toxicants myristicin, related aromatic ethers and falcarinol.

    PubMed

    Wulf, L W; Nagel, C W; Branen, A L

    1978-11-21

    The naturally occurring toxicants myristicin, twelve related aromatic ethers and the toxic acetylenic alcohol, falcarinol, were separated from one another by high-pressure liquid chromatography (HPLC). The technique employed a microparticulate nitrile phase column and used heptane and tetrahydrofuran as the eluting solvents. Preparative HPLC with 5-micrometer silica allowed isolation of gram quantities of parsleyapiole and dillapiole from extracts of plain parsley seeds and dill seeds, respectively. Commercially available myristicin as well as other aromatic ethers were also purified in gram quantities with the preparative column.

  12. Incorporation of carbon nanotubes in a silica HPLC column to enhance the chromatographic separation of peptides: theoretical and practical aspects.

    PubMed

    André, Claire; Aljhani, Rania; Gharbi, Tijani; Guillaume, Yves C

    2011-06-01

    The retention mechanism of a series of peptides on a single-wall carbon nanotube (SWCNT) stationary phase inside an HPLC column was investigated over a wide range of mobile phase compositions. While the similar size C18 column exhibited an efficiency of 11.5 μm, the SWCNT column increased the efficiency, i.e. 7.10 μm at a flow rate of 0.8 mL/min, and significantly affected the separation quality of the peptides. The values of enthalpy (ΔH) and entropy (ΔS(*)) of transfer of the peptides from the mobile to the SWCNT stationary phase were determined. The method studied each factor, i.e. ACN fraction x in the ACN/water mixture and column temperature. The changes in retention factor, ΔH and ΔS(*) as a function of the ACN fraction in the mobile phase were examined. These variations are explained using the organization of ACN in clusters in the ACN/water mixture and on the steric and electronic forces implied in the retention process. The information obtained in this work makes this SWCNT stationary phase useful for peptide research and demonstrated the role of ACN to improve the separation quality.

  13. Effect of monomer mixture composition on structure and chromatographic properties of poly(divinylbenzene-co-ethylvinylbenzene-co-2-hydroxyethyl methacrylate) monolithic rod columns for separation of small molecules.

    PubMed

    Smirnov, Konstantin N; Dyatchkov, Ivan A; Telnov, Maxim V; Pirogov, Andrey V; Shpigun, Oleg A

    2011-07-29

    Porous poly(divinylbenzene-co-ethylvinylbenzene-co-2-hydroxyethyl methacrylate) monoliths were synthesized via thermally initiated free-radical polymerization in confines of surface-vinylized glass columns (150 mm × 3 mm i.d.) and applied to the reversed-phase separation of low-molecular-weight aromatic compounds. In order to compensate for the polymer shrinkage during the synthesis and prevent the monolith from detachment from the column wall, polymerization was conducted under nitrogen pressure. The reaction proceeded at 60°C for 22 h. 2,2'-Azo-bis-isobutironitrile was used as the initiator and 1-dodecanol was used as the porogen. A series of monoliths with different monomer ratios were obtained. All the monoliths had high specific surface areas ranging from 370 to 490 m(2)/g. In the studied range of monomer mixture compositions, the mechanical stability of the stationary phase in water/acetonitrile eluents was found to be high enough and practically insensitive to the fraction of 2-hydroxyethyl methacrylate (HEMA). Increasing the molar fraction of HEMA from 10.5% to 14.7% resulted in the decrease of column permeability by two orders of magnitude (from 1.1×10(-12) to 1.8×10(-14) m(2)) and led to weaker retention of alkylbenzenes. The higher HEMA content was shown to reduce the plate height of the columns in the separation of small molecules from 160-490 μm to 40-76 μm. This was attributed mainly to the decrease of the domain size of the monoliths leading to lower eddy dispersion and mass transfer resistance in the column.

  14. Preparation of a New Chiral Stationary Phase Based on Macrocyclic Amide Chiral Selector for the Liquid Chromatographic Chiral Separations.

    PubMed

    Sung, Ji Yeong; Choi, Seung Hyuck; Hyun, Myung Ho

    2016-03-01

    A new chiral stationary phase (CSP) based on macrocyclic amide receptor was prepared starting from (1R,2R)-1,2-diphenylethylenediamine. The new CSP was successfully applied to the resolution of various N-(substituted benzoyl)-α-amino amides with reasonably good separation factors and resolutions (α = 1.75 ~ 2.97 and RS  = 2.89 ~ 6.82 for 16 analytes). The new CSP was also applied to the resolution of 3-substituted 1,4-benzodiazepin-2-ones and some diuretic chiral drugs including bendroflumethiazide and methylchlothiazide and metolazone. The resolution results for 3-substituted 1,4-benzodiazepin-2-ones and some diuretic chiral drugs were also reasonably good.

  15. Determination of methyl mercury by aqueous phase Eehylation, followed by gas chromatographic separation with cold vapor atomic fluorescence detection

    USGS Publications Warehouse

    De Wild, John F.; Olsen, Mark L.; Olund, Shane D.

    2002-01-01

    A recent national sampling of streams in the United States revealed low methyl mercury concentrations in surface waters. The resulting median and mean concentrations, calculated from 104 samples, were 0.06 nanograms per liter (ng/L) and 0.15 ng/L, respectively. This level of methyl mercury in surface water in the United States has created a need for analytical techniques capable of detecting sub-nanogram per liter concentrations. In an attempt to create a U.S. Geological Survey approved method, the Wisconsin District Mercury Laboratory has adapted a distillation/ethylation/ gas-phase separation method with cold vapor atomic fluorescence spectroscopy detection for the determination of methyl mercury in filtered and unfiltered waters. This method is described in this report. Based on multiple analyses of surface water and ground-water samples, a method detection limit of 0.04 ng/L was established. Precision and accuracy were evaluated for the method using both spiked and unspiked ground-water and surface-water samples. The percent relative standard deviations ranged from 10.2 to 15.6 for all analyses at all concentrations. Average recoveries obtained for the spiked matrices ranged from 88.8 to 117 percent. The precision and accuracy ranges are within the acceptable method-performance limits. Considering the demonstrated detection limit, precision, and accuracy, the method is an effective means to quantify methyl mercury in waters at or below environmentally relevant concentrations

  16. Capillary gas chromatographic separation of organic bases using a pH-adjusted basic water stationary phase.

    PubMed

    Darko, Ernest; Thurbide, Kevin B

    2016-09-23

    The use of a pH-adjusted water stationary phase for analyzing organic bases in capillary gas chromatography (GC) is demonstrated. Through modifying the phase to typical values near pH 11.5, it is found that various organic bases are readily eluted and separated. Conversely, at the normal pH 7 operating level, they are not. Sodium hydroxide is found to be a much more stable base than ammonium hydroxide for altering the pH due to the higher volatility and evaporation of the latter. In the basic condition, such analytes are not ionized and are observed to produce good peak shapes even for injected masses down to about 20ng. By comparison, analyses on a conventional non-polar capillary GC column yield more peak tailing and only analyte masses of 1μg or higher are normally observed. Through carefully altering the pH, it is also found that the selectivity between analytes can be potentially further enhanced if their respective pKa values differ sufficiently. The analysis of different pharmaceutical and petroleum samples containing organic bases is demonstrated. Results indicate that this approach can potentially offer unique and beneficial selectivity in such analyses.

  17. Supercritical fluid carbon dioxide extraction and liquid chromatographic separation with electrochemical detection of methylmercury from biological samples

    USGS Publications Warehouse

    Simon, N.S.

    1997-01-01

    Using the coupled methods presented in this paper, methylmercury can be accurately and rapidly extracted from biological samples by modified supercritical fluid carbon dioxide and quantitated using liquid chromatography with reductive electrochemical detection. Supercritical fluid carbon dioxide modified with methanol effectively extracts underivatized methylmercury from certified reference materials Dorm-1 (dogfish muscle) and Dolt-2 (dogfish liver). Calcium chloride and water, with a ratio of 5:2 (by weight), provide the acid environment required for extracting methylmercury from sample matrices. Methylmercury chloride is separated from other organomercury chloride compounds using HPLC. The acidic eluent, containing 0.06 mol L-1 NaCl, insures the presence of methylmercury chloride and facilitates the reduction of mercury on a glassy carbon electrode. If dual glassy carbon electrodes are used, a positive peak is observed at -0.65 to -0.70 V and a negative peak is observed at -0.90V with the organomercury compounds that were tested. The practical detection limit for methylmercury is 5 X 10-8 mol L-1 (1 X 10-12 tool injected) when a 20 ??L injection loop is used.

  18. Comprehensive ultra-performance liquid chromatographic separation and mass spectrometric analysis of eicosanoid metabolites in human samples.

    PubMed

    Wang, Yan; Armando, Aaron M; Quehenberger, Oswald; Yan, Chao; Dennis, Edward A

    2014-09-12

    Over the past decade, the number of known eicosanoids has expanded immensely and we have now developed an ultra-performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometric (UPLC-QTRAP/MS/MS) method to monitor and quantify numerous eicosanoids. The UPLC-QTRAP/MS/MS approach utilizes scheduled multiple reaction monitoring (MRM) to optimize sensitivity, number of metabolites that can be analyzed and the time requirement of the analysis. A total of 184 eicosanoids including 26 deuterated internal standards can be separated and monitored in a single 5min UPLC run. To demonstrate a practical application, human plasma samples were analyzed following solid-phase extraction (SPE) and the recovery rate and matrix effects were determined for the 26 deuterated internal standards added to the plasma. The method was validated and shown to be sensitive with the limit of quantitation at pg levels for most compounds, accurate with recovery rates of 70-120%, and precise with a CV<30 for all compounds. Also, the method showed a linear response over a range spanning several orders of magnitude. In a QC human plasma sample, we identified and rigorously quantified over 120 eicosanoids.

  19. A novel approach for quantitation of nonderivatized sialic acid in protein therapeutics using hydrophilic interaction chromatographic separation and nano quantity analyte detection.

    PubMed

    Chemmalil, Letha; Suravajjala, Sreekanth; See, Kate; Jordan, Eric; Furtado, Marsha; Sun, Chong; Hosselet, Stephen

    2015-01-01

    This paper describes a novel approach for the quantitation of nonderivatized sialic acid in glycoproteins, separated by hydrophilic interaction chromatography, and detection by Nano Quantity Analyte Detector (NQAD). The detection technique of NQAD is based on measuring change in the size of dry aerosol and converting the particle count rate into chromatographic output signal. NQAD detector is suitable for the detection of sialic acid, which lacks sufficiently active chromophore or fluorophore. The water condensation particle counting technology allows the analyte to be enlarged using water vapor to provide highest sensitivity. Derivatization-free analysis of glycoproteins using HPLC/NQAD method with PolyGLYCOPLEX™ amide column is well correlated with HPLC method with precolumn derivatization using 1, 2-diamino-4, 5-methylenedioxybenzene (DMB) as well as the Dionex-based high-pH anion-exchange chromatography (or ion chromatography) with pulsed amperometric detection (HPAEC-PAD). With the elimination of derivatization step, HPLC/NQAD method is more efficient than HPLC/DMB method. HPLC/NQAD method is more reproducible than HPAEC-PAD method as HPAEC-PAD method suffers high variability because of electrode fouling during analysis. Overall, HPLC/NQAD method offers broad linear dynamic range as well as excellent precision, accuracy, repeatability, reliability, and ease of use, with acceptable comparability to the commonly used HPAEC-PAD and HPLC/DMB methods.

  20. Liquid chromatographic determination of seven antioxidants in dry food.

    PubMed

    Page, B D; Charbonneau, C F

    1989-01-01

    The liquid chromatographic determinative step of the official method for propyl gallate, trihydroxybutyrophenone, tert-butylhydroquinone, nordihydroguaiaretic acid, butylated hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxymethylphenol, and butylated hydroxytoluene (BHT) in fats and oils has been applied to their determination in a number of dry foods. A representative sample (10 g) is homogenized first with hexane (25 mL), then with 5 mL added water, and finally with 75 mL added acetonitrile. The hexane and acetonitrile are decanted, filtered, and separated; the hexane and rehydrated food are reextracted with 2 additional portions of acetonitrile, and the combined acetonitrile extracts are concentrated and diluted to 10 mL. An aliquot is analyzed as described in the official method, using a 150 x 4.6 mm 5 microns C-18 column. The need for rehydration to maximize the recovery of BHA and other antioxidants from marketplace dry food samples such as potato flakes, dry coffee whiteners, and dessert topping mixes was demonstrated. Rehydration was not required for cheese snacks, breakfast cereals, cake mixes, and some other foods. The need for rehydration should be determined by analyzing other foods with and without the addition of water. Potato and corn chips, popcorn and cheese snacks, breakfast cereals, dry beverage mixes, rice, potato flakes, french fried potatoes, and cake mixes were spiked with the above antioxidants at 10-50 ppm. Overall recoveries ranged from 64.3 to 105.6% and repeatabilities ranged from 0.7 to 10.8%. A total of 109 samples of the above foods were analyzed, and 64% contained detectable (greater than 1-2 ppm) antioxidants, mainly BHA and BHT.

  1. Combined cation-exchange and extraction chromatographic method of preconcentration and concomitant separation of bismuth(III) with high molecular mass liquid cation exchanger.

    PubMed

    Mandal, Bhabatosh; Ghosh, Niladri

    2010-10-15

    A selective method has been developed for the extraction chromatographic separation of Bi(III) with Versatic 10 coated on silanized silica gel (SSG). Bi(III) has been quantitatively extracted from 0.1 M acetate buffer at the range of pH 5.0-5.5. The result showed that the solution pH, influent volume, flow-rate and solution temperature would affect the sorption of Bi(III). The sorbed Bi(III) was eluted with 0.1 M H(2)SO(4). The extractor system has got good values of exchange capacity (1.42 meq. of H(+) g(-1) of dry exchanger at 25 degrees C), break-through capacity (19.75 mg g(-1) at pH 5.5) and column efficiencies (300) with respect to Bi(III). The positive value of DeltaH (12.63 kJ mol(-1)) and DeltaS (0.271 kJ mol(-1) K(-1)) and negative value of DeltaG (-68.241 kJ mol(-1)) indicated that the sorption process was endothermic, entropy gaining and spontaneous in nature. P.F. has been optimized at 76.4+/-0.3 and the desorption constants K(desorption) (8x10(-3)) and K'(desorption) (1.4x10(-1)) have been determined. R(f) values and selectivity factors for diverse metal ions with respect to that of Bi(III) have been determined by ion-exchange paper chromatography. Bi(III) has been separated from synthetic mixtures containing its congeners and other metal ions associated with it in ores and alloy samples. The method was found effective for removal of Bi(III) from different water samples. A plausible mechanism for the extraction of Bi(III) has been suggested.

  2. Improvement of the chromatographic separation performance of an imidazolium ionic liquid functionalized silica column by in situ anion-exchange with dodecyl sulfonate and dodecylbenzene sulfonate anions.

    PubMed

    Sun, Min; Feng, Juanjuan; Chen, Wenjie; Li, Leilei; Duan, Huimin; Luo, Chuannan

    2014-06-01

    The anionic part of ionic liquids can provide additional interactions during chromatographic separations. In this work, the chromatographic separation performance of a silica column functionalized with 1-propyl-3-methylimidazolium chloride ionic liquid was improved by in situ anion-exchange from chloride anions to dodecyl sulfonate anions and dodecylbenzene sulfonate anions. The separation performances of these ionic liquid functionalized phases were investigated and compared with each other using polycyclic aromatic hydrocarbons, phthalates, parabens, and phenols as model compounds. Results indicated that the new columns presented a better chromatographic separation than the original one. This was ascribed retention mechanism from organic anions. The introduction of dodecyl sulfonate anions increased the hydrophobicity of stationary phase. Furthermore, the phenyl groups of dodecylbenzene sulfonate anions could provide an enhanced selectivity to aromatic compounds such as polycyclic aromatic hydrocarbons by π-π interactions. Analysis repeatability of the new columns was satisfactory (RSD of retention time, 0.10-0.40%; RSD of peak area, 0.66-0.84%).

  3. Highly sensitive gas chromatographic determination of ethanol in human urine samples.

    PubMed

    Zilly, Michael; Langmann, Peter; Lenker, Ulrike; Satzinger, Verena; Schirmer, Diana; Klinker, Hartwig

    2003-12-25

    In order to evaluate recent alcohol consumption, a very sensitive and specific gas chromatographic method for ethanol determination in human urine samples was developed. The non-invasive method was performed without any pretreatment and carried out on a Stabilwax capillary column, 30 m x 0.53 mm x 1.0 microm film thickness. Helium was used as carrier gas with a constant inlet pressure of 27.72 kPa (0.277 bar) and a flame ionization detector (FID). Quantification was performed with the use of acetonitrile as an internal standard (IS). The calibration curve was linear throughout the concentration range from 0.5 to 500 mg/l. The calculated intra- and inter-day coefficients of variation were below 8%. A clear chromatographic separation of ethanol from methanol, acetone, 1-propanol and 2-propanol was achieved.

  4. Development of liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality-by-design methodology.

    PubMed

    Pantović, Jasmina; Malenović, Anđelija; Vemić, Ana; Kostić, Nađa; Medenica, Mirjana

    2015-01-01

    In this paper, the development of reversed-phase liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality by design (QbD) approach is presented. The defined analytical target profile (ATP) was the efficient baseline separation and the accurate determination of the investigated analytes. The selected critical quality attributes (CQAs) were the separation criterions between the critical peak pairs because the mixture complexity imposed a gradient elution mode. The critical process parameters (CPPs) studied in this research were acetonitrile content at the beginning of gradient program, acetonitrile content at the end of gradient program and the gradient time. Plan of experiments was defined by Box-Behnken design. The experimental domains of the three selected factors x1--content of the acetonitrile at the start of linear gradient, x2--content of the acetonitrile at the end of linear gradient and x3--gradient time (tG) were [10%, 30%], [48%, 60%] and [8 min, 15 min], respectively. In order to define the design space (DS) as a zone where the desired quality criteria is met providing also the quality assurance, Monte Carlo simulations were performed. The uniform error distribution equal to the calculated standard error was added to the model coefficient estimates. Monte Carlo simulation included 5000 iterations in each of 3969 defined grid points and the region having the probability π ≥ 95% to achieve satisfactory values of all defined CQAs was computed. As a working point, following chromatographic conditions suited in the middle of the DS were chosen: 22% acetonitrile at the start of gradient program, 55.5% acetonitrile at the end of gradient program end and the gradient time of 11.5 min. The developed method was validated in order to prove its reliability.

  5. Chromatographic separation of PTAD-derivatized 25-hydroxyvitamin D3 and its C-3 epimer from human serum and murine skin.

    PubMed

    Teegarden, Matthew D; Riedl, Kenneth M; Schwartz, Steven J

    2015-06-01

    The detection of 25-hydroxyvitamin D at low levels in biological samples is facilitated by the use of chemical derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) in concert with liquid chromatography-tandem mass spectrometry (LC-MS/MS). This mode of analysis is notably hampered by chromatographic co-elution of 25-hydroxyvitamin D3 (25OHD3) and its C-3 epimer (C3epi). The objective of this work was to improve upon current LC-MS/MS methods used for the analysis of PTAD-derivatized 25-hydroxyvitamin D3 by resolving it from C3epi. Additionally, the applicability of this method in human serum and murine skin was investigated. C18 columns of increasing length and varying particle sizes were assessed for performance using a mixed standard of PTAD-derivatized 25OHD3 and C3epi. Serum samples were processed using solid phase extraction, and skin was powdered and extracted for lipophilic compounds. The samples were derivatized with PTAD and subsequently analyzed using isotope dilution LC-MS/MS with atmospheric pressure chemical ionization operated in positive mode. Near baseline resolution of PTAD-25OHD3 from PTAD-C3epi was achieved on a 250mm C18 column with 3μm sized particles. This separation allowed for detection and quantification of both metabolites in serum and skin samples. PTAD-C3epi represented a significant confounding analyte in all samples, and comprised up to 20% of the status measurement in skin. This method is a significant improvement on the chromatography of PTAD-derivatized vitamin D metabolites that could greatly influence the assessment of vitamin D status and C3epi biology in low abundance samples.

  6. Exploitation of nano alumina for the chromatographic separation of clinical grade 188Re from 188W: a renaissance of the 188W/188Re generator technology.

    PubMed

    Chakravarty, Rubel; Shukla, Rakesh; Ram, Ramu; Venkatesh, Meera; Tyagi, Avesh Kumar; Dash, Ashutosh

    2011-08-15

    The (188)W/(188)Re generator using an acidic alumina column for chromatographic separation of (188)Re has remained the most popular procedure world over. The capacity of bulk alumina for taking up tungstate ions is limited (∼50 mg W/g) necessitating the use of very high specific activity (188)W (185-370 GBq/g), which can be produced only in very few high flux reactors available in the world. In this context, the use of high-capacity sorbents would not only mitigate the requirement of high specific activity (188)W but also facilitate easy access to (188)Re. A solid state mechanochemical approach to synthesize nanocrystalline γ-Al(2)O(3) possessing very high W-sorption capacity (500 mg W/g) was developed. The structural and other investigations of the material were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer Emmett Teller (BET) surface area analysis, thermogravimetric-differential thermal analysis (TG-DTA), and dynamic light scattering (DLS) techniques. The synthesized material had an average crystallite size of ∼5 nm and surface area of 252 ± 10 m(2)/g. Sorption characteristics such as distribution ratios (K(d)), capacity, breakthrough profile, and elution behavior were investigated to ensure quantitative uptake of (188)W and selective elution of (188)Re. A 11.1 GBq (300 mCi) (188)W/(188)Re generator was developed using nanocrystalline γ-Al(2)O(3), and its performance was evaluated for a period of 6 months. The overall yield of (188)Re was >80%, with >99.999% radionuclidic purity and >99% radiochemical purity. The eluted (188)Re possessed appreciably high radioactive concentration and was compatible for the preparation of (188)Re labeled radiopharmaceuticals.

  7. Deconvolution of gas chromatographic data

    NASA Technical Reports Server (NTRS)

    Howard, S.; Rayborn, G. H.

    1980-01-01

    The use of deconvolution methods on gas chromatographic data to obtain an accurate determination of the relative amounts of each material present by mathematically separating the merged peaks is discussed. Data were obtained on a gas chromatograph with a flame ionization detector. Chromatograms of five xylenes with differing degrees of separation were generated by varying the column temperature at selected rates. The merged peaks were then successfully separated by deconvolution. The concept of function continuation in the frequency domain was introduced in striving to reach the theoretical limit of accuracy, but proved to be only partially successful.

  8. Peptide separation by Hydrophilic-Interaction Chromatography: a review.

    PubMed

    Yoshida, Tatsunari

    2004-09-30

    Recent developments in the separation of peptides by high-performance liquid chromatography (HPLC) using polar sorbents with less polar eluents are summarized in this review. This separation mode is now commonly referred to as Hydrophilic-Interaction Chromatography (HILIC). The retention mechanism and chromatographic behavior of polar solutes under HILIC conditions are studied on TSKgel Amide-80 columns, which consist of carbamoyl groups bonded to a silica gel matrix, using a mixture of acetonitrile (MeCN)-water containing 0.1% trifluoroacetic acid (TFA). Some applications are given in peptide field using Hydrophilic-Interaction Chromatography.

  9. A Small-Scale Low-Cost Gas Chromatograph

    ERIC Educational Resources Information Center

    Gros, Natasa; Vrtacnik, Margareta

    2005-01-01

    The design and application of a small-scale portable gas chromatograph for learning of the basic concepts of chromatography is described. The apparatus consists of two basic separable units, which includes a chromatographic unit and an electronic unit.

  10. Use of a macrocyclic antibiotic as the chiral selector for enantiomeric separations by TLC

    SciTech Connect

    Armstrong, D.W.; Zhou, Y. . Dept. of Chemistry)

    1994-01-01

    The macrocyclic antibiotic, vancomycin, was used as a chiral mobile phase additive for the thin layer chromatographic (TLC) resolution of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatized amino acids, racemic drugs and dansyl-amino acids. Excellent separations were achieved for most of these compounds in the reversed phase mode. Both the nature of the stationary phase and the composition of the mobile phase strongly influenced enantiomeric resolution. The best results were obtained using diphenyl stationary phases. Acetonitrile was the organic modifier that produced the most effective separations with the shortest development times. It is highly likely that macrocyclic antibiotics will play a major role in future enantiomeric separations.

  11. Sorption of substituted indoles on highly cross-linked polystyrene from water-acetonitrile solutions

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Myakishev, A. A.; Il'Ina, E. A.; Il'in, M. M.; Davankov, V. A.; Bulanova, A. V.

    2011-07-01

    The sorption of first synthesized indole derivatives by highly cross-linked polystyrenes from water-acetonitrile solutions was studied by high-performance liquid chromatography. The retention factors and differences in the Gibbs energy of adsorption from infinite diluted solutions were calculated, and the applicability of the Snyder-Soczewinski and Scott-Kucera models for describing the chromatographic retention of sorbates on a polymer network of highly cross-linked polystyrene was shown.

  12. Effect of the physicochemical parameters of benzimidazole molecules on their retention by a nonpolar sorbent from an aqueous acetonitrile solution

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Safonova, I. A.; Bulanova, A. V.

    2015-09-01

    The effect of the structure of benzimidazoles on their chromatographic retention on octadecyl silica gel from an aqueous acetonitrile eluent was studied. One- and many-parameter correlation equations were obtained by linear regression analysis, and their prognostic potential in determining the retention factors of benzimidazoles under study was analyzed.

  13. Chromatographic methods of fractionation.

    PubMed

    Friesen, A D

    1987-01-01

    Chromatography's functional versatility, separation efficiency, gentle non-denaturing separating process and ease of automation and scale-up make it attractive for industrial scale protein purification. The Winnipeg Rh Institute's new Plasma Fractionation facility is an example of the use of chromatography for the large scale purification of plasma protein fractions. The fractionation facility has a capacity to process 800 litres of plasma per batch into blood clotting factor VIII and IX, albumin and intravenous immune serum globulin (i.v. ISG). Albumin and i.v. ISG are purified using ion exchange columns of DEAE-Sepharose (230 litre size), DEAE-Biogel (150 litre size) and CM-Sepharose (150 litre size). The chromatographic process is automated using a Modicon 584 Programmable Logic Controller to regulate valves, pumps and sensors which control plasma flow during fractionation. The stainless steel tanks and piping are automatically cleaned-in-place. The high degree of automation and cleaning provides efficient operation and sanitary processing. Chromatographic methods (DEAE-Sepharose and metal chelation) are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells. Characterization of the protein fractions produced by chromatography has shown them to be of equal or higher quality than fractions produced by other techniques.

  14. Identification of Furosemide Photodegradation Products in Water-Acetonitrile Mixture.

    PubMed

    Katsura, Shinji; Yamada, Nobuo; Nakashima, Atsushi; Shiraishi, Sumihiro; Furuishi, Takayuki; Ueda, Haruhisa

    2015-01-01

    The aim of this study was to identify the chemical structure of the photodegradation products of furosemide in a water-acetonitrile mixture (1 : 1). Furosemide solution was irradiated with a D65 fluorescent lamp and the products were isolated by preparative HPLC. The fractions were evaporated to dryness in vacuo. The purity of the photodegradation products was measured by HPLC. The purity of products 1, 3, and 4 was greater than 90%, whereas that of product 2 was 13%, therefore, photodegradation product 2 was unstable. We identified photodegradation products 1 and 3 as 4-chloro-5-sulfamoylanthranilic acid and 4-hydroxy-N-furfuryl-5-sulfamoylanthranilic acid, respectively, by LC/MS and NMR. Additionally, we assumed that photodegradation product 4 was methyl 2-((furan-2-ylmethyl)amino)-4-hydroxy-3-(methyleneamino)-5-sulfamoylbenzoate by LC/MS and NMR. This showed that furosemide underwent hydrolysis and substitution, and reacted with the acetonitrile under the light of a D65 fluorescent lamp. We were furthermore able to determine the elution times of the photodegradation products of furosemide by applying the Japanese Pharmacopoeia chromatographic method for related substances to the isolated products.

  15. Microminiature gas chromatograph

    DOEpatents

    Yu, C.M.

    1996-12-10

    A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

  16. Microminiature gas chromatograph

    DOEpatents

    Yu, Conrad M.

    1996-01-01

    A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

  17. Proteome analysis of Myxococcus xanthus by off-line two-dimensional chromatographic separation using monolithic poly-(styrene-divinylbenzene) columns combined with ion-trap tandem mass spectrometry.

    PubMed

    Schley, Christian; Altmeyer, Matthias O; Swart, Remco; Müller, Rolf; Huber, Christian G

    2006-10-01

    Myxobacteria are potent producers of secondary metabolites exhibiting diverse biological activities and pharmacological potential. The proteome of Myxococcus xanthus DK1622 was characterized by two-dimensional chromatographic separation of tryptic peptides from a lysate followed by tandem mass spectrometric identification. The high degree of orthogonality of the separation system employing polymer-based strong cation-exchange and monolithic reversed-phase stationary phases was clearly demonstrated. Upon automated database searching, 1312 unique peptides were identified, which were associated with 631 unique proteins. High-molecular polyketide synthetases and nonribosomal peptide synthetases, known to be involved in the biosynthesis of various secondary metabolites, were readily detected. Besides the identification of gene products associated with the production of known secondary metabolites, proteins could also be identified for six gene clusters, for which no biosynthetic product has been known so far.

  18. Column chromatographic separation of Hg(II), La(III), Ce(III), and In(III) from other metal ions in NH/sub 4/Cl-CH/sub 3/COOH medium by cation exchange

    SciTech Connect

    Srivastava, U.; Mahan, A.; Ghose, A.K.; Dey, A.K.

    1980-01-01

    Cation exchange equilibrium distribution coefficients (K) with the (Dowex 50W-X8) H/sup +/ form have been determined for 21 metal ions in media consisting of mixtures of 0.7 mol/dm/sup 3/ acetic acid and varying concentrations (0.16, 0.32, 0.48, 0.64, 0.96, and 1.28 mol/dm/sup 3/) of ammonium chloride. The distribution coefficients were determined by the batch technique for finding the conditions for the mentioned separations. The column chromatographic separations achieved were all quantitative. The results of the resolution of the synthetic binary and ternary mixtures along with the elution curves are presented. 3 figures, 4 tables.

  19. Vertical distribution of acetonitrile in the atmosphere

    NASA Technical Reports Server (NTRS)

    Ingels, J.; Nevejans, D.; Arijs, E.

    1985-01-01

    The presence of acetonitrile in the atmosphere was confirmed by results of surface and stratospheric investigations. Stratospheric measurements give mixing ratios typically decreasing with height from 3 ppt at 25 km to 0.5 ppt at 40 km. Measurements at the Earth's surface are less unanimous, although a ground level background mixing ratio of a few times 10 ppt seems realistic. Measurements are compatible with a small global surface source of acetonitrile and a small tropospheric loss. The vertical distribution of acetonitrile presented in consistent with general knowledge of its atmospheric chemistry.

  20. Optimization and validation of high-performance chromatographic condition for simultaneous determination of adapalene and benzoyl peroxide by response surface methodology.

    PubMed

    Chen, Yi-Cheng; Tsai, Pi-Ju; Huang, Yaw-Bin; Wu, Pao-Chu

    2015-01-01

    The aim of this study was to develop a simple and reliable high-performance chromatographic (HPLC) method for simultaneous analysis of adapalene and benzoyl peroxide in pharmaceutical formulation by response surface methodology (RSM). An optimized mobile phase composed of acetonitrile, tetrahydrofuran and water containing 0.1% acetic acid at a ratio of 25:50:25 by volume was successfully predicted by using RSM. An isocratic separation was achieved by using the condition. Furthermore, the analytical method was validated in terms of specificity, linearity, accuracy and precision in a range of 80% to 120% of the expected concentration. Finally, the method was successfully applied to the analysis of a commercial product.

  1. Vibrational Spectroscopy of Chromatographic Interfaces

    SciTech Connect

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  2. Separation of microcystins and nodularins by ultra performance liquid chromatography.

    PubMed

    Spoof, Lisa; Neffling, Milla-Riina; Meriluoto, Jussi

    2009-11-15

    Four ultra performance liquid chromatography (UPLC) columns with different reversed-phase characteristics were tested in the chromatographic separation of 10 microcystins and three nodularins, cyanobacterial peptide toxins. The columns had been designed by the manufacturer to withstand the ultra-high pressure generated by sub-2microm stationary phase particles and the Waters ACQUITY UPLC system in ultra-fast separations. The gradient mobile phase consisted of water and acetonitrile, both acidified with trifluoroacetic acid, with three gradient rise times: 1, 1.5 and 2min. The UV detection of the toxins was performed by a photodiode array detector. The chromatographic performance was evaluated both visually and by calculating chromatographic parameters such as capacity factor, resolution, peak width at half height, selectivity and peak asymmetry. The best chromatographic performance as judged by visual inspection was given by the ACQUITY BEH Shield RP18 and ACQUITY BEH Phenyl columns. The BEH Shield RP18 column showed excellent selectivity and resolution of chosen peak pairs considered as critical. A further advantage of the UPLC system was the high sample throughput with a total analysis time of 3.12min (injection-to-injection) equalling to 461 separations per 24h.

  3. Chromatographic resolution of closely related species in pharmaceutical chemistry: dehalogenation impurities and mixtures of halogen isomers.

    PubMed

    Regalado, Erik L; Zhuang, Ping; Chen, Yadan; Makarov, Alexey A; Schafer, Wes A; McGachy, Neil; Welch, Christopher J

    2014-01-07

    In recent years, the use of halogen-containing molecules has proliferated in the pharmaceutical industry, where the incorporation of halogens, especially fluorine, has become vitally important for blocking metabolism and enhancing the biological activity of pharmaceuticals. The chromatographic separation of halogen-containing pharmaceuticals from associated isomers or dehalogenation impurities can sometimes be quite difficult. In an attempt to identify the best current tools available for addressing this important problem, a survey of the suitability of four chromatographic method development platforms (ultra high-performance liquid chromatography (UHPLC), core shell HPLC, achiral supercritical fluid chromatography (SFC) and chiral SFC) for separating closely related mixtures of halogen-containing pharmaceuticals and their dehalogenated isosteres is described. Of the 132 column and mobile phase combinations examined for each mixture, a small subset of conditions were found to afford the best overall performance, with a single UHPLC method (2.1 × 50 mm, 1.9 μm Hypersil Gold PFP, acetonitrile/methanol based aqueous eluents containing either phosphoric or perchloric acid with 150 mM sodium perchlorate) affording excellent separation for all samples. Similarly, a survey of several families of closely related halogen-containing small molecules representing the diversity of impurities that can sometimes be found in purchased starting materials for synthesis revealed chiral SFC (Chiralcel OJ-3 and Chiralpak IB, isopropanol or ethanol with 25 mM isobutylamine/carbon dioxide) as well as the UHPLC (2.1 × 50 mm, 1.8 μm ZORBAX RRHD Eclipse Plus C18 and the Gold PFP, acetonitrile/methanol based aqueous eluents containing phosphoric acid) as preferred methods.

  4. Partition efficiencies of newly fabricated universal high-speed counter-current chromatograph for separation of two different types of sugar derivatives with organic-aqueous two-phase solvent systems

    PubMed Central

    Shinomiya, Kazufusa; Sato, Kazuki; Yoshida, Kazunori; Tokura, Koji; Maruyama, Hiroshi; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2013-01-01

    Universal high-speed counter-current chromatograph (HSCCC) was newly designed and fabricated in our laboratory. It holds a set of four column holders symmetrically around the rotary frame at a distance of 11.2 cm from the central axis. By engaging the stationary gear on the central axis of the centrifuge to the planetary gears on the column holder shaft through a set of idle gears, two pairs of diagonally located column holders simultaneously rotate about their own axes in the opposite directions: one forward (type-J planetary motion) and the other backward (type-I planetary motion) each synchronously with the revolution. Using the eccentric coil assembly, partition efficiencies produced by these two planetary motions were compared on the separation of two different types of sugar derivatives (4-methylumbelliferyl and 5-bromo-4-chloro-3-indoxyl sugar derivatives) using organic-aqueous two-phase solvent systems composed of n-hexane/ethyl acetate/1-butanol/methanol/water and aqueous 0.1 M sodium tetraborate, respectively. With lower phase mobile, better peak resolution was obtained by the type-J forward rotation for both samples probably due to higher retention of the stationary phase. With upper phase mobile, however, similar peak resolutions were obtained between these two planetary motions for both sugar derivatives. The overall results indicate that the present universal HSCCC is useful for counter-current chromatographic separation since each planetary motion has its specific applications: e.g., vortex CCC by the type-I planetary motion and HSCCC by the type-J planetary motion both for separation of various natural and synthetic products. PMID:24267319

  5. Partition efficiencies of newly fabricated universal high-speed counter-current chromatograph for separation of two different types of sugar derivatives with organic-aqueous two-phase solvent systems.

    PubMed

    Shinomiya, Kazufusa; Sato, Kazuki; Yoshida, Kazunori; Tokura, Koji; Maruyama, Hiroshi; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2013-12-27

    A new design of universal high-speed counter-current chromatograph (HSCCC) was fabricated in our laboratory. It holds a set of four column holders symmetrically around the rotary frame at a distance of 11.2cm from the central axis. By engaging the stationary gear on the central axis of the centrifuge to the planetary gears on the column holder shaft through a set of idle gears, two pairs of diagonally located column holders simultaneously rotate about their own axes in the opposite directions: one forward (type-J planetary motion) and the other backward (type-I planetary motion) each synchronously with the revolution. Using the eccentric coil assembly, partition efficiencies produced by these two planetary motions were compared on the separation of two different types of sugar derivatives (4-methylumbelliferyl and 5-bromo-4-chloro-3-indoxyl sugar derivatives) using organic-aqueous two-phase solvent systems composed of n-hexane/ethyl acetate/1-butanol/methanol/water and aqueous 0.1M sodium tetraborate, respectively. With lower phase mobile, better peak resolution was obtained by the type-J forward rotation for both samples probably due to higher retention of the stationary phase. With upper phase mobile, however, similar peak resolutions were obtained between these two planetary motions for both sugar derivatives. The overall results indicate that the present universal HSCCC is useful for counter-current chromatographic separation since each planetary motion has its specific applications: e.g., vortex CCC by the type-I planetary motion and HSCCC by the type-J planetary motion both for separation of various natural and synthetic products.

  6. Liquid chromatographic analysis of oxytocin and its related substances.

    PubMed

    Ashenafi, Dunge; Van Hemelrijck, Elise; Chopra, Shruti; Hoogmartens, Jos; Adams, Erwin

    2010-01-05

    A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

  7. A nitromethane-based HPLC system alternative to acetonitrile for carotenoid analysis of fruit and vegetables.

    PubMed

    Sandmann, Gerhard

    2010-01-01

    Acetonitrile-based HPLC systems are the most commonly used for carotenoid analysis from different plant tissues. Because of the acetonitrile shortage, an HPLC system for the separation of carotenoids on C(18) reversed-phase columns was developed in which an acetonitrile-alcohol-based mobile phase was replaced by nitromethane. This solvent comes closest to acetonitrile with respect to its elutrophic property. Our criterion was to obtain similar separation and retention times for a range of differently structured carotenoids. This was achieved by further increase in the lipophilicity with ethylacetate. For all the carotenoids which we tested, we found co-elution only of β-cryptoxanthin and lycopene. By addition of 1% of water, separation of this pair of carotenoids was also achieved. The final recommended mobile phase consisted of nitromethane : 2-propanol : ethyl acetate : water (79 : 10 : 10 : 1, by volume). On Nucleosil C(18) columns and related ones like Hypersil C(18), we obtained separation of carotenes, hydroxyl, epoxy and keto derivatives, which resembles the excellent separation properties of acetonitrile-based mobile phases on C(18) reversed phase columns. We successfully applied the newly developed HPLC system to the separation of carotenoids from different vegetables and fruit.

  8. High-performance liquid chromatographic assay for the determination of novel triazole antifungal agents in tissue. Application to tissue distribution studies.

    PubMed

    Khan, J K; Montaseri, H; Poglod, M; Bu, H Z; Daneshtalab, M; Micetich, R G

    2000-08-01

    A simple and rugged reversed-phase high-performance liquid chromatographic method with ultraviolet absorbance detection at 263 nm was developed and validated for the analysis of novel triazole antifungal agents SYN-2869 and its derivatives in tissues. The method involved homogenization with 0.01 M phosphate buffer (pH 7.8) for lung, brain and spleen tissues. The liver and kidneys were homogenized with acetonitrile:acetone (1:1). The plasma proteins were precipitated with ice-cold acetonitrile and supernatent was evaporated to dryness. The reconstituted samples were injected onto an HPLC system. SYN-2869 was separated from the matrix components on a symmetry C(18) column using a aqueous mobile phase of acetonitrile and water with a flow rate of 1 mL/min. A step gradient of 40-80% acetonitrile eluted SYN-2869 and the internal standard (SYN-2506). The linear range was 0.5-10 microgram/g (r(2) > 0.99). The limit of quantitation was 0.5 microgram/g. The inter-day precision and accuracy for SYN 2869 standard concentration were from 2.6 to 7.4% and from -1.56 to +3.29%, respectively. The method was applied to tissue samples collected from single intravenous administration to mice to evaluate the distribution of these novel antifungal agents to different tissues.

  9. A new direct laser photo-induced fluorescence method coupled on-line with liquid chromatographic separation for the simultaneous determination of anilides pesticides.

    PubMed

    Mbaye, O M A; Maroto, A; Gaye-Seye, M D; Stephan, L; Deschamps, L; Aaron, J J; Giamarchi, P

    2015-01-01

    A new direct laser photo-induced fluorescence high performance liquid chromatography (DL-PIF-HPLC) method is developed for the simultaneous determination of three anilide pesticides, namely carboxin, monalide and propanil. DL-PIF-HPLC uses a tunable Nd:YAG-OPO laser to obtain fluorescent photoproduct(s) and to simultaneously analyze their fluorescence in a short acquisition time with an intensified CCD camera, which improves the selectivity (by choosing the suitable excitation wavelength), increases the sensitivity (due to the high energy of the laser beam) and reduces the time of analysis, relative to the classical PIF methods. However, one of the main drawbacks of PIF methods is the presence of interferences with other compounds, such as other pesticides from the same group yielding similar fluorescent photoproducts, which reduces their selectivity. The analytical interest of DL-PIF-HPLC to avoid these interferences is demonstrated. The DL-PIF spectra, chromatographic conditions and analytical performances of DL-PIF-HPLC are presented for the simultaneous determination of three anilide pesticides. The calibration curves are linear over one order of magnitude and the limits of detection are in the ng mL(-1) range. The new DL-PIF-HPLC system has the advantage to combine the performances of both techniques, DL-PIF and liquid chromatography, and to improve the analysis selectivity.

  10. Analysis of Phenacylester Derivatives of Fatty Acids from Human Skin Surface Sebum by Reversed-Phase HPLC: Chromatographic Mobility as a Function of Physico-Chemical Properties

    PubMed Central

    Bodoprost, Juliana; Rosemeyer, Helmut

    2007-01-01

    A set of 13 fatty acids was transformed into their phenacyl esters by reaction with phenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions for the RP-18 HPL chromatographic separation of most of the esters has been worked out. Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test persons was taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane. Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in the sebum of all test persons. In the second part of the work the chromatographic mobility (RE values) of fatty acid phenacyl esters is correlated with calculated physico-chemical parameters of the corresponding acids. The best linear correlation was found between the RE and the logP values. This is helpful for the structural elucidation of un-identified fatty acids in a chromatogram.

  11. Core-Shell in Liquid Chromatography: Application for Determining Sulphonamides in Feed and Meat Using Conventional Chromatographic Systems

    PubMed Central

    Armentano, Antonio; Summa, Simona; Magro, Sonia Lo; D’Antini, Pasquale; Palermo, Carmen; Muscarella, Marilena

    2016-01-01

    A C18 column packed with core-shell particles was used for the chromatographic separation of sulphonamides in feed and meat by a conventional high performance liquid chromatography system coupled with a diode array detector. Two analytical methods, already used in our laboratory, have been modified without any changes in the extraction and clean-up steps and in the liquid chromatography instrumentation. Chromatographic conditions applied on a traditional 5-µm column have been optimized on a column packed with 2.6 µm core-shell particles. A binary mobile phase [acetate buffer solution at pH 4.50 and a mixture of methanol acetonitrile 50: 50 (v/v)] was employed in gradient mode at the flow rate of 1.2 mL with an injection volume of 6 µL. These chromatographic conditions allow the separation of 13 sulphonamides with an entire run of 13 minutes. Preliminary studies have been carried out comparing blanks and spiked samples of feed and meat. A good resolution and the absence of interferences were achieved in chromatograms for both matrices. Since no change was made to the sample preparation, the optimized method does not require a complete revalidation and can be used to make routine analysis faster. PMID:28217560

  12. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    NASA Astrophysics Data System (ADS)

    Li, Yi; Du, Xiaosong; Wang, Yang; Tai, Huiling; Qiu, Dong; Lin, Qinghao; Jiang, Yadong

    2014-05-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m.

  13. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    PubMed Central

    2014-01-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m. PMID:24899869

  14. Computer simulation for the convenient optimization of isocratic reversed-phase liquid chromatographic separations by varying temperature and mobile phase strength.

    PubMed

    Wolcott, R G; Dolan, J W; Snyder, L R

    2000-02-11

    Software is described which allows the rapid development of separations by means of isocratic reversed-phase liquid chromatography (RP-LC), based on the optimization of column temperature (T) and mobile phase strength (%B). For a given sample, four initial experiments are carried out at two different temperatures, using either isocratic or (better) gradient elution. If isocratic experiments are chosen for computer simulation, it is necessary to select appropriate values of %B for these initial runs. Literature data for solute retention as a function of T are reviewed, as a basis for estimating suitable values of %B at the two values of T selected. The use of optimized values of T and %B led to acceptable separations for three representative samples. The prediction of isocratic separation on the basis of initial gradient experiments is more convenient than the use of initial isocratic experiments, but less reliable. When gradient experiments are used, one additional isocratic experiment can improve the accuracy of such predictions by a "reflection" procedure. The latter approach was confirmed for predictions of both isocratic and gradient separation from initial gradient experiments.

  15. Chromatographic resolution of drug analogues: 3-hydroxy-3-methylglutarylcoenzyme A reductase inhibitors (statins).

    PubMed

    Tahir, Muhammad Saqlain; Adnan, Ahmad; Syed, Quratulain

    2016-05-01

    A high performance liquid chromatographic method for the simultaneous determination both qualitative and quantitative of cholesterol lowering statin drugs in pharmaceutical formulations has been developed. The most important advantage of developed method is that all seven statin drugs can be determined on a single chromatographic system without modification in detection wavelength. An organic modifier addition (25% v/v methanol) in the presence of buffer (20mM ammonium acetate; pH 4.0 adjusted with dilute acetic acid) played a key role in the resolution of statin drugs in gradient elution with acetonitrile. The drugs were separated on a Purospher Star 4.6mm × 25cm, 5μm, C18 column maintained at 25°C with 1mLmin(-1) flow rate using ultra violet detection at 240nm. Good separation (Rs > 2.5) was achieved in a short analysis allowing simultaneous determination of all seven statins. The effect of variation in flow rate, detection wavelength and column oven temperature was also studied. The proposed method was statistically validated in terms of precision, accuracy, linearity, specificity and robustness. The newly developed method proved to be specific, robust and accurate for the quantification of seven statins in commercial pharmaceutical formulations.

  16. High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases.

    PubMed

    Matarashvili, Iza; Shvangiradze, Iamze; Chankvetadze, Lali; Sidamonidze, Shota; Takaishvili, Nino; Farkas, Tivadar; Chankvetadze, Bezhan

    2015-12-01

    The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination.

  17. Counter-current chromatographic separation of glycoprotein components from Morchella esculenta (L.) with a polymer phase system by a cross-axis coil planet centrifuge.

    PubMed

    Wei, Y; Zhang, T; Ito, Y

    2001-05-11

    Using a cross-axis coil planet centrifuge, glycoproteins were separated from fermentation media of Morchella esculenta (L.) by high-speed counter-current chromatography. The performance of the apparatus was optimized with four standard proteins including pepsin, lysozyme, ovalbumin and hemoglobin and a polymer phase system composed of 12.5% (w/w) polyethylene glycol 8000 and 25% (w/w) potassium phosphate in distilled water at various pH values. Separations were performed by eluting the lower phosphate-rich phase at a flow-rate of 1.0 ml/min. Under the optimized conditions three glycoprotein components in Morchella esculenta (L.) were resolved within 6 h.

  18. Chromatographic and spectroscopic studies on the chiral recognition of sulfated beta-cyclodextrin as chiral mobile phase additive enantiomeric separation of a chiral amine.

    PubMed

    Ma, Shengli; Shen, Sherry; Haddad, Nizar; Tang, Wenjun; Wang, Jing; Lee, Heewon; Yee, Nathan; Senanayake, Chris; Grinberg, Nelu

    2009-02-20

    A fast enantiomeric separation of a chiral aromatic amine was achieved, using ultra high pressure liquid chromatography and highly sulfated beta-cyclodextrin (S-beta-CD) as a chiral additive in the mobile phase. The stationary phase consisted of a core-shell support with a particle size of 2.7mum. Under these conditions the base-line separation was obtained within 2.5min. The influence of the concentration of the additive, along with the thermodynamics of the separation, was studied. Vibrational circular dichroism (VCD) spectroscopy was applied to assess the absolute configuration of the two enantiomeric analytes, as well as the interaction of these enantiomers with the S-beta-CD. The VCD results revealed that S-beta-CD undergoes a temperature-induced conformational change. Further, VCD experiments indicate that the interactions of the two enantiomers with the S-beta-CD occur through an inclusion of the aromatic part of the analyte, as well as through electrostatic interaction between the protonated amine and the sulfate groups located at the narrow part of the S-beta-CD. Molecular mechanics calculations performed according to the VCD results are consistent with experimental data, providing further evidence of these interactions.

  19. Ultra high pressure in the second dimension of a comprehensive two-dimensional liquid chromatographic system for carotenoid separation in red chili peppers.

    PubMed

    Cacciola, Francesco; Donato, Paola; Giuffrida, Daniele; Torre, Germana; Dugo, Paola; Mondello, Luigi

    2012-09-14

    A comprehensive normal-phase × reversed-phase (NP-LC × RP-LC) liquid chromatography system was developed, and applied for analysis of the intact carotenoid composition of red chili peppers, with photodiode array and mass spectrometry detection. A micro-bore cyano column (250 mm × 1.0 mm, 5 μm d.p.) was chosen for the first dimension ((1)D) separation, interfaced to a second dimension ((2)D) C18 column (30 mm × 4.6 mm, 2.7 μm d.p.) packed with fused-core particles. Subsequently, two columns of the same stationary phase were coupled serially for second dimension separation, and operated under ultra high pressure LC conditions (UHPLC), within a cycle time of 1.50 or 1.00 min, and equal modulation times. Performances of the three different set-ups were evaluated, in terms of peak capacity values (n(c)), and afterwards corrected by taking into account both the under-sampling, and the orthogonality effects. After these adjustments, the peak capacity values were estimated as follows: n(c) 526, for the NP-LC × RP-LC system, n(c) 373, for the NP-LC × RP-UHPLC system with a 1.50 min modulation time, n(c) 639, for the NP-LC × RP-UHPLC system, with a 1.00 min modulation time. A total of 33 compounds were separated into 10 different chemical classes in the two-dimensional space, and identified by accurate IT-TOF (ion trap-time of flight) MS detection.

  20. New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

    PubMed

    Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

    2015-03-20

    Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.

  1. Parabens determination in cosmetic and personal care products exploiting a multi-syringe chromatographic (MSC) system and chemiluminescent detection.

    PubMed

    Rodas, Melisa; Portugal, Lindomar A; Avivar, Jessica; Estela, José Manuel; Cerdà, Víctor

    2015-10-01

    Parabens are widely used in dairy products, such as in cosmetics and personal care products. Thus, in this work a multi-syringe chromatographic (MSC) system is proposed for the first time for the determination of four parabens: methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) in cosmetics and personal care products, as a simpler, practical, and low cost alternative to HPLC methods. Separation was achieved using a 5mm-long precolumn of reversed phase C18 and multi-isocratic separation, i.e. using two consecutive mobile phases, 12:88 acetonitrile:water and 28:72 acetonitrile:water. The use of a multi-syringe buret allowed the easy implementation of chemiluminescent (CL) detection after separation. The chemiluminescent detection is based on the reduction of Ce(IV) by p-hydroxybenzoic acid, product of the acid hydrolysis of parabens, to excite rhodamine 6G (Rho 6G) and measure the resulting light emission. Multivariate designs combined with the concepts of multiple response treatments and desirability functions have been employed to simultaneously optimize and evaluate the responses. The optimized method has proved to be sensitive and precise, obtaining limits of detection between 20 and 40 µg L(-1) and RSD <4.9% in all cases. The method was satisfactorily applied to cosmetics and personal care products, obtaining no significant differences at a confidence level of 95% comparing with the HPLC reference method.

  2. Coal liquefaction process streams characterization and evaluation: Application of liquid chromatographic separation methods to THF-soluble portions of integrated two-stage coal liquefaction resids

    SciTech Connect

    Green, J.B.; Pearson, C.D.; Young, L.L.; Green, J.A. )

    1992-05-01

    This study demonstrated the feasibility of using non-aqueous ion exchange liquid chromatography (NIELC) for the examination of the tetrahydrofuran (THF)-soluble distillation resids and THF-soluble whole oils derived from direct coal liquefaction. The technique can be used to separate the material into a number of acid, base, and neutral fractions. Each of the fractions obtained by NIELC was analyzed and then further fractionated by high-performance liquid chromatography (HPLC). The separation and analysis schemes are given in the accompanying report. With this approach, differences can be distinguished among samples obtained from different process streams in the liquefaction plant and among samples obtained at the same sampling location, but produced from different feed coals. HPLC was directly applied to one THF-soluble whole process oil without the NIELC preparation, with limited success. The direct HPLC technique used was directed toward the elution of the acid species into defined classes. The non-retained neutral and basic components of the oil were not analyzable by the direct HPLC method because of solubility limitations. Sample solubility is a major concern in the application of these techniques.

  3. Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization.

    PubMed

    Pilon, Alan Cesar; Carnevale Neto, Fausto; Freire, Rafael Teixeira; Cardoso, Patrícia; Carneiro, Renato Lajarim; Da Silva Bolzani, Vanderlan; Castro-Gamboa, Ian

    2016-03-01

    A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min(-1) flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i-propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min(-1) flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols.

  4. Chromatographic behaviour of synthetic high pressure high temperature diamond in aqueous normal phase chromatography.

    PubMed

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

    2016-10-28

    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated under the conditions of hydrophilic interaction liquid chromatography (HILIC). A 50×4.6mm ID stainless steel column packed with HPHT particles of mean diameter 1.6μm and specific surface area 5.1m(2)g(-1) is used. According to the results of acid-base titration with NaOH the purified HPHT batch contains 4.59μeqg(-1) of protogenic, mainly carboxyl- and hydroxyl-, groups, which make this polar adsorbent suitable for use as a stationary phase in HILIC. The retention behaviour of several classes of polar compounds including benzoic and benzenesulfonic acids, nitro- and chlorophenols, various organic bases, and quaternary ammonium compounds are studied using acetonitrile and methanol based mobile phases containing 5-30v/v% of water. The effects of the buffer pH and concentration, column temperature and organic solvent content on retention of model compounds are also investigated. It is shown that both pH and acetonitrile/methanol ratio in the mobile phase can be used to vary the separation selectivity. Molecular adsorption mechanism (related to aqueous normal phase mode), rather than partitioning is established to be responsible for the retention.

  5. Thermodynamic characteristics of sorption extraction and chromatographic separation of anionic complexes of erbium and cerium with Trilon B on weakly basic anionite

    NASA Astrophysics Data System (ADS)

    Cheremisina, O. V.; Ponomareva, M. A.; Sagdiev, V. N.

    2016-03-01

    The adsorption of anionic complexes of erbium with Trilon B on D-403 anionite is studied at ionic strengths of 1 and 2 mol/kg (NaNO3) and temperatures of 298 and 343 K. The values of the stability constants of complex ions of REE with Trilon B and the Gibbs energies of complexation are calculated. The values of the Gibbs energy and the enthalpy and entropy of ion exchange are determined. Using the obtained thermo-dynamic and sorption characteristics, the possible separation of anionic complexes of erbium and cerium with Trilon B is demonstrated via frontal ion-exchange chromatography. A series of sorption capacities of anionic complexes of cerium, yttrium, and erbium is presented using the values of the Gibbs energy of ion exchange.

  6. In-line respeciation: an ion-exchange ion chromatographic method applied to the separation of degradation products of chemical warfare nerve agents in soil.

    PubMed

    Vermillion, W D; Crenshaw, M D

    1997-05-16

    The natural background of anions encountered when analyzing soil samples by ion chromatography (IC) present significant problems in the separation, detection and quantification of isopropyl methylphosphonic acid (IMPA) and methylphosphonic acid (MPA), the degradation products of sarin, a chemical warfare nerve agent. Using chemically-suppressed IC with conductivity detection, a commercially available ion-exchange column, and an isocratic binary eluent system, IMPA and MPA were determined in aqueous extracts of soil at sub-ppm (microgram/g) concentrations without the need for gradient elution or organic solvent eluent modifiers. Common soil anions such as chloride, nitrate, sulfate and phosphate do not interfere with the analysis method due to the composition of the binary eluent allowing for greater mobilization of multivalent anions (e.g., MPA, carbonate, and sulfate) while monovalent anions (e.g., IMPA and nitrate) are relatively unaffected. Carbonate is selectively removed by in-line respeciation to bicarbonate.

  7. Role of substituents in cyclodextrin derivatives for enantioselective gas chromatographic separation of chiral terpenoids in the essential oils of Mentha spicata.

    PubMed

    Pragadheesh, V S; Yadav, Anju; Chanotiya, Chandan Singh

    2015-10-01

    Enantioselective GC-FID and enantioselective GC-MS have been utilized under temperature gradient mode with differently substituted heptakis- and octakis-cyclodextrins to achieve the resolution of chiral terpenoids in the essential oil of indigenously grown cultivars of Mentha spicata. Modified cyclodextrins were derivatized in GC column for the separation of chiral terpenoids. A 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin doped into 14% cyanopropylphenyl/86%dimethylpolysiloxane (TBDE-β-CD) showed good enantioselectivity for all the studied chiral compounds excluding carvone. Carvone enantiomers were well resolved in 2,3-diacetoxy-6-tert-butyldimethylsilyl-β-cyclodextrin column (TBDA-β-CD) with enantioseparation (Es) of 1.006. A TBDE-β-CD provides maximum enantiomeric separation for β-pinene (Es 1.038), sabinene (Es 1.051), limonene (Es 1.045), isomenthone (Es 1.029) and α-terpineol (Es 1.014). Furthermore, enantiomer elution order reversal was observed for sabinene, menthone, terpinen-4-ol and menthol while changing from β- to γ-cyclodextrin phase. Carvone exhibits enantiomer elution order reversal by changing substituents i.e., methyl to acetyl at 2- & 3- position of the cyclodextrin derivative. Chiral constituents such as (+)-isomenthone, (-)-menthone, (1R,2S,5R)-(-)-menthol and (4S)-(+)-piperitone exist as a single enantiomer with >99% excess. Existence of (R)-(+)-limonene and (S)-(+)-carvone enantiomers has been proven first time in M. spicata essential oils and can be used as the marker for Indian origin.

  8. Stacking open-capillary electroosmotic pumps in series to boost the pumping pressure to drive high-performance liquid chromatographic separations.

    PubMed

    He, Chiyang; Zhu, Zaifang; Gu, Congying; Lu, Joann; Liu, Shaorong

    2012-03-02

    Numerous micropumps have been developed, but few of them can produce adequate flow rate and pressure for high-performance liquid chromatography (HPLC) applications. We have recently developed an innovative hybrid electroosmotic pump (EOP) to solve this problem. The basic unit of a hybrid pump consists of a +EOP (the pumping element is positively charged) and a -EOP (the pumping element is negatively charged). The outlet of the +EOP is then joined with the inlet of the -EOP, forming a basic pump unit, while the anode of a positive high voltage (HV) power supply is placed at the joint. The inlet and outlet of this pump unit are electrically grounded. With this configuration, we can stack many of such pump units in series to boost the pumping power. In this work, we describe in details how an open-capillary hybrid EOP is constructed and characterize this pump systematically. We also show that a hybrid EOP with ten serially stacked pump units can deliver a maximum pressure of 21.5 MPa (∼3100 psi). We further demonstrate the feasibility of using this hybrid EOP to drive eluents for HPLC separations of proteins and peptides.

  9. Stacking open-capillary electroosmotic pumps in series to boost the pumping pressure to drive high-performance liquid chromatographic separations

    DOE PAGES

    He, Chiyang; Zhu, Zaifang; Gu, Congying; ...

    2012-01-09

    Numerous micropumps have been developed, but few of them can produce adequate flow rate and pressure for high-performance liquid chromatography (HPLC) applications. We have recently developed an innovative hybrid electroosmotic pump (EOP) to solve this problem. The basic unit of a hybrid pump consists of a +EOP (the pumping element is positively charged) and a -EOP (the pumping element is negatively charged). The outlet of the +EOP is then joined with the inlet of the -EOP, forming a basic pump unit, while the anode of a positive high voltage (HV) power supply is placed at the joint. The inlet andmore » outlet of this pump unit are electrically grounded. With this configuration, we can stack many of such pump units in series to boost the pumping power. In this work, we describe in details how an open-capillary hybrid EOP is constructed and characterize this pump systematically. We also show that a hybrid EOP with ten serially stacked pump units can deliver a maximum pressure of 21.5 MPa (~3100 psi). Here, we further demonstrate the feasibility of using this hybrid EOP to drive eluents for HPLC separations of proteins and peptides.« less

  10. Stacking open-capillary electroosmotic pumps in series to boost the pumping pressure to drive high-performance liquid chromatographic separations

    SciTech Connect

    He, Chiyang; Zhu, Zaifang; Gu, Congying; Lu, Joann; Liu, Shaorong

    2012-01-09

    Numerous micropumps have been developed, but few of them can produce adequate flow rate and pressure for high-performance liquid chromatography (HPLC) applications. We have recently developed an innovative hybrid electroosmotic pump (EOP) to solve this problem. The basic unit of a hybrid pump consists of a +EOP (the pumping element is positively charged) and a -EOP (the pumping element is negatively charged). The outlet of the +EOP is then joined with the inlet of the -EOP, forming a basic pump unit, while the anode of a positive high voltage (HV) power supply is placed at the joint. The inlet and outlet of this pump unit are electrically grounded. With this configuration, we can stack many of such pump units in series to boost the pumping power. In this work, we describe in details how an open-capillary hybrid EOP is constructed and characterize this pump systematically. We also show that a hybrid EOP with ten serially stacked pump units can deliver a maximum pressure of 21.5 MPa (~3100 psi). Here, we further demonstrate the feasibility of using this hybrid EOP to drive eluents for HPLC separations of proteins and peptides.

  11. Simultaneous spectrophotometric determination of phosphate and silicate ions in river water by using ion-exclusion chromatographic separation and post-column derivatization.

    PubMed

    Nakatani, Nobutake; Kozaki, Daisuke; Masuda, Wakako; Nakagoshi, Nobukazu; Hasebe, Kiyoshi; Mori, Masanobu; Tanaka, Kazuhiko

    2008-06-30

    The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) by using ultra pure water as an eluent. After the post-column derivatization with molybdate and ascorbic acid, so-called molybdenum-blue, both ions were determined simultaneously by spectrophotometry. The effects of sulfuric acid, sodium molybdate and ascorbic acid concentrations and reaction coil length, which have relation to form the reduced complexes of molybdate and ions, on the detector response for phosphate and silicate ions were investigated. Under the optimized conditions (color-forming reactant, 50 mM sulfuric acid-10 mM sodium molybdate; reducing agent, 50 mM ascorbic acid; reaction coil length, 6 m), the calibration curves of phosphate and silicate ions were linear in the range of 50-2000 microg L(-1) as P and 250-10,000 microg L(-1) as Si. This method was successfully applied to water quality monitoring of Kurose-river watershed and it suggested that the effluent from a biological sewage treatment plant was significant source of phosphate ion in Kurose-river water.

  12. Acetone potentiation of acute acetonitrile toxicity in rats

    SciTech Connect

    Freeman, J.J.; Hayes, E.P.

    1985-01-01

    The purpose of these studies was to investigate the nature and mechanism of a toxicologic interaction between acetonitrile and acetone. Results of oral doe-response studies utilizing 1:1 (w/w) mixture of acetonitrile and acetone, or varying doses of acetonitrile administered together with a constant dose of acetone, indicated that acetone potentiated acute acetonitrile toxicity three- to fourfold in rats. The onset of severe toxicity (manifested by tremors and convulsions) was delayed in the groups dosed with both solvents compared to the groups that received acetonitrile or acetone alone. Blood cyanide (a metabolite of acetonitrile) and serum acetonitrile and acetone concentrations were measured after oral administration of 25% aqueous solutions of acetonitrile, acetone, or acetonitrile plus acetone. Concentrations of cyanide in the blood of rats given acetonitrile plus acetone remained near baseline, in contrast to the high concentrations found in rats dosed with acetonitrile alone. At 34-36 h, high blood cyanide concentrations were found in rats dosed with both of the solvents. This delayed onset of elevation of blood cyanide coincided with the occurrence of clinical signs and with the disappearance of serum acetone. In further pharmacokinetic studies, blood cyanide concentrations were measured after similar dosage regimens of acetone and acetonitrile. Peak cyanide concentrations were found to be significantly greater in rats dosed with both solvents than in rats given only acetonitrile. Administration of either sodium thiosulfate or a second dose of acetone prevented the toxicity associated with exposure to both solvents.

  13. Strong anion exchange liquid chromatographic separation of protein amino acids for natural 13C-abundance determination by isotope ratio mass spectrometry.

    PubMed

    Abaye, Daniel A; Morrison, Douglas J; Preston, Tom

    2011-02-15

    Amino acids are the building blocks of proteins and the analysis of their (13)C abundances is greatly simplified by the use of liquid chromatography (LC) systems coupled with isotope ratio mass spectrometry (IRMS) compared with gas chromatography (GC)-based methods. To date, various cation exchange chromatography columns have been employed for amino acid separation. Here, we report strong anion exchange chromatography (SAX) coupled to IRMS with a Liquiface interface for amino acid δ(13)C determination. Mixtures of underivatised amino acids (0.1-0.5 mM) and hydrolysates of representative proteins (prawns and bovine serum albumin) were resolved by LC/IRMS using a SAX column and inorganic eluents. Background inorganic carbon content was minimised through careful preparation of alkaline reagents and use of a pre-injector on-line carbonate removal device. SAX chromatography completely resolved 11 of the 16 expected protein amino acids following acid hydrolysis in underivatised form. Basic and neutral amino acids were resolved with 35 mM NaOH in isocratic mode. Elution of the aromatic and acidic amino acids required a higher hydroxide concentration (180 mM) and a counterion (NO 3-, 5-25 mM). The total run time was 70 min. The average δ(13)C precision of baseline-resolved peaks was 0.75‰ (range 0.04 to 1.06‰). SAX is a viable alternative to cation chromatography, especially where analysis of basic amino acids is important. The technology shows promise for (13)C amino acid analysis in ecology, archaeology, forensic science, nutrition and protein metabolism.

  14. Development and Validation of Reversed-Phase High Performance Liquid Chromatographic Method for Hydroxychloroquine Sulphate.

    PubMed

    Singh, A; Roopkishora; Singh, C L; Gupta, R; Kumar, S; Kumar, M

    2015-01-01

    In the present work new, simple reversed-phase high performance liquid chromatographic method was developed and validated for the determination of hydroxychloroquine sulphate in blood plasma. Chloroquine sulphate was used as an internal standard. The chromatographic separation was achieved with octadecyl silane Hypersil C18 column (250×6 mm, 5 μm) using water and organic (acetonitrile:methanol: 50:50, v/v) mobile phase in 75:25 v/v ratio, with sodium 1-pentanesulfonate and phosphoric acid. This organic phase was maintained at pH 3.0 by orthophosphoric acid. The flow rate of 2.0 ml/min(.) with detection at 343 nm was used in the analysis. The calibration curve of standard hydroxychloroquine sulphate was linear in range 0.1-20.0 μg/ml. The method was validated with respected to linearity, range, precision, accuracy, specificity and robustness studies according to ICH guidelines. The method was found to be accurate and robust to analyze the hydroxychloroquine sulphate in plasma samples.

  15. Aqueous Two-Phase Systems formed by Biocompatible and Biodegradable Polysaccharides and Acetonitrile.

    PubMed

    de Brito Cardoso, Gustavo; Souza, Isabela Nascimento; Pereira, Matheus M; Freire, Mara G; Soares, Cleide Mara Faria; Lima, Álvaro Silva

    2014-11-05

    In this work, it is shown that novel aqueous two-phase systems can be formed by the combination of acetonitrile and polysaccharides, namely dextran. Several ternary phase diagrams were determined at 25 °C for the systems composed of water + acetonitrile + dextran. The effect of the dextran molecular weight (6,000, 40,000 and 100,000 g.mol(-1)) was ascertained toward their ability to undergo liquid-liquid demixing. An increase in the dextran molecular weight favors the phase separation. Furthermore, the effect of temperature (25, 35 and 45 °C) was evaluated for the system constituted by the dextran of higher molecular weight. Lower temperatures are favorable for phase separation since lower amounts of dextran and acetonitrile are required for the creation of aqueous two-phase systems. In general, acetonitrile is enriched in the top phase while dextran is majorly concentrated in the bottom phase. The applicability of this new type of two-phase systems as liquid-liquid extraction approaches was also evaluated by the study of the partition behavior of a well-known antioxidant - vanillin - and used here as a model biomolecule. The optimized conditions led to an extraction efficiency of vanillin of 95% at the acetonitrile-rich phase.

  16. Aqueous Two-Phase Systems formed by Biocompatible and Biodegradable Polysaccharides and Acetonitrile

    PubMed Central

    de Brito Cardoso, Gustavo; Souza, Isabela Nascimento; Pereira, Matheus M.; Freire, Mara G.; Soares, Cleide Mara Faria; Lima, Álvaro Silva

    2015-01-01

    In this work, it is shown that novel aqueous two-phase systems can be formed by the combination of acetonitrile and polysaccharides, namely dextran. Several ternary phase diagrams were determined at 25 °C for the systems composed of water + acetonitrile + dextran. The effect of the dextran molecular weight (6,000, 40,000 and 100,000 g.mol−1) was ascertained toward their ability to undergo liquid-liquid demixing. An increase in the dextran molecular weight favors the phase separation. Furthermore, the effect of temperature (25, 35 and 45 °C) was evaluated for the system constituted by the dextran of higher molecular weight. Lower temperatures are favorable for phase separation since lower amounts of dextran and acetonitrile are required for the creation of aqueous two-phase systems. In general, acetonitrile is enriched in the top phase while dextran is majorly concentrated in the bottom phase. The applicability of this new type of two-phase systems as liquid-liquid extraction approaches was also evaluated by the study of the partition behavior of a well-known antioxidant – vanillin - and used here as a model biomolecule. The optimized conditions led to an extraction efficiency of vanillin of 95% at the acetonitrile-rich phase. PMID:25729320

  17. Determination of biocides as well as some biocide metabolites from facade run-off waters by solid phase extraction and high performance liquid chromatographic separation and tandem mass spectrometry detection.

    PubMed

    Bester, K; Lamani, X

    2010-08-06

    Biocides are used to protect buildings, boats, and other materials from microbial infestations. A huge variety of compounds are being used: isothiazolinones, e.g., to prevent bacterial growth in paints, triazines and phenylureas against algal growth on water exposed materials while carbamates are used against fungal investations. However these biocides can be leached from the respective materials. As these are very effective compounds it is important to know the concentrations of these biocides in the leachates as well as their leaching behaviour to assess their risk to the environment. In this study, a method for the determination of biocides from facade material run-off water by means of high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed. Due to the amphiphilic character and the expected varying pH-values in the samples, the extractions as well as the HPLC-method development proved to be demanding. The water samples (leachates) were buffered with a phosphate buffer to pH 7. As some of the biocides are very hydrophilic, different SPE cartridges were tested to identify the SPE material with the highest recovery rates for all compounds. For gaining a good separation, analyte trapping was performed on the HPLC column. Quantification was performed using a mass spectrometer in multi-reaction monitoring with two transitions per compound. The final recovery rates were conducted using a cartridge with a divenylbenzyl polymer sorbent. A combination of methanol and acetonitrile as eluents was used to reach recovery rates in the range of 70-100%. The limit of quantification for the compounds of interest ranged from 0.01 to 0.1 microg/L.

  18. 40 CFR 721.10118 - Substituted aryl acetonitrile (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted aryl acetonitrile (generic... Specific Chemical Substances § 721.10118 Substituted aryl acetonitrile (generic). (a) Chemical substance... substituted aryl acetonitrile (PMN P-05-35) is subject to reporting under this section for the significant...

  19. 40 CFR 721.10118 - Substituted aryl acetonitrile (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Substituted aryl acetonitrile (generic... Specific Chemical Substances § 721.10118 Substituted aryl acetonitrile (generic). (a) Chemical substance... substituted aryl acetonitrile (PMN P-05-35) is subject to reporting under this section for the significant...

  20. 40 CFR 721.10118 - Substituted aryl acetonitrile (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Substituted aryl acetonitrile (generic... Specific Chemical Substances § 721.10118 Substituted aryl acetonitrile (generic). (a) Chemical substance... substituted aryl acetonitrile (PMN P-05-35) is subject to reporting under this section for the significant...

  1. 40 CFR 721.10118 - Substituted aryl acetonitrile (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Substituted aryl acetonitrile (generic... Specific Chemical Substances § 721.10118 Substituted aryl acetonitrile (generic). (a) Chemical substance... substituted aryl acetonitrile (PMN P-05-35) is subject to reporting under this section for the significant...

  2. 40 CFR 721.10118 - Substituted aryl acetonitrile (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Substituted aryl acetonitrile (generic... Specific Chemical Substances § 721.10118 Substituted aryl acetonitrile (generic). (a) Chemical substance... substituted aryl acetonitrile (PMN P-05-35) is subject to reporting under this section for the significant...

  3. Rapid ion-pair liquid chromatographic method for the determination of fenbendazole marker residue in fermented dairy products.

    PubMed

    Vousdouka, Venetia I; Papapanagiotou, Elias P; Angelidis, Apostolos S; Fletouris, Dimitrios J

    2017-04-15

    A simple, rapid and sensitive liquid chromatographic method that allows for the quantitative determination of fenbendazole residues in fermented dairy products is described. Samples were extracted with a mixture of acetonitrile-phosphoric acid and the extracts were defatted with hexane to be further partitioned into ethyl acetate. The organic layer was evaporated to dryness and the residue was reconstituted in mobile phase. Separation of fenbendazole and its sulphoxide, sulphone, and p-hydroxylated metabolites was carried out isocratically with a mobile phase containing both positively and negatively charged pairing ions. Overall recoveries ranged from 79.8 to 88.8%, while precision data, based on within and between days variations, suggested an overall relative standard deviation of 6.3-11.0%. The detection and quantification limits were lower than 9 and 21μg/kg, respectively. The method has been successfully applied to quantitate fenbendazole residues in Feta cheese and yoghurt made from spiked and incurred ovine milk.

  4. Liquid chromatographic determination of sitagliptin either alone or in ternary mixture with metformin and sitagliptin degradation product.

    PubMed

    El-Bagary, Ramzia I; Elkady, Ehab F; Ayoub, Bassam M

    2011-07-15

    Two reversed-phase liquid chromatographic (RP-LC) methods have been developed for the determination of sitagliptin phosphate monohydrate (STG). The first method comprised the determination of STG alone in bulk and plasma; and in its pharmaceutical preparation. This method was based on isocratic elution of STG using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (7.8)-acetonitrile (70:30, v/v) at a flow rate of 1 mL min(-1) with flourometric detection. The flourometric detector was operated at 267 nm for excitation and 575 nm for emission. In the second method, the simultaneous determination of STG and metformin (MET) in the presence of sitagliptin alkaline degradation product (SDP) has been developed. In this method, the ternary mixture of STG, MET and SDP was separated using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile-methanol (30:50:20, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 220 nm. Chromatographic separation in the two methods was achieved on a Symmetry(®) Waters C18 column (150 mm×4.6 mm, 5 μm). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.25-200 μg mL(-1) for STG with the first method and 5-160 μg mL(-1), 25-800 μg mL(-1) for STG and MET, respectively with the second method. The optimized methods were validated and proved to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical preparations.

  5. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-13

    A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

  6. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  7. Selective separation of flavonoid glycosides in Dalbergia odorifera by matrix solid-phase dispersion using titania.

    PubMed

    Xu, Lingyan; Shi, Hui; Liang, Tu; Feng, Jiatao; Jin, Yu; Ke, Yanxiong; Liang, Xinmiao

    2011-06-01

    Dalbergia odorifera contains high concentrations of flavonoid aglycones and trace flavonoid glycosides. In this study, trace flavonoid glycosides were separated from D. odorifera by titania with matrix solid-phase dispersion (MSPD). Before the MSPD experiment, four standards, including two isoflavone glycosides (genistin and formononetin-8-C-apiosyl (1-6)-glucoside) and their aglycones (genistein and formononetin), were used to compare their retention on a titania column. The effect of acetonitrile concentration and pH on their retention was investigated and a conclusion was drawn that high acetonitrile concentration and pH lead to the greatest difference in the retention of flavonoid as glycosides and aglycones. Besides hydrophilic interaction and ligand-exchange interaction may exist between sugar moiety of flavonoid glycoside and titania, so that flavonoid glycosides have stronger retention than that of aglycones. Based on the chromatographic rule of flavonoid as glycosides and aglycones on the titania column, the MSPD method was optimized to elute high concentration flavonoid aglycones first with 90% acetonitrile and 10% water containing 100 mM ammonium acetate buffer, and then to elute trace flavonoid glycosides with 20% acetonitrile and 80% water containing 1% trifluoroacetate (TFA). Isolated flavonoid glycosides were further analyzed by UPLC-MS/MS, and their fragmentation in MS(2) showed they are C-glycosyl flavonoids.

  8. Combined cation-exchange and extraction chromatographic method of pre-concentration and concomitant separation of Cu(II) with high molecular mass liquid cation exchanger after its online detection.

    PubMed

    Mandal, B; Roy, U S; Datta, D; Ghosh, N

    2011-08-19

    A selective method has been developed for the extraction chromatographic trace level separation of Cu(II) with Versatic 10 (liquid cation exchanger) coated on silanised silica gel (SSG-V10). Cu(II) has been extracted from 0.1M acetate buffer at the range of pH 4.0-5.5. The effects of foreign ions, pH, flow-rate, stripping agents on extraction and elution have been investigated. Exchange capacity of the prepared exchanger at different temperatures with respect to Cu(II) has been determined. The extraction equilibrium constant (K(ex)) and different standard thermodynamic parameters have also been calculated by temperature variation method. Positive value of ΔH (7.98 kJ mol⁻¹) and ΔS (0.1916 kJ mol⁻¹) and negative value of ΔG (-49.16 kJ mol⁻¹) indicated that the process was endothermic, entropy gaining and spontaneous. Preconcentration factor was optimized at 74.7 ± 0.2 and the desorption constants K(desorption)¹(1.4 × 10⁻²) and K(desorption)²(9.8 × 10⁻²) were determined. The effect of pH on R(f) values in ion exchange paper chromatography has been investigated. In order to investigate the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. Cu(II) has been separated from synthetic binary and multi-component mixtures containing various metal ions associated with it in ores and alloy samples. The method effectively permits sequential separation of Cu(II) from synthetic quaternary mixture containing its congeners Bi(III), Sn(II), Hg(II) and Cu(II), Cd(II), Pb(II) of same analytical group. The method was found effective for the selective detection, removal and recovery of Cu(II) from industrial waste and standard alloy samples following its preconcentration on the column. A plausible mechanism for the extraction of Cu(II) has been suggested.

  9. Design of a coil satellite centrifuge and its performance on counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives with polar organic-aqueous two-phase solvent systems.

    PubMed

    Shinomiya, Kazufusa; Tokura, Koji; Kimura, Emiru; Takai, Midori; Harikai, Naoki; Yoshida, Kazunori; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2015-05-01

    A new high-speed counter-current chromatograph, named coil satellite centrifuge (CSC), was designed and fabricated in our laboratory. The CSC apparatus produces the satellite motion such that the coiled column simultaneously rotates around the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3). In order to achieve this triplicate rotary motion without twisting of the flow tube, the rotation of each axis was determined by the following formula: ω1=ω2+ω3. This relation enabled to lay out the flow tube without twisting by the simultaneous rotation of three axes. The flow tube was introduced from the bottom side of the apparatus into the sun axis of the first rotary frame reaching the upper side of the planet axis and connected to the column in the satellite axis. The performance of the apparatus was examined on separation of 4-methylumbelliferyl (MU) sugar derivatives as test samples with organic-aqueous two-phase solvent systems composed of ethyl acetate/1-butanol/water (3:2:5, v/v) for lower phase mobile and (1:4:5, v/v) for upper phase mobile. With lower phase mobile, five 4-MU sugar derivatives including β-D-cellobioside (Cel), β-D-glucopyranoside, α-D-mannopyranoside, β-D-fucopyranoside and α-L-fucopyranoside (α-L-Fuc) were separated with the combined rotation around each axis at counterclockwise (CCW) (ω1) - CCW (ω2) - CCW (ω3) by the flow tube distribution. With upper phase mobile, three 4-MU sugar derivatives including α-L-Fuc, β-D-galactopyranoside and Cel were separated with the combined rotation around each axis at clockwise (CW) (ω1) - CW (ω2) - CW (ω3) by the flow tube distribution. A series of experiments on peak resolution and stationary phase retention revealed that better partition efficiencies were obtained at the flow rate of 0.5 mL/min (column 1) and 0.8 mL/min (column 2) for lower phase mobile and 0.2 mL/min (column 1) and 0.4 mL/min (column 2) for upper phase

  10. Effect of dilution on compressibility of naproxen in acetonitrile studied by ultrasonic method

    NASA Astrophysics Data System (ADS)

    Marczak, W.; Kowalska, T.; Bucek, M.; Piotrowski, D.; Sajewicz, M.

    2006-11-01

    Naproxen, ibuprofen, and ketoprofen are non-steroidal anti-inflammatory drugs. All of them belong to chiral 2-arylpropionic acids (2-APAs). Chiral compounds may remain in a patient's body as two antimers, even if administered as a single one, due to transenantiomerization. That is dangerous if therapeutic enantiomer has a toxic antipode. Chromatographic data suggest that solutions of S-(+)-naproxen in acetonitrile are stiffer than the pure solvent that favours oscillatory transenantiomerisation. Acoustic and volumetric studies of dilute solutions of naproxen in acetonitrile have been undertaken to verify that supposition. The molar adiabatic compressibility and volume depend linearly on the molar percent of naproxen at temperatures from 298.15 K to 313.15 K. Limiting partial compressibility of naproxen is close to zero and decreases slightly with increasing temperature. Thus, the compressibility of dilute solutions is mainly due to compressibility of acetonitrile, while naproxen is virtually incompressible. The hydrogen-bonded dimers of naproxen probably remain intact, even at infinite dilution.

  11. Formation and recombination of protonated acetonitrile clusters

    NASA Astrophysics Data System (ADS)

    Plasil, R.; Glosík, J.; Zakouril, P.

    1999-07-01

    Formation of the protonated acetonitrile cluster ions CH3CNH+.CH3CN and their subsequent dissociative recombination with electrons was studied in a high-pressure flowing afterglow using the axially movable Langmuir probe. The first step is the binary proton transfer reaction of H3O+ with CH3CN with the rate coefficient k1 = (5.9±1.9) × 10-9 cm3 s-1. Resulting CH3CNH+ ions further associate with the neutral acetonitrile molecules at pressures 3-5 Torr with the effective binary rate coefficient k2eff = (2.1±0.7) × 10-9 cm3 s-1 forming the clusters H+.(CH3CN)2. Further reaction of these clusters with CH3CN is very slow with the effective binary rate coefficient k3eff = (1.1±0.3) × 10-12 cm3 s-1. The large difference between k2eff and k3eff facilitated the study of dissociative recombination of H+.(CH3CN)2 cluster ions with electrons at thermal energy and pressure p = 4.5-7.0 Torr. The recombination rate coefficient thus obtained is (2.8±1) × 10-6 cm3 s-1.

  12. Calixarene-based extraction chromatographic separation of ¹³⁵Cs and ¹³⁷Cs in environmental and waste samples prior to sector field ICP-MS analysis.

    PubMed

    Russell, Ben C; Warwick, Phil E; Croudace, Ian W

    2014-12-02

    Advances in the sensitivities achievable by sector field inductively coupled plasma mass spectrometry (ICP-SFMS) offer the prospect of low-level measurement of shorter and longer lived radionuclides, thus expanding options for environmental and radioactively contaminated land assessment. In ICP-SFMS, the critical requirement for accurate detection is the effective chemical separation of isobaric and polyatomic interferences prior to sample introduction. As instrumental detection limit capability improves, accurate radionuclide determination requires highly effective separation materials that combine high analyte selectivity with subsequent quantitative analyte recovery compatible with ICP-SFMS detection. Two radioactive isotopes measurable by ICP-SFMS are the high yield fission products (135)Cs and (137)Cs that have entered the environment as a result of anthropogenic nuclear activities. ICP-SFMS enables reliable measurement of (135)Cs/(137)Cs ratios, which can be used as a forensic tool in determining the source of nuclear contamination. The critical requirement for accurate detection is the effective removal of isobaric interferences from (135)Ba and (137)Ba prior to measurement. A number of exchange materials can effectively extract Cs; however, non-quantitative elution of Cs makes subsequent ICP-SFMS quantification challenging. A novel extraction chromatographic resin has been developed by dissolving calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) in octan-1-ol and loading onto an Amberchrom CG-71 prefilter resin material. Preparation of the material takes less than 1 h and, at an optimal concentration of 3 M HNO3, shows high selectivity toward Cs, which is effectively eluted in 0.05 M HNO3. The procedure developed shows high Cs selectivity and Ba decontamination from digests of complex matrixes including a saltmarsh sediment contaminated by aqueous discharges from a nuclear fuel reprocessing facility. Repeated tests show the resin can be reused up to

  13. Assessment of acetone as an alternative to acetonitrile in peptide analysis by liquid chromatography/mass spectrometry.

    PubMed

    Fritz, Ria; Ruth, Wolfgang; Kragl, Udo

    2009-07-01

    Acetonitrile as a solvent used in liquid chromatography/mass spectrometry (LC/MS) of peptides and proteins is a relatively toxic solvent (LD50 oral; rat; 2,460 mg/kg) compared to alternatives like methanol (LD50 oral; rat; 5,628 mg/kg) and acetone (LD50 oral; rat; 5,800 mg/kg). Strategies to minimize its consumption in LC are either to reduce the inner diameter of the column or replace acetonitrile with a suitable alternative. Methanol is often recommended to replace acetonitrile in peptide analysis. In this study however, the main focus lies on another alternative solvent for LC/MS of peptides; acetone. A number of model proteins were tryptically digested and the peptide solutions were analyzed on a linear trap quadrupole (LTQ) mass spectrometer. The performances of acetonitrile, methanol and acetone were compared according to the quality of the chromatograms obtained and identification of the peptides using the BioWorks software developed by Thermo Scientific. In accordance to the elutropic series, acetone was found to significantly reduce the retention times of peptides separated by C18 column material with regard to acetonitrile while methanol led to increased retention times. Acetone was the superior solvent to methanol for most of the tested model proteins reaching similar sequence coverage and numbers of identified peptides as acetonitrile. We therefore propose acetone as an alternative to acetonitrile in LC/MS of peptides.

  14. Stability-indicating chromatographic methods for the determination of some oxicams.

    PubMed

    Taha, Elham Anwer; Salama, Nahla Nour; Abdel Fattah, Laila el-Said

    2004-01-01

    Two sensitive and selective methods were developed for the determination of some oxicams, namely, lornoxicam (LOX), tenoxicam (TEX), and meloxicam (MEX), in the presence of their alkaline degradation products. The first method is based on the thin-layer chromatographic separation of the 3 drugs from their alkaline degradation products, followed by densitometric measurement of the intact drug spots for LOX, TEX, and MEX at 380, 370, and 364 nm, respectively. The developing systems used for separation are ethyl acetate-methanol-26% ammonia (17 + 3 + 0.35, v/v/v) for LOX and TEX and chloroform-n-hexane-96.0% acetic acid (18 + 1 + 1, v/v/v) for MEX. The linear ranges were 0.25-6.0 microg/spot for LOX and TEX and 0.5-10 microg/spot for MEX, with mean recoveries of 99.80 +/- 1.32, 100.57 +/- 1.34, and 100.71 +/- 1.57%, respectively. The second method is based on the liquid chromatographic separation of the 3 drugs from their alkaline degradation products on a reversed-phase C18 column, using mobile phases of methanol-acetonitrile-acetate buffer, pH 4.6 (4.5 + 0.5 + 5.0, v/v/v) for LOX and MEX and methanol-acetonitrile-acetate buffer, pH 4.6 (1.9 + 0.1 + 3.0, v/v/v) for TEX at ambient temperature. Quantification is achieved by UV detection at 280 nm, based on peak area. The linear ranges were 0.5-20 microg/mL for LOX and TEX and 1.25-50 microg/mL for MEX, with mean recoveries of 99.81 +/- 1.01, 98.90 +/- 1.61, and 100.86 +/- 1.55%, respectively. The methods were validated according to guidelines of the International Conference on Harmonization. The developed methods were successfully applied to the determination of LOX, TEX, and MEX in bulk powder, laboratory-prepared mixtures containing different percentages of degradation products, and pharmaceutical dosage forms.

  15. Application of Analytical Quality by Design concept for bilastine and its degradation impurities determination by hydrophilic interaction liquid chromatographic method.

    PubMed

    Terzić, Jelena; Popović, Igor; Stajić, Ana; Tumpa, Anja; Jančić-Stojanović, Biljana

    2016-06-05

    This paper deals with the development of hydrophilic interaction liquid chromatographic (HILIC) method for the analysis of bilastine and its degradation impurities following Analytical Quality by Design approach. It is the first time that the method for bilastine and its impurities is proposed. The main objective was to identify the conditions where an adequate separation in minimal analysis duration could be achieved within a robust region. Critical process parameters which have the most influence on method performance were defined as acetonitrile content in the mobile phase, pH of the aqueous phase and ammonium acetate concentration in the aqueous phase. Box-Behnken design was applied for establishing a relationship between critical process parameters and critical quality attributes. The defined mathematical models and Monte Carlo simulations were used to identify the design space. Fractional factorial design was applied for experimental robustness testing and the method is validated to verify the adequacy of selected optimal conditions: the analytical column Luna(®) HILIC (100mm×4.6mm, 5μm particle size); mobile phase consisted of acetonitrile-aqueous phase (50mM ammonium acetate, pH adjusted to 5.3 with glacial acetic acid) (90.5:9.5, v/v); column temperature 30°C, mobile phase flow rate 1mLmin(-1), wavelength of detection 275nm.

  16. C₁₈-bound porous silica monolith particles as a low-cost high-performance liquid chromatography stationary phase with an excellent chromatographic performance.

    PubMed

    Ali, Faiz; Cheong, Won Jo

    2014-12-01

    Ground porous silica monolith particles with an average particle size of 2.34 μm and large pores (363 Å) exhibiting excellent chromatographic performance have been synthesized on a relatively large scale by a sophisticated sol-gel procedure. The particle size distribution was rather broad, and the d(0.1)/d(0.9) ratio was 0.14. The resultant silica monolith particles were chemically modified with chlorodimethyloctadecylsilane and end-capped with a mixture of hexamethyldisilazane and chlorotrimethylsilane. Very good separation efficiency (185,000/m) and chromatographic resolution were achieved when the C18 -bound phase was evaluated for a test mixture of five benzene derivatives after packing in a stainless-steel column (1.0 mm × 150 mm). The optimized elution conditions were found to be 70:30 v/v acetonitrile/water with 0.1% trifluoroacetic acid at a flow rate of 25 μL/min. The column was also evaluated for fast analysis at a flow rate of 100 μL/min, and all the five analytes were eluted within 3.5 min with reasonable efficiency (ca. 60,000/m) and resolution. The strategy of using particles with reduced particle size and large pores (363 Å) combined with C18 modification in addition to partial-monolithic architecture has resulted in a useful stationary phase (C18 -bound silica monolith particles) of low production cost showing excellent chromatographic performance.

  17. Application of optically pure amines as chiral auxiliaries to develop trichloro-s-triazine-based new chiral derivatizing reagents for reversed-phase high-performance liquid chromatographic enantioseparation of DL-selenomethionine.

    PubMed

    Bhushan, Ravi; Lal, Manohar

    2013-08-01

    (R)-(+)-naphthylethyl amine and (S)-(+)-1-benzyl-3-aminopyrrolidine were incorporated as chiral auxiliaries, by nucleophilic substitution of chlorine atoms, in cyanuric chloride (CC) or its 6-butoxy derivative. There were obtained four new chiral derivatizing reagents (CDRs) as two dichloro and two monochloro triazine reagents. The CDRs so obtained were characterized and their optical purity was ascertained. Diastereomers of dl-selenomethionine were synthesized under microwave irradiation for 60 or 90 s (at 80% power of 800 W). Reversed-phase high-performance liquid chromatographic separation of diastereomers was carried out on a C18 column using mixtures of acetonitrile with aqueous trifluoroacetic acid as mobile phase. The detection was made at 230 nm using a photodiode array detector. The separation behaviors in terms of retention times and resolutions were compared. The separation method was validated for limit of detection, linearity, accuracy, precision, and recovery.

  18. Pyrolysis and Combustion of Acetonitrile (CH{sub 3}CN)

    SciTech Connect

    Britt, P.F.

    2002-05-22

    Acetonitrile (CH{sub 3}CN) is formed from the thermal decomposition of a variety of cyclic, noncyclic, and polymeric nitrogen-containing compounds such as pyrrole and polyacrylonitrile. The pyrolysis and combustion of acetonitrile have been studied over the past 30 years to gain a more detailed understanding of the complex mechanisms involved in the release of nitrogen-containing compounds such as hydrogen cyanide (HCN) in fires and nitrogen oxides (NOx) in coal combustion. This report reviews the literature on the formation of HCN and NOx from the pyrolysis and combustion of acetonitrile and discusses the possible products found in an acetonitrile fire.

  19. A validated stability-indicating liquid chromatographic method for the determination of retapamulin in topical dosage form.

    PubMed

    Nalwade, Santaji; Reddy, Vangala Ranga

    2014-03-01

    A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of retapamulin in topical dosage form. The chromatographic separation is achieved by using a C18 column (XTerra RP 18 250 × 4.6 mm, 5 µm) at 30°C. The mobile phase comprises a mixture of 0.05M potassium dihydrogen phosphate buffer (pH 6.1), acetonitrile and methanol in the ratio of 35:50:15 (v/v/v). The flow rate is set at 1.0 mL/min and chromatograms are extracted at 243 nm using a photodiode array detector. The method is validated with respect to linearity, accuracy, precision, robustness and forced degradation studies, which further prove the stability-indicating supremacy of the method. During forced degradation studies, retapamulin is observed to be labile to oxidative and base hydrolysis stress and stable in thermal, photolytic and acid hydrolysis stress. The degradation products are well separated from the retapamulin peak, thus proving the stability-indicating superiority of the method. The method is found to be sensitive for retapamulin, with a detection limit of 25 ng/mL and a quantification limit of 80 ng/mL. The proposed method is found to be very sensitive and accurate for the determination of retapamulin in topical dosage form. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate and column temperature.

  20. Design of a novel coil satellite centrifuge and its performance on counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives with organic-aqueous two-phase solvent systems

    PubMed Central

    Shinomiya, Kazufusa; Tokura, Koji; Kimura, Emiru; Takai, Midori; Harikai, Naoki; Yoshida, Kazunori; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2015-01-01

    A new high-speed counter-current chromatograph, named coil satellite centrifuge (CSC), was designed and fabricated in our laboratory. The CSC apparatus produces the satellite motion such that the coiled column simultaneously rotates around the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3). In order to achieve this triplicate rotary motion without twisting of the flow tube, the rotation of each axis was determined by the following formula: ω1 = ω2 + ω3. This relation enabled to lay out the flow tube by two different ways, the SS type and the JS type. In the SS type, the flow tube was introduced from the upper side of the apparatus into the sun axis of the first rotary frame and connected to the planet axis of the second rotary frame like a double letter SS. In the JS type, the flow tube was introduced from the bottom of the apparatus into the sun axis reaching the upper side of the planet axis an inversed letter J, followed by distribution as in the SS type. The performance of the apparatus was examined on separation of 4-methylumbelliferyl (MU) sugar derivatives as test samples with organic-aqueous two-phase solvent systems composed of ethyl acetate/1-butanol/water (3 : 2 : 5, v/v) for lower phase mobile and (1 : 4 : 5, v/v) for upper phase mobile. With lower phase mobile, five 4-MU sugar derivatives including β-D-cellobioside (Cel), β-D-glucopyranoside, α-D-mannopyranoside, β-D-fucopyranoside and α-L-fucopyranoside (α-L-Fuc) were separated with the combined rotation around each axis at counterclockwise (CCW) (ω1) – CCW (ω2) – CCW (ω3) by the JS type flow tube distribution. With upper phase mobile, three 4-MU sugar derivatives including α-L-Fuc, β-D-galactopyranoside and Cel were separated with the combined rotation around each axis at clockwise (CW) (ω1) – CW (ω2) – CW (ω3) by the JS type flow tube distribution. A series of experiments on peak resolution and

  1. A simple 96-well liquid-liquid extraction with a mixture of acetonitrile and methyl t-butyl ether for the determination of a drug in human plasma by high-performance liquid chromatography with tandem mass spectrometry.

    PubMed

    Xue, Y-J; Pursley, Janice; Arnold, Mark E

    2004-02-04

    A simple 96-well plate liquid-liquid extraction (LLE), liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of a basic drug candidate in human plasma. Against the wisdom of conventional approaches, an aqueous/organic miscible solvent, acetonitrile, was used for liquid-liquid extraction along with methyl t-butyl ether. The use of acetonitrile effectively eliminated the formation of the irregular emulsion between aqueous/organic interfaces and modulated the polarity of the extraction solvents to achieve the desired recovery. This approach, which solved the emulsion problem, permitted the method to be automated using standard 96-well plate technology. A practical application was demonstrated through the use of this technique in the measurement of a novel drug in human plasma samples by LC/MS/MS. Chromatographic separation was achieved isocratically on a Phenomenox C18(2) Luna column (2 mm x 50 mm, 5 microm). The mobile phase contained 60% of 0.1% formic acid and 40% acetonitrile. Detection was by positive ion electrospray tandem mass spectrometry. The standard curve, which ranged from 1.22 to 979ng/ml, was fitted to a 1/x2 weighted quadratic regression model. The validation results show that this method was very rugged and had excellent precision and accuracy. The actual sample analysis results further demonstrated that this extraction procedure is well suited for real life applications. It is expected that with some modifications, this approach can be applied for the extraction of similar compounds from various biological fluids.

  2. Optimisation of the separation of herbicides by linear gradient high performance liquid chromatography utilising artificial neural networks.

    PubMed

    Tran, Anh T K; Hyne, Ross V; Pablo, Fleur; Day, W Roy; Doble, P

    2007-02-28

    An artificial neural network (ANN) was employed to model the chromatographic response surface for the linear gradient separation of 10 herbicides that are commonly detected in storm run-off water in agricultural catchments. The herbicides (dicamba, simazine, 2,4-D, MCPA, triclopyr, atrazine, diuron, clomazone, bensulfuron-methyl and metolachlor) were separated using reverse phase high performance liquid chromatography and detected with a photodiode array detector. The ANN was trained using the pH of the mobile phase and the slope of the acetonitrile/water gradient as input variables. A total of nine experiments were required to generate sufficient data to train the ANN to accurately describe the retention times of each of the herbicides within a defined experimental space of mobile phase pH range 3.0-4.8 and linear gradient slope 1-4% acetonitrile/min. The modelled chromatographic response surface was then used to determine the optimum separation within the experimental space. This approach allowed the rapid determination of experimental conditions for baseline resolution of all 10 herbicides. Illustrative examples of determination of these components in Milli-Q water, Sydney mains water and natural water samples spiked at 0.5-1mug/L are shown. Recoveries were over 70% for solid-phase extraction using Waters Oasis((R)) HLB 6cm(3) cartridges.

  3. Different Spectrophotometric and Chromatographic Methods for Determination of Mepivacaine and Its Toxic Impurity.

    PubMed

    Abdelwahab, Nada S; Fared, Nehal F; Elagawany, Mohamed; Abdelmomen, Esraa H

    2017-02-21

    Stability-indicating spectrophotometric, TLC-densitometric, and ultra-performance LC (UPLC) methods were developed forthe determination of mepivacaine HCl (MEP) in the presence of its toxic impurity, 2,6-dimethylanaline (DMA). Different spectrophotometric methods were developed for the determination of MEP and DMA. In a dual-wavelength method combined with direct spectrophotometric measurement, the absorbance difference between 221.4 and 240 nm was used for MEP measurements, whereas the absorbance at 283 nm was used for measuring DMA in the binary mixture. In the second-derivative method, amplitudes at 272.2 and 232.6 nm were recorded and used for the determination of MEP and DMA, respectively. The developed TLC-densitometric method depended on chromatographic separation using silica gel 60 F254 TLC plates as a stationary phase and methanol-water-acetic acid (9 + 1 + 0.1, v/v/v) as a developing system, with UV scanning at 230 nm. The developed UPLC method depended on separation using a C18 column (250 × 4.6 mm id, 5 μm particle size) as a stationary phase and acetonitrile-water (40 + 60, v/v; pH 4 with phosphoric acid) as a mobile phase at a flow rate of 0.4 mL/min, with UV detection at 215 nm. The chromatographic run time was approximately 1 min. The proposed methods were validated with respect to International Conference on Harmonization guidelines regarding precision, accuracy, ruggedness, robustness, and specificity.

  4. Comparison of protein profiles between acetonitrile- and non-acetonitrile-treated sera from patients with nasopharyngeal carcinomas.

    PubMed

    Huang, Yuan-Jiao; Deng, Kai-Feng; Xuan, Chao; Zhang, Bei-Bei; Zhou, Yi; Yang, Xiaoli; He, Ming

    2011-05-01

    Serum proteins may be abnormally increased or decreased during the occurrence and development of nasopharyngeal carcinoma (NPC). However, currently there are no simple or effective methods to collect and differentiate these abnormally secreted proteins from abundant serum proteins. In this study, acetonitrile was used to remove the majority of high-abundance proteins from serum samples obtained from patients with NPC. The samples were subjected to surface-enhanced laser desorption/ionization time-of-flight mass spectrometry with a CM10 (weak cation exchange) ProteinChip, and the resulting protein profiles were compared with those of non-acetonitrile-treated serum samples. The results showed that the protein profiles differed between the acetonitrile- and non-acetonitrile-treated sera from patients with NPC. A large proportion of the non-acetonitrile-treated NPC serum protein peaks were <6000 kDa, while the detection rate of protein peaks >6000 kDa was relatively higher in the acetonitrile-treated NPC sera, accounting for more than half of all protein peaks (26.2+37.5%). Few differentially upregulated proteins were lost, and the peak value density increased after acetonitrile treatment. In conclusion, acetonitrile treatment of serum samples is effective in removing high-abundance macromolecular proteins. Therefore, acetonitrile treatment can be applied for the investigation of serum proteomics and may aid in the identification of differentially expressed proteins.

  5. Quantitative analysis and chromatographic fingerprinting for the quality evaluation of Scutellaria baicalensis Georgi using capillary electrophoresis.

    PubMed

    Yu, Ke; Gong, Yifei; Lin, Zhongying; Cheng, Yiyu

    2007-01-17

    Quantitative analysis and chromatographic fingerprinting for the quality evaluation of a Chinese herb Scutellaria baicalensis Georgi using capillary electrophoresis (CE) technique was developed. The separation was performed with a 50.0cm (42.0cm to the detector window)x75mum i.d. fused-silica capillary, and the CE fingerprint condition was optimized using the combination of central composite design and multivariate analysis. The optimized buffer system containing 15mM borate, 40mM phosphate, 15mM SDS, 15% (v/v) acetonitrile and 7.5% (v/v) 2-propanol was employed for the method development, and the baseline separation was achieved within 15min. The determination of the major active components (Baicalin, Baicalein and Wogonin) was carried out using the optimized CE condition. Good linear relationships were provided over the investigated concentration ranges (the values of R(2): 0.9997 for Baicalin, 0.9992 for Baicalein, and 0.9983 for Wogonin, respectively). The average recoveries of these target components ranged between 96.1-105.6%, 98.6-105.2%, and 96.3-105.0%, respectively. CE fingerprints combined with the quantitative analysis can be used for the quality evaluation of S. baicalensis.

  6. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design.

    PubMed

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder

    2015-08-01

    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance.

  7. Acetonitrile boosts conductivity of imidazolium ionic liquids.

    PubMed

    Chaban, Vitaly V; Voroshylova, Iuliia V; Kalugin, Oleg N; Prezhdo, Oleg V

    2012-07-05

    We apply a new methodology in the force field generation (Phys. Chem. Chem. Phys.2011, 13, 7910) to study binary mixtures of five imidazolium-based room-temperature ionic liquids (RTILs) with acetonitrile (ACN). Each RTIL is composed of tetrafluoroborate (BF(4)) anion and dialkylimidazolium (MMIM) cations. The first alkyl group of MIM is methyl, and the other group is ethyl (EMIM), butyl (BMIM), hexyl (HMIM), octyl (OMIM), and decyl (DMIM). Upon addition of ACN, the ionic conductivity of RTILs increases by more than 50 times. It significantly exceeds an impact of most known solvents. Unexpectedly, long-tailed imidazolium cations demonstrate the sharpest conductivity boost. This finding motivates us to revisit an application of RTIL/ACN binary systems as advanced electrolyte solutions. The conductivity correlates with a composition of ion aggregates simplifying its predictability. Addition of ACN exponentially increases diffusion and decreases viscosity of the RTIL/ACN mixtures. Large amounts of ACN stabilize ion pairs, although they ruin greater ion aggregates.

  8. Liquid chromatographic determination of serum levels of d,l-4-amino-N-(alpha-methylbenzyl)-benzamide, a new benzamide anticonvulsant.

    PubMed

    Dockens, R C; Ravis, W R; Clark, C R

    1988-01-01

    A method for the high-performance liquid chromatographic (HPLC) determination of serum concentrations of d,l-4-amino-N-(alpha-methylbenzyl)-benzamide and its N-acetylated metabolite is described. The compounds are isolated from a 50-microL sample of serum using solid phase extraction. The compounds and internal standard are eluted from the extraction column with acetonitrile. Quantitation is performed via UV detection at 275 nm following isocratic reversed-phase (C18) separation using a ternary solvent system. The assay procedure is useful for the determination of concentrations of parent compound from 0.63 to 87.9 micrograms/mL from 50 microL of serum.

  9. Optimization and Validation of High-Performance Chromatographic Condition for Simultaneous Determination of Adapalene and Benzoyl Peroxide by Response Surface Methodology

    PubMed Central

    Huang, Yaw-Bin; Wu, Pao-Chu

    2015-01-01

    The aim of this study was to develop a simple and reliable high-performance chromatographic (HPLC) method for simultaneous analysis of adapalene and benzoyl peroxide in pharmaceutical formulation by response surface methodology (RSM). An optimized mobile phase composed of acetonitrile, tetrahydrofuran and water containing 0.1% acetic acid at a ratio of 25:50:25 by volume was successfully predicted by using RSM. An isocratic separation was achieved by using the condition. Furthermore, the analytical method was validated in terms of specificity, linearity, accuracy and precision in a range of 80% to 120% of the expected concentration. Finally, the method was successfully applied to the analysis of a commercial product. PMID:25793581

  10. Real-time observation of liposome bursting induced by acetonitrile.

    PubMed

    Yoshida, Kazunari; Horii, Keitaro; Fujii, Yasuhiro; Nishio, Izumi

    2014-10-06

    We show the bursting process of dioleoylphosphatidylcholine (DOPC) liposomes in response to the addition of acetonitrile, a small toxic molecule widely used in the fields of chemistry and industry. The percentage of destroyed liposomes is reduced upon decreasing the acetonitrile fraction in the aqueous solution and vesicle bursting is not observed at volume ratios of 4:6 and below. This indicates that a high fraction of acetonitrile causes the bursting of liposomes, and it is proposed that this occurs through insertion of the molecules into outer leaflet of the lipid bilayer. The elapsed time between initial addition of acetonitrile and liposome bursting at each vesicle is also measured and demonstrated to be dependent on the volume fraction of acetonitrile and the vesicle size.

  11. A model potential for acetonitrile: from small clusters to liquid.

    PubMed

    Albertí, M; Amat, A; De Angelis, F; Pirani, F

    2013-06-13

    A portable model potential, representing the intermolecular interaction of acetonitrile with itself and with ions, is proposed. Such model, formulated as a combination of a few effective components, given in terms of the polarizability and dipole moment values of the molecular partners, is here adopted as a building block of the force field of acetonitrile clusters in molecular dynamics simulations. Its reliability is tested by comparing the predicted features for both small ionic and neutral clusters containing acetonitrile with ab initio results and experimental information. Its application to molecular dynamics simulations of liquid acetonitrile and of the solvated Li(+), Na(+), K(+), and I(-), performed at several values of the temperature, discloses an ample and interesting phenomenology, described in an internally consistent way. Such model will be useful to assess the effect of intermolecular interactions on the dynamics of acetonitrile processes occurring in various environments of applied relevance, with emphasis on the dye-sensitized solar cell framework.

  12. Greening pharmaceutical applications of liquid chromatography through using propylene carbonate-ethanol mixtures instead of acetonitrile as organic modifier in the mobile phases.

    PubMed

    Tache, Florentin; Udrescu, Stefan; Albu, Florin; Micăle, Florina; Medvedovici, Andrei

    2013-03-05

    Substitution of acetonitrile (ACN) as organic modifier in mobile phases for liquid chromatography by mixtures of propylene carbonate (PC) and ethanol (EtOH) may be considered a greener approach for pharmaceutical applications. Such a replacement is achievable without any major compromise in terms of elution order, chromatographic retention, efficiency and peak symmetry. This has been equally demonstrated for reverse phase (RP), ion pair formation (IP) and hydrophilic interaction liquid chromatography (HILIC) separation modes. The impact on the sensitivity induced by the replacement between these organic solvents is discussed for UV-vis and mass spectrometric detection. A comparison between Van Deemter plots obtained under elution conditions based on ACN and PC/EtOH is presented. The alternative elution modes were also compared in terms of thermodynamic parameters, such as standard enthalpy (ΔH⁰) and entropic contributions to the partition between the mobile and the stationary phases, for some model compounds. Van't Hoff plots demonstrated that differences between the thermodynamic parameters are minor when shifting from ACN/water to PC/EtOH/water elution on an octadecyl chemically modified silicagel stationary phase. As long as large volume injection (LVI) of diluents non-miscible with the mobile phase is a recently developed topic having a high potential of greening the sample preparation procedures through elimination of the solvent evaporation stage, this feature was also assessed in the case of ACN replacement by PC/EtOH.

  13. Theoretical studies on the anionic association of phenol and its derivatives in acetonitrile

    NASA Astrophysics Data System (ADS)

    Wiśniewska, Marta; Makowski, Mariusz

    2014-11-01

    The potentials of mean force (PMF) were determined for homoconjugated systems of anionic complexes composed of phenol and its derivatives with their conjugate anionic bases in acetonitrile (ACN). For each acid-base pair studied, a series of umbrella-sampling molecular dynamics simulations using the AMBER force field with explicit solvent was carried out; the respective PMF was calculated using the Weighted Histogram Analysis Method (WHAM). Subsequently, association equilibrium constants were calculated by numerical integration of the PMF profiles. The PMF curves had a typical shape, i.e., a very deep and narrow contact-minimum, a desolvation maximum, and a shallow solvent-separated minimum. All pairs formed complexes in solution, which was confirmed by the presence of contact minima corresponding to the existence of hydrogen bonds in the PMF curves. The calculated association constants in acetonitrile were subsequently compared with experimentally obtained values for the same solvent. Ab initio methods at the RHF level (utilizing the Gaussian 6-31++G** basis set) enabled the in vacuo calculation of energies and Gibbs free energies of interaction for each phenol derivative and anionic base pair along with a molecule of acetonitrile; this allowed the contribution of the solvent molecule to the PMF to be assessed. It was found that the interaction energies of anionic bases in acetonitrile are stronger than their related neutral phenol derivatives.

  14. High-performance liquid chromatographic determination of memantine hydrochloride in rat plasma using sensitive fluorometric derivatization.

    PubMed

    Xie, Mei-Fen; Zhou, Wei; Tong, Xin-Yi; Chen, Yi-Le; Cai, Yi; Li, Yan; Duan, Geng-Li

    2011-02-01

    In this study, we investigated a simple, sensitive and reliable liquid chromatography-fluorescence detection method for the determination of memantine hydrochloride in rat plasma which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). For the first time, FMOC-Cl was introduced into derivatization of memantine hydrochloride in rat plasma. The amino groups of memantine hydrochloride and amantadine hydrochloride (internal standard) were trapped with FMOC-Cl to form memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions, which can be very compatible for LC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C(18) column (DIAMONSIL 150 × 4.6 mm, id 5 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL/min. The retention times of memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions were 23.69 and 40.27 min, respectively. Optimal conditions for the derivatization of memantine hydrochloride were also described. The limit of quantification (LOQ) was 25 ng/mL for memantine hydrochloride in plasma, the linear range was 0.025-5.0 μg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 4.46-12.19 and 5.23-11.50%, respectively. The validated method was successfully applied to the determination of memantine hydrochloride in rat plasma samples.

  15. Development of an improved method to extract pesticide residues in foods using acetonitrile with magnesium sulfate and chloroform.

    PubMed

    Liu, Guozhu; Rong, Lei; Guo, Bin; Zhang, Mingshan; Li, Shengjun; Wu, Qing; Chen, Jitao; Chen, Bo; Yao, Shouzhuo

    2011-03-18

    A multiresidue method was developed based on extraction of 10 g sample with 10 mL acetonitrile and subsequent liquid-liquid partitioning formed by adding 4 g MgSO₄ plus 1 mL chloroform. During the partitioning process, the extraction recoveries of polar analytes were found to be essentially determined by the acetonitrile content in the aqueous phase. The use of MgSO₄ gave the least acetonitrile left in the aqueous phase (lower than 5%) and thus promoting complete partitioning of analytes into the organic phase. At the same time, removal of water from the acetonitrile phase was achieved by adding only a small amount of chloroform with no influence on the acetonitrile content in the aqueous phase, thus leading to decreasing the co-extraction of polar matrix components. The most complete mutual separation of acetonitrile and water was achieved by the joint use of MgSO₄ and chloroform and thus the optimal extraction recovery and analytical selectivity were obtained simultaneously. The new method, with higher recoveries of polar analytes, better analytical selectivity and simpler manipulation, is a claimed improvement to the original QuEChERS method. The proposed method was finally validated by the determination of 20 pesticides in a mixed food matrix by using liquid chromatography tandem mass spectrum (LC-MS/MS). Acceptable linearity, sensitivity, recovery, precision and selectivity results were obtained.

  16. Chromatographic Degradation of Phloridzin

    PubMed Central

    Grochowska, Maria J.

    1966-01-01

    Phloridzin, the main phenolic glucoside in apple leaves, has been found to undergo transformation during chromatography. When chromatographed repeatedly in ammoniacal solvents, at least 2 new derivatives appeared. One of these was identified as phloretic acid. When bioassayed in the presence of indole-3-acetic acid this substance behaved as though it promoted the destruction of the auxin. Comparative bioassay with naphthaleneacetic acid suggested that phloretic acid acts on indoleacetic acid destruction via stimulation of indoleacetic acid oxidase. However, at low concentration and in presence of a small amount of phloridzin it also showed a synergistic effect with indoleacetic acid. A substance with the same characteristics was obtained directly from apple leaves, which are known to contain phloridzin when the extracts were chromatographed only once in the same (alkaline) solvent. While not completely confirmed, this suggests that phloretic acid is normally present in apple leaves, where it may affect growth there by promoting indoleacetic acid oxidation. Images PMID:16656273

  17. Gas chromatograph injection system

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Henderson, M. E.; Donaldson, R. W., Jr. (Inventor)

    1975-01-01

    An injection system for a gas chromatograph is described which uses a small injector chamber (available in various configurations). The sample is placed in the chamber while the chamber is not under pressure and is not heated, and there is no chance of leakage caused by either pressure or heat. It is injected into the apparatus by changing the position of a valve and heating the chamber, and is volatilized and swept by a carrier gas into the analysis apparatus.

  18. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

    2002-01-01

    This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

  19. Coupling of acetonitrile deproteinization and salting-out extraction with acetonitrile stacking in chiral capillary electrophoresis for the determination of warfarin enantiomers.

    PubMed

    Wang, Min; Cai, Zongwei; Xu, Lin

    2011-07-01

    Concurrent sample clean-up and enhancement in detection sensitivity for chiral capillary electrophoresis was demonstrated based on the coupling of salting-out extraction with acetonitrile stacking and the use of dimethyl-beta-cyclodextrin as the chiral selector for the sensitive and enantioselective separation of warfarin enantiomers in urine samples. By optimizing the pH of salting-out extraction, warfarin enantiomers can be efficiently extracted from the aqueous sample solution into a smaller volume organic solvent (acetonitrile) phase. The pressure injection of the enriched acetonitrile phase (containing ca. 1% NaCl) into the CE capillary at 10% capillary volume resulted in additional concentration of the warfarin enantiomers. The limit of detection for both warfarin enantiomers was as low as 1.5 ng/mL in urine sample. Our results show that the novel strategy offers improved sensitivity compared to conventional CE analysis, reaching a combined enrichment factor higher than 1000. Calibration curves of warfarin enantiomers in urine samples were found to be linear between 10 and 1000 ng/mL, and intra- and inter-day precision (N=9) for both warfarin enantiomers in terms of migration time and peak area were found to be within the range of 0.1-0.8% and 1.0-6.7%, respectively. The recovery of warfarin enantiomers from urine was ca. 90%.

  20. Development and validation of a hydrophilic interaction liquid chromatographic method for determination of aromatic amines in environmental water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, precise, and accurate hydrophilic interaction liquid chromatographic (HILIC) method has been developed for the determination of 5 aromatic amines in environmental water samples. Chromatography was carried out on a bare silica column, using a mixture of acetonitrile: phosphate buffer (10 mM...

  1. Chromatographic methods in the study of autism.

    PubMed

    Żurawicz, Ewa; Kałużna-Czaplińska, Joanna; Rynkowski, Jacek

    2013-10-01

    Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

  2. Microstructure and hydrogen bonding in water-acetonitrile mixtures.

    PubMed

    Mountain, Raymond D

    2010-12-16

    The connection of hydrogen bonding between water and acetonitrile in determining the microheterogeneity of the liquid mixture is examined using NPT molecular dynamics simulations. Mixtures for six, rigid, three-site models for acetonitrile and one water model (SPC/E) were simulated to determine the amount of water-acetonitrile hydrogen bonding. Only one of the six acetonitrile models (TraPPE-UA) was able to reproduce both the liquid density and the experimental estimates of hydrogen bonding derived from Raman scattering of the CN stretch band or from NMR quadrupole relaxation measurements. A simple modification of the acetonitrile model parameters for the models that provided poor estimates produced hydrogen-bonding results consistent with experiments for two of the models. Of these, only one of the modified models also accurately determined the density of the mixtures. The self-diffusion coefficient of liquid acetonitrile provided a final winnowing of the modified model and the successful, unmodified model. The unmodified model is provisionally recommended for simulations of water-acetonitrile mixtures.

  3. Intermolecular forces in acetonitrile + ethanol binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Elangovan, A.; Shanmugam, R.; Arivazhagan, G.; Mahendraprabu, A.; Karthick, N. K.

    2015-10-01

    FTIR spectral measurements have been carried out on the binary mixtures of acetonitrile with ethanol at 1:0 (acetonitrile:ethanol), 1:1, 1:2, 1:3 and 0:1 at room temperature. DFT and isosurface calculations have been performed. The acetonitrile + ethanol binary mixtures consist of 1:1, 1:2, 1:3 and 1:4 complexes formed through both the red and blue shifting H-bonds. Inter as well as intra molecular forces are found to exist in 1:3 and 1:4 complexes.

  4. Validated spectrophotometric and chromatographic methods for simultaneous determination of ketorolac tromethamine and phenylephrine hydrochloride.

    PubMed

    Belal, T S; El-Kafrawy, D S; Mahrous, M S; Abdel-Khalek, M M; Abo-Gharam, A H

    2016-07-01

    This work describes five simple and reliable spectrophotometric and chromatographic methods for analysis of the binary mixture of ketorolac tromethamine (KTR) and phenylephrine hydrochloride (PHE). Method I is based on the use of conventional Amax and derivative spectrophotometry with the zero-crossing technique where KTR was determined using its Amax and (1)D amplitudes at 323 and 341nm respectively, while PHE was determined by measuring the (1)D amplitudes at 248.5nm. Method II involves the application of the ratio spectra derivative spectrophotometry. For KTR, 12μg/mL PHE was used as a divisor and the (1)DD amplitudes at 265nm were plotted against KTR concentrations; while - by using 4μg/mL KTR as divisor - the (1)DD amplitudes at 243.5nm were found proportional to PHE concentrations. Method III depends on ratio-difference measurement where the peak to trough amplitudes between 260 and 284nm were measured and correlated to KTR concentration. Similarly, the peak to trough amplitudes between 235 and 260nm in the PHE ratio spectra were recorded. For method IV, the two compounds were separated using Merck HPTLC sheets of silica gel 60 F254 and a mobile phase composed of chloroform/methanol/ammonia (70:30:2, by volume) followed by densitometric measurement of KTR and PHE spots at 320 and 278nm respectively. Method V depends on HPLC-DAD. Effective chromatographic separation was achieved using Zorbax eclipse plus C8 column (4.6×250mm, 5μm) with a mobile phase consisting of 0.05M o-phosphoric acid and acetonitrile (50:50, by volume) at a flow rate 1mL/min and detection at 313 and 274nm for KTR and PHE respectively. Analytical performance of the developed methods was statistically validated according to the ICH guidelines with respect to linearity, ranges, precision, accuracy, detection and quantification limits. The validated spectrophotometric and chromatographic methods were successfully applied to the simultaneous analysis of KTR and PHE in synthetic mixtures

  5. Chromatographic Analysis of a Multicomponent Mixture of B1, B6, B12, Benfotiamine, and Diclofenac; Part I: HPLC and UPLC Methods for the Simultaneous Quantification of These Five Components in Tablets and Capsules.

    PubMed

    Fayed, Ahmed Salah; Hegazy, Maha Abdel-Monem; Wahab, Nada Sayed Abdel

    2016-11-01

    New, simple, highly sensitive, precise, and accurate gradient reversed-phase chromatographic methods were developed using HPLC and ultra-HPLC (UPLC) systems for the determination of five components, namely thiamine, pyridoxine, cyanocobalamin, benfotiamine, and diclofenac in tablets and capsules. The methods were compared for their efficiency in the separation and determination of these five compounds using two different C18 columns (250 × 4.6 mm, 5 μm; and 100 × 4.6 mm, 2.6 μm) for HPLC and UPLC, respectively. Chromatographic separation was performed with a mobile phase containing acetonitrile and 0.025 M phosphate buffer (pH 3.5), with a gradient program and a flow rate of 1.5 and 1.0 mL/min for both methods, respectively. The methods were validated according to International Conference on Harmonization guidelines. Linearity was achieved in the range of 5.00 to 150.00 μg/mL for each of the five compounds. Ruggedness and intermediate precision were confirmed by different analysts on different columns on different days. Moreover, the components were subjected to an accelerated stability study under acidic, alkaline, and oxidative stress conditions and no interfering peaks were observed. The five compounds were efficiently separated in <20 min by HPLC, whereas for UPLC, separation was achieved in <8 min, which dramatically decreased the consumption of organic solvents.

  6. Hand-held multiple system gas chromatograph

    DOEpatents

    Yu, Conrad M.

    2001-01-01

    A multiple parallel hand-held gas chromatograph (GC) system which includes several independent GCs. Each independent GC has its own injector, separation column, detector and oven and the GCs are mounted in a light weight hand-held assembly. Each GC operates independently and simultaneously. Because of different coatings in different separation columns, different retention times for the same gas will be measured. Thus, for a GC system with multiple parallel GCs, the system can measure, in a short period, different retention times and provide a cross-reference in the determination of the measured gas and to become a two-dimensional system for direct field use.

  7. Thin layer chromatographic determination of deoxynivalenol in processed grain products.

    PubMed

    Trucksess, M W; Flood, M T; Page, S W

    1986-01-01

    The thin layer chromatographic (TLC) method of Trucksess et al. (J. Assoc. Off. Anal. Chem. (1984) 67, 40-43) was modified for the determination of deoxynivalenol (DON) in high-sugar breakfast cereals, corn syrup, and beer. Celite was added to the substrate before extraction with acetonitrile-water (84 + 16). After filtration through an alumina-charcoal-Celite (0.5 + 0.7 + 0.3) column, the filtrate was evaporated to dryness and redissolved in water, which was passed through an octylsilyl reverse phase column. DON was eluted with anhydrous ethyl ether. The residue remaining after the eluate was evaporated to dryness was dissolved in CHCl3-acetonitrile (4 + 1) and chromatographed on AlCl3-impregnated silica gel TLC plates. The blue fluorescent DON spot was quantitated fluorodensitometrically after the TLC plate was heated at 120 degrees C for 7 min. Recoveries of DON added to breakfast cereals at 100, 200, and 400 ng/g levels and to syrup and beer at 50, 100, and 200 ng/g levels averaged 86%. The limit of determination in these products was about 50 ng/g.

  8. Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Colizza, Kevin; Mahoney, Keira E.; Yevdokimov, Alexander V.; Smith, James L.; Oxley, Jimmie C.

    2016-11-01

    Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression.

  9. Monoalkylation of acetonitrile by primary alcohols catalyzed by iridium complexes.

    PubMed

    Anxionnat, Bruno; Pardo, Domingo Gomez; Ricci, Gino; Cossy, Janine

    2011-08-05

    The monoalkylation of acetonitrile by primary alcohols was achieved in a one-pot sequence in the presence of iridium catalysts. A diversity of nitriles has been obtained from aryl- and alkyl-methanols in excellent yield.

  10. Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry.

    PubMed

    Colizza, Kevin; Mahoney, Keira E; Yevdokimov, Alexander V; Smith, James L; Oxley, Jimmie C

    2016-11-01

    Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression. Graphical Abstract ᅟ.

  11. An improved liquid chromatographic method for the analysis of tylosin and its impurities.

    PubMed

    Ashenafi, Dunge; Hoogmartens, Jos; Adams, Erwin

    2011-10-01

    A selective reversed-phase (RP) liquid chromatographic (LC) method coupled with UV for the determination of tylosin and its related substances is described. The gradient method uses a Capcell pak C18 ACR column (25 cm×4.6 mm id, 5 μm) maintained at a temperature of 60°C. The mobile phases consist of acetonitrile, phosphate buffer pH 5.5 and water: (A; 27.5:10:62.5 v/v/v) and (B; 50:10:40 v/v/v). The flow rate is 1.0 mL/min and UV detection is performed at 280 nm. It allows the separation of all known and 22 other unknown related substances (≥0.02%) from the main compound and from one another. The method shows good precision, sensitivity, linearity (between 0.2 μg/mL and 1.25 mg/mL) and robustness. The limit of quantification is 0.2 μg/mL, corresponding to 0.020%. Seven bulk tylosin samples containing a large number of impurities were examined using this method.

  12. High performance liquid chromatographic determination of etofibrate and its hydrolysis products.

    PubMed

    el-Gindy, Alaa; Hadad, Ghada M; Mahmoud, Waleed M M

    2007-01-04

    High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied.

  13. Liquid chromatographic method for the simultaneous determination of imipenem and sulbactam in mouse plasma.

    PubMed

    Aparicio, Irene; Bello, Miguel Angel; Callejón, Manuel; Jiménez, Juan Carlos

    2006-10-01

    The first analytical method is developed and validated for the simultaneous determination of imipenem and sulbactam in mouse plasma. Sample treatment is based on plasma stabilization with 4-(2-hydroxyethyl)piperazine-ethanesulfonic acid (HEPES) (0.5 mol/L; pH 7.0)-water-ethylene glycol (2:1:1, v/v/v), precipitation of plasma proteins with acetonitrile, centrifugation, evaporation, and reconstitution with borate buffer. Analytical determination is carried out by high-performance liquid chromatography with diode-array detection. Chromatographic separation is achieved within 11 min on a C(18) column by gradient elution with borate buffer (0.1 mol/L, pH 7.2) and methanol. Imipenem and sulbactam are monitored at 295 and 230 nm, respectively. The overall interday accuracy is in the range of 95% to 100% and from 98% and 101% for imipenem and sulbactam, respectively. Interday precision is below 8% and 4% for imipenem and sulbactam, respectively. Limits of quantitation of imipenem and sulbactam are 0.05 and 1.0 microg/mL, respectively. The mean extraction recoveries are 94.5% and 94.2% for imipenem and sulbactam, respectively. The described method allows an accurate, simple, and rapid identification and quantitation of imipenem and sulbactam in mouse plasma. This method is applied to the analysis of imipenem and sulbactam in mouse plasma after drug administration.

  14. Enantioseparation of cetirizine by chromatographic methods and discrimination by 1H-NMR.

    PubMed

    Taha, Elham A; Salama, Nahla N; Wang, Shudong

    2009-03-01

    Cetirizine is an antihistaminic drug used to prevent and treat allergic conditions. It is currently marketed as a racemate. The H1-antagonist activity of cetirizine is primarily due to (R)-levocetirizine. This has led to the introduction of (R)-levocetirizine into clinical practice, and the chiral switching is expected to be more selective and safer. The present work represents three methods for the analysis and chiral discrimination of cetirizine. The first method was based on the enantioseparation of cetirizine on silica gel TLC plates using different chiral selectors as mobile phase additives. The mobile phase enabling successful resolution was acetonitrile-water 17: 3, (v/v) containing 1 mM of chiral selector, namely hydroxypropyl-beta-cyclodextrin, chondroitin sulphate or vancomycin hydrochloride. The second method was a validated high performance liquid chromatography (HPLC), based on stereoselective separation of cetirizine and quantitative determination of its eutomer (R)-levocetirizine on a monolithic C18 column using hydroxypropyl-beta-cyclodextrin as a chiral mobile phase additive. The resolved peaks of (R)-levocetirizine and (S)-dextrocetirizine were confirmed by further mass spectrometry. The third method used a (1)H-NMR technique to characterize cetirizine and (R)-levocetirizine. These methods are selective and accurate, and can be easily applied for chiral discrimination and determination of cetirizine in drug substance and drug product in quality control laboratory. Moreover, chiral purity testing of (R)-levocetirizine can also be monitored by the chromatographic methods.

  15. Glucaminium ionic liquid-functionalized stationary phase for the separation of nucleosides in hydrophilic interaction chromatography.

    PubMed

    Jiang, Qiong; Zhang, Mingliang; Wang, Xusheng; Guo, Yong; Qiu, Hongdeng; Zhang, Shusheng

    2015-10-01

    A glucaminium-based ionic liquid stationary phase was prepared via facile epoxy-amine reaction and subsequent quaternization. Successful immobilization of glucaminium-based ionic liquid onto silica surface was validated by elemental analysis and infrared spectroscopy. The new stationary phase was evaluated for the separation of nucleosides in hydrophilic interaction liquid chromatography (HILIC). Effects of various factors, such as acetonitrile concentration, salt concentration, pH value, as well as column temperature, on the chromatographic behavior toward nucleosides were studied in detail. The results indicated that this new stationary phase can be used for separation of water-soluble polar substances in HILIC mode. The retention of solutes on the stationary phase was influenced by a mixed-mode retention mechanism with a combination of adsorptive and partitioning interactions.

  16. Liquid chromatographic determination of progestogens in animal fat.

    PubMed

    Andresen, M T; Fesser, A C

    1996-01-01

    A liquid chromatographic method was developed for determination of 3 progestogens-melengestrol acetate, megestrol acetate, and chlormadinone acetate-found in edible tissue at concentrations between 10 and 1000 ppb. These progestogens are commonly used as feed additives to control herd estrus and to improve feed efficiency. Rendered fat was extracted with acetonitrile, washed with hexane, and dried. The remaining lipids were saponified with sodium hydroxide and precipitated with magnesium chloride. The progestogens were extracted from the basic solution with hexane, dried, and cleaned up on a cyanopropyl solid-phase extraction column in the normal-phase mode. The eluate was dried and reconstituted with acetonitrile-water (7 + 3, v/v). Chromatography was performed on a 5 microns high-carbon load C18 column with acetonitrile-water (7 + 3, v/v) at 1 mL/min and UV detection at 291 nm. Recoveries from fortified samples ranged from 84 to 116%. The limit of quantitation was 10 ppb for both beef and pork. The detection limit was 3 ppb.

  17. Inhalation developmental toxicology studies: Acetonitrile in rats. Final report

    SciTech Connect

    Mast, T.J.; Weigel, R.J.; Westerberg, R.B.; Boyd, P.J.; Hayden, B.K.; Evanoff, J.J.; Rommereim, R.L.

    1994-02-01

    The potential for acetonitrile to cause developmental toxicity was assessed in Sprague-Dawley rats exposed to 0, 100, 400, or 1200 ppM acetonitrile, 6 hours/day, 7 days/week. Exposure of rats to these concentrations of acetonitrile resulted in mortality in the 1200 ppM group (2/33 pregnant females; 1/10 non-pregnant females). However, there were no treatment-related effects upon body weights or reproduction indices at any exposure level, nor was there a significant increase in the incidence of fetal malformations or variations. The only effect observed in the fetuses was a slight, but not statiscally significant, exposure-correlated increase in the incidence of supernumerary ribs. Determination of acetonitrile and cyanide concentrations in maternal rat blood showed that acetonitrile concentration in the blood increased with exposure concentration for all exposed maternal rats. Detectable amounts of cyanide in the blood were found only in the rats exposed to 1200 ppM acetonitrile ({approximately}2 {mu}g cyanide/g of blood).

  18. Chromatographic purification of highly active yeast ribosomes.

    PubMed

    Meskauskas, Arturas; Leshin, Jonathan A; Dinman, Jonathan D

    2011-10-24

    Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

  19. Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities.

    PubMed

    Jovanović, Marko; Rakić, Tijana; Tumpa, Anja; Jančić Stojanović, Biljana

    2015-06-10

    This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm.

  20. Simultaneous separation of water- and fat-soluble vitamins in isocratic pressure-assisted capillary electrochromatography using a methacrylate-based monolithic column.

    PubMed

    Yamada, Hiroki; Kitagawa, Shinya; Ohtani, Hajime

    2013-06-01

    A method of simultaneous separation of water- and fat-soluble vitamins using pressure-assisted CEC with a methacrylate-based capillary monolithic column was developed. In the proposed method, water-soluble vitamins were mainly separated electrophoretically, while fat soluble-ones were separated chromatographically by the interaction with a methacrylate-based monolith. A mixture of six water-soluble and four fat-soluble vitamins was separated simultaneously within 20 min with an isocratic elution using 1 M formic acid (pH 1.9)/acetonitrile (30:70, v/v) containing 10 mM ammonium formate as a mobile phase. When the method was applied to a commercial multivitamin tablet and a spiked one, the vitamins were successfully analyzed, and no influence of the matrix contained in the tablet was observed.

  1. Mixed-mode chromatography integrated with high-performance liquid chromatography for protein analysis and separation: Using bovine serum albumin and lysozyme as the model target.

    PubMed

    Xia, Hai-Feng; Don, Bin-Bin; Zheng, Meng-Jie

    2016-05-01

    A type of mixed-mode chromatography was integrated with high-performance liquid chromatography for protein analysis and separation. The chromatographic behavior was tested using bovine serum albumin and lysozyme as model proteins. For the mixed-mode column, the silica beads were activated with γ-(2,3-epoxypropoxy)-propytrimethoxysilane and coupled with 4-mercaptopyridine as the functional ligand. The effects of pH, salt, and the organic solvent conditions of the mobile phase on the retention behavior were studied, which provided valuable clues for separation strategy. When eluted with a suitable pH gradient, salt concentration gradient, and acetonitrile content gradient, the separation behavior of bovine serum albumin and lysozyme could be controlled by altering the conditions of the mobile phase. The results indicated this type of chromatography might be a useful method for protein analysis and separation.

  2. ELECTRICALLY ACTUATED, PRESSURE-DRIVEN LIQUID CHROMATOGRAPHY SEPARATIONS IN MICROFABRICATED DEVICES

    PubMed Central

    Fuentes, Hernan V.; Woolley, Adam T.

    2012-01-01

    Electrolysis-based micropumps integrated with microfluidic channels in micromachined glass substrates are presented. Photolithography combined with wet chemical etching and thermal bonding enabled the fabrication of multi-layer devices containing electrically actuated micropumps interfaced with sample and mobile phase reservoirs. A stationary phase was deposited on the microchannel walls by coating with 10% (w/w) chlorodimethyloctadecylsilane in toluene. Pressure-balanced injection was implemented by controlling the electrolysis time and voltage applied in the two independent micropumps. Current fluctuations in the micropumps due to the stochastic formation of bubbles on the electrode surfaces were determined to be the main cause of variation between separations. On-chip electrochemical pumping enabled the loading of pL samples with no dead volume between injection and separation. A mobile phase composed of 70% acetonitrile and 30% 50 mM acetate buffer (pH 5.45) was used for the chromatographic separation of three fluorescently labeled amino acids in <40 s with an efficiency of >3000 theoretical plates in a 2.5-cm-long channel. Our results demonstrate the potential of electrochemical micropumps integrated with microchannels to perform rapid chromatographic separations in a microfabricated platform. Importantly, these devices represent a significant step toward the development of miniaturized and fully integrated liquid chromatography systems. PMID:17960281

  3. Liquid chromatographic methods for the determination of vildagliptin in the presence of its synthetic intermediate and the simultaneous determination of pioglitazone hydrochloride and metformin hydrochloride.

    PubMed

    El-Bagary, Ramzia I; Elkady, Ehab F; Ayoub, Bassam M

    2011-09-01

    Two reversed-phase liquid chromatographic (RP-LC) methods are described for the determination of two binary mixtures of hypoglycemic agents. In the first method, vildagliptin (VDG) was determined in the presence of 3-amino-1-adamantanol (AAD), a synthetic intermediate and impurity of VDG. In the second method, pioglitazone hydrochloride (PGZ) and metformin hydrochloride (MET) were simultaneously determined in their binary mixture. Chromatographic separation in the two methods was achieved on a Symmetry(®) Waters C18 column (150 mm × 4.6 mm, 5 μm). In the first mixture, isocratic elution using a mobile phase of potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile - methanol (30:50:20, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 220 nm was performed. In the second method, isocratic elution based on potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile (60:40, v/v) at a flow rate of 1 mL min(-1) with UV detection at 210 nm was performed. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 5-200 μg mL(-1), 0.5-3 μg mL(-1) and 10-150 μg mL(-1) for VDG, PGZ and MET, respectively. The optimized methods were validated and proved to be specific, robust, precise and accurate for the quality control of the drugs in their pharmaceutical preparations.

  4. New liquid chromatographic-chemometric approach for the determination of sunset yellow and tartrazine in commercial preparation.

    PubMed

    Dinç, Erdal; Aktaş, A Hakan; Ustündağ, Ozgür

    2005-01-01

    A new liquid chromatographic (LC)-chemometric approach was developed for the determination of sunset yellow (SUN) and tartrazine (TAR) in commercial preparations. This approach uses LC and chemometric calibration methods, i.e., classical least-squares (CLS), principal component regression (PCR), and partial-least squares (PLS), simultaneously. The combined LC-chemometric approaches, denoted as LC-CLS, LC-PCR, and LC-PLS, are based on photodiode array (PDA) detection at multiple wavelengths. Optimum chromatographic separation of SUN and TAR with allura red as the internal standard (IS) was obtained by using a Waters Symmetry C18 column, 5 microm, 4.6 x 250 mm, and 0.2 M acetate buffer (pH 5)-acetonitrile-methano-bidistilled water (55 + 20 + 15 + 10, v/v) as the mobile phase at a flow rate of 1.9 mL/min. The LC data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using PDA detection at 5 wavelengths (465, 470, 475, 480, and 485 nm). LC-chemometric calibrations for SUN and TAR were separately constructed by using the relationship between the peak-area ratio and the training sets for each colorant. LC-chemometric approaches were tested for different synthetic mixtures containing SUN and TAR in the presence of the IS. These LC-chemometric calibrations were applied to a commercial preparation of the 2 colorants. The experimental results of the LC-chemometric approaches were compared with those obtained by a developed classical LC method using single-wavelength detection.

  5. An HPLC-DAD and LC-MS study of condensation oscillations with S(+)-ketoprofen dissolved in acetonitrile.

    PubMed

    Sajewicz, Mieczysław; Gontarska, Monika; Kronenbach, Dorota; Berry, Etienne; Kowalska, Teresa

    2012-03-01

    In our earlier studies, a spontaneous chiral conversion of the selected low-molecular-weight carboxylic acids (i.e., amino acids, hydroxy acids, and profen drugs) dissolved in aqueous ethanol medium, running in vitro was described. Then it became clear that this spontaneous chiral conversion is accompanied by the spontaneous condensation of the discussed compounds. With several acids, it was established that this condensation is also oscillatory in nature. The theoretical models were developed aiming to give a rough explanation of the observed non-linear processes. In this paper, the results of these studies on the dynamics of condensation with S(+)-ketoprofen, a very popular profen drug, when stored for certain amount of time dissolved in a non-aqueous medium (i.e., acetonitrile) is presented. These investigations were carried out with the aid of two independent high-performance liquid chromatographic systems with the diode array detection and of a third high-performance liquid chromatographic system equipped with mass spectrometric detection. In one cycle of chromatographic measurements, it was possible to monitor condensation of S(+)-ketoprofen in 25-min intervals for 30 h, thus obtaining kinetic information on the progress of this process. Mass spectrometric detection confirmed the presence of new species in the stored solution with molecular weights much higher than that of S(+)-ketoprofen, which can be attributed to the condensation products. The obtained data show that condensation of S(+)-ketoprofen dissolved in acetonitrile progresses in a rapid manner, and that the observed oscillatory concentration changes with S(+)-ketoprofen and with the main condensation product characterize with an irregularity and shallow amplitudes. A theoretical model was referenced that jointly describes the oscillatory chiral conversion and the oscillatory condensation with the low-molecular-weight chiral carboxylic acids.

  6. An improved validated ultra high pressure liquid chromatography method for separation of tacrolimus impurities and its tautomers.

    PubMed

    Subasranjan, Acharya; C, Srinivasulu; Hemant, Raoutray

    2010-03-01

    A selective, specific and sensitive ultra high pressure liquid chromatography (UHPLC) method was developed for determination of tacrolimus degradation products and tautomers in the preparation of pharmaceuticals. The chromatographic separation was performed on Waters ACQUITY UPLC system and BEH C₈ column using gradient elution of mobile phase A (90:10 v/v of 0.1% v/v triflouroacetic acid solution and Acetonitrile) and mobile phase B (90:10 v/v acetonitrile and water) at a flow rate of 0.6 mL min⁻¹. Ultraviolet detection was performed at 210 nm. Tacrolimus, tautomers and impurities were chromatographed with a total run time of 25 min. Calibration showed that the response of impurity was a linear function of concentration over the range 0.3-6 µg mL⁻¹ (r² ≥ 0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity and specificity. For precision study, percentage relative standard deviation of each impurity was < 15% (n = 6). The method was found to be precise, accurate, linear and specific. The proposed method was successfully employed for estimation of tacrolimus impurities in pharmaceutical preparations.

  7. A novel validated ultra-performance liquid chromatography Method for separation of eszopiclone impurities and its degradants in drug products.

    PubMed

    Sharma, Nitish; Rao, Surendra Singh; Kumar, Namala Durga Atchuta; Reddy, Annarapu Malleswara

    2013-01-01

    A selective, specific, and sensitive ultra-performance LC (UPLC) method was developed for determination of eszopiclone and its degradation products. The chromatographic separation was performed with a Waters ACQUITY UPLC system and BEH C18 column using gradient elution with mobile phases A and B. Mobile phase A was 0.01 M phosphate buffer with 0.2% (w/v) 1-octane sulfonic acid sodium salt as an ion pair reagent, adjusted pH 2.2 with orthophosphoric acid-acetonitrile (85 + 15, v/v). Mobile phase B was pH 2.2 buffer-acetonitrile (20 + 80, v/v). UV detection was performed at 303 nm. Eszopiclone and its impurities were chromatographed with a total run time of 13 min. A calibration study showed that the response for each of the impurities A, B, C, and D was linear between concentrations of 0.02 and 7.2 microg/mL (r2 > or = 0.999). The method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, RSD of each impurity was <5% (n = 6). The method was found to be precise, accurate, linear, and specific. The proposed method was successfully used for determination of eszopiclone impurities in pharmaceutical preparations.

  8. Physicochemical study of the acetonitrile insertion into polypyrrole films.

    PubMed

    Oliveira Costa, S D; Fernández Romero, A J; López Cascales, J J

    2010-04-14

    A study by molecular dynamics (MD) simulation of the acetonitrile diffusion into a polypyrrole film was carried out with atomic detail in a 0.1N lithium perchlorate solution. From the simulated trajectories, the acetonitrile behavior was estimated from bulk solution to the interior of the polypyrrole film, across the polypyrrole/solution interface, for a neutral (reduced) and charged (oxidized) state of the polymer. Among other properties, the translational diffusion coefficient and rotational relaxation time of the acetonitrile were calculated, where a diminution in the translational diffusion coefficient was measured in the interior of the polypyrrole matrix compared to bulk, independently of the oxidation state of the polymer, in contrast with the behavior of the rotational relaxation time that increases from bulk to the interior of the polymer for both oxidation states. In addition, the difference of free energy DeltaG associated to the acetonitrile penetration into the polymer was calculated. From the results, it was evidenced that the scarce affinity of acetonitrile to diffuse into the polymer in its reduced state is related with the positive uniform difference of free energy DeltaG approximately 20 kJ/mol, while in the oxidized state, an important free energy barrier of DeltaG approximately 10 kJ/mol has to pass trough for reaching stable sites inside the polymer with values of DeltaG up to -10 kJ/mol.

  9. Prediction of pesticides chromatographic lipophilicity from the computational molecular descriptors.

    PubMed

    Casoni, Dorina; Petre, Jana; David, Victor; Sârbu, Costel

    2011-02-01

    Quantitative structure-property relationship models were developed for the prediction of pesticides and some PAH compounds lipophilicity based on a wide set of computational molecular descriptors and a set of experimental chromatographic data. The chromatographic lipophilicity of pesticides has been evaluated by high-performance liquid chromatography (HPLC) using different chemically bonded (C18, C8, CN and Phenyl HPLC columns) stationary phases and two different organic modifiers (methanol and acetonitrile, respectively) in the mobile phase composition. Through a systematic study, by using the classic multivariate analysis, several quantitative structure-property/lipophilicity multi-dimensional models were established. Multiple linear regression and genetic algorithm for the variable subset selection were used. The internal and external statistical evaluation procedures revealed some appropriate models for the chromatographic lipophilicity prediction of pesticides. Moreover, the statistical parameters of regression and those obtained by applying t-test for the intercept (a(0)) and for the slope (a(1)) in order to evaluate relationship between experimental and predicted octanol-water partition coefficients in case of the test set compounds, revealed two statistically valid models that can be successfully used in lipophilicity prediction of pesticides.

  10. Development and validation of a simple stability-indicating high performance liquid chromatographic method for the determination of miconazole nitrate in bulk and cream formulations.

    PubMed

    De Zan, María M; Cámara, María S; Robles, Juan C; Kergaravat, Silvina V; Goicoechea, Héctor C

    2009-08-15

    A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB - C18 (4.6 mm x 150 mm, 5 microm particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 degrees C and 10 microL of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis.

  11. High-performance liquid chromatographic determination of polyamines in milk as their 9-fluorenylmethoxycarbonyl derivatives using a column-switching technique.

    PubMed

    Bellagamba, F; Moretti, V M; Mentasti, T; Albertini, A; Luzzana, U; Valfrè, F

    1997-12-12

    A high-performance liquid chromatographic method for the determination of polyamines in milk is milk is described. Polyamines were extracted in perchloric acid and derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl). The excess of reagent was reacted with aspartic acid before the analysis on a column-switching system. Linearity of derivatization was calculated for each amine and the coefficient of regression ranged from 0.994 to 0.999. Chromatographic separation of FMOC-polyamines was achieved with a gradient elution programme of water-acetonitrile. The correlation coefficients of the standard curves in the concentration range from 0.5 to 5 nmol ml-1 were higher than 0.991. The repeatability of the method, expressed as R.S.D. for each polyamines ranged from 3.0 to 8.6%. The percent mean recoveries at 1 nmol ml-1 spiking level were 49 +/- 3, 58 +/- 5, 61 +/- 5 and 48 +/- 4 for putrescine, cadaverine, spermidine and spermine, respectively. The limit of detection, calculated on the basis of three times signal-to-noise ratio, was 50 pmol ml-1 for each polyamine.

  12. Stability-indicating liquid chromatographic method for determination of saxagliptin and structure elucidation of the major degradation products using LC-MS.

    PubMed

    Abdel-Ghany, Maha F; Abdel-Aziz, Omar; Ayad, Miriam F; Tadros, Mariam M

    2015-04-01

    A new, simple, selective, reproducible and sensitive stability-indicating liquid chromatographic method was developed and subsequently validated for the determination of saxagliptin (SXG). SXG was subjected to oxidation, thermal, acid hydrolysis, alkali hydrolysis and photodegradation according to ICH guidelines. The major degradation products were separated from the pure drug and the proposed structures' elucidation was performed, using an LC-MS technique. Isocratic chromatographic elution was achieved on a Symmetry(®) C18 column (150 × 4.6 mm, 5 µm), using a mobile phase of potassium dihydrogen phosphate buffer (pH 4.6)-acetonitrile-methanol (40 : 30 : 30, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 208 nm. Linearity, accuracy and precision were found to be acceptable over the concentration range of 25-400 µg mL(-1). All the results were statistically compared with the reference method, using one-way analysis of variance. The developed method was validated and proved to be specific and accurate for quality control of SXG in pharmaceutical dosage form.

  13. Optimization of poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based capillary monoliths for separation of low, medium, and high molecular-weight analytes.

    PubMed

    Lubbad, Said H

    2016-04-22

    Poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based monolithic capillary columns were optimized for separation of low, medium, and high molecular-weight analytes. The morphology and consequently the chromatographic performance of these monoliths were tuned by changes in the volume-ratio of monomer to macroporogen, establishing good monolithic flow-through and retention pores. Two monoliths were prepared and analyzed by reversed-phase chromatographic separation of low molecular-weight analytes such as alkyl benzenes and β-blockers, as well as medium and high molecular-weight analytes such as peptides and proteins, respectively. The microstructure was studied by scanning electron microscopy (SEM), and by inverse-size exclusion chromatography (ISEC). Monolith 1 demonstrated a high retention of alkyl benzenes, which coeluted from the column at the washing step of absolute acetonitrile; yet this monolith established a baseline separation of 9-peptide and 8-protein mixtures. Monolith 2 demonstrated efficient separation of the three analyte groups of different molecular weights. Six alkyl benzenes and five β-blockers were base-line separated in less than 5 and 2min, respectively, with good resolution and very small values of peak width at half height. Moreover, a comparable performance of efficient separation of the 9-peptide mixture and a fast separation of 5- and 8-protein mixtures were achieved. Both monoliths were characterized by high mechanical strength, high permeability, and excellent reproducibility.

  14. Tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate

    SciTech Connect

    Derry, Paul J.; Wang, Xiaoping; Smucker, Bradley W.

    2008-01-01

    The improved synthesis and characterization of tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate, [Pt(C4H4N2)4](BF4)2 0.5CH3CN, is reported. The unit cell contains a half equivalent of an acetonitrile solvent molecule per tetrapyrazineplatinum(II) ion. The coordination geometry of the PtII ion is almost square-planar, with the Pt atom residing on an inversion center. The BF4- counter-anion, located at a general position, has an idealized tetrahedral geometry and an acetonitrile solvent molecule, the methyl group of which is disordered over two equal positions, sits on a twofold rotation axis.

  15. Water versus acetonitrile coordination to uranyl. Effect of chloride ligands.

    PubMed

    Bühl, Michael; Sieffert, Nicolas; Chaumont, Alain; Wipff, Georges

    2012-02-06

    Optimizations at the BLYP and B3LYP levels are reported for the mixed uranyl chloro/water/acetonitrile complexes [UO(2)Cl(n)(H(2)O)(x)(MeCN)(5-n-x)](2-n) (n = 1-3) and [UO(2)Cl(n)(H(2)O)(x)(MeCN)(4-n-x)](2-n) (n = 2-4), in both the gas phase and a polarizable continuum modeling acetonitrile. Car-Parrinello molecular dynamics (CPMD) simulations have been performed for [UO(2)Cl(2)(H(2)O)(MeCN)(2)] in the gas phase and in a periodic box of liquid acetonitrile. According to population analyses and dipole moments evaluated from maximally localized Wannier function centers, uranium is less Lewis acidic in the neutral UO(2)Cl(2) than in the UO(2)(2+) moiety. In the gas phase the latter binds acetonitrile ligands more strongly than water, whereas in acetonitrile solution, the trend is reversed due to cooperative polarization effects. In the polarizable continuum the chloro complexes have a slight energetic preference for water over acetonitrile ligands, but several mixed complexes are so close in free energy ΔG that they should exist in equilibrium, in accord with previous interpretations of EXAFS data in solution. The binding strengths of the fifth neutral ligands decrease with increasing chloride content, to the extent that the trichlorides should be formulated as four-coordinate [UO(2)Cl(3)L](-) (L = H(2)O, MeCN). Limitations to their accuracy notwithstanding, density functional calculations can offer insights into the speciation of a complex uranyl system in solution, a key feature in the context of nuclear waste partitioning by complexant molecules.

  16. Laser synthesis and spectroscopy of acetonitrile/silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Akin, S. T.; Liu, X.; Duncan, M. A.

    2015-11-01

    Silver nanoparticles with acetonitrile ligands are produced in a laser ablation flow reactor. Excimer laser ablation produces gas phase metal clusters which are thermalized with helium or argon collisions in the flowtube, and reactions with acetonitrile vapor coordinate this ligand to the particle surface. The gaseous mixture is captured in a cryogenic trap; warming produces a solution of excess ligand and coated particles. TEM images reveal particle sizes of 10-30 nm diameter. UV-vis absorption and fluorescence spectra are compared to those of standard silver nanoparticles with surfactant coatings. Deep-UV ligand absorption is strongly enhanced by nanoparticle adsorption.

  17. Evaluation of sequential injection chromatography for reversed phase separation of triazine herbicides exploiting monolithic and core-shell columns.

    PubMed

    de Prá Urio, Ricardo; Masini, Jorge C

    2015-01-01

    This paper describes the development of reversed phase sequential injection chromatography (SIC) methods for separation of simazine (SIM) and atrazine (AT), as well as their metabolites deethylatrazine (DEA), deisopropylatrazine (DIA) and hydroxyatrazine (HAT) exploiting silica based monolithic (50 × 4.6 mm) and core-shell (30 × 4.6 mm, 2.7 µm particles) columns. The separation was made by stepwise elution with two mobile phases: MP1 composed of 15:85 (v/v) acetonitrile: 2.5 mmol L(-1) acetic acid/ammonium acetate buffer (pH 4.2), and MP2, composed of 35:65 (v/v) acetonitrile: 2.5 mmol L(-1) acetic acid/ammonium acetate buffer (pH 4.2).The less hydrophobic compounds (DIA, HAT and DEA) eluted with MP1, whereas SIM and AT eluted with MP2. The method using core-shell column exhibited better chromatographic efficiency compared with monolithic column for separation of SIM and AT, but failed to provide base line separation of DIA and HAT. The proposed composition of mobile phases enabled the monolithic column to separate all the studied compounds with resolution >2.3 at flow rate of 35 µL s(-1) and sampling throughput of 8 analyses per hour, whereas in the core-shell the maximum flow rate allowed in the SIC system was 8 µL s(-1) (sampling throughput of 3 analyses per hour). The limits of detection were between 24 µg L(-1) (AT) and 40 µg L(-1) (DEA) using the monolithic column, and between 20 µg L(-1) (SIM) and 38 µg L(-1) (DEA) with the core-shell. Ultrasound-assisted extraction (80:20 v/v acetonitrile:water) of a soil sample enriched with the five triazines (250, 500 and 1000 µg kg(-1)) resulted recoveries between 51% and 121% of the spiked concentrations.

  18. Concurrent high-performance liquid chromatographic measurement of loxapine and amoxapine and of their hydroxylated metabolites in plasma.

    PubMed

    Hüe, B; Palomba, B; Giacardy-Paty, M; Bottaï, T; Alric, R; Petit, P

    1998-06-01

    The dibenzoxazepine neuroleptic loxapine, its N-demethylated metabolite amoxapine, and their 7- and 8-hydroxymetabolites were measured simultaneously in plasma by reversed-phase high-performance chromatographic method. An original liquid-liquid extraction procedure was performed, consisting in coextraction of the substances together with a water-miscible solvent (acetonitrile) by a non-water-miscible solvent (toluene). The substances were separated on a 5-microm CN 25-cm column, and eluted with a mobile phase consisting of acetonitrile-acetic acid 0.5 N (30:70) and hexylamine (0.05%). They were detected by ultraviolet spectrophotometry at 310 nm. Clozapine was used as internal standard. Linearity was demonstrated in the range of 10 to 250 microg/l, and detection limits were found to be 3.5 to 6.3 microg/l according to the substance. Within-day repeatability ranged from 2.7% to 6.5%, and between-day reproducibility ranged from 0.9% to 20.2%. The extraction procedure provided a mean absolute recovery of 51.1% (range, 40.7% to 58.6%) with a mean coefficient of variation of 4.2%. This technique was applied to the concurrent determination of plasma concentrations of the compounds in 10 patients administered loxapine 75 to 600 mg daily. Steady state plasma levels of loxapine were significantly correlated with oral doses (n = 10, r = 0.858, p < 0.002). In conclusion, the method proved to be a convenient and reproducible procedure allowing the simultaneous measurement of loxapine, amoxapine, and their metabolites in patients.

  19. Quantifying process tradeoffs in the operation of chromatographic sequences.

    PubMed

    Ngiam, Sheau-Huey; Bracewell, Daniel G; Zhou, Yuhong; Titchener-Hooker, Nigel J

    2003-01-01

    A method for the rapid representation of key process tradeoffs that need to be made during the analysis of chromatographic sequences has been proposed. It involves the construction of fractionation and maximum purification factor versus yield diagrams, which can be completed easily on the basis of chromatographic data. The output of the framework developed reflects the degree of tradeoff between levels of yield and purity and provides a fast and precise prediction of the sample fraction collection strategy needed to meet a desired process specification. The usefulness of this approach for the purposes of product purification and contaminant removal in a single chromatographic step has been successfully demonstrated in an earlier paper and it is now extended by application to a chromatographic sequence: the separation of a hypothetical three-component protein system by hydrophobic interaction chromatography (HIC) followed by size exclusion chromatography (SEC). The HIC operation has a strong impact upon the subsequent SEC step. The studies show how the analysis of performance in such a chromatographic sequence can be carried out easily and in a straightforward fashion using the fractionation diagram approach. The methodology proposed serves as a useful tool for identifying the process tradeoffs that must be made during operation of a sequence of chromatographic steps and indicates the impact on further processing of the cut-point decisions that are made.

  20. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOEpatents

    Grindstaff, Quirinus G.

    1992-01-01

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  1. Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C.

    PubMed

    Acquaviva, A; Tascon, M; Padró, J M; Gagliardi, L G; Castells, C B

    2014-09-01

    We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development.

  2. Study of the cerium(IV)-picrate system in acetonitrile.

    PubMed

    Kratochvil, B; Tipler, M; McKay, B

    1966-07-01

    A potentiometric and spectrophotometric study has been made of the reaction between hexanitratocerate and picrate in dry acetonitrile. Several cerium(IV)-picrate complexes are formed; the formation constant for the first is estimated to be 4 from spectrophotometric measurements. The catalytic effect of picrate on hydroquinone oxidation by nitratocerate is postulated to be due to more rapid electron transfer by cerium picrate complexes.

  3. Separation of peptides from myoglobin enzymatic digests by RPLC. Influence of the mobile-phase composition and the pressure on the retention and separation

    SciTech Connect

    Marchetti, Nicola; Guiochon, Georges A

    2005-06-01

    The influence of the mobile-phase composition and the pressure on the chromatographic separation of the peptides from the enzymatic digest of myoglobin was studied under linear conditions. The retention behavior of these tryptic peptides was measured under isocratic conditions with different mobile-phase compositions, ranging from 9 to 28% (v/v) acetonitrile in 0.1% (v/v) aqueous trifluoroacetic acid. The effect of the pressure was studied by analyzing the separation of the tryptic peptides under different average column pressures between 14 and 220 bar, at 13, 20, and 26% (v/v) acetonitrile. The differences between the partial molar volumes of these peptides in the stationary and mobile phases were derived from these results. All the measurements were performed on a 10-cm-long C{sub 18}-bonded, end-capped monolithic column. The results obtained illustrate the highly complicated behavior of the complex peptide mixtures afforded by tryptic digestion. The capacity factors of the analyzed peptides do not depend linearly on the acetonitrile concentration but follow exactly a quadratic relationship. The adsorption changes of partial molar volumes are in good agreement with other literature data. The consequences of the influence of the average column pressure (hence of the flow rate) on the column phase ratio and on the retention factors of the peptides are discussed. The retention pattern of the complex mixture is affected by both the mobile-phase composition and the pressure, and the resolution of certain peptide pairs is so much affected by the pressure that inversions in the elution order of some pairs are observed.

  4. Nanofluidic Size-Exclusion Chromatograph

    NASA Technical Reports Server (NTRS)

    Feldman, Sabrina; Svehla, Danielle; Grunthaner, Frank; Feldman, Jason; Shakkottai, P.

    2004-01-01

    Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a laboratory on a chip that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically, it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples. Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size-exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of molecules: basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights. Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights.

  5. On the ion chromatographic determination of S(IV)

    NASA Astrophysics Data System (ADS)

    Dasgupta, Purnendu K.

    Ion Chromatographie determination of S(IV) is described with special reference to the determination of SO 2(g) and/or aerosol S(IV) along with chloride, nitrate and sulfate in particulate matter. A method is presented for the baseline separation of the above species. The Chromatographic behavior of hydroxymethanesulfonate under various eluent conditions is discussed.

  6. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everwhere else around the annulus. The rotation of the sorbent bed causes the separation components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m0-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory.

  7. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 17 references, 9 figures, 1 table.

  8. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 9 figures, 1 table.

  9. A salting out-acetonitrile homogeneous extraction coupled with gas chromatography-mass spectrometry method for the simultaneous determination of thirteen N-nitrosamines in skin care cosmetics.

    PubMed

    Dong, Hao; Guo, Xindong; Xian, Yanping; Luo, Haiying; Wang, Bin; Wu, Yuluan

    2015-11-27

    A sensitive gas chromatography-mass spectrometry method was established for the simultaneous determination of thirteen N-nitrosamines (NAs) in skin care cosmetics. The cosmetics samples were firstly dispersed by water and subsequently extracted and purified using salting out-acetonitrile homogeneous extraction method. Finally, the extracting solution was concentrated by slow nitrogen gas blowing. All of the samples were separated by INNOWAX capillary chromatographic column, and detected by selected ion monitoring (SIM) mode of gas chromatography-mass spectrometry (GC-MS) and quantified by isotope internal standard method. The method was validated for linearity and range, accuracy, precision and sensitivity. Under the optimized condition, the calibration curves were linear over the selected concentration ranges of 2-500μg/L for all the thirteen analytes, with calculated coefficients of determination (R(2)) of greater than 0.996. The limits of detection (LODs) and the limits of quantitation (LOQs) of the method were 3-15μg/kg and 10-50μg/kg, respectively. Recoveries were calculated at three levels of concentration spiked in two kinds of cosmetics (skin care cream and water). The values were found between 93.8% and 121.0% with relative standard deviation (RSD) values of 2.5-7.2% for intra-day precision (n=6) and 3.3-6.7% for inter-day precision (n=5). The method was successfully applied to analyze twenty-two cosmetics samples and N-nitrosodimethylamine (NDMA) was detected in one sample with the concentration of 207μg/kg.

  10. Improved Chiral Separation of (R,S)-Goitrin by SFC: An Application in Traditional Chinese Medicine

    PubMed Central

    Nie, Lixing; Dai, Zhong; Ma, Shuangcheng

    2016-01-01

    Like chemical drugs, research and development of herbal medicine also have a need to resolve enantiomers. To help illustrating the antiviral bioactivity of Isatidis Radix, a widely used traditional Chinese medicine (TCM), supercritical fluid chromatography (SFC) was used for analytical and preparative separation of (R,S)-goitrin, which was reported as the active ingredient of the herbal. Improved resolution was achieved on Chiralpak IC column, using acetonitrile as the organic modifier, representing a tenfold increase in speed, compared to the previous normal phase HPLC (NPLC) method. The newly developed chromatographic method was validated in terms of linearity, precision, limit of detection (LOD), and limit of quantitation (LOQ). Scale-up purification of (R)-goitrin and (S)-goitrin was performed on a preparative column with >90% total recovery. The absolute stereochemical assignment of the purified isomers was determined through optical rotation study. This attempt explored SFC's application in chiral research of traditional Chinese medicine. PMID:27022502

  11. Development of easy-to-use reverse-phase liquid chromatographic methods for determining PRE-084, RC-33 and RC-34 in biological matrices. The first step for in vivo analysis of sigma1 receptor agonists.

    PubMed

    Marra, Annamaria; Rossi, Daniela; Maggi, Lauretta; Corana, Federica; Mannucci, Barbara; Peviani, Marco; Curti, Daniela; Collina, Simona

    2016-04-01

    Over the years there has been a growing interest in the therapeutic potential for central nervous system pathologies of sigma receptor modulators. The widely studied PRE-084 and our compounds RC-33 and RC-34 are very potent and selective sigma 1 receptor agonists that could represent promising drug candidates for Amyotrophic Lateral Sclerosis (ALS). Herein, we develop and validate robust and easy-to-use reverse-phase chromatographic methods suitable for detecting and quantifying PRE-084, RC-33 and RC-34 in mouse blood, brain and spinal cord. An HPLC/UV/ESI-MS system was employed for analyzing PRE-084 and an HPLC/UV-PDA system for determining RC-33 and RC-34. Chromatographic separations were achieved on Waters Symmetry RP18 column (150 × 3.9 mm, 5 µm), eluting with water and acetonitrile (both containing 0.1% formic acid) in gradient conditions. The recovery of PRE-084, RC-33 and RC-34 was >95% in all the considered matrices. Their limits of quantitation and detection were also determined. Validation proved the methods be suitable for separating tested compounds from endogenous interferences, being characterized by good sensitivity, linearity, precision and accuracy. A preliminary central nervous system distribution study showed a high distribution of RC-33 in brain and spinal cord, with concentration values well above the determined limit of quantitation. The proposed methods will be used in future preclinical investigations.

  12. The adsorption of hetero- and alicyclic thiophene derivatives from water-acetonitrile solutions on the surface of porous graphitic carbon under high-performance liquid chromatography conditions

    NASA Astrophysics Data System (ADS)

    Saifutdinov, B. R.; Emel'yanova, N. S.; Kurbatova, S. V.; Pimerzin, A. A.

    2012-07-01

    The adsorption of hetero- and alicyclic thiophene derivatives synthesized for the first time from water-acetonitrile solutions with various compositions on the surface of porous graphitic carbon was studied by the high-performance liquid chromatography method. The retention factor and Henry adsorption constant values and equilibrium constants of quasi-chemical reactions of the adsorption and solvation of the heterocyclic compounds studied were calculated using the Lanin-Nikitin equation. The influence of the structure of hetero- and alicyclic thiophene derivative molecules on their adsorption on the surface of porous graphitic carbon and solvation in water-acetonitrile solutions was discussed. The Lanin-Nikitin model was found to be more informative in the interpretation of the adsorption-chromatographic experiment data compared with the Snyder-Soczewinski and Scott-Kucera models.

  13. Versatile gas/particle ion chromatograph.

    PubMed

    Ullah, S M Rahmat; Takeuchi, Masaki; Dasgupta, Purnendu K

    2006-02-01

    A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.

  14. High performance hand-held gas chromatograph

    SciTech Connect

    Yu, C.M.

    1998-04-28

    The Microtechnology Center of Lawrence Livermore National Laboratory has developed a high performance hand-held, real time detection gas chromatograph (HHGC) by Micro-Electro-Mechanical-System (MEMS) technology. The total weight of this hand-held gas chromatograph is about five lbs., with a physical size of 8{close_quotes} x 5{close_quotes} x 3{close_quotes} including carrier gas and battery. It consumes about 12 watts of electrical power with a response time on the order of one to two minutes. This HHGC has an average effective theoretical plate of about 40k. Presently, its sensitivity is limited by its thermal sensitive detector at PPM. Like a conventional G.C., this HHGC consists mainly of three major components: (1) the sample injector, (2) the column, and (3) the detector with related electronics. The present HHGC injector is a modified version of the conventional injector. Its separation column is fabricated completely on silicon wafers by means of MEMS technology. This separation column has a circular cross section with a diameter of 100 pm. The detector developed for this hand-held GC is a thermal conductivity detector fabricated on a silicon nitride window by MEMS technology. A normal Wheatstone bridge is used. The signal is fed into a PC and displayed through LabView software.

  15. Liquid Chromatographic Determination of Amnesic Shellfish Poison in Mussels

    NASA Astrophysics Data System (ADS)

    Duxbury, Mark

    2000-10-01

    A simple, rapid, high-performance liquid chromatographic experiment suitable for undergraduate students is described for determining amnesic shellfish poison in mussels. The poison itself is an unusual naturally occurring amino acid, domoic acid, that has been found in seafood, particularly shellfish, worldwide. The symptoms of poisoning include amnesia (memory loss), loss of balance, mental confusion, nausea, vomiting, diarrhea, coma, and in extreme cases death. The domoic acid is extracted from homogenized mussel tissue by boiling in water for 5 minutes. The homogenate is cooled and centrifuged, and an aliquot of the supernatant is diluted and analyzed by isocratic HPLC using a C18 column and an acetonitrile-water mobile phase at pH 2.5 with UV detection at 242 nm.

  16. New HPLC method for separation of blood plasma phospholipids.

    PubMed

    Suchocka, Zofia; Gronostajska, Dorota; Suchocki, Piotr; Pachecka, Jan

    2003-08-08

    The aim of the present work was to develop a new HPLC method for separation of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lysophosphatidylcholine (LPC) from small-volume samples of blood plasma. Human plasma glycerophospholipids were separated by liquid-liquid extraction method followed by solid phase extraction (SPE) on aminopropyl columns. Reversed-phase Sephasil C8 column (10 cm x 2.1 mm, I.D. 5 microm) and micropreparative chromatograph "SMART" were used for separation of PC, PE, LPC and PI from SPE phospholipids extract. Binary-step gradient of eluent A: acetonitrile-methanol (130:5, v/v) and B (0.01% trifluoroacetic acid) provided good, fast and reproducible resolution of investigated phospholipids classes in 12 min at 30 degrees C. Eluted phospholipids were detected at wavelengths lambda=235 and 254 nm. This method made it possible to determine quantitatively: 5 microg ml(-1) PC, 1 microg ml(-1) LPC, 4 microg ml(-1) PE and 3 microg ml(-1) PI in blood plasma samples.

  17. DEVELOPMENT AND VALIDATION OF AN ION CHROMATOGRAPHIC METHOD FOR DETERMINING PERCHLORATE IN FERTILIZERS

    EPA Science Inventory

    A method has been developed for the determination of perchlorate in fertilizers. Materials are leached with deionized water to dissolve any soluble perchlorate compounds. Ion chromatographic separation is followed by suppressed conductivity for detection. Perchlorate is retained ...

  18. Simultaneous high-performance liquid chromatographic determination of puerarin, daidzin, paeoniflorin, liquiritin, cinnamic acid, cinnamaldehyde and glycyrrhizin in Kampo medicines.

    PubMed

    Okamura, N; Miki, H; Orii, H; Masaoka, Y; Yamashita, S; Kobayashi, H; Yagi, A

    1999-03-01

    We report a high-performance liquid chromatographic method to determine the quantities of puerarin, daidzin, paeoniflorin, liquiritin, cinnamic acid, cinnamaldehyde and glycyrrhizin in Kampo medicine. All seven compounds were separated in less than 30 min with a Wakosil-II 5C18 AR column by linear gradient elution using 0.01% (v/v) phosphoric acid acetonitrile (0 min 90:10, 10 min 88:12, 22 min 70:30, 30 min 30:70) as the mobile phase at a flow-rate of 1.0 ml/min(-1), and detection at 250 nm. The detection limits of these compounds are 0.15-0.3 microM with response linearity. This method was applied to determine the quantities in eight Kampo decoctions; Mao-to, Makyo-yokukan-to, Makyo-kanseki-to, Yokuinin-to, Sho-seiryu-to, Keima-kakuhan-to, Kakkon-to and Kakkon-to-ka-senkyu-sin'i. Glycyrrhizin content was lower in both the decoction and the methanol-diluted decoction of Sho-seiryu-to compared with the others. Low pH due to organic acids of Schisandrae fructus in the decoction caused inhibition for glycyrrhizin dissolution in Sho-seiryu-to.

  19. A Robust Liquid Chromatographic Method for Confirmation of Drug Stability of Azithromycin in Bulk Samples, Tablets and Suspensions

    PubMed Central

    Okaru, Alex O.; Abuga, Kennedy O.; Kamau, Franco N.; Ndwigah, Stanley N.; Lachenmeier, Dirk W.

    2017-01-01

    A simple, isocratic and robust RP-HPLC method for the analysis of azithromycin was developed, validated and applied for the analysis of bulk samples, tablets and suspensions. The optimum chromatographic conditions for separation were established as a mobile phase comprised of acetonitrile-0.1 M KH2PO4 pH 6.5–0.1 M tetrabutyl ammonium hydroxide pH 6.5-water (25:15:1:59 v/v/v/v) delivered at a flow rate of 1.0 mL/min. The stationary phase consisted of reverse-phase XTerra® (250 mm × 4.6 mm i.d., 5 µm particle size) maintained at a temperature of 43 °C with a UV detection at 215 nm. The method was found to be linear in the range 50%–150% (r2 = 0.997). The limits of detection and quantification were found to be 0.02% (20 µg) and 0.078% (78 µg), respectively, with a 100.7% recovery of azithromycin. Degradation products of azithromycin in acidic and oxidative environments at 37 °C were resolved from the active pharmaceutical ingredient and thus the method is fit for the purpose of drug stability confirmation. PMID:28245574

  20. Chromatographic fingerprint analysis and simultaneous determination of eight lignans in Justicia procumbens and its compound preparation by HPLC-DAD.

    PubMed

    Wang, Linan; Pan, Jianyu; Yang, Meihua; Wu, Jun; Yang, Junshan

    2011-03-01

    HPLC fingerprints were developed for the quality evaluation of Justicia procumbens and its compound preparation, Jian-er syrup, together with the simultaneous quantification of eight arylnaphthalide lignans (6'-hydroxy justicidin B, 6'-hydroxy justicidin A, 6'-hydroxy justicidin C, justicidin B, chinensinaphthol methyl ether, justicidin C, taiwanin C, and neojusticin A). Samples were separated with a Shiseido Capcell Pak C(18) reversed-phase column (250×4.6 mm id, 5 μm) using acetonitrile and water as the mobile phase. The column temperature was maintained at 35°C and the wavelength of detector was set at 256 nm. For fingerprint analysis, 17 peaks were selected as the characteristic peaks for the evaluation of the similarities among different J. procumbens samples collected in different places. The structures of lignans were confirmed by diagnostic fragments in the positive ESI-MS(n) . The new method was successfully applied for the chromatographic fingerprint analysis and simultaneous determination of eight lignans in its compound preparation, Jian-er syrup. All the results indicated that HPLC fingerprint assay in combination with multi-marker determination afforded a useful method for the quality control of J. procumbens and its compound preparation, Jian-er syrup.

  1. Ultra-high performance liquid chromatographic determination of antioxidants in teas using inkjet-printed graphene-polyaniline electrode.

    PubMed

    Bardpho, Chayanee; Rattanarat, Poomrat; Siangproh, Weena; Chailapakul, Orawon

    2016-02-01

    A development of ultra-high performance liquid chromatographic coupled with a novel inkjet-printed conductive ink-modified electrode for a fast and simultaneous determination of polyphenolic antioxidants was achieved. Two printing techniques were selected for fabrication and modification including (i) an in-house screen-printing method and (ii) an inkjet-printing method, respectively. A conductive ink containing graphene and polyaniline nanocomposite (G-PANI) was precisely casted onto the surface of screen-printed carbon electrode (SPCE) using a dimatix inkjet material printer. Compared to a bare SPCE, the G-PANI-modified screen-printed carbon electrode (G-PANI/SPCE) exhibited higher electrochemical sensitivity with increase (2-4 times) of peak current of each antioxidant. Moreover, four antioxidants were successfully separated and determined within 3 min using a reverse phase ultra-high performance liquid chromatography (UHPLC) with a mobile phase containing phosphate buffer and acetonitrile (90:10 v/v). Under an optimal detection potential at +1.2V vs. Ag/AgCl, linear calibrations and limits of detection (S/N=3) for antioxidants were found to be 0.01-10 µg mL(-1) and 1.38-1.94 ng mL(-1), respectively. Finally, this proposed method has been successfully used for the determination of antioxidants in tea samples, the results obtained from our presented method were within a highly good agreement those obtained from a standard UHPLC-UV method.

  2. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets

    PubMed Central

    Sharmila, D.; Rao, A. Lakshmana; Kalyani, L.

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r2=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  3. Salting-out assisted liquid/liquid extraction with acetonitrile: a new high throughput sample preparation technique for good laboratory practice bioanalysis using liquid chromatography-mass spectrometry.

    PubMed

    Zhang, Jun; Wu, Huaiqin; Kim, Elaine; El-Shourbagy, Tawakol A

    2009-04-01

    Acetonitrile, an organic solvent miscible with aqueous phase, has seen thousands of publications in the literature as an efficient deproteinization reagent. The use of acetonitrile for liquid-liquid extraction (LLE), however, has seen very limited application due to its miscibility with aqueous phase. The interest in LLE with acetonitrile has been pursued and reported in the literature by significantly lowering the temperature of the mixture or increasing the salt concentration in the mixture of acetonitrile and aqueous phase, resulting in the separation of the acetonitrile phase from aqueous phase, as observed in conventional LLE. However, very limited application of these methods has been reported. The throughput was limited. In this report, we report a new sample preparation technique, salting-out assisted liquid-liquid extraction with acetonitrile, for high-throughput good laboratory practice sample analysis using LCMS, Two compounds from an approved drug, Kaletra, were used to demonstrate the extractability of drugs from human plasma matrix. Magnesium sulfate was used as the salting-out reagent. Extracts were diluted and then injected into a reversed phase LC-MS/MS system directly. One 96-well plate was extracted with this new approach to evaluate multiple parameters of a good laboratory practice analytical method. Results indicate that the method is rapid, reliable and suitable for regulated bioanalysis. With minimal modification, this approach has been used for high-throughput good laboratory practice analysis of a number of compounds under development at Abbott.

  4. The use of acetone as a substitute for acetonitrile in analysis of peptides by liquid chromatography/electrospray ionization mass spectrometry.

    PubMed

    Keppel, Theodore R; Jacques, Martin E; Weis, David D

    2010-01-01

    The recent worldwide shortage of acetonitrile has prompted interest in alternative solvents for liquid chromatography/mass spectrometry (LC/MS). In this work, acetone was substituted for acetonitrile in the separation of a peptide mixture by reversed-phase high-performance liquid chromatography (RP-HPLC) and in the positive electrospray ionization mass spectrometry (ESI-MS) of individual peptides. On both C12 and C18 stationary phases, the substitution of acetone for acetonitrile as the organic component of the mobile phase did not alter the gradient elution order of a five-peptide retention standard, but did increase peak width, shorten retention times, and increase peak tailing. Positive ESI mass spectra were obtained for angiotensin I, bradykinin, [Leu(5)]-enkephalin, and somatostatin 14 dissolved in both acetonitrile/water/formic acid (25%/75%/0.1%) and acetone/water/formic acid (25%/75%/0.1%). Under optimized ESI-MS conditions, the mass spectral response of [Leu(5)]-enkephalin was increased two-fold when the solvent contained acetone. The substitution of acetone for acetonitrile resulted in only slight changes in the responses of the remaining peptides. A higher capillary voltage was required for optimum response when acetone was used. Compared with acetonitrile/water/formic acid (50/50/0.1%), more interfering species below m/z = 140 were found in the ESI-MS spectra of acetone/water/formic acid (50/50/0.1%).

  5. Another glimpse over the salting-out assisted liquid-liquid extraction in acetonitrile/water mixtures.

    PubMed

    Valente, Inês Maria; Gonçalves, Luís Moreira; Rodrigues, José António

    2013-09-20

    The use of the salting-out effect in analytical chemistry is very diverse and can be applied to increase the volatility of the analytes in headspace extractions, to cause the precipitation of proteins in biological samples or to improve the recoveries in liquid-liquid extractions. In the latter, the salting-out process can be used to create a phase separation between water-miscible organic solvents and water. Salting-out assisted liquid-liquid extraction (SALLE) is an advantageous sample preparation technique aiming HPLC-UV analysis when developing analytical methodologies. In fact, some new extraction methodologies like QuEChERS include the SALLE concept. This manuscript discusses another point of view over SALLE with particular emphasis over acetonitrile-water mixtures for HPLC-UV analysis; the influence of the salting-out agents, their concentration and the water-acetonitrile volume ratios were the studied parameters. α-dicarbonyl compounds and beer were used as test analytes and test samples, respectively. The influence of the studied parameters was characterized by the obtained phase separation volume ratio and the fraction of α-dicarbonyls extracted to the acetonitrile phase. Results allowed the distribution of salts within three groups according to the phase separation and their extractability: (1) chlorides and acetates, (2) carbonates and sulfates and (3) magnesium sulfate; of all tested salts, sodium chloride had the highest influence on the α-dicarbonyls fraction extracted.

  6. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  7. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  8. Chromatographic separation of reaction products from the choline acetyltransferase and carnitine acetyltransferase assay: differential ChAT and CrAT activity in brain extracts from Alzheimer's disease versus controls.

    PubMed

    Bailey, Jason A; Lahiri, Debomoy K

    2012-08-01

    Choline acetyltransferase (ChAT) catalyzes the reaction between choline and acetylcoenzyme A (AcCoA) to form acetylcholine (ACh) in nerve terminals. ACh metabolism has implications in numerous aspects of physiology and varied disease states, such as Alzheimer's disease. Therefore a specific, sensitive, and reliable method for detecting ChAT enzyme activity is of great utility in a number of situations. Using an existing radionuclide-based enzyme activity assay, we have observed detectable ChAT signals from non-cholinergic cells, suggesting a contaminant in the assay producing an artifactual signal. Previous reports have suggested that L-acetylcarnitine (LAC) contaminates many assays of ChAT activity, because of difficulties in separating LAC from ACh by organic extraction. To determine the source of this hypothesized artifact and to rectify the problem, we have developed a paper chromatography-based assay for the detection of acetylcholine and other contaminating reaction products of this assay, including LAC. Our first goal was to develop a simple and economical method for resolving and verifying the identities of various reaction products or contaminants that could be performed in most laboratories without specialized equipment. Our second goal was to apply this separation method in postmortem human brain tissue samples. Our assay successfully detected several contaminants, especially in assays using brain tissue, and allowed the separation of the intended ACh product from these contaminants. We further demonstrate that this assay can be used to measure carnitine acetyltransferase (CrAT) activity in the same samples, and assays comparing ChAT and CrAT show that CrAT is highly active in neuronal tissues and in neuronal cell cultures relative to ChAT. Thus, the simple chromatography-based assay we describe allows the measurement of specific reaction products separated from contaminants using commonly available and inexpensive materials. Further, we show that Ch

  9. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  10. Chromatographic extraction with di(2-ethylhexyl)orthophosphoric acid for production and purification of promethium-147

    DOEpatents

    Boll, Rose A [Knoxville, TN

    2008-10-14

    A method of producing and purifying promethium-147 including the steps of: irradiating a target material including neodymium-146 with neutrons to produce promethium-147 within the irradiated target material; dissolving the irradiated target material to form an acidic solution; loading the acidic solution onto a chromatographic separation apparatus containing HDEHP; and eluting the apparatus to chromatographically separate the promethium-147 from the neodymium-146.

  11. New small-scale cross-axis coil planet centrifuge. The design of the apparatus and its application to counter-current chromatographic separation of proteins with aqueous-aqueous polymer phase systems.

    PubMed

    Shinomiya, Kazufusa; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2006-02-03

    The cross-axis coil planet centrifuge (X-axis CPC) is useful for partitioning macromolecules with aqueous-aqueous polymer phase systems. The floor model we have built with a pair of separation columns had some shortcomings such as requirement of large space, short life of the flow tubes, and difficulty in installing columns. In order to improve the partition efficiency and the utility of counter-current chromatography (CCC), a new small-scale X-axis CPC was designed and fabricated in our laboratory. The down-sizing of the apparatus was done by reducing the scale to about 1/2 of our original model of X-1.5L type with several improvements. Performance of the apparatus was evaluated on protein separation using an aqueous-aqueous polymer phase system composed of polyethylene glycol 1000 and dibasic potassium phosphate with four multilayer coiled columns. A series of experiments revealed that the combination of right- and left-handed coils produced the best partition efficiencies for both lower and upper mobile phases by selecting the revolution direction. The overall results indicate that the head-tail elution mode substantially affects to the peak resolution and stationary phase retention. This new X-axis CPC would be useful for the separation of various kinds of biologically active compounds.

  12. Coulometric determination of americium in acetonitrile solution of phosphoric acid

    SciTech Connect

    Perevalov, S.A.; Kulyakov, Yu.M.; Lebedev, I.A.; Myasoedov, B.F.

    1986-10-20

    A procedure was developed for the coulometric determination of americium using the electrochemical couple Am(IV)-Am(III). An acetonitrile solution of 0.3-0.2 M H/sub 3/PO/sub 4/ was used as the electrolyte. Americium can be determined in the presence of large amounts of Cm, Pu, Ce, and other impurities; limit of detection approx. 10 ..mu..g.

  13. Capillary electrochromatography with monolithic silica column: I. Preparation of silica monoliths having surface-bound octadecyl moieties and their chromatographic characterization and applications to the separation of neutral and charged species.

    PubMed

    Allen, Darin; El Rassi, Ziad

    2003-01-01

    Monolithic silica columns with surface-bound octadecyl (C18) moieties have been prepared by a sol-gel process in 100 microm ID fused-silica capillaries for reversed-phase capillary electrochromatography of neutral and charged species. The reaction conditions for the preparation of the C18-silica monoliths were optimized for maximum surface coverage with octadecyl moieties in order to maximize retention and selectivity toward neutral and charged solutes with a sufficiently strong electroosmotic flow (> 2 mm/s) to yield rapid analysis time. Furthermore, the effect of the pore-tailoring process on the silica monoliths was performed over a wide range of treatment time with 0.010 M ammonium hydroxide solution in order to determine the optimum time and conditions that yield mesopores of narrow pore size distribution that result in high separation efficiency. Under optimum column fabrication conditions and optimum mobile phase composition and flow velocity, the average separation efficiency reached 160 000 plates/m, a value comparable to that obtained on columns packed with 3 microm C18-silica particles with the advantages of high permeability and virtually no bubble formation. The optimized monolithic C18-silica columns were evaluated for their retention properties toward neutral and charged analytes over a wide range of mobile phase compositions. A series of dimensionless retention parameters were evaluated and correlated to solute polarity and electromigration property. A dimensionless mobility modulus was introduced to describe charged solute migration and interaction behavior with the monolithic C18-silica in a counterflow regime during capillary electrochromatography (CEC )separations. The mobility moduli correlated well with the solute hydrophobic character and its charge-to-mass ratio.

  14. Antioxidant and antibacterial activities of acetonitrile and hexane extracts of Lentinus tigrinus and Pleurotus djamour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper highlighted the antioxidant and antibacterial activities of Lentinus tigrinus and Pleurotus djamour. Extracts of mushroom fruiting bodies were obtained using hexane and acetonitrile solvents. Acetonitrile extracts of both mushrooms exhibited higher biological activities than hexane extrac...

  15. Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation

    PubMed Central

    Musmade, Kranti P.; Trilok, M.; Dengale, Swapnil J.; Bhat, Krishnamurthy; Reddy, M. S.; Musmade, Prashant B.; Udupa, N.

    2014-01-01

    A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection has been developed and validated for quantification of naringin (NAR) in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C18 (250.0 × 4.6 mm, 5 μm) column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v) as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1). The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV) less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity. PMID:26556205

  16. A method for the analysis of tabun in multisol using gas chromatographic flame photometric detection.

    PubMed

    Logan, Thomas P; Allen, Edward D; Way, Mark R; Swift, Austin T; Soni, Sunil-Datta; Koplovitz, Irwin

    2006-01-01

    Preparation and analysis of tabun (GA) solutions are necessary for the continued development of countermeasures to this nerve agent. GA solutions must be stable and compatible for use in the test systems chosen for study; however, GA is very unstable in saline solutions. In the past we have found GA in saline at 2 mg/mL to be stable for a month or less at -70 degrees C, whereas saline solutions of sarin (GB), soman (GD), and cyclosarin (GF) were stable for many months. Previous studies have shown that Multisol (48.5% H(2)O, 40% propylene glycol, 10% ethanol, and 1.5% benzyl alcohol) provides stable solutions of GA. We confirmed the stability of GA in Multisol with phosphorus nuclear magnetic resonance (P horizontal line NMR) and developed a method for the analysis of GA in Multisol using gas chromatographic flame photometric detection (GCFPD) in the phosphorus mode. The GC method used acetonitrile (CH(3)CN) for a dilution solvent because of its miscibility with GA in chloroform (CHCl(3)) standards and GA in Multisol samples at 1% (v/v). Furthermore, the dilutions with CH(3)CN made the phosphorus mode interference peak present in CHCl(3) analytically manageable, reduced the interferences of Multisol in the GC separation, and contributed to a safe and reliable analysis of GA at 20 mug/mL. We demonstrated the stability of GA in Multisol stored for more than a year at 70 degrees C. This method contributes a suitable technique for the preparation and analysis of reliable solutions of GA in nerve agent medical research and demonstrates the extended stability of GA in Multisol.

  17. High-performance liquid chromatographic determination of tianeptine in plasma applied to pharmacokinetic studies.

    PubMed

    Gaulier, J M; Marquet, P; Lacassie, E; Desroches, R; Lachatre, G

    2000-10-10

    An improved analytical method for the quantitative measurement of tianeptine and its main metabolite MC5 in human plasma was designed. Extraction involved ion-paired liquid-liquid extraction of the compounds from 1.0 ml of human plasma adjusted to pH 7.0. HPLC separation was performed using a Nucleosil C18, 5 microm column (150x4.6 mm I.D.) and a mixture of acetonitrile and pH 3, 2.7 g l(-1) solution of sodium heptanesulfonate in distilled water (40:60, v/v) as mobile phase. UV detection was performed using a diode array detector in the 200-400 nm passband, and quantification of the analytes was made at 220 nm. For both tianeptine and MC5 metabolite, the limit of quantitation was 5 microg l(-1) and the calibration curves were linear from 5 to 500 microg l(-1). Intra- and inter-assay precision and accuracy fulfilled the international requirements. The recovery of tianeptine and its metabolite from plasma was, respectively, 71.5 and 74.3% at 20 microg l(-1), 71.2 and 70.8% at 400 microg l(-1). The selectivity of the method was checked by verifying the absence of chromatographic interference from pure solutions of the most commonly associated therapeutic drugs. This method, validated according to the criteria established by the Journal of Chromatography B, was applied to the determination of tianeptine and MC5-metabolite in human plasma in pharmacokinetic studies.

  18. Rapid extraction and reverse phase-liquid chromatographic separation of mercury(II) and methylmercury in fish samples with inductively coupled plasma mass spectrometric detection applying oxygen addition into plasma.

    PubMed

    Döker, Serhat; Boşgelmez, İffet İpek

    2015-10-01

    A simple and sensitive procedure was developed for extraction and speciation of mercury in fish. Species separation was accomplished with reverse phase-high performance liquid chromatography (HPLC) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS). Oxygen addition into plasma allowed use of organic-rich mobile phase, achieving species separation in 4 min. Mercury species extraction was achieved by microwave exposure for 2 min at mild conditions (60°C, pH 2.0), avoiding necessity of neutralizing sample prior to injection in HPLC, and reducing number of sample preparation steps, analytical source of errors and inter conversion of species. Limit of detection for entire procedure was found to be 0.2 and 0.1 ng g(-1) for mercuric ion and methylmercury, respectively. The method was applied to certified reference materials (TORT-2 and DORM-2) and commercialized fish samples (Mullus barbatus, Sparus aurata, Trachurus mediterraneus, Mugil soiuy, Dicentrarchus labrax, and Pomatomus saltatrix) from Black Sea.

  19. Photophysics of Diphenylbutadiynes in Water, Acetonitrile-Water, and Acetonitrile Solvent Systems: Application to Single Component White Light Emission.

    PubMed

    Pati, Avik Kumar; Jana, Rounak; Gharpure, Santosh J; Mishra, Ashok K

    2016-07-28

    Diacetylenes have been the subject of current research because of their interesting optoelectronic properties. Herein, we report that substituted diphenylbutadiynes exhibit locally excited (LE) and excimer emissions in water and multiple emissions from the LE, excimer, and intramolecular charge transfer (ICT) states in acetonitrile-water solvent systems. The LE, excimer, and ICT emissions are clearly distinguishable for a diphenylbutadiynyl derivative with push (-NMe2)-pull (-CN) substituents and those are closely overlapped for non-push-pull analogues. In neat acetonitrile, the excimer emission disappears and the LE and ICT emissions predominate. In the case of the push (-NMe2)-pull (-CN) diphenylbutadiyne, the intensity of the ICT emission increases with increasing the fluorophore concentration. This suggests that the ICT emission accompanies with intermolecular CT emission which is of exciplex type. As the LE and exciplex emissions of the push-pull diphenylbutadiyne together cover the visible region (400-700 nm) in acetonitrile, a control of the fluorophore concentration makes the relative intensities of the LE and exciplex emissions such that pure white light emission is achieved. The white light emission is not observed in those diphenylbutadiynyl analogues in which the peripheral substituents of the phenyl rings do not possess strong push-pull character.

  20. Liquid-chromatographic determination of sarafloxacin residues in channel catfish muscle-tissue

    USGS Publications Warehouse

    Meinertz, J.R.; Dawson, V.K.; Gingerich, W.H.; Cheng, B.; Tubergen, M.M.

    1994-01-01

    A liquid chromatographic method is described for the determination of sarafloxacin hydrochloride residues i n channel catfish (ictalurus punctatus) fillets. Sarafloxacin was extracted from fillet tissue with acetonitrile=water (1 + 1). The extract was centrifuged and the supernatant was partitioned with hexane. The aqueous fraction was filtered through a 0.45 Mum filter and evaporated to dryness. The sample was redissolved with 20% acetonitrile-methanol (3 + 2) and 80% trifluoroacetic acid (0.1%), Centrifuged, and filtered to remove proteins. Samples were analyzed by chromatography with gradient elution on a c18 column and with fluorescence detection (excitation at 280 nm and emission above 389 nm). Mean recoveries ranged from 85.4 To 104%, and relative standard deviations ranged from 1.06 To 5.58% In samples spiked at concentrations of 10.0-863.8 Ng/g. The method detection limit for sarafloxacin was 1.4 Ng/g.

  1. Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives.

    PubMed

    Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

    2017-01-20

    Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3) according to the following formula: ω1=ω2+ω3. Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3: 2: 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω1, ω2, ω3)=(300, 150, 150rpm), and (1:4:5, v/v) for the upper mobile phase at (300:100:200rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω2 and ω3 under the constant revolution speed at ω1=300rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω2 and ω3, while with the upper mobile phase these two values were sensitively varied according to the different combination of ω2 and ω3. For example, when ω2=147 or 200rpm is used, no stationary phase was retained in the coiled column while ω2=150rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω1, ω2, ω3)=(300, 300, 0rpm) or (300, 0, 300rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300rpm) with the upper mobile phase. At lower rotation speed of ω1=300rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω3) than by the planetary motion (ω2), or ω3>ω2. The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n

  2. Development of a stability-indicating high-performance liquid chromatographic method for the simultaneous determination of alprazolam and sertraline in combined dosage forms.

    PubMed

    Pathak, Ashutosh; Rajput, Sadhana J

    2008-01-01

    The objective of the current study was to develop a validated stability-indicating high-performance liquid chromatographic method for alprazolam and sertraline in combined dosage forms. The method was validated by subjecting the drugs to forced decomposition under hydrolysis, oxidation, photolysis, and thermal stress conditions prescribed by the International Conference on Harmonization. The drugs were successfully separated from major and minor degradation products on a reversed-phase C18 column by using 75 mM potassium dihydrogen phosphate buffer (pH 4.3)-acetonitrile-methanol (50 + 45 + 5, v/v/v) as the mobile phase with determination at 227 nm. The flow rate was 0.9 mL/min. The method was validated with respect to linearity, precision, accuracy, system suitability, and robustness. The responses were linear over the ranges of 1-80 and 5-200 microg/mL for alprazolam and sertraline, respectively. The recoveries of both drugs from a mixture of degradation products were in the range of 97-101%. The utility of the procedure was verified by its application to marketed formulations that were subjected to accelerated stability studies. The method distinctly separated the drugs and degradation products, even in actual samples. The products formed in marketed tablets were similar to those formed during stress studies.

  3. A validated stability-indicating liquid chromatographic method for determination of process related impurities and degradation behavior of Irbesartan in solid oral dosage.

    PubMed

    Goswami, Nishant

    2014-01-01

    The present work describes the development and validation of a stability-indicating RP-HPLC method for the estimation of degradation and process related impurities of Irbesartan, namely Impurity-1, Impurity-2, Impurity-3 and Impurity-4. The developed LC method was validated with respect to specificity, limit of detection and quantification, linearity, precision, accuracy and robustness. The chromatographic separation was achieved on Hypersil Octadecylsilyl (4.6 mm × 150 mm, 3 μm) column by using mobile phase containing a gradient mixture of solvent A (0.55% v/v ortho-phosphoric acid, pH adjusted to 3.2 with triethyl amine) and B (95:5 v/v mixture of acetonitrile and solvent A) at a flow rate of 1.2 mL/min. The detection was carried out at a wavelength of 220 nm. During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The method is stability-indicating in nature and can be used for routine analysis of production samples and to check the stability of the Irbesartan HCl tablets.

  4. Ion-exclusion chromatographic separations of C1-C6 aliphatic carboxylic acids on a sulfonated styrene-divinylbenzene co-polymer resin column with 5-methylhexanoic acid as eluent.

    PubMed

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

    2003-05-16

    The application of C7 aliphatic carboxylic acids (heptanoic, 2-methylhexanoic, 5-methylhexanoic and 2,2-dimethyl-n-valeric acids) as eluents in ion-exclusion chromatography with conductimetric detection for C1-C6 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic and caproic acids) was carried out using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as a stationary phase. When using 0.05 mM sulfuric acid at pH 4.0 as the eluent, peak shapes of hydrophobic carboxylic acids (isovaleric, valeric, isocaproic and caproic acids) were tailed strongly. In contrast, when using 1 mM these C7 carboxylic acids at pH ca. 4 as the eluents, although system peaks (vacant peaks) corresponding to these C7 carboxylic acids appeared, peak shapes of these hydrophobic acids were improved drastically. Excellent simultaneous separation and relatively high sensitive conductimetric detection for these C1-C6 aliphatic carboxylic acids were achieved in 25 min on the TSKgel SCX column (150 x 6 mm I.D.) using 1 mM 5-methylhexanoic acid at pH 4.0 as the eluent.

  5. Cooperativity and cluster growth patterns in acetonitrile: a DFT study.

    PubMed

    Remya, Karunakaran; Suresh, Cherumuttathu H

    2014-05-05

    Cooperativity in intermolecular interactions and cluster growth patterns of acetonitrile has been studied using M06L density functional theory. Cyclic, ladder-type, stacked, cross-stacked, and mixed patterns are studied. Total interaction energy (E(int)) and interaction energy per monomer (E(m)) show maximum stability and cooperativity in stacked clusters followed by cross-stacked ones. As cluster size increased, magnitude of E(m) showed significant increase. Compared to E(m) of dimer (-2.97 kcal/mol), the increase is 2.6-fold for 27mer. Higher stabilization in larger clusters is attributed to strong cooperativity in intermolecular C-H···N and dipolar interactions. Enhanced cooperativity in stacked structures is supported by atoms-in-molecule electron density (ρ) data. Sum of ρ at intermolecular bond critical points is the highest for stacked clusters. Further, area of negative-valued molecular electrostatic potential is linearly related with E(int) and showed the lowest value in stacked followed by cross-stacked clusters, indicating maximum utilization of lone pair density and maximum cooperativity in such growth patterns. A red shift in the average C-N stretching frequencies with increase in the number of monomers and its direct correlation with E(int) in stacked clusters also supported their stability. Further, two known crystal patterns of acetonitrile (α and β) with 16 monomers are optimized and compared with the most stable hexadecamer pattern and are found to show lower values for E(int) and E(m) compared to the latter. Based on this result, we predict the existence of a third crystal pattern for acetonitrile which will be more ordered and more stable than α and β forms.

  6. Tris(acetonitrile)chloropalladium tetrafluoroborate synthesis, application and structural analysis

    NASA Astrophysics Data System (ADS)

    Dybała, Izabela; Demchuk, Oleg M.

    2016-10-01

    Results of the single crystal X-ray diffraction analysis of tris(acetonitrile)chloropalladium tetrafluoroborate [PdCl(CH3CN)3]BF4 are presented in details. It was found that the title compound crystallises in the monoclinic system, in the space group C2/c. The role of charge-assisted C-HṡṡṡF-B interactions in crystal architecture was investigated. Due to its untypical properties the prepared [PdCl(CH3CN)3]BF4 has proved to be an excellent palladium source in the synthesis of phosphine-palladium complexes.

  7. Breath testing and personal exposure--SIFT-MS detection of breath acetonitrile for exposure monitoring.

    PubMed

    Storer, Malina; Curry, Kirsty; Squire, Marie; Kingham, Simon; Epton, Michael

    2015-05-26

    Breath testing has potential for the rapid assessment of the source and impact of exposure to air pollutants. During the development of a breath test for acetonitrile using selected ion flow tube mass spectrometry (SIFT-MS) raised acetonitrile concentrations in the breath of volunteers were observed that could not be explained by known sources of exposure. Workplace/laboratory exposure to acetonitrile was proposed since this was common to the volunteers with increased breath concentrations. SIFT-MS measurements of acetonitrile in breath and air were used to confirm that an academic chemistry laboratory was the source of exposure to acetonitrile, and quantify the changes that occurred to exhaled acetonitrile after exposure. High concentrations of acetonitrile were detected in the air of the chemistry laboratory. However, concentrations in the offices were not significantly different across the campus. There was a significant difference in the exhaled acetonitrile concentrations of people who worked in the chemistry laboratories (exposed) and those who did not (non-exposed). SIFT-MS testing of air and breath made it possible to determine that occupational exposure to acetonitrile in the chemistry laboratory was the cause of increased exhaled acetonitrile. Additionally, the sensitivity was adequate to measure the changes to exhaled amounts and found that breath concentrations increased quickly with short exposure and remained increased even after periods of non-exposure. There is potential to add acetonitrile to a suite of VOCs to investigate source and impact of poor air quality.

  8. Ask the experts: chromatographic baselines.

    PubMed

    Smith, Graeme; James, Christopher A; Scott, Rebecca; Woolf, Eric

    2014-05-01

    Bioanalysis invited a selection of leading researchers to express their views on chromatographic baseline assignment in the bioanalytical laboratory. The topics discussed include the challenges presented with ensuring automated baseline assignment is correct, when reintegration is necessary, regulation and consistency in terminology. Their enlightening responses provide a valuable insight into developing an industry consensus towards reintegration. An accompanying commentary article in this issue, authored by Howard Hill and colleagues (Huntingdon Life Sciences), provides background to this much debated topic.

  9. Polystyrene bound stationary phase of excellent separation efficiency based on partially sub-2μm silica monolith particles.

    PubMed

    Ali, Faiz; Cheong, Won Jo; A L Othman, Zeid A; A L Majid, Abdullah M

    2013-08-16

    Partially sub-2μm porous silica monolith particles have been synthesized by a renovated procedure and modified to polystyrene coated silica particles with excellent separation efficiency when used as chromatographic media. In the procedure of preparing silica monolith particles in this study, subtle control of formulation of the reaction mixture and multi-step heating followed by calcination, without any washing and sieving process, enabled formation of silica particles characterized by proper particle and pore size distribution for high separation efficiency. 3-Chloropropyl trimethoxysilane was used as the halogen terminal spacer to combine the initiator to silica particles. Uniform and thin coating of polystyrene layer on initiator attached silica particles was formed via reversible addition-fragmentation chain transfer (RAFT) polymerization. Micro-columns (1.0mm ID and 300mm length) were packed with the resultant phase and their chromatographic performance was elucidated by HPLC. A mobile phase of 60/40 (v/v) acetonitrile/water containing 0.1% TFA and a flow rate of 15μL/min were found to be the optimized conditions leading to number of theoretical plates close to 50,000 (165,000m(-1)). This is the very first study to get such highly efficient HPLC columns using a silica monolith particulate stationary phase.

  10. Rapid separation of desloratadine and related compounds in solid pharmaceutical formulation using gradient ion-pair chromatography.

    PubMed

    Zheng, Jinjian; Rustum, Abu M

    2010-01-05

    We reported the development of an ion-pair chromatographic method to separate desloratadine and all known related compounds in Clarinex Tablets, which use desloratadine as active pharmaceutical ingredient (API). For the first time, baseline separation for desloratadine and all known related compounds was achieved by utilizing a YMC-Pack Pro C(18) column (150 mm x 4.6 mm I.D., 3 microm particle size, 120A pore size) and a gradient elution method. The mobile phase A contains 3 mM sodium dodecylsulfate (SDS), 15 mM sodium citrate buffer at pH 6.2, and 40 mM sodium sulfate, while the mobile phase B is acetonitrile. Chromsword, an artificial intelligence method development tool, was used to optimize several key chromatographic parameters simultaneously including buffer pH/solvent strength, and temperature/gradient profile. The resolution of desloratadine and desloratadine 3,4-dehydropiperidine derivative, one of the critical pairs was improved by adding 40 mM sodium sulfate. Ultraviolet detection at 267 nm was used to achieve the detection for desloratadine and all compounds. This method has been successfully validated according to ICH guidelines in terms of linearity, accuracy, quantitation limit/detection limit, precision, specificity and robustness. It could be used as a stability indicating method for desloratadine drug substances or drug products that use desloratadine as active pharmaceutical ingredient.

  11. Characterization of Gas Chromatographic Liquid Phases Using McReynolds Constants. An Experiment for Instrumental Analysis Laboratory.

    ERIC Educational Resources Information Center

    Erskine, Steven R.; And Others

    1986-01-01

    Describes a laboratory experiment that is designed to aid in the understanding of the fundamental process involved in gas chromatographic separations. Introduces the Kovats retention index system for use by chemistry students to establish criteria for the optimal selection of gas chromatographic stationary phases. (TW)

  12. Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices.

    PubMed

    Zayats, M F; Leschev, S M; Petrashkevich, N V; Zayats, M A; Kadenczki, L; Szitás, R; Szemán Dobrik, H; Keresztény, N

    2013-04-24

    Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides (P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system LgP≫0, and the difference in LgP values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of LgP values reaching 9.5 units. The majority of LgP values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides LgP values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides.

  13. Metal-Organic Frameworks for Thin-Layer Chromatographic Applications.

    PubMed

    Schenk, Claudia; Kutzscher, Christel; Drache, Franziska; Helten, Stella; Senkovska, Irena; Kaskel, Stefan

    2017-01-25

    Preparation of thin-layer chromatographic (TLC) plates based on metal-organic frameworks (MOFs) as porous stationary phases is described. DUT-67 (DUT = Dresden University of Technology), a zirconium based MOF, was used in combination with a fluorescent indicator as stationary phase for analyzing a small selection of a wide spectrum of relevant analytes. The successful separation of benzaldehyde from trans-cinnamaldehyde and 4-aminophenol from 2-aminotoluene is reported as a model system using optimized eluent mixtures containing acetic acid.

  14. Development and validation of a rapid column-switching high-performance liquid chromatographic method for the determination of Lamotrigine in human serum.

    PubMed

    Brunetto, María del Rosario; Contreras, Yaritza; Delgado, Yelitza; Gallignani, Máximo; Estela, José Manuel; Martin, Víctor Cerdà

    2009-07-01

    This study describes a simple and sensitive column-switching high-performance liquid chromatographic method with UV detection for the determination of Lamotrigine in 50 microL of serum. After solid-phase extraction of Lamotrigine on an Oasis HLB extraction precolumn (20 x 3.9 mm; dp: 25 microm), chromatographic separation was achieved at 30 degrees C on a Chromolith RP-18e column (50 mm x 4.6 mm i.d.) using a solution of 20% acetonitrile in 15 mM phosphate buffer (pH 7.0) as the mobile phase, at a flow-rate of 2.0 mL/min. The eluant was detected at 215 nm. The retention time for Lamotrigine was 1.28 min. The total analysis time was ca. 5 min. However, the overlap of sample preparation, analysis, and reconditioning of the precolumn increased the overall sample throughput to one injection every 3 min. The method was validated for system suitability, linearity, precision, accuracy, robustness, and limit of quantitation. The linearity of the calibration lines, expressed by the linear correlation coefficient, was better than 0.9996. Recovery studies achieved from Lamotrigine spiked plasma samples showed values greater than 93%, demonstrating the excellent extraction efficiency of the precolumn. Intra- and inter-day precision were generally acceptable; the coefficient of variation was < 2.3% in all cases. The detection limits for Lamotrigine at a signal-to-noise ratio of 3 was 0.002 microg/mL when a sample volume of 50 microL was injected. However, it was possible to enhance the sensitivity further by injecting larger volumes, up to 200 microL. The method was shown to be robust and the results were within the acceptable range. The method was successfully applied to the determination of Lamotrigine in human serum samples of patients submitted to Lamotrigine therapy.

  15. Capacitance of edge plane of pyrolytic graphite in acetonitrile solutions

    SciTech Connect

    Minick, S.K.; Ishida, Takanobu.

    1991-05-01

    The capacitance of the edge plane of pyrolytic graphite electrodes, in acetonitrile solutions, is measured by recording the current response to an applied triangular voltage sweep; TVS, and then fitting the current response with an appropriate function, (via a set of adjustable parameters). The pretreatment of the electrodes, the supporting electrolyte concentration used, and the frequency of the input TVS, were all found to affect the measured capacitance. In these experiments, a background current was also seen and the shape of the current output for the TVS; the charging/discharging curve, is shown to correlate with the magnitude of this background current. In addition, the size of the background current was found to have some dependence on the type of electrode pretreatment procedure used. 60 refs., 49 figs., 3 tabs.

  16. Photodegradation of Oryzalin in aqueous isopropanol and acetonitrile.

    PubMed

    Pramanik, Sukhendu Kumar; Joarder, Soumen; Das, Saktipada; Roy, Sankhajit; Bhattacharyya, Anjan

    2016-01-01

    The phototransformation of Oryzalin was studied under UV light (λmax ≥ 290 nm) and sunlight (λmax ≥ 250 nm) in aqueous isopropanol and acetonitrile solution in absence and presence of TiO2 as sensitizer. The rate of photodegradation of Oryzalin in different solvent system followed first-order kinetics, and calculated half-lives were found to be in the range of 23.52-53.75 h for UV light and 41.23-61.43 h for sunlight. From this study, total 12 photoproducts were identified and characterized on the basis of column chromatography and Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved was hydrolysis, breaking of sulfonic bond, and loss of amino and sulfonic acid group.

  17. Coulometric titration of bases in acetic acid and acetonitrile media.

    PubMed

    Vajgand, V J; Mihajlović, R

    1969-09-01

    The working conditions and the results for coulometric titration of milligram amounts of some bases in 0.1M sodium perchlorate in a mixture of acetic acid and acetic anhydride (1:6), are given. Determinations were made both by coulometric back-titration or direct titration at the platinum anode. Back-titration was done in the catholyte, by coulometric titration of the excess of added perchloric acid. The titration end-point was detected photometrically with Crystal Violet as indicator. The direct titration of bases was done at the platinum anode, in the same electrolyte, to which hydroquinone was added as anode depolarizer and as the source of hydrogen ions, Malachite Green being used as indicator. Similarly, bases can be determined in acetonitrile if sodium perchlorate, hydroquinone and Malachite Green are added to the solvent. Errors are below 1 %, and the precision is satisfactory.

  18. High productivity chromatographic separations on monolithic capillary columns

    NASA Astrophysics Data System (ADS)

    Korolev, A. A.; Shiryaeva, V. E.; Popova, T. P.; Kurganov, A. A.

    2013-03-01

    The productivity of monolithic capillary columns based on silica gel and polymers of different polarities (divinylbenzene and ethyleneglycol dimethacrylate) is investigated using a model mixture of light hydrocarbons. It is shown that the productivity of a column is noticeably affected by the type of gas carrier. The highest productivity is observed when using carbon dioxide or dinitrogen monoxide as the gas carrier. The lowest productivity is observed when uisng hydrogen or helium.

  19. cis- and trans-Stilbenes: Chromatographic Separation and Photochemical Isomerization.

    ERIC Educational Resources Information Center

    Levine, Samuel G.; And Others

    1988-01-01

    Describes an experiment that is to be performed midway in the first semester of an undergraduate organic chemistry laboratory coinciding with the students' introduction to cis-trans isomerism in the study of alkenes. Discusses the apparatus, materials, experimental procedure, historical significance, and results. (CW)

  20. The chromatographic separation of enantiomers through nanoscale design.

    PubMed

    Sancho, Raquel; Minguillón, Cristina

    2009-03-01

    The pharmacological implications of chirality in drugs and the strict legislation in this regard have led to the development of efficient enantioselective technologies to obtain enantiomerically pure compounds and to analyze their quality. However, although the most popular technique for enantioselective analysis is HPLC, the advent of nanotechnologies opens up great possibilities regarding the development of high throughput methods and processes. This tutorial review describes the state of the art in the application of nanoparticles or nanostructured materials to enantioseparation. The possibilities for this kind of materials, previously modified to include conventional chiral selectors, or the use as chiral selectors of those intrinsically chiral are considered.

  1. Binary Solvent Organization at Silica/Liquid Interfaces: Preferential Ordering in Acetonitrile-Methanol Mixtures.

    PubMed

    Gobrogge, Eric A; Walker, Robert A

    2014-08-07

    Nonlinear vibrational spectroscopy experiments examined solvent organization at the silica/binary solvent interface where the binary solvent consisted of methanol and acetonitrile in varying mole fractions. Data were compared with surface vibrational spectra acquired from silica surfaces exposed to a vapor phase saturated with the same binary solvent mixtures. Changes in vibrational band intensities suggest that methanol ideally adsorbs to the silica/vapor interface but acetonitrile accumulates in excess relative to vapor-phase composition. At the silica/liquid interface, acetonitrile's signal increases until a solution phase mole fraction of ∼0.85. At higher acetonitrile concentrations, acetonitrile's signal decreases dramatically until only a weak signature persists with the neat solvent. This behavior is ascribed to dipole-paired acetonitrile forming a bilayer with the first sublayer associating with surface silanol groups and a second sublayer consisting of weakly associating, antiparallel partners. On the basis of recent simulations, we propose that the second sublayer accumulates in excess.

  2. Bioconversion of cyanide and acetonitrile by a municipal-sewage-derived anaerobic consortium

    SciTech Connect

    Nagle, N.J.; Rivard, C.J.; Mohagheghi, A.; Philippidis, G.

    1995-12-31

    In this study, an anaerobic consortium was examined for its ability to adapt to and degrade the representative organonitriles, cyanide and acetonitrile. Adaptation to cyanide and acetonitrile was achieved by adding increasing levels of cyanide and acetonitrile to the anaerobic consortium, followed by extensive incubation over a 90-day period. The anaerobic consortium adapted most rapidly to the lower concentrations of each substrate and resulted in reductions of 85% and 83% of the cyanide and acetonitrile, respectively, at the 50 mg/L addition level. Increasing the concentration of both cyanide and acetonitrile resulted in reduced bioconversion. Two continuously stirred tank reactors (CSTR) were set up to examine the potential for continuous bioconversion of organonitriles. The anaerobic consortium was adapted to continuous infusion of acetonitrile at an initial concentration of 10 mg/L{center_dot}day in phosphate buffer.

  3. Using Aspen to Teach Chromatographic Bioprocessing: A Case Study in Weak Partitioning Chromatography for Biotechnology Applications

    ERIC Educational Resources Information Center

    Evans, Steven T.; Huang, Xinqun; Cramer, Steven M.

    2010-01-01

    The commercial simulator Aspen Chromatography was employed to study and optimize an important new industrial separation process, weak partitioning chromatography. This case study on antibody purification was implemented in a chromatographic separations course. Parametric simulations were performed to investigate the effect of operating parameters…

  4. Investigation on enantiomeric separations of fluorenylmethoxycarbonyl amino acids and peptides by high-performance liquid chromatography using native cyclodextrins as chiral stationary phases.

    PubMed

    Tang, Y; Zukowski, J; Armstrong, D W

    1996-09-06

    A systematic study was carried out to investigate enantiomeric separations of fluorenylmethoxycarbonyl (FMOC) amino acids and their peptides. Twenty amino acids were derivatized by 9-fluorenylmethyl chloroformate (FMOC-Cl) and its analogues, FMOC-glycyl-Cl and FMOC-beta-alanyl-Cl. All derivatives were chromatographed on native beta- and gamma-cyclodextrin columns using acetonitrile as the main mobile phase component. The results indicated that glycyl and beta-alanyl groups between FMOC and amino acid moieties enhanced chiral selectivities of amino acid derivatives. The addition of modifiers, triethylamine, acetic acid and methanol, into the mobile phase caused alterations in retention, enantiorecognition and elution order. The structures of amino acids and the type of chiral stationary phase employed exhibited significant impacts on chiral resolutions. It is also found that the number and position of glycyl moieties affect the retentions and enantioselectivities of FMOC derivatized glycyl containing peptides.

  5. Development of a validated RP-LC/ESI-MS-MS method for separation, identification and determination of related substances of tamsulosin in bulk drugs and formulations.

    PubMed

    Nageswara Rao, R; Kumar Talluri, M V N; Narasa Raju, A; Shinde, Dhananjay D; Ramanjaneyulu, G S

    2008-01-07

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method for evaluation of purity of tamsulosin in bulk drugs and pharmaceuticals was developed. The separation was accomplished on an Inertsil C(18) column using 10 mM ammonium acetate: acetonitrile as a mobile phase in a gradient elution mode. A photodiode array detector set at 280 nm was used for detection. The impurities were identified by ESI-MS-MS. The detection limits were 0.06-0.11 microg/ml. The method was validated with respect to accuracy, precision, linearity, ruggedness and limits of detection and quantification. It finds application not only for monitoring the reactions during the process development but also on quality assurance of tamsulosin.

  6. Improved high-performance liquid chromatographic analysis of some carboxylic acids in food and beverages as their p-nitrobenzyl esters.

    PubMed

    Badoud, R; Pratz, G

    1986-06-06

    An improved, straightforward and accurate method for the derivatization and quantitative high-performance liquid chromatographic analysis of carboxylic acids in food and beverages is presented. Thirty-two p-nitrobenzyl esters were prepared in high yields by direct reaction of the free acid with O-(4-nitrobenzyl)-N,N'-diisopropylisourea in dioxane-water (9:1). Benzylmalonic acid was used as a new internal standard. Excess of reagent was removed on a strong cation-exchange resin. The advantage of this original and very convenient procedure over the usual clean-up step involving filtration through a disposable silica cartridge is discussed. The p-nitrobenzyl ester derivatives were readily separated using a single linear gradient of solvent (acetonitrile in water). With a high-performance liquid chromatography column of conventional size (20-25 cm X 4.6 mm I.D.), the analysis lasted for less than 20 min. This analysis time was even shorter (less than 12 min) when using modern small-bore (100 X 2.1 mm I.D.) columns. Applications of the method to the analysis of the main carboxylic acids in coffee, wine and fruit juices are presented.

  7. Development and validation of a reversed-phase column liquid chromatographic method for the determination of five cephalosporins in pharmaceutical preparations.

    PubMed

    Elkady, Ehab F; Abbas, Samah S

    2011-01-01

    A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.

  8. High-performance liquid chromatographic method for profiling 2-oxo acids in urine and its application in evaluating vitamin status in rats.

    PubMed

    Shibata, Katsumi; Nakata, Chifumi; Fukuwatari, Tsutomu

    2016-01-01

    B-group vitamins are involved in the catabolism of 2-oxo acids. To identify the functional biomarkers of B-group vitamins, we developed a high-performance liquid chromatographic method for profiling 2-oxo acids in urine and applied this method to urine samples from rats deficient in vitamins B1 and B6 and pantothenic acid. 2-Oxo acids were reacted with 1,2-diamino-4,5-methylenebenzene to produce fluorescent derivatives, which were then separated using a TSKgel ODS-80Ts column with 30 mmol/L of KH2PO4 (pH 3.0):acetonitrile (7:3) at a flow rate of 1.0 mL/min. Vitamin B1 deficiency increased urinary levels of all 2-oxo acids, while vitamin B6 deficiency only increased levels of sum of 2-oxaloacetic acid and pyruvic acid, and pantothenic acid deficiency only increased levels of 2-oxoisovaleric acid. Profiles of 2-oxo acids in urine samples might be a non-invasive way of clarifying the functional biomarker of B-group vitamins.

  9. cis-cis-trans-Bis(acetonitrile-κN)dichloridobis(triphenyl­phosphine-κP)ruthenium(II) acetonitrile disolvate

    PubMed Central

    Al-Far, Ahmad M.; Slaughter, LeGrande M.

    2008-01-01

    The title compound, [RuCl2(C2H3N)2(C18H15P)2]·2C2H3N, was obtained upon stirring an acetonitrile/ethanol solution of [RuCl2(PPh3)3]. In the crystal structure, each RuII ion is coordinated by two Cl [Ru—Cl = 2.4308 (7) and 2.4139 (7) Å], two N [Ru—N = 2.016 (2) and 2.003 (2) Å], and two P [Ru—P = 2.3688 (7) and 2.3887 (7) Å] atoms in a distorted octa­hedral geometry. Packing inter­actions include typical C—H⋯π contacts involving phenyl groups as well as weak hydrogen bonds between CH3CN methyl H atoms and Cl or solvent CH3CN N atoms. PMID:21200532

  10. Determination of pKa values of organic bases in aqueous acetonitrile solutions using capillary electrophoresis.

    PubMed

    Buckenmaier, Stephan M C; McCalley, David V; Euerby, Melvin R

    2003-07-04

    Capillary electrophoresis (CE) was used for the determination of ionisation constants (pKa) of a variety of organic bases in aqueous acetonitrile solutions over the range 0-60% (v/v) acetonitrile. These bases are used as test compounds in HPLC column evaluation, thus knowledge of their pKa in hydro-organic solutions is useful. The base pKa decreased with acetonitrile concentration and significant shifts from the aqueous pKa (up to -0.8) were found using 60% acetonitrile. The CE application was confirmed to be very suitable for fast and accurate pKa measurement in aqueous organic solutions.

  11. Liquid chromatographic determination of multiple sulfonamides, nitrofurans, and chloramphenicol residues in pasteurized milk.

    PubMed

    Perez, Norma; Gutierrez, Rey; Noa, Mario; Diaz, Gilberto; Luna, Hector; Escobar, Irma; Munive, Zenaida

    2002-01-01

    A rapid and selective liquid chromatographic method was developed to detect 6 sulfonamides, 3 nitrofurans, and chloramphenicol residues in pasteurized milk. The 10 drugs were extracted with chloroform-acetone and the organic phase was evaporated; the residues were dissolved in an aqueous sodium acetate buffer solution 0.02M (pH = 4.8), and the fat was removed by washing with hexane. The aqueous layer was collected, filtered, and injected. The 6 sulfonamides and chloramphenicol were detected at 275 nm ultraviolet (UV) using a gradient system starting with sodium acetate buffer solution-acetonitrile (95 + 5) and finishing with sodium acetate buffer solution-acetonitrile (80 + 20). Nitrofurans were detected at 375 nm (UV) isocratically with sodium acetate buffer solution-acetonitrile (80 + 20). For 50 ppb fortified milk, the average recoveries were (sulfathiazole) 65.52%; (sulfamerazine) 75.36%; (sulfamethazine) 93.94%; (sulfachlorpyridazine) 75.94%; (sulfamethoxazole) 85.18%; (sulfamonomethoxine) 83.45%; (chloramphenicol) 104.17%; (nitrofurazone) 91.81%; (furazolidone) 100.76%; and (furaltadone) 72.38%. Method detection limits ranged from 4 ppb (nitrofurazone) to 16 ppb (sulfamethazine). Some matrix interferences (3-7 ppb) were observed only with sulfonamides.

  12. Separation of a BMS drug candidate and acyl glucuronide from seven glucuronide positional isomers in rat plasma via high-performance liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Xue, Y-J; Simmons, Neal J; Liu, Jane; Unger, Steve E; Anderson, Danielle F; Jenkins, Rand G

    2006-01-01

    A high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of a BMS drug candidate and its acyl glucuronide (1-O-beta glucuronide) in rat plasma. A 50-microL aliquot of each plasma sample was fortified with acetonitrile containing the internal standard to precipitate proteins and extract the analytes of interest. After mixing and centrifugation, the supernatant from each sample was transferred to a 96-well plate and injected into an LC/MS/MS system. Chromatographic separation was achieved isocratically on a Phenomenex Luna C(18), 3 mm x 150 mm, 3 microm column. The mobile phase contained 0.075% formic acid in 70:30 (v/v) acetonitrile/water. Under the optimized chromatographic conditions, the BMS drug candidate and its acyl glucuronide were separated from its seven glucuronide positional isomers within 10 min. Resolution of the parent from all glucuronides and acyl glucuronide from its positional isomers was critical to avoid their interference with quantitation of parent or acyl glucuronide. Detection was by positive ion electrospray MS/MS on a Sciex API 4000. The standard curve, which ranged from 5 to 5000 ng/mL, was fitted to a 1/x(2) weighted quadratic regression model for both the BMS drug candidate and its acyl glucuronide. Whole blood and plasma stability experiments were conducted to establish the sample collection, storage, and processing conditions. The validation results demonstrated that this method was rugged and repeatable. The same methodology has also been used in mouse and human plasma for the determination of the BMS drug candidate and its acyl glucuronide.

  13. Comparison of three liquid chromatographic methods for egg-white protein analysis.

    PubMed

    Awadé, A C; Efstathiou, T

    1999-02-19

    This paper describes and compares three chromatographic methods for the analysis of egg-white proteins. Gel-permeation chromatography allowed the separation of seven peaks from egg white, with an almost total protein recovery. A clean separation of ovomucin and lysozyme from the bulk of the proteins was obtained with this method. Reversed-phase high-performance liquid chromatography led to the fractionation of at least eight peaks. With this chromatographic method, the recovery was relatively poor. Approximately 30% of the ovalbumin was retained in the column after the elution. Finally, eleven chromatographic peaks were separated from egg white by high-performance liquid chromatography on an anion-exchange column. The recovery of proteins was almost total. The latter method afforded higher resolution.

  14. Rapid separation and determination of process-related substances of paracetamol using reversed-phase HPLC with photo diode array as a detector.

    PubMed

    Rao, R Nageswara; Narasaraju, A

    2006-02-01

    A simple and rapid gradient reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of paracetamol and its related compounds in bulk drugs and pharmaceutical formulations has been developed. As many as nine process impurities and one degradation product of paracetamol have been separated on a Symmetry C18 column (4.6 x 250 mm i.d., particle size 5 microm) with gradient elution using 0.01 M potassium dihydrogen phosphate buffer (pH 3.0) and acetonitrile as mobile phase and photo diode array detection at 215 nm. The chromatographic behavior of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH values. The correlation coefficients for calibration curves for paracetamol as well as impurities were in the range of 0.9951 - 0.9994. The proposed RP-LC method was successfully applied to the analysis of commercial formulations; the recoveries of paracetamol were in the range of 99-101%. The method could be of use not only for rapid and routine evaluation of the quality of paracetamol in bulk drug manufacturing units but also for detection of its impurities in pharmaceutical formulations.

  15. Development and validation of a reversed-phase HPLC method for separation and simultaneous determination of process-related substances of mirtazapine in bulk drugs and formulations.

    PubMed

    Rao, R Nageswara; Raju, A Narasa

    2009-03-01

    A simple and rapid reversed-phase high-performance liquid chromatographic method has been developed for the separation and simultaneous determination of related substances of mirtazapine in bulk drugs and pharmaceutical formulations. Six impurities, including one degradation product of mirtazapine, have been separated on a BDS Hypersil (4.6 x 250 mm; particle size 5 microm) column with a mobile phase consisting of 0.3% triethylamine (pH 3.0)-acetonitrile (78:22 v/v) eluted in an isocratic mode and monitored with a photo diode array detector at 215 nm. The chromatographic behavior of all the analytes was studied under variable compositions of different solvent systems, temperatures, buffer concentrations, and pH values. The method was validated in terms of accuracy, precision, and linearity. The inter- and intra-day assay precision was found to be < 0.98% [relative standard deviation; (RSD)] and the recoveries were in the range 95.54-102.22% with RSD < 2.21%. The correlation coefficients for calibration curves for mirtazapine as well as impurities were in the range of 0.9941-0.9999. The method was successfully applied to the analysis of commercial formulations and the recoveries of mirtazapine were in the range of 99.38-100.73% with < 0.52% RSD. The method is useful not only for rapid evaluation of the purity of mirtazapine, but also for the simultaneous determination of related substances in bulk drugs and pharmaceutical formulations.

  16. Separation and quantification of beer carbohydrates by high-performance liquid chromatography with evaporative light scattering detection.

    PubMed

    Nogueira, Luciana C; Silva, Filipe; Ferreira, Isabel M P L V O; Trugo, L C

    2005-02-18

    An HPLC method with an evaporative light scattering detector was optimized and validated for quantification of carbohydrates in beer. The chromatographic separation was achieved using a Spherisorb NH2, 5 microm chromatographic column and gradient elution with acetonitrile/water. The determinations were performed in the linear range of 0.05-5.0 g/L for fructose, 0.05-5.0 g/L for glucose, 0.05-15.0 g/L for maltose, 0.05-10.0 g/L for maltotriose, and 0.05-5.0 g/L for maltotetraose. The detection limits were 0.005 g/L for fructose, 0.008 g/L for glucose, and 0.01 g/L for maltose, maltotriose, and maltotetraose. The reliability of the method in terms of precision and accuracy was evaluated in three beer matrices, low alcohol beer, 6% alcohol beer, and beer made with part of adjuncts (4.5% alcohol). Relative standard deviations (RSDs) ranged between 1.59 and 5.95% (n = 10), and recoveries ranged between 94 and 98.4%.

  17. Interaction of acetonitrile with thin films of solid water

    SciTech Connect

    Bahr, S.; Kempter, V.

    2009-06-07

    Thin films of water were prepared on Ag at 124 K. Their properties were studied with metastable impact electron spectroscopy, reflection absorption infrared spectroscopy, and temperature programmed desorption. The interaction of acetonitrile (ACN) with these films was studied with the abovementioned techniques. From the absence of any infrared activity in the initial adsorption stage, it is concluded that ACN adsorbs linearly and that the C{identical_to}N axis is aligned parallel to the water surface (as also found on neat Ag). Initially, the interaction with water surface species involves their dangling OD groups. During the completion of the first adlayer the ACN-ACN lateral interaction becomes of importance as well, and the ACN molecules become tilted with respect to the water surface. ACN shows propensity to stay at the surface after surface adsorption even during annealing up to the onset of desorption. The present results for the ACN-water interaction are compared with available classical molecular dynamics calculations providing the orientation profile for ACN on water as well as the ACN bonding properties.

  18. Lithium solvation in dimethyl sulfoxide-acetonitrile mixtures

    SciTech Connect

    Semino, Rocío; Zaldívar, Gervasio; Calvo, Ernesto J.; Laria, Daniel

    2014-12-07

    We present molecular dynamics simulation results pertaining to the solvation of Li{sup +} in dimethyl sulfoxide-acetonitrile binary mixtures. The results are potentially relevant in the design of Li-air batteries that rely on aprotic mixtures as solvent media. To analyze effects derived from differences in ionic size and charge sign, the solvation of Li{sup +} is compared to the ones observed for infinitely diluted K{sup +} and Cl{sup −} species, in similar solutions. At all compositions, the cations are preferentially solvated by dimethyl sulfoxide. Contrasting, the first solvation shell of Cl{sup −} shows a gradual modification in its composition, which varies linearly with the global concentrations of the two solvents in the mixtures. Moreover, the energetics of the solvation, described in terms of the corresponding solute-solvent coupling, presents a clear non-ideal concentration dependence. Similar nonlinear trends were found for the stabilization of different ionic species in solution, compared to the ones exhibited by their electrically neutral counterparts. These tendencies account for the characteristics of the free energy associated to the stabilization of Li{sup +}Cl{sup −}, contact-ion-pairs in these solutions. Ionic transport is also analyzed. Dynamical results show concentration trends similar to those recently obtained from direct experimental measurements.

  19. Interaction of acetonitrile with thin films of solid water.

    PubMed

    Bahr, S; Kempter, V

    2009-06-07

    Thin films of water were prepared on Ag at 124 K. Their properties were studied with metastable impact electron spectroscopy, reflection absorption infrared spectroscopy, and temperature programmed desorption. The interaction of acetonitrile (ACN) with these films was studied with the abovementioned techniques. From the absence of any infrared activity in the initial adsorption stage, it is concluded that ACN adsorbs linearly and that the C identical withN axis is aligned parallel to the water surface (as also found on neat Ag). Initially, the interaction with water surface species involves their dangling OD groups. During the completion of the first adlayer the ACN-ACN lateral interaction becomes of importance as well, and the ACN molecules become tilted with respect to the water surface. ACN shows propensity to stay at the surface after surface adsorption even during annealing up to the onset of desorption. The present results for the ACN-water interaction are compared with available classical molecular dynamics calculations providing the orientation profile for ACN on water as well as the ACN bonding properties.

  20. Interaction of acetonitrile with thin films of solid water

    NASA Astrophysics Data System (ADS)

    Bahr, S.; Kempter, V.

    2009-06-01

    Thin films of water were prepared on Ag at 124 K. Their properties were studied with metastable impact electron spectroscopy, reflection absorption infrared spectroscopy, and temperature programmed desorption. The interaction of acetonitrile (ACN) with these films was studied with the abovementioned techniques. From the absence of any infrared activity in the initial adsorption stage, it is concluded that ACN adsorbs linearly and that the C≡N axis is aligned parallel to the water surface (as also found on neat Ag). Initially, the interaction with water surface species involves their dangling OD groups. During the completion of the first adlayer the ACN-ACN lateral interaction becomes of importance as well, and the ACN molecules become tilted with respect to the water surface. ACN shows propensity to stay at the surface after surface adsorption even during annealing up to the onset of desorption. The present results for the ACN-water interaction are compared with available classical molecular dynamics calculations providing the orientation profile for ACN on water as well as the ACN bonding properties.

  1. Liquid chromatographic determination of beta-naphthoxyacetic acid in tomatoes.

    PubMed

    Gökmen, V; Acar, J

    1998-03-06

    An alternative high-performance liquid chromatographic method for the determination of beta-naphthoxyacetic acid (BNOA) in tomatoes is described. BNOA was extracted from tomatoes with acetone-dichloromethane (2:1). The extract was cleaned up by Bio-Beads S-X3 gel-permeation chromatography and by partitioning. A reversed-phase C18 column was used for HPLC analysis. The mobile phase was acetonitrile-2% acetic acid in water (50:50, v/v) pumped at a flow-rate of 1.0 ml/min. Retention time of BNOA was ca. 7 min with a percentage coefficient of variation of 0.71. Resolution of BNOA was good on the column. Percentage recoveries of BNOA were 79.5 +/- 6.82, 94.8 +/- 2.70 and 86.4 +/- 16.43 for the corresponding spiking levels of 0.5, 1.0 and 2.0 micrograms per g tomato, respectively. Analysis of 10 greenhouse tomato samples from local markets in Ankara showed no BNOA residue.

  2. Molar absorptivities of aflatoxins B1, B2, G1, and G2 in acetonitrile, methanol, and toluene-acetonitrile (9 + 1) (modification of AOAC Official Method 971.22): collaborative study.

    PubMed

    Nesheim, S; Trucksess, M W; Page, S W

    1999-01-01

    Four laboratories participated in a mini-collaborative study of AOAC Official Method 971.22, Standards for Aflatoxins, Thin-Layer Chromatographic Method, to extend the method to 3 replacement solvents for benzene for calibration of standard aflatoxin solutions. Triplicate test sample vials, each containing 25 micrograms of the respective aflatoxin for each of the 4 aflatoxins and for each of the solvents, were prepared and sent to each collaborator. The collaborators dissolved the aflatoxin in each vial in 2 mL solvent, measured the UV spectrum, and reported the absorptivity maxima near 350 nm. The concentrations of the aflatoxins in the test samples were determined by dissolving identical test samples in benzene-acetonitrile (98 + 2) and following the procedure described in AOAC Official Method 971.22. These concentrations were, in turn, used to determine the molar absorptivities in the other 3 solvents (see Table 1). AOAC Official Method 971.22 has been modified to extend its applicability to 3 replacement solvents for benzene for calibration of standard aflatoxin solutions.

  3. 78 FR 14241 - Acetonitrile; Community Right-to-Know Toxic Chemical Release Reporting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... Technical Review of Acetonitrile (Methyl Cyanide) (Ref. 2). The sections below summarize the human health...) (70 FR 37698). A. Metabolism Acetonitrile is metabolized to inorganic cyanide through the intermediate production of hydrogen cyanide. Data demonstrate that the metabolism to cyanide is oxygen- and...

  4. UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.

    PubMed

    Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

    2012-10-01

    The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of irinotecan hydrochloride in pharmaceutical dosage forms.

  5. Determination of new Cu+, Cu2+, and Zn2+ Lennard-Jones ion parameters in acetonitrile.

    PubMed

    Torras, Juan; Alemán, Carlos

    2013-09-12

    We present new Lennard-Jones (LJ) parameters for Cu(+), Cu(2+), and Zn(2+) ion-acetonitrile interactions. The adjustment of ion parameters is made to reproduce simultaneously experimental solvation free energy and structural properties, namely ion-N distance and coordination numbers. Initially, the methodology has been validated deriving parameters for well-studied Na(+) and Cl(-) ions in acetonitrile being compared with experimental and theoretical data. The transferability of parameters is checked by the calculation of thermodynamic and structural properties with three different acetonitrile models. The results obtained for transition metal ions show an overall agreement with reference values. The solvation free energy calculated with new LJ trained parameters using a six-site acetonitrile model, and two older three- and six-site acetonitrile models presents, respectively, percent differences of 0.4, 4.8, and 7.3% when compared with experimental values.

  6. [[Chiral separation of five arylpropionic acid drugs and determination of their enantiomers in pharmaceutical preparations by reversed-phase high performance liquid chromatography with cellulose-tris-(4-methylbenzoate) stationary phase

    PubMed

    Luo, An; Wan, Qiang; Fan, Huajun; Chen, Zhi; Wu, Xuehao; Huang, Xiaowen; Zang, Linquan

    2014-09-01

    Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1% (v/v) formic acid except naproxen by acetonitrile-0.1% (v/v) formic acid at 25 °C. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.

  7. Enantiomeric Separations of Pyriproxyfen and its Six Chiral Metabolites by High-Performance Liquid Chromatography.

    PubMed

    Zhang, Chuntao; Liu, Hui; Liu, Donghui; Wang, Liying; Gao, Jing; Zhou, Zhiqiang; Wang, Peng

    2016-03-01

    Pyriproxyfen is a chiral insecticide, and over 10 metabolites have been identified in the environment. In this work the separations of the enantiomers of pyriproxyfen and its six chiral metabolites were studied by high-performance liquid chromatography (HPLC). Both normal phase and reverse phase were applied using the chiral columns Chiralpak IA, Chiralpak IB, Chiralpak IC, Chiralcel OD, Chiralcel OD-RH, Chiralpak AY-H, Chiralpak AD-H, Chiracel OJ-H, (R,R)-Whelk-O 1, and Lux Cellulose-3. The effects of the chromatographic parameters such as mobile phase composition and temperature on the separations were investigated and the enantiomers were identified with an optical rotation detector. The enantiomers of these targets could obtain complete separations (resolution factor Rs > 1.5) on Chiralpak IA, Chiralpak IB, Chiralcel OD, Chiralpak AY-H, or Chiracel OJ-H under normal conditions. Chiralcel OJ-H showed the best chiral separation results with n-hexane as mobile phase and isopropanol (IPA) as modifier. The simultaneous enantiomeric separation of pyriproxyfen and four chiral metabolites was achieved on Chiralcel OJ-H under optimized condition: n-hexane/isopropanol = 80/20, 15°C, flow rate of 0.8 ml/min, and UV detection at 230 nm. The enantiomers of pyriproxyfen and the metabolites , , and obtained complete separations on Chiralpak IA, Chiralpak IC, and Lux Cellulose-3 under reverse phase using acetonitrile/water as the mobile phase. The retention factors (k) and selectivity factors (α) decreased with increasing temperature, and the separations were better under low temperature in most cases. The work is of significance for the investigation of the environmental behaviors of pyriproxyfen on an enantiomeric level.

  8. High-performance liquid chromatographic determination of benzalkonium and naphazoline or tetrahydrozoline in nasal and ophthalmic solutions.

    PubMed

    Santoni, G; Medica, A; Gratteri, P; Furlanetto, S; Pinzauti, S

    1994-11-01

    A high-performance liquid chromatographic method is described for the determination of benzalkonium chloride homologues and naphazoline nitrate or tetrahydrozoline hydrochloride in ophthalmic and nasal solutions. The technique involves a one-step dilution (1:5) for sample preparation and direct injection onto a 5 mm RP C-8 column. The mobile phase is acetonitrile-diluted acetic acid (80:20, v/v) with 6 mM tetramethylammonium bromide. Detection is carried out at 260 nm with a diode array. The method is rapid, specific, reproducible and is especially useful for quality control procedures.

  9. Gas chromatographic analysis of trace gas impurities in tungsten hexafluoride.

    PubMed

    Laurens, J B; de Coning, J P; Swinley, J M

    2001-03-09

    Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low-microg/l levels included oxygen, nitrogen, carbon dioxide, carbon monoxide, sulfur hexafluoride and hydrogen. This paper describes the use of a system utilising backflush column switching to protect the columns and detectors in the analysis of trace gas impurities in tungsten hexafluoride. Two separate channels were used for the analysis of H2, O2, N2, CO, CO2 and SF6 impurities with pulsed discharge helium ionisation detection.

  10. Methods and apparatus for analysis of chromatographic migration patterns

    DOEpatents

    Stockham, Thomas G.; Ives, Jeffrey T.

    1993-01-01

    A method and apparatus for sharpening signal peaks in a signal representing the distribution of biological or chemical components of a mixture separated by a chromatographic technique such as, but not limited to, electrophoresis. A key step in the method is the use of a blind deconvolution technique, presently embodied as homomorphic filtering, to reduce the contribution of a blurring function to the signal encoding the peaks of the distribution. The invention further includes steps and apparatus directed to determination of a nucleotide sequence from a set of four such signals representing DNA sequence data derived by electrophoretic means.

  11. Methods and apparatus for analysis of chromatographic migration patterns

    DOEpatents

    Stockham, T.G.; Ives, J.T.

    1993-12-28

    A method and apparatus are presented for sharpening signal peaks in a signal representing the distribution of biological or chemical components of a mixture separated by a chromatographic technique such as, but not limited to, electrophoresis. A key step in the method is the use of a blind deconvolution technique, presently embodied as homomorphic filtering, to reduce the contribution of a blurring function to the signal encoding the peaks of the distribution. The invention further includes steps and apparatus directed to determination of a nucleotide sequence from a set of four such signals representing DNA sequence data derived by electrophoretic means. 16 figures.

  12. Chromatographic analysis of wheatgrass extracts

    PubMed Central

    Khan, Masood Shah; Parveen, Rabea; Mishra, Kshipra; Tulsawani, Rajkumar; Ahmad, Sayeed

    2015-01-01

    Aim: Wheatgrass (WG) is the shoot of Triticum aestivum Linn. belongs to the family Gramineae, and possess high chlorophyll content and essential vitamins, minerals, vital enzymes, amino acids, dietary fibers etc., It has been shown to possess anti-cancer, anti-ulcer, antioxidant, and anti-arthritic activity due to the presence of biologically active compounds, and minerals. Therefore, in the present study, high-performance thin layer chromatography (HPTLC), and high-performance liquid chromatography (HPLC) methods for qualitative and quantitative analysis have been proposed, which will help in quality evaluation of wheat grass extract. Materials and Methods: Samples for analysis were prepared in methanol and water simply by sonication. These were applied on pre-coated silica plate and chromatograms were developed using toluene: Ethyl acetate: Formic acid. HPLC analysis was done on Waters HPLC system using water, methanol, and acetonitrile as mobile phase. Merck C18 column has been used. Results: HPTLC finger printing of alcoholic extracts of WG was carried out and found 10–11 spots at different wavelengths 254, 366, and 435 nm. HPLC fingerprinting produced 22 peaks at 256 nm. Quantitative HPTLC analysis was done to determine the gallic acid content, and was found to be 0.077% w/w in aqueous extract. By HPLC, the content of gallic acid and rutin was found to be 0.07%, and 0.04% w/w in aqueous extract of WG. Conclusion: The developed HPLC and HPTLC fingerprinting method can be used for the quality control, and standardization of WG and its extracts used as nutritional supplement. PMID:26681880

  13. Acetonitrile adduct formation as a sensitive means for simple alcohol detection by LC-MS.

    PubMed

    Bogseth, Roy; Edgcomb, Eric; Jones, Christopher M; Chess, Edward K; Hu, Peifeng

    2014-11-01

    Simple alcohols formed protonated acetonitrile adducts containing up to two acetonitrile molecules when analyzed by ESI or APCI in the presence of acetonitrile in the solvent. These acetonitrile adducts underwent dissociation to form a nitrilium ion, also referred to as the substitution ion. Diols and triols behaved differently. In ESI, they formed only one acetonitrile adduct containing one acetonitrile. The S ion was not observed in ESI and was only weakly observed from the dissociation of the (M + ACN + H)(+) ion. On the other hand, the S ion was abundantly formed from the diols in APCI. This formation of acetonitrile adducts and substitution ion from simple alcohols/diols offers an opportunity to detect simple alcohols/diols sensitively by LC-MS interfaced by ESI or APCI. The utility of this chemistry was demonstrated in a method developed for the quantification of cyclohexanol in rat plasma by monitoring the CID-induced fragmentation from the S ion to a fragment ion.

  14. Electrochemical detection of benzo(a)pyrene in acetonitrile-water binary medium.

    PubMed

    Du, Chunyan; Hu, Yaqi; Li, Yunchao; Fan, Louzhen; Li, Xiaohong

    2015-06-01

    Electrochemical oxidation of adsorbed benzo(a)pyrene (BaP) on the glassy carbon electrode (GCE) was explored in acetonitrile-water. When the GCE was incubated in 100 nM BaP acetonitrile-water (V(water):V(acetonitrile)=1:1) for 10 min at open circuit, and then transferred into blank acetonitrile-water (V(water):V(acetonitrile)=1:1, pH= 0.70) for differential pulse voltammetry measurement, a distinct oxidation peak at 0.98 V (vs. Ag/AgCl) was observed. The peak potential was about 180 mV lower than that in acetonitrile. Importantly, the peak current was more than 22 times greater. The effects of water on BaP preconcentration on the electrode and electrochemical oxidation were revealed, respectively. Based on the results, an electrochemical assay for BaP detection was developed. The GCE was respectively incubated in acetonitrile-water (V(water):V(acetonitrile)=1:1)with BaP concentration ranged from 0 nM to 1000 nM, and then transferred into the corresponding blank acetonitrile-water (pH= 0.70) for DPV measurements. When the BaP concentration was increased, an increased oxidative current at 0.98 V (vs. Ag/AgCl) was observed, and a detection limit of 0.67 nM was achieved. Because all other priority polycyclic aromatic hydrocarbons could not be electrochemically oxidized at 0.98 V, the electrochemical assay showed very high selectivity to BaP. Finally, the developed electrochemical assay was successfully applied to determination of BaP in a series of real world samples, such as drinking water, tap water, lake water and river water.

  15. Evaluation of Comprehensive 2-D Gas Chromatography-Time-Of-Flight Mass Spectrometry for 209 Chlorinated Biphenyl Congeners in Two Chromatographic Runs

    EPA Science Inventory

    This research evaluates a recently developed comprehensive 2-D GC coupled with a time-of-flight (TOF) mass spectrometer for the potential separation of 209 PCB congeners, using a sequence of 1-D and 2-D chromatographic modes. In two consecutive chromatographic runs, using a 40 m,...

  16. Laboratory investigations of irradiated acetonitrile-containing ices on an interstellar dust analog

    SciTech Connect

    Abdulgalil, Ali G. M.; Marchione, Demian; Rosu-Finsen, Alexander; Collings, Mark P.; McCoustra, Martin R. S.

    2012-07-15

    Reflection-absorption infrared spectroscopy is used to study the impact of low-energy electron irradiation of acetonitrile-containing ices, under conditions close to those in the dense star-forming regions in the interstellar medium. Both the incident electron energy and the surface coverage were varied. The experiments reveal that solid acetonitrile is desorbed from its ultrathin solid films with a cross section of the order of 10{sup -17} cm{sup 2}. Evidence is presented for a significantly larger desorption cross section for acetonitrile molecules at the water-ice interface, similar to that previously observed for the benzene-water system.

  17. Gas Chromatographic Determination of Enrivonmentally Significant Pesticides.

    ERIC Educational Resources Information Center

    Rudzinski, Walter E.; Beu, Steve

    1982-01-01

    A chromatographic procedure for analyzing organophosphorus pesticides (such as PCB's, nitrosamines, and phthalate esters) in orange juice is described, including a summary of the method, instrumentation, methodology, results/discussion, and calculations. (JN)

  18. A Versatile, Automatic Chromatographic Column Packing Device

    ERIC Educational Resources Information Center

    Barry, Eugene F.; And Others

    1977-01-01

    Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

  19. A Quantitative Gas Chromatographic Ethanol Determination.

    ERIC Educational Resources Information Center

    Leary, James J.

    1983-01-01

    Describes a gas chromatographic experiment for the quantitative determination of volume percent ethanol in water ethanol solutions. Background information, procedures, and typical results are included. Accuracy and precision of results are both on the order of two percent. (JN)

  20. Fast non-aqueous reversed-phase liquid chromatography separation of triacylglycerol regioisomers with isocratic mobile phase. Application to different oils and fats.

    PubMed

    Tamba Sompila, Arnaud W G; Héron, Sylvie; Hmida, Dorra; Tchapla, Alain

    2017-01-15

    The distribution of fatty acid species at the sn-1/3 position or the sn-2 position of triacylglycerols (TAGs) in natural fats and oils affects their physical and nutritional properties. In fats and oils, determining the presence of one or two regioisomers and the identification of structure, where they do have one, as well as their separation, became a problem of fundamental importance to solve. A variety of instrumental technics has been proposed, such as MS, chromatography-MS or pure chromatography. A number of studies deal with the optimization of the separation, but very often, they are expensive in time. In the present study, in order to decrease the analysis time while maintaining good chromatographic separation, we tested different monomeric and polymeric stationary phases and different chromatographic conditions (mobile phase composition and analysis temperature) using Non-Aqueous Reversed Phase Liquid Chromatography (NARP-LC). It was demonstrated that mixed polymeric stationary bonded silica with accessible terminal hydroxyl groups leads to very good separation for the pairs of TAGs regioisomers constituted by two saturated and one unsaturated fatty acid (with double bond number: from 1 to 6). A Nucleodur C18 ISIS percolated by isocratic mobile phase (acetonitrile/2-propanol) at 18°C leads to their separations in less than 15min. The difference of retention times between two regioisomers XYX and XXY are large enough to confirm, as application, the presence of POP, SOP, SOS and PLP and no PPO, SPO, SSO and PPL in Theobroma cacao butter. In the same way, this study respectively shows the presence of SOS, SOP and no SSO, PSO in Butyrospermum parkii butter, POP, SOP, SOS and no PPO, PSO and SSO in Carapa oil and finally POP and no PPO in Pistacia Lentiscus oil.

  1. Comparison of physicochemical and gas chromatographic polarity measures for simple organic compounds.

    PubMed

    Héberger, Károly; Zenkevich, Igor G

    2010-04-23

    The comparison of different polarity measures (parameters, descriptors, variables, scales, etc.) indicates that evaluation of interrelations between these measures is important for better understanding and interpretation of chemical and/or analytical data, especially for chromatographic separation. The best linear correlation between gas chromatographic and non-chromatographic polarity descriptors is revealed for the first time: this pair of variables is the difference of gas chromatographic retention indices on standard polar and non-polar phases as well as the difference between non-dimensional indices of boiling points (known in chromatography since mid-1980s as dispersion indices) and indices of molar refractions. The correlation helps chromatographers to find preferable chemical variables (features) to understand better the separation phenomena and to find better correlations in QSRR models. Principal component analysis (PCA) of ten frequently applied polarity measures shows their similarity and, at the same time, it shows the absence of anomalies within the set of simple organic molecules. A novel ranking method for ten polarity parameters points out that the two most informative polarity measures are (i) the non-dimensional index for boiling point and (ii) the difference in chromatographic retention indices on standard polar and non-polar stationary phases. On the other hand, the hydrophobicity parameter, log P, sometimes considered as polarity parameter in HPLC seems to be the worst one in description of "polarity" in gas chromatography. Surprisingly, such polarity measures like dipole moment and permittivity used often in organic chemistry does not provide the best correlation with gas chromatographic polarity measures.

  2. Preparation of dye-ligand affinity chromatographic packings based on monodisperse poly(glycidylmethacrylate-co-ethylenedimethacrylate) beads and their chromatographic properties.

    PubMed

    Wu, Feiyan; Zhu, Yan; Jia, Zhishen

    2006-11-17

    Monodisperse porous particles, poly(glycidylmethacrylate-co-ethylenedimethacrylate), P(GMA-EDMA) beads with diameter of 7 microm were prepared by a single-step swelling and polymerization method. The polymer particles were advantaged through immobilization of Procion Bule MX-R, which was incubated by epichlorohydrin via the epoxide groups on the particles surface. The Procion Bule MX-R-immobilized P(GMA-EDMA) beads were mechanically stable and acted as the rigid matrix for column chromatography in HPLC mode. The chromatographic properties of the dye-ligand affinity chromatographic stationary phase for biopolymers separation are discussed. This affinity column has advantages of enabling biopolymer separation, high efficiency and low backpressure. Lysozyme and BSA were fast separated within 10min using this affinity column. The column was also used for the purification of lysozyme from chicken egg white.

  3. A chromatographic survey of methods for extacting long-chain grass fructans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fructans were extracted under different conditions from four cool-season forages in order to develop extraction, cleanup, and chromatographic separation protocols permitting optimal analysis of long-chain fructans. Adequate sample cleanup was achieved by passage through a C18 solid-phase extractio...

  4. Thermodynamics of Complexation between Thiourea-based Receptor and Acetate in Water/Acetonitrile Mixture.

    PubMed

    Suzuki, Takaya; Shibuya, Yuuta; Sato, Takaya; Nishizawa, Seiichi; Sato, Itaru; Yamaguchi, Akira

    2016-01-01

    A thiourea-based receptor has been extensively studied for selective anion recognition for reasons of its strong hydrogen bond donor ability. In the present study, the thermodynamics of complexation between a thiourea-based receptor and acetate was examined in a water/acetonitrile mixture. The receptor used in this study was N,N'-bis(p-nitrophenyl)thiourea (BNPTU). UV/vis spectroscopic titration and isothermal titration calorimetry (ITC) experiments clearly revealed endothermic and entropy-driven complexation of BNPTU with acetate in water/acetonitrile mixtures. Since the endothermic peaks found in water/acetonitrile mixtures were about three times greater than those in acetonitrile, it appears that preferential hydration of both receptor and acetate was responsible for the endothermic and entropy-driven complexation reaction. The thermodynamic properties found in this study have the potential to contribute to the design of a thiourea-based anion receptor.

  5. Detection of adulteration in acetonitrile using near infrared spectroscopy coupled with pattern recognition techniques.

    PubMed

    Hu, Le-Qian; Yin, Chun-Ling; Zeng, Zhi-Peng

    2015-12-05

    In this paper, near infrared spectroscopy (NIR) in cooperation with the pattern recognition techniques were used to determine the type of neat acetonitrile and the adulteration in acetonitrile. NIR spectra were collected between 400 nm and 2498 nm. The experimental data were first subjected to analysis of principal component analysis (PCA) to reveal significant differences and potential patterns between samples. Then support vector machine (SVM) were applied to develop classification models and the best parameter combination was selected by grid search. Under the best parameter combination, the classification accuracy rates of three types of neat acetonitrile reached 87.5%, and 100% for the adulteration with different concentration levels. The results showed that NIR spectroscopy combined with SVM could be utilized for determining the potential adulterants including water, ethanol, isopropyl alcohol, acrylonitrile, methanol, and by-products associated with the production of acetonitrile.

  6. Facilitated diffusion of acetonitrile revealed by quantitative breath analysis using extractive electrospray ionization mass spectrometry.

    PubMed

    Li, Ming; Ding, Jianhua; Gu, Haiwei; Zhang, Yan; Pan, Susu; Xu, Ning; Chen, Huanwen; Li, Hongmei

    2013-01-01

    By using silver cations (Ag⁺) as the ionic reagent in reactive extractive electrospray ionization mass spectrometry (EESI-MS), the concentrations of acetonitrile in exhaled breath samples from the volunteers including active smokers, passive smokers, and non-smokers were quantitatively measured in vivo, without any sample pretreatment. A limit of detection (LOD) and relative standard deviation (RSD) were 0.16 ng/L and 3.5% (n = 8), respectively, for the acetonitrile signals in MS/MS experiments. Interestingly, the concentrations of acetonitrile in human breath continuously increased for 1-4 hours after the smoker finished smoking and then slowly decreased to the background level in 7 days. The experimental data of a large number of (> 165) samples indicated that the inhaled acetonitrile is excreted most likely by facilitated diffusion, instead of simple diffusion reported previously for other volatile compounds.

  7. Membrane-aerated biofilm reactor for the treatment of acetonitrile wastewater.

    PubMed

    Li, Tinggang; Liu, Junxin; Bai, Renbi; Wong, F S

    2008-03-15

    A membrane-aerated biofilm reactor (MABR) was studied for the treatment of wastewater containing acetonitrile, a typical organonitrile compound. The MABR used hydrophobic hollow fiber membranes as the diffusers for bubbleless aeration as well as the carriers for biofilm growth. The objectives were to prevent the stripping-loss of acetonitrile during aeration and to achieve acetonitrile biodegradation plus nitrogen removal simultaneously in a single biolfilm on the membranes. In the MABR, oxygen and substrates were supplied to the biofilm from opposite sides, in contrast to those from the same side in conventional biofilm bioreactors. Operational factors, including surface loading rate and upflow fluid velocity in the bioreactor, on the effect of acetonitrile biodegradation performance were examined. The profiles of dissolved oxygen concentration and microbial activities and populations in the biofilm were investigated. Experimental results showed that, with the adapted microorganisms, removal of acetonitrile at approximately 98.6 and 83.3%, in terms of total organic carbon and total nitrogen, were achieved at a surface loading rate (in terms of membrane surface) of up to 11.29 g acetonitrile/ m2 x d with an upflow fluid velocity of 12 cm/s and a hydraulic retention time of 30 h. The biofilm on the membranes developed an average thickness of about 1.6 mm in the steady state and consisted of oxic/anoxic/anaerobic zones that provided different functions for acetonitrile degradation, nitrification, and denitrification. The acetonitrile-degrading bacteria in the MABR appeared to secrete more extracellular polymeric substances that enhanced the attachment and development of the biofilm on the membranes. The study demonstrated the potential of using the MABR for the treatment of organonitrile wastewater.

  8. The potential of the acetonitrile biodegradation by Mesorhizobium sp. F28.

    PubMed

    Feng, Yun-Shu; Lee, Chi-Mei

    2009-05-30

    Mesorhizobium sp. F28 was used in the NHase/amidase enzyme system to convert acetonitrile into acetamide and acetic acid, and the cells grew with the production of acetic acid. The NHase activity of the strain F28 was 78 U mg(-1)dcw, observed in the conversion of 19.5mM acetonitrile at 0.2h. As the initial pH value was between 6.5 and 8.3, 18.3mM acetonitrile completely converted into acetamide within 2h and the accumulation of acetamide subsequently converted into acetic acid and ammonia within 46h. When 20.3mM acetamide was added in the medium, the conversion rate of acetonitrile was 80% at 2h and the conversion rate of the accumulative acetamide was slightly affected. The concentrations of acetic acid and ammonia were respectively 6.01 and 6.68 mM at 46h. The addition of acetic acid decreased the activities of the NHase and amidase. The conversion rate of acetonitrile was 94% at 9.5h and traces of acetic acid (0.25 mM) and ammonia (0.29 mM) were produced. The effects of product-inhibition indicated that the appropriate operation of bioreactor would be beneficial for Mesorizobium sp. F28 to degrade acetonitrile continuously.

  9. Cavity-Enhanced Near-Infrared Laser Absorption Spectrometer for the Measurement of Acetonitrile in Breath.

    PubMed

    Gianella, Michele; Ritchie, Grant A D

    2015-07-07

    Elevated concentrations of acetonitrile have been found in the exhaled breath of patients with cystic fibrosis1 and may indicate the severity of their condition or the presence of an accompanying bacterial infection of the airways. There is therefore interest in detecting acetonitrile in exhaled breath. For this purpose, a cavity-enhanced laser absorption spectrometer (λ = 1.65 μm) with a preconcentration stage was built and is described here. The spectrometer has a limit of detection of 72 ppbv and 114 ppbv of acetonitrile in nitrogen and breath, respectively, with a measurement duration of just under 5 min. The preconcentration stage, which employs a carbon molecular sieve and an adsorption/thermal desorption cycle, can increase the acetonitrile concentration by up to a factor 93, thus, lowering the overall limit of detection to approximately 1 ppbv. The suitability of the system for acetonitrile measurements in breath is demonstrated with breath samples taken from the authors, which yielded acetonitrile concentrations of 23 ± 3 ppbv and 29 ± 3 ppbv, respectively.

  10. Airborne measurements of acetonitrile and other organic tracers during MIRAGE- MEX

    NASA Astrophysics Data System (ADS)

    Apel, E. C.; Hills, A.; Emmons, L.; Orlando, J.; Riemer, D.; Sive, B.

    2007-05-01

    Biomass burning (BB) plumes are known to impact air quality throughout the globe and can be important sources of pollution in megacities. A number of chemical tracers for BB have been used in the recent past with acetonitrile, a long-lived (~6 months) organic trace gas, among them. However, the atmospheric budget of acetonitrile is not well-known. It has been accepted in the recent literature that the primary source for acetonitrile is from BB, but a recent study points to an oceanic source. Loss is believed to be by reaction with OH and oceanic uptake. Earlier studies indicated that acetonitrile may be produced in emissions from automobile exhaust but a study done in the late 1990s appeared to discredit this. We use measurements from the Trace Organic Gas Analyzer (TOGA) onboard the NCAR C-130 aircraft to investigate the sources and sinks of acetonitrile in and around the Mexico City Metropolitan Area, investigate its utility as a tracer of emissions, and present data on emissions characterization based on measurements of acetonitrile and other co-measured VOCs.

  11. Development and validation of a high performance chromatographic method for determining sumatriptan in niosomes.

    PubMed

    Cózar-Bernal, M J; Rabasco, A M; González-Rodríguez, M L

    2013-01-01

    In this paper, a novel, precise, specific, accurate and rapid reversed-phase high performance liquid chromatographic method was developed, optimized and validated for determining sumatriptan succinate in niosomes with the best chromatographic peak resolution, reduced run time and low cost of analysis. The formulation has been previously optimized in terms of composition and preparation technique to obtain a high drug encapsulation efficiency and adequate vesicle size distribution. This method showed the best resolution by using Spherisorb OSD2 C18 column (250 mm × 4.6 mm, 5 μm) using phosphate buffer (0.05 M):acetonitrile (80:20, v/v; pH adjusted to 6.0) as a mobile phase at a flow rate of 1 mL/min and wavelength of 214 nm. The main objective of this research was to demonstrate the robustness of the reversed-phase HPLC method development by applying the Taguchi robust methodology. The signal-to-noise ratio (S/N) was employed as a quality measurement. This tool permits to establish the influence of some selected factors (acetonitrile:phosphate ratio, pH buffer, oven temperature and flow rate) on two responses (peak areas and retention time). On the basis of the results obtained, we can conclude that this analytical method was robust for all the factors studies, as exception of the flow rate, where the higher quality was obtained for the fewer values (0.8 mL/min). Therefore, this parameter must be carefully controlled when this method was employed, to avoid any modification in the peak areas overall.

  12. Chromatographic determination of the diffusion coefficients of light hydrocarbons in polymers

    NASA Astrophysics Data System (ADS)

    Yakubenko, E. E.; Korolev, A. A.; Chapala, P. P.; Bermeshev, M. V.; Kanat'eva, A. Yu.; Kurganov, A. A.

    2017-01-01

    Gas-chromatographic determination of the diffusion coefficients that allows for the compressibility of the mobile phase has been suggested. The diffusion coefficients were determined for light hydrocarbons C1-C4 in four polymers with a high free volume, which are candidates for use as gas-separating membranes. The diffusion coefficients calculated from chromatographic data were shown to be one or two orders of magnitude smaller than the values obtained by the membrane method. This may be due to the presence of an additional flow through the membrane caused by the pressure gradient across the membrane in membrane methods.

  13. Simultaneous liquid chromatographic determination of lamotrigine, oxcarbazepine monohydroxy derivative and felbamate in plasma of patients with epilepsy.

    PubMed

    Contin, Manuela; Balboni, Monica; Callegati, Erica; Candela, Carmina; Albani, Fiorenzo; Riva, Roberto; Baruzzi, Agostino

    2005-12-15

    A very simple and fast method has been developed and validated for simultaneous determination of the new generation antiepileptic drugs (AEDs) lamotrigine (LTG), oxcarbazepine's (OXC) main active metabolite monohydroxycarbamazepine and felbamate in plasma of patients with epilepsy using high-performance liquid chromatography (HPLC) with spectrophotometric detection. Plasma sample (500 microL) pre-treatment was based on simple deproteinization by acetonitrile. Liquid chromatographic analysis was carried out on a Synergi 4 microm Hydro-RP, 150 mm x 4 mm I.D. column, using a mixture of potassium dihydrogen phosphate buffer (50mM, pH 4.5) and acetonitrile/methanol (3/1) (65:35, v/v) as the mobile phase, at a flow rate of 1.0 mL/min. The UV detector was set at 210 nm. Calibration curves were linear (mean correlation coefficient >0.999 for all the three analytes) over a range of 1-20 mg/mL for lamotrigine, 2-40 microg/mL for monohydroxycarbamazepine and 10-120 microg/mL for felbamate. Both intra and interassay precision and accuracy were lower than 7.5% for all three analytes. Absolute recoveries ranged between 100 and 104%. The present procedure describes for the first time the simultaneous determination of these three new antiepileptic drugs. The simple sample pre-treatment, combined with the fast chromatographic run permit rapid processing of a large series of patient samples.

  14. A simple high-performance liquid chromatographic assay for ciprofloxacin in human serum.

    PubMed

    Jim, L K; el-Sayed, N; al-Khamis, K I

    1992-04-01

    A simple and selective high-performance liquid chromatographic (HPLC) method for the determination of ciprofloxacin in serum has been developed and evaluated. Serum protein was precipitated with acetonitrile. The drug and the internal standard (quinine) were evaluated from a 10 microns U-Bondapack C-18 cartridge at ambient temperature with a mobile phase consisting of acetonitrile: 0.1 M sodium dihydrogen phosphate (20:80%, v/v) adjusted to pH 3.9 with phosphoric acid, and at a flow rate of 2.5 ml/min. The effluent was monitored on a fluorescence detector using an excitation and emission wavelength of 280 and 455 nm, respectively. Each analysis required no longer than 6 min. Quantification was achieved by the measurement of the peak-height ratio and the limit of quantification for ciprofloxacin in serum is 25 ng/ml. The intraday coefficient of variation (CV) ranged from 0.4 to 5.8%, and interday CV from 4.6 to 8.8% at three different concentrations. Relative recovery ranged from 98 to 100.2% at three different concentrations. Preliminary stability tests show that ciprofloxacin is stable for at least 3 weeks in serum after freezing.

  15. High-performance liquid chromatographic method for the simultaneous detection of malonaldehyde, acetaldehyde, formaldehyde, acetone and propionaldehyde to monitor the oxidative stress in heart.

    PubMed

    Cordis, G A; Bagchi, D; Maulik, N; Das, D K

    1994-02-11

    Lipid peroxidation (LPO) is the oxidative deterioration of polyunsaturated fatty acids (PUFA) with the production of lipid hydroperoxides, cyclic peroxides, cyclic endoperoxides, and finally fragmentation to ketones and aldehydes (including malonaldehyde, MDA). Estimation of LPO through MDA formation measured by assaying thiobarbituric acid (TBA) reactive products remains the method of choice to study the development of oxidative stress in tissues. However, MDA estimation by TBA reactive products is non-specific and often gives erroneous results. In this report we describe a method using high-performance liquid chromatographic separation to estimate MDA, formaldehyde (FDA), acetaldehyde (ADA), acetone, and propionaldehyde (PDA), the degradation products of oxygen-derived free radicals (ODFR) and PUFA, as presumptive markers for LPO. Oxidative stress was induced in the tissue by perfusing an isolated rat heart with hydroxyl radical generating system (xanthine + xanthine oxidase + FeCl3 + EDTA). The coronary effluents were collected, derivatized with 2,4-dinitrophenylhydrazine (DNPH), and extracted with pentane. Aliquots of 25 microliters in acetonitrile were injected onto a Beckman Ultrasphere C18 (3 microns) column. The products were eluted isocratically with a mobile phase containing acetonitrile-water-acetic acid (40:60:0.1, v/v/v), measured at three different wavelengths (307, 325 and 356 nm) using a Waters M-490 multichannel UV detector and collected for gas chromatography-mass spectrometry (GC-MS) analysis. The peaks were identified by cochromatography with DNPH derivatives of authentic standards, peak addition, UV pattern of absorption at the three wavelengths, and by GC-MS. The retention items of MDA, FDA, ADA, acetone, and PDA were 5.3, 6.6, 10.3, 16.5, and 20.5 min, respectively. The results of our study indicated progressive increase of all five lipid metabolites as a function of the duration of ODFR perfusion. Hydroxyl radical scavengers, superoxide

  16. HILIC separation mechanisms of tetracyclines on amino bonded silica column

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of mobile phase variations on the chromatographic separation on amino bonded silica column in hydrophilic interaction chromatography (HILIC) were investigated for four zwitterionic tetracyclines (TCs): oxytetracycline, doxycycline, chlortetracycline and tetracycline. A mixed-mode retention m...

  17. Water versus acetonitrile coordination to uranyl. Density functional study of cooperative polarization effects in solution.

    PubMed

    Bühl, Michael; Sieffert, Nicolas; Chaumont, Alain; Wipff, Georges

    2011-01-03

    Optimizations at the BLYP and B3LYP levels are reported for mixed uranyl-water/acetonitrile complexes [UO(2)(H(2)O)(5-n)(MeCN)(n)](2+) (n = 0-5), in both the gas phase and a polarizable continuum modeling acetonitrile. Car-Parrinello molecular dynamics (CPMD) simulations have been performed for these complexes in the gas phase, and for selected species (n = 0, 1, 3, 5) in a periodic box of liquid acetonitrile. According to structural and energetic data, uranyl has a higher affinity for acetonitrile than for water in the gas phase, in keeping with the higher dipole moment and polarizability of acetonitrile. In acetonitrile solution, however, water is the better ligand because of specific solvation effects. Analysis of the dipole moment of the coordinated water molecule in [UO(2)(H(2)O)(MeCN)(4)](2+) reveals that the interaction with the second-shell solvent molecules (through fairly strong and persistent O-H···N hydrogen bonds) causes a significant increase of this dipole moment (by more than 1 D). This cooperative polarization of water reinforces the uranyl-water bond as well as the water solvation via strengthened (UO(2))OH(2)···NCMe hydrogen bonds. Such cooperativity is essentially absent in the acetonitrile ligands that make much weaker (UO(2))NCMe···NCMe hydrogen bonds. Beyond the uranyl case, this study points to the importance of cooperative polarization effects to enhance the M(n+) ion affinity for water in condensed phases involving M(n+)-OH(2)···A fragments, where A is a H-bond proton acceptor and M(n+) is a hard cation.

  18. Interaction of acetonitrile with the surfaces of amorphous and crystalline ice

    SciTech Connect

    Schaff, J.E.; Roberts, J.T.

    1999-10-12

    The adsorption of acetonitrile (CH{sub 3}CN) on ultrathin films of ice under ultrahigh vacuum was investigated with temperature-programmed desorption ass spectrometry (TPD) and Fourier transform infrared reflection absorption spectroscopy (FTIRAS). Two types of film were studied, amorphous and crystalline. On the amorphous films, two sates of adsorbed acetonitrile were observed by TPD and FTIRAS. One of the states is attributed to acetonitrile that is hydrogen bonded to agree OH group at the ice surface; the other state is assigned to acetonitrile that is purely physiorbed. Evidence for the hydrogen-bonded state is two-fold. First, there is a large kinetic isotope effect for desorption from H{sub 2}O-and D{sub 2}O-ice: the desorption temperatures from ice-h{sub 2} and ice-d{sub 2} are {approximately}161 and {approximately}176 K, respectively. Second, the C{triple{underscore}bond}N stretching frequency (2,265 cm{sup {minus}1}) is 16 cm{sup {minus}1} is greater than that of physisorbed acetonitrile, and it is roughly equal to that of acetonitrile which is hydrogen bonded to an OH group at the air-liquid water interface. On the crystalline films, there is no evidence for a hydrogen-bonded state in the TPD spectra. The FTIRAS spectra do show that some hydrogen-bonded acetonitrile is present but at a maximum coverage that is roughly one-sixth of that on the amorphous surface. The difference between the amorphous and crystalline surfaces cannot be attributed to a difference n surface areas. Rather, this work provides additional evidence that the surface chemical properties of amorphous ice are different from those of crystalline ice.

  19. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Eckels, Joel D.; Kimmons, James F.; Myers, David W.

    1996-01-01

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  20. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Eckels, J.D.; Kimmons, J.F.; Myers, D.W.

    1996-06-11

    A gas chromatograph-mass spectrometer (GC-MS) is described for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units. 4 figs.

  1. Portable gas chromatograph-mass spectrometer

    SciTech Connect

    Andresen, B.D.; Eckels, J.D.; Kimmins, J.F.; Myers, D.W.

    1994-12-31

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  2. Chromatographic properties PLOT multicapillary columns.

    PubMed

    Nikolaeva, O A; Patrushev, Y V; Sidelnikov, V N

    2017-03-10

    Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD). These MCCs have the efficiency of 4000-10000 theoretical plates per meter (TP/m) and at a column length of 25-30cm can separate within 10-20s multicomponent mixtures of substances belonging to different classes of chemical compounds. The sample amount not overloading the column is 0.03-1μg and depends on the features of a porous layer. Examples of separations on some of the studied columns are considered.

  3. Origin of anomalous electronic circular dichroism spectrum of RuPt2(tppz)2Cl2(PF6)4 in acetonitrile.

    PubMed

    Yu, Hua-Gen

    2014-07-24

    We report a theoretical study of the structures, energetics, and electronic spectra of the Pt(II)/Ru(II) mixed-metal complex RuPt2(tppz)2Cl2(PF6)4 (tppz = 2,3,5,6-tetra(2-pyridyl)pyrazine) in acetonitrile. The hybrid B3LYP density functional theory and its TDDFT methods were used with a complete basis set (CBS) extrapolation scheme and a conductor polarizable continuum model (C-PCM) for solvation effects. Results showed that the trinuclear complex has four types of stable conformers and/or enantiomers. They are separated by high barriers owing to the repulsive H/H geometrical constraints in tppz. A strong entropy effect was found for the dissociation of RuPt2(tppz)2Cl2(PF6)n in acetonitrile. The UV-visible and emission spectra of the complex were also simulated. They are in good agreement with experiments. In this work we have largely focused on exploring the origin of anomalous electronic circular dichroism (ECD) spectra of the RuPt2(tppz)2Cl2(PF6)4 complex in acetonitrile. As a result, a new mechanism has been proposed together with a clear illustration by using a physical model.

  4. Selective Photodissociation of Acetonitrile Ligands in Ruthenium Polypyridyl Complexes Studied by Density Functional Theory.

    PubMed

    Tu, Yi-Jung; Mazumder, Shivnath; Endicott, John F; Turro, Claudia; Kodanko, Jeremy J; Schlegel, H Bernhard

    2015-08-17

    Metal complexes that release ligands upon photoexcitation are important tools for biological research and show great potential as highly specific therapeutics. Upon excitation with visible light, [Ru(TQA)(MeCN)2](2+) [TQA = tris(2-quinolinylmethyl)amine] exchanges one of the two acetonitriles (MeCNs), whereas [Ru(DPAbpy)MeCN](2+) [DPAbpy = N-(2,2'-bipyridin-6-yl)-N,N-bis(pyridin-2-ylmethyl)amine] does not release MeCN. Furthermore, [Ru(TQA)(MeCN)2](2+) is highly selective for release of the MeCN that is perpendicular to the plane of the two axial quinolines. Density functional theory calculations provide a clear explanation for the photodissociation behavior of these two complexes. Excitation by visible light and intersystem crossing leads to a six-coordinate (3)MLCT state. Dissociation of acetonitrile can occur after internal conversion to a dissociative (3)MC state, which has an occupied dσ* orbital that interacts in an antibonding fashion with acetonitrile. For [Ru(TQA)(MeCN)2](2+), the dissociative (3)MC state is lower than the (3)MLCT state. In contrast, the (3)MC state of [Ru(DPAbpy)MeCN](2+) that releases acetonitrile has an energy higher than that of the (3)MLCT state, indicating dissociation is unfavorable. These results are consistent with the experimental observations that efficient photodissociation of acetonitrile occurs for [Ru(TQA)(MeCN)2](2+) but not for [Ru(DPAbpy)MeCN](2+). For the release of the MeCN ligand in [Ru(TQA)(MeCN)2](2+) that is perpendicular to the axial quinoline rings, the (3)MLCT state has an occupied quinoline π* orbital that can interact with a dσ* Ru-NCCH3 antibonding orbital as the Ru-NCCH3 bond is stretched and the quinolines bend toward the departing acetonitrile. This reduces the barrier for the formation of the dissociative (3)MC state, leading to the selective photodissociation of this acetonitrile. By contrast, when the acetonitrile is in the plane of the quinolines or bpy, no interaction occurs between the ligand

  5. Fast chiral chromatographic method development and validation for the quantitation of eszopiclone in human plasma using LC/MS/MS.

    PubMed

    Meng, Min; Rohde, Lisa; Cápka, Vladimír; Carter, Spencer J; Bennett, Patrick K

    2010-12-01

    Traditional chiral chromatographic separation method development is time consuming even for an experienced chromatographer. This paper describes the application of computer software ACD Lab to facilitate the development of chiral separation for the quantitation of eszopiclone using LC-MS/MS technology. Assisted by ACD/Chrom Manager and LC Simulator software, the optimal chiral chromatographic development was completed within hours. The baseline chiral separation was achieved with a total cycle time of 3 min. For sample extraction method development, a Waters Oasis Sorbent Selection Plate containing four different sorbents was utilized. Optimal conditions were determined using a single plate under various load, wash and elution conditions. This was followed by a GLP validation which demonstrated excellent intra- and inter-day accuracy and precision for the quantitation of eszopiclone in human plasma at 1.00-100 ng/mL range using LC/MS/MS technology. This method was utilized to support multiple clinic bioequivalence studies.

  6. ESP and ESM1 mediate indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate in Arabidopsis.

    PubMed

    Burow, Meike; Zhang, Zhi-Yong; Ober, James A; Lambrix, Virginia M; Wittstock, Ute; Gershenzon, Jonathan; Kliebenstein, Daniel J

    2008-02-01

    Glucosinolates are plant secondary metabolites that act as direct defenses against insect herbivores and various pathogens. Recent analysis has shown that methionine-derived glucosinolates are hydrolyzed/activated into either nitriles or isothiocyanates depending upon the plants genotype at multiple loci. While it has been hypothesized that tryptophan-derived glucosinolates can be a source of indole-acetonitriles, it has not been explicitly shown if the same proteins control nitrile production from tryptophan-derived glucosinolates as from methionine-derived glucosinolates. In this report, we formally test if the proteins involved in controlling aliphatic glucosinolate hydrolysis during tissue disruption can control production of nitriles during indolic glucosinolate hydrolysis. We show that myrosinase is not sufficient for indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate and requires the presence of functional epithospecifier protein in planta and in vitro to produce significant levels of indol-3-acetonitrile. This reaction is also controlled by the Epithiospecifier modifier 1 gene. Thus, like formation of nitriles from aliphatic glucosinolates, indol-3-acetonitrile production following tissue disruption is controlled by multiple loci raising the potential for complex regulation and fine tuning of indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate.

  7. Kinetic sonication effects in aqueous acetonitrile solutions. Reaction rate levelling by ultrasound.

    PubMed

    Piiskop, Sander; Salmar, Siim; Tuulmets, Ants; Kuznetsov, Aleksei; Järv, Jaak

    2013-11-01

    The kinetics of the pH-independent hydrolysis of 4-methoxyphenyl dichloroacetate were investigated with and without ultrasonic irradiation in acetonitrile-water binary mixtures containing 0.008 to 35 wt.% of acetonitrile and the kinetic sonication effects (kson/knon) were calculated. Molecular dynamics (MD) simulations of the structure of the solutions were performed with ethyl acetate as the model ester. The ester is preferentially solvated by acetonitrile. The excess of acetonitrile over water in the solvation shell grows fast with an increase in the co-solvent content in the bulk solution. In parallel, the formation of a second solvation shell rich in acetonitrile takes place. Significant kinetic sonication effects for the hydrolysis were explained with facile destruction of the diffuse second solvation shell followed by a rearrangement of the remaining solvent layer under sonication. The rate levelling effect of ultrasound was discussed. In an aqueous-organic binary solvent, independent of the solvent composition, the ultrasonic irradiation evokes changes in the reaction medium which result in an almost identical solvation state of the reagent thus leading to the reaction rate levelling.

  8. Characterization of acetonitrile-tolerant marine bacterium Exiguobacterium sp. SBH81 and its tolerance mechanism.

    PubMed

    Kongpol, Ajiraporn; Kato, Junichi; Tajima, Takahisa; Vangnai, Alisa S

    2012-01-01

    A Gram-positive marine bacterium, Exiguobacterium sp. SBH81, was isolated as a hydrophilic organic-solvent tolerant bacterium, and exhibited high tolerance to various types of toxic hydrophilic organic solvents, including acetonitrile, at relatively high concentrations (up to 6% [v/v]) under the growing conditions. Investigation of its tolerance mechanisms illustrated that it does not rely on solvent inactivation processes or modification of cell surface characteristics, but rather, increase of the cell size lowers solvent partitioning into cells and the extrusion of solvents through the efflux system. A test using efflux pump inhibitors suggested that secondary transporters, i.e. resistance nodulation cell division (RND) and the multidrug and toxic compound extrusion (MATE) family, are involved in acetonitrile tolerance in this strain. In addition, its acetonitrile tolerance ability could be stably and significantly enhanced by repetitive growth in the presence of toxic acetonitrile. The marked acetonitrile tolerance of Exiguobacterium sp. SBH81 indicates its potential use as a host for biotechnological fermentation processes as well as bioremediation.

  9. [Effect of Acetonitrile and n-hexane on the Immunoassay of Environmental Representative Pollutants].

    PubMed

    Lou, Xue-ning; Zhou, Li-ping; Song, Dan; Yang, Rong; Long, Feng

    2016-01-15

    Based on indirect competitive immunoassay mechanism, bisphenol A (BPA) was detected by the evanescent wave all-fiber immunosensor previously developed with the detection limit of 0.2 microg x L(-1) and the linear detection range of 0.3-33.4 microg x L(-1). The effects of two commonly used organic solvents, including acetonitrile and n-hexane, on the immunosensing assay of BPA were investigated. The influence mechanism of organic solvents on immunosensing assay was discussed. The experimental results showed that the effect of n-hexane on immunosensing assay was negligible even at a high concentration of up to 10%, whereas the effect of acetonitrile on the immunosensing assay was relatively great. BPA could be detected in solutions containing a low concentration of acetonitrile. However, the specific binding reaction between antibody and antigen in homogeneous solution was completely inhibited by high concentrations of acetonitrile, and the quantitative analysis of BPA was not achieved. This might result from the changes of antibody conformation or binding capability between antibody and antigen because acetonitrile replaced a part of the water molecules on the antibody surface.

  10. Ethanol and acetonitrile induces conformational changes in porcine pepsin at alkaline denatured state.

    PubMed

    Shanmugam, Ganesh; Selvi, C Chinnarul; Mandal, Asit Baran

    2012-11-01

    Pepsin, a member of the aspartate protease family, exists in a partially unfolded state at alkaline pH where the N-terminal domain of pepsin has a flexible structure while the C-terminal domain has a highly folded structure. In this work, the conformational stability of porcine pepsin in an alkaline denatured (A(D)) state against acetonitrile and ethanol solvents was studied using a combination of electronic circular dichroism (ECD) and fluorescence techniques. The ECD results demonstrate that both ethanol and acetonitrile induce secondary structural changes in pepsin at A(D) state. However, the minimum concentration required to induce significant secondary structural changes in pepsin varies for ethanol (>30%, v/v) and acetonitrile (>60%, v/v) solvents. At maximum concentration used (90%, v/v), both solvents induce predominantly β-sheet conformation. Unlike acetonitrile, ethanol induces significant amount of non-native α-helical conformations at the intermediate concentrations (50-80%). The tryptophan fluorescence results demonstrate that both acetonitrile and ethanol induce substantial changes in the tertiary structure of pepsin in the A(D) state above certain concentrations. The current results have important implications in understanding the effect of co-solvents on the conformation of proteins in the "denatured state".

  11. Liquid chromatographic method for the determination of uridine in human serum.

    PubMed

    Zilly, M; Langmann, P; Winzer, R; Benesic, A; Schirmer, D; Walker, U A; Klinker, H

    2004-04-25

    To evaluate uridine levels in humans we developed a very sensitive and specific high-performance liquid chromatographic method for the determination of uridine in serum. We use techniques which are available in a standard analytical laboratory. Chromatographic analysis was carried out on a Phenomenex Aqua C18 5 micro 125A column protected by a guard cartridge system. Potassium dihydrogen phosphate buffer-acetonitrile was used as an eluent and oxypurinol as the internal standard. All sample preparation steps were done at 4 degrees C and the autosampler was cooled down to 4 degrees C. The calibration curve was linear throughout the calibration range from 0.25 to 100 micromol/l. This method was primarily established to evaluate uridine serum levels in patients with HIV infection since patients on highly active antiretroviral therapy (HAART) might develop metabolic disturbances that could lead to severe and fatal lactic acidosis due to mitochondrial toxicity. It is suggested that a limited or inadequate uridine supply is at least in part responsible for the onset of such deterioration.

  12. Utilization of deep eutectic solvents as novel mobile phase additives for improving the separation of bioactive quaternary alkaloids.

    PubMed

    Tan, Ting; Zhang, Mingliang; Wan, Yiqun; Qiu, Hongdeng

    2016-01-01

    Deep eutectic solvents (DESs) were used as novel mobile phase additives to improve chromatographic separation of four quaternary alkaloids including coptisine chloride, sanguinarine, berberine chloride and chelerythrine on a C18 column. DESs as a new class of ionic liquids are renewably sourced, environmentally benign, low cost and easy to prepare. Seven DESs were obtained by mixing different hydrogen acceptors and hydrogen-bond donors. The effects of organic solvents, the concentration of DESs, the types of DESs and the pH values of the buffer solution on the separation of the analytes were investigated. The composition of acetonitrile and 1.0% deep eutectic solvents aqueous solution (pH 3.3, adjusted with hydrochloric acid) in a 32:68 (v/v) ratio was used as optimized mobile phase, with which four quaternary alkaloids were well separated. When a small amount of DESs was added in the mobile phase for the separation of alkaloids on the C18 column, noticeable improvements were distinctly observed such as decreasing peak tailing and improving resolution. The separation mechanism mediated by DESs as mobile phase additives can be attributed to combined effect of both hydrogen acceptors and hydrogen-bond donors. For example, choline chloride can effectively cover the residual silanols on silica surface and ethylene glycol can reduce the retention time of analytes. The proposed method has been applied to determine BerbC in Lanqin Chinese herbal oral solution and BerbC tablet. Utilization of DESs in mobile phase can efficiently improve separation and selectivity of analytes from complex samples.

  13. A novel ion-pairing chromatographic method for the simultaneous determination of both nicarbazin components in feed additives: chemometric tools for improving the optimization and validation.

    PubMed

    De Zan, María M; Teglia, Carla M; Robles, Juan C; Goicoechea, Héctor C

    2011-07-15

    The development, optimization and validation of an ion-pairing high performance liquid chromatography method for the simultaneous determination of both nicarbazin (NIC) components: 4,4'-dinitrocarbanilide (DNC) and 2-hydroxy-4,6-dimethylpyrimidine (HDP) in bulk materials and feed additives are described. An experimental design was used for the optimization of the chromatographic system. Four variables, including mobile phase composition and oven temperature, were analyzed through a central composite design exploring their contribution to analyte separation. Five responses: peak resolutions, HDP capacity factor, HDP tailing and analysis time, were modelled by using the response surface methodology and were optimized simultaneously by implementing the desirability function. The optimum conditions resulted in a mobile phase consisting of 10.0 mmol L(-1) of 1-heptanesulfonate, 20.0 mmol L(-1) of sodium acetate, pH=3.30 buffer and acetonitrile in a gradient system at a flow rate of 1.00 mL min(-1). Column was an INERSTIL ODS-3 (4.6 mm×150 mm, 5 μm particle size) at 40.0°C. Detection was performed at 300 nm by a diode array detector. The validation results of the method indicated a high selectivity and good precision characteristics, with RSD less than 1.0% for both components, both in intra and inter-assay precision studies. Linearity was proved for a range of 32.0-50.0 μg mL(-1) of NIC in sample solution. The recovery, studied at three different fortification levels, varied from 98.0 to 101.4 for HDP and from 99.1 to 100.2 for DNC. The applicability of the method was demonstrated by determining DNC and HDP content in raw materials and commercial formulations used for coccidiosis prevention. Assays results on real samples showed that considerable differences in molecular ratio DNC:HDP exist among them.

  14. An high-performance liquid chromatographic method for the simultaneous analysis of acetylcarnitine taurinate, carnosine, asparagine and potassium aspartate and for the analysis of phosphoserine in alimentary supplements.

    PubMed

    Gatti, R; Andreatta, P; Boschetti, S

    2013-07-12

    A RP-HPLC method with pre-column derivatization was developed and validated for the simultaneous quantification of carnosine (Carn), acetylcarnitine taurinate (AC-Tau), asparagine (Asn), potassium aspartate (Asp) and for the determination of phosphoserine (p-Ser) in new and commercial alimentary supplements. The effect of complex matrices was evaluated by the study of the amino acid derivatization reaction with 2,4-dinitrofluorobenzene (DNFB) both in standard and placebo solutions. The reaction was carried out for 20 min at 70 °C in alkaline medium (pH10) for p-Ser analysis, whereas for 60 min in the case of Carn, AC-Tau, Asn and Asp analysis. The adducts have been separated on a Discovery RP Amide C16 (250 mm×4.6mm, i.d.) column using a mobile phase consisting of acetonitrile (ACN) and triethylammonium (TEA) phosphate buffer (pH 3, 0.05 M) under gradient elution conditions at a flow-rate of 0.8 mL/min. Detection was set at λ=360 nm. The validation parameters such as linearity, sensitivity, accuracy, precision and specificity were found to be highly satisfactory. Linear responses were observed by placebo solutions (determination coefficient ≤0.9996). Intra-day precision (relative standard deviation, RSD) was ≤1.06% for corrected peak area and ≤0.99% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all examined compounds (from 97.7% to 101.5%) with RSD ranging from 0.5% to 1.3%). The high stability of derivatized compound solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of a large number of samples and consecutive chromatographic analyses by the use of an autosampler. The developed method can be considered suitable for the quality control of new and commercial products.

  15. Separation and estimation of process-related impurities of gefitinib by reverse-phase high-performance liquid chromatography.

    PubMed

    Chandrashekara, Karunakara A; Udupi, Aparna; Reddy, Chandrasekara G

    2014-09-01

    A simple and rapid reverse-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous separation and estimation of gefitinib (an anti-cancer drug) and its process-related impurities. Five process-related impurities of gefitinib were separated on an Inertsil ODS-3V column (250 × 4.6 mm i.d.; particle size 5 μm) using 130 mM ammonium acetate and acetonitrile (63:37, v/v) as mobile phase (pH 5.0) with a photodiode array (PDA) detector. The correlation coefficients for gefitinib and its process-related impurities were in the range of 0.9991-0.9994 with limit of detection and limit of quantification in the range of 0.012-0.033 and 0.04-0.10 µg/mL, respectively. The recovery values were in the range of 98.26-99.90% for gefitinib and 95.99-100.55% for process-related impurities, while precision values were less than 3%. The method was found to be specific, precise and reliable for the determination of gefitinib and its impurities in gefitinib bulk drug.

  16. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  17. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  18. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  19. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; dle Castillo, L.; White, V.

    2002-01-01

    This poster describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through a microcolumn containing nano-fabricated features will have characteristics elution times that directly correlate to molecular weight.

  20. Functional chromatographic technique for natural product isolation†

    PubMed Central

    Lau, Eric C.; Mason, Damian J.; Eichhorst, Nicole; Engelder, Pearce; Mesa, Celestina; Kithsiri Wijeratne, E. M.; Gunaherath, G. M. Kamal B.; Leslie Gunatilaka, A. A.

    2015-01-01

    Natural product discovery arises through a unique interplay between chromatographic purification and biological assays. Currently, most techniques used for natural product purification deliver leads without a defined biological action. We now describe a technique, referred to herein as functional chromatography, that deploys biological affinity as the matrix for compound isolation. PMID:25588099

  1. The Triply Deprotonated Acetonitrile Anion CCN(3-) Stabilized in a Solid.

    PubMed

    Jach, Franziska; Brückner, Stephan Ingmar; Ovchinnikov, Alexander; Isaeva, Anna; Bobnar, Matej; Groh, Matthias Friedrich; Brunner, Eike; Höhn, Peter; Ruck, Michael

    2017-03-06

    The unprecedented, fully deprotonated form of acetonitrile, the acetonitriletriide anion CCN(3-) , is experimentally realized for the first time in the stabilizing bulk host framework of the Ba5 [TaN4 ][C2 N] nitridometalate via a one-pot synthesis from the elements under moderate conditions (920 K). The molecular structure of this long-sought acetonitrile derivative is confirmed by X-ray diffraction, as well as NMR, IR, and Raman spectroscopy. The anion is isoelectronic to the CO2 molecule, and, in contrast to acetonitrile (H3 C-C≡N), the electron pairs are shifted towards two double bonds, that is, [C=C=N](3-) .

  2. Comparison of chlorine dioxide photochemistry in acetonitrile and water using subpicosecond pump probe spectroscopy

    NASA Astrophysics Data System (ADS)

    Philpott, Matthew J.; Charalambous, Sophia; Reid, Philip J.

    1997-12-01

    The photochemical reaction dynamics of chlorine dioxide (OClO) dissolved in water and acetonitrile are investigated using subpicosecond pump-probe spectroscopy. The spectral dynamics observed at 267 and 400 nm demonstrate that the quantum yield for geminate recombination of ClO and O to form OClO is reduced in acetonitrile relative to water. However, the dynamics at 800 nm are similar for both solvents consistent with ClOO rather than OClO being responsible for the evolution at this wavelength. The kinetics for ground-state ClOO production and decomposition are significantly slower in acetonitrile relative to water suggesting that solvent-solute hydrogen bonding is important in defining the ground state reactivity of this photoproduct.

  3. Titration of selected bases in benzene-acetonitrile binary solvent system.

    PubMed

    Amirjahed, K; al-Khamis, K I

    1980-10-01

    The benzene-acetonitrile binary solvent system was used in the determination of the half-neutralization potentials (hnp) of selected bases varying widely in basicity (pKb). The solvent mixtures had specific dielectric constants (Dm). The hnp values of the bases determined in a solvent of a specific Dm value were related to the corresponding pKb values. The slopes of these linear relationships were related to Dm values. A certain mixture of the binary solvent system was selected, and successful differentiating titration of various base mixtures was demonstrated in this medium. The delta hnp/delta pK versus Dm data for acids were compared with those of bases in the benzene-acetonitrile binary solvent system. The resulting data on bases were compared with previously published data on acids, and the present report describes the behavior of acids and bases in the entire composition spectrum of the benzene-acetonitrile binary solvent system.

  4. Method to fabricate silicon chromatographic column comprising fluid ports

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.; Heller, Edwin J.; Adkins, Douglas R.

    2004-03-02

    A new method for fabricating a silicon chromatographic column comprising through-substrate fluid ports has been developed. This new method enables the fabrication of multi-layer interconnected stacks of silicon chromatographic columns.

  5. Polarizability anisotropy relaxation in nanoconfinement: molecular simulation study of acetonitrile in silica pores.

    PubMed

    Milischuk, Anatoli A; Ladanyi, Branka M

    2013-12-12

    We present the results of a molecular simulation study of polarizability anisotropy relaxation of liquid acetonitrile confined in approximately cylindrical silica pores of diameters in the range of 20-40 Å. Grand Canonical Monte Carlo simulation is used to determine the density of acetonitrile in pores in equilibrium with the bulk liquid, and canonical-ensemble molecular dynamics is then used to calculate the trajectories of the filled pores prepared in this way. We find that the pores are wetting, partially due to hydrogen bonding between acetonitrile nitrogen and pore silanol groups and that acetonitrile molecules have preferential orientations relative to the interface. The mobility of molecules in interfacial regions is considerably reduced and dependent mainly on their proximity to the interface. We include the contributions of molecular and interaction-induced polarizabilities to the collective polarizability anisotropy relaxation. We find that this relaxation includes a slowly relaxing component absent from the corresponding process in bulk acetonitrile and that the amplitude of this component increases as the pore diameter decreases. These results are in agreement with optical Kerr effect experiments on acetonitrile in silica pores in a similar diameter range. Further analysis of our data indicates that collective reorientation and predominantly translational "collision-induced" polarizability dynamics both contribute to the slowly relaxing portion of polarizability anisotropy decay. We further find that pore anisotropy plays a role, giving rise to different relaxation rates of polarizability anisotropy components with a different mix of axial and radial character and that collective reorientation contributing to polarizability anisotropy relaxation is somewhat faster at long times than single-molecule orientational relaxation.

  6. Improving the determination of moisture in edible oils by FTIR spectroscopy using acetonitrile extraction.

    PubMed

    Meng, Xianghe; Sedman, J; van de Voort, F R

    2012-11-15

    A Fourier transform infrared (FTIR) method developed for the analysis of moisture in edible oils using dry acetonitrile as the extraction solvent was re-examined with the objective of improving its overall sensitivity and reproducibility. Quantitation was based on the H-O-H bending absorption at ∼1630 cm(-1) instead of the bands in the OH stretching region, fewer interferences being an issue in the former as opposed to the latter region. In addition, a spectroscopic dilution correction procedure was developed to compensate for any miscibility of oil samples with acetonitrile, and gap-segment 2nd derivative spectra were employed to minimise the associated possibility of spectral interferences from absorptions of the oils. In comprehensive standard addition experiments using a variety of edible oils, the FTIR method was shown to recover the amounts of water quantitatively added to dry oil with an accuracy of ±20 ppm when the spectra of the acetonitrile extracts of the water-spiked oils were ratioed against the spectra of the acetonitrile extracts of the corresponding dry oils. The accuracy deteriorated substantially when the spectra of the acetonitrile extracts of the water-spiked oils were ratioed against the spectrum of the acetonitrile extraction solvent only. However, the primary variable affecting the apparent difference in the accuracy of the two approaches was determined to be the variability in the residual moisture content of the dried oils used in the standard addition experiments, as confirmed by an FTIR procedure based on H-D exchange with D(2)O. The FTIR method as structured is amenable to automation (>120 samples/h) and provides a very competitive means by which to routinely measure moisture present in a variety of hydrophobic materials that are normally the domain of Karl Fischer titration, such as edible oils, mineral oils, biodiesel and fuels.

  7. Tadpole toxicity prediction using chromatographic systems.

    PubMed

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Fuguet, Elisabet; Rosés, Martí

    2015-10-30

    Toxicity has been emulated in tadpole species through chromatographic systems. The parameter studied to evaluate the non-specific toxicity of a compound is the narcosis concentration (Cnar), which is defined as the concentration needed for the immobilization of the organism. Because experimental investigation with animals is lengthy, costly, technically difficult, and ethically questionable, there is a great interest in developing surrogate physicochemical systems able to emulate biological systems to obtain the same information in a faster, more economic, and easier manner. In order to see which chromatographic systems would be able to emulate tadpole narcosis, both, tadpole narcosis data and data in several chromatographic and electrophoretic systems, were fitted to a linear solvation energy relationship (LSER) model. Thus, by comparison of the models it was possible to see which of the chromatographic systems were more similar to the biological one. The physicochemical systems that best emulate tadpole narcosis were an HPLC system based on an immobilized artificial membrane (IAM) column, and two micellar electrokinetic chromatography (MEKC) systems based on sodium taurocholate (STC) and a mixture of sodium dodecylsulphate (SDS) and Brij 35 as surfactants. A system based on a RP18 HPLC column also was selected for comparison because it is a common column in most analytical laboratories. To establish the models, a set of compounds with known Cnar values were analyzed in the chromatographic, and electrophoretic selected systems and, then, the retention factor (k) was correlated to the concentration of narcosis. Statistics showed that the system based on STC micelles was the best to emulate toxicity in tadpoles. The robustness and predictive ability of the developed models were validated.

  8. On-line SPE-UHPLC method using fused core columns for extraction and separation of nine illegal dyes in chilli-containing spices.

    PubMed

    Khalikova, Maria A; Satínský, Dalibor; Smidrkalová, Tereza; Solich, Petr

    2014-12-01

    The presented work describes the development of a simple, fast and effective on-line SPE-UHPLC-UV/vis method using fused core particle columns for extraction, separation and quantitative analysis of the nine illegal dyes, most frequently found in chilli-containing spices. The red dyes Sudan I-IV, Sudan Red 7B, Sudan Red G, Sudan Orange G, Para Red, and Methyl Red were separated and analyzed in less than 9 min without labor-consuming pretreatment procedure. The chromatographic separation was performed on Ascentis Express RP-Amide column with gradient elution using mixture of acetonitrile and water, as a mobile phase at a flow rate of 1.0 mL min(-1) and 55°C of temperature. As SPE sorbent for cleanup and pre-concentration of illegal dyes short guard fused core column Ascentis Express F5 was used. The applicability of proposed method was proven for three different chilli-containing commercial samples. Recoveries for all compounds were between 90% and 108% and relative standard deviation ranged from 1% to 4% for within- and from 2% to 6% for between-day. Limits of detection showed lower values than required by European Union regulations and were in the range of 3.3-10.3 µg L(-1) for standard solutions, 5.6-235.6 µg kg(-1) for chilli-containing spices.

  9. Adsorption of water from aqueous acetonitrile on silica-based stationary phases in aqueous normal-phase liquid chromatography.

    PubMed

    Soukup, Jan; Jandera, Pavel

    2014-12-29

    Excess adsorption of water from aqueous acetonitrile mobile phases was investigated on 16 stationary phases using the frontal analysis method and coulometric Karl-Fischer titration. The stationary phases include silica gel and silica-bonded phases with different polarities, octadecyl and cholesterol, phenyl, nitrile, pentafluorophenylpropyl, diol and zwitterionic sulfobetaine and phosphorylcholine ligands bonded on silica, hybrid organic-silica and hydrosilated matrices. Both fully porous and core-shell column types were included. Preferential uptake of water by the columns can be described by Langmuir isotherms. Even though a diffuse rather than a compact adsorbed discrete layer of water on the adsorbent surface can be formed because of the unlimited miscibility of water with acetonitrile, for convenience, the preferentially adsorbed water was expressed in terms of a hypothetical monomolecular water layer equivalent in the inner pores. The uptake of water strongly depends on the polarity and type of the column. Less than one monomolecular water layer equivalent was adsorbed on moderate polar silica hydride-based stationary phases, Ascentis Express F5 and Ascentis Express CN column at the saturation capacity, while on more polar stationary phases, several water layer equivalents were up-taken from the mobile phase. The strongest affinity to water was observed on the ZIC cHILIC stationary phases, where more than nine water layer equivalents were adsorbed onto its surface at its saturation capacity. Columns with bonded hydroxyl and diol ligands show stronger water adsorption in comparison to bare silica. Columns based on hydrosilated silica generally show significantly decreased water uptake in comparison to stationary phases bonded on ordinary silica. Significant correlations were found between the water uptake and the separation selectivity for compounds with strong polarity differences.

  10. Isolation of flavonoids from Aleurites moluccana using chitosan modified with benzaldehyde (CH-Bz) as chromatographic support.

    PubMed

    Girardi, L G J; Morsch, M; Cechinel-Filho, V; Meyre-Silva, C; Rodrigues, C A

    2003-09-01

    This paper describes the preparation, characterization and use of a derivative of chitosan as a chromatographic sorbent. Chitosan modified with benzenic ring (CH-Bz) was used to separate two flavonoids, swertisin and 2"-O-rhamnosylswertisin, from ethyl acetate fraction of Aleurites moluccana. The results showed that CH-Bz can be used as a sorbent for the separation of flavonoid compounds. The studies showed that CH-Bz in column chromatography produces goods results, separation of the flavonoid compounds.

  11. RAPID MEASUREMENTS OF NEPTUNIUM OXIDATION STATES USING CHROMATOGRAPHIC RESINS

    SciTech Connect

    Diprete, D; C Diprete, C; Mira Malek, M; Eddie Kyser, E

    2009-03-24

    The Savannah River Site's (SRS) H-Canyon facility uses ceric ammonium nitrate (CAN) to separate impure neptunium (Np) from a high sulfate feed stream. The material is processed using a two-pass solvent extraction purification which relies on CAN to oxidize neptunium to Np(VI) during the first pass prior to extraction. Spectrophotometric oxidation-state analyses normally used to validate successful oxidation to Np(VI) prior to extraction were compromised by this feed stream matrix. Therefore, a rapid chromatographic method to validate successful Np oxidation was developed using Eichrom Industries TRU and TEVA{reg_sign} resins. The method was validated and subsequently transferred to existing operations in the process analytical laboratories.

  12. Allyl-silica Hybrid Monoliths For Chromatographic Application

    NASA Astrophysics Data System (ADS)

    Guo, Wenjuan

    Column technology continues to be the most investigated topics in the separation world, since the column is the place where the chromatographic separation happens, making it the heart of the separation system. Allyl-silica hybrid monolithic material has been exploited as support material and potential stationary phases for liquid chromatography; the stationary phase anchored to the silica surface by Si-C bond, which is more pH stable than traditional stationary phase. First, nuclear magnetic resonance spectroscopy has been used to study the sol in the synthesis of allyl-silica hybrid monoliths. Allyl-trimethoxysilane (allyl-TrMOS), dimethyldimethoxysilane (DMDMOS) and tetramethoxysilane (TMOS) have been served as co-precursors in the sol-gel synthesis of organo-silica hybrid monolithic columns for liquid chromatography (LC). 29Si nuclear magnetic resonance (NMR) and 1H NMR spectroscopy were employed to monitor reaction profiles for the acid-catalyzed hydrolysis and initial condensation reactions of the individual precursor and the hybrid system. 29Si-NMR has also been used to identify different silane species formed during the reactions. The overall hydrolysis rate has been found to follow the trend DMDMOS > allyl-TrMOS > TMOS, if each precursor is reacted individually (homo-polymerization). Precursors show different hydrolysis rate when reacted together in the hybrid system than they are reacted individually. Cross-condensation products of TMOS and DMDMOS (QD) arise about 10 minutes of initiation of the reaction. The allyl-silica monolithic columns for capillary liquid chromatography can only be prepared in capillaries with 50 im internal diameter with acceptable performance. One of the most prominent problems related to the synthesis of silica monolithic structures is the volume shrinkage. The synthesis of allylfunctionalized silica hybrid monolithic structures has been studied in an attempt to reduce the volume shrinkage during aging, drying and heat treatment

  13. How Much Can We Learn from a Single Chromatographic Experiment? A Bayesian Perspective.

    PubMed

    Wiczling, Paweł; Kaliszan, Roman

    2016-01-05

    In this work, we proposed and investigated a Bayesian inference procedure to find the desired chromatographic conditions based on known analyte properties (lipophilicity, pKa, and polar surface area) using one preliminary experiment. A previously developed nonlinear mixed effect model was used to specify the prior information about a new analyte with known physicochemical properties. Further, the prior (no preliminary data) and posterior predictive distribution (prior + one experiment) were determined sequentially to search towards the desired separation. The following isocratic high-performance reversed-phase liquid chromatographic conditions were sought: (1) retention time of a single analyte within the range of 4-6 min and (2) baseline separation of two analytes with retention times within the range of 4-10 min. The empirical posterior Bayesian distribution of parameters was estimated using the "slice sampling" Markov Chain Monte Carlo (MCMC) algorithm implemented in Matlab. The simulations with artificial analytes and experimental data of ketoprofen and papaverine were used to test the proposed methodology. The simulation experiment showed that for a single and two randomly selected analytes, there is 97% and 74% probability of obtaining a successful chromatogram using none or one preliminary experiment. The desired separation for ketoprofen and papaverine was established based on a single experiment. It was confirmed that the search for a desired separation rarely requires a large number of chromatographic analyses at least for a simple optimization problem. The proposed Bayesian-based optimization scheme is a powerful method of finding a desired chromatographic separation based on a small number of preliminary experiments.

  14. Separation of sugars by continuous annular chromatography

    SciTech Connect

    Howard, A.J.; Carta, G.; Byers, C.H.

    1987-08-01

    Continuous chromatographic separations of aqueous fructose-glucose-sucrose solutions have been investigated in a laboratory-scale continuous annular chromatograph (CAC) using calcium-exchanged Dowex 50W-X8 resin. Comparative studies have also been conducted using a conventional fixed-bed column packed with the same resin. Complete resolution of fructose-glucose mixtures could be obtained both in a 60-cm-long CAC and in a conventional column of the same length with a sugar feed concentration of up to 200 g/L. Partial resolution of sucrose in three component mixtures was also obtained, and the three sugars were completely separated from added higher-molecular-weight saccharides. Results have been analyzed in terms of approximate linear chromatographic theories and orthogonal collocation of exact mass transfer model equations for fixed and rotating beds. A systematic, comparative evaluation of factors affecting process performance and design procedures is presented.

  15. Continuous separation of proteins by annular chromatography

    SciTech Connect

    Bloomingburg, G.F.; Bauer, J.S.; Carta, G. ); Byers, C.H. )

    1991-05-01

    In this paper, the separation of protein mixtures by continuous annular chromatography (CAC) is studied in a preparative-scale apparatus. S-Sepharose, a strong-acid porous cation-exchange resin is used as the separation medium, and mixtures of albumin, hemoglobin and cytochrome c are used as model separation system. Equilibrium and mass-transfer parameters are developed for this system on the basis of fixed-bed chromatograph experiments. A mathematical model is then successfully used in conjunction with these parameters to simulate the performance of the CAC separations. The continuous separation performance of the annular apparatus is found to be essentially the same as the batchwise performance of an equivalent conventional chromatograph, making the unit attractive for preparative and process-scale applications where continuous throughput is desirable.

  16. High-performance liquid chromatographic method for the determination of HIV-1 non-nucleoside reverse transcriptase inhibitor efavirenz in plasma of patients during highly active antiretroviral therapy.

    PubMed

    Langmann, P; Schirmer, D; Väth, T; Zilly, M; Klinker, H

    2001-05-05

    A new high-performance liquid chromatographic method for the determination of efavirenz in human plasma is described. Quantitative recovery following liquid-liquid extraction with diethylether from 200 microl of human plasma was achieved. Subsequently, the assay was performed with 67 mM potassium dihydrogen phosphate-acetonitrile as a mobile phase, a XTerraRP 18 column protected with a Phenomenex C18 column and UV detection at 246 nm. Linear standard curves were obtained for concentrations ranging from 25 to 15,000 ng/ml. The calculated intra- and inter-day coefficients of variation were below 10%.

  17. [High-performance liquid chromatography of peptide bioregulators, their fragments and derivatives. I. Chromatographic pattern of corticotropin fragments of Zorbax ODS sorbent].

    PubMed

    Grigor'ev, V D; Shats, V D; Brivkalne, L A; Chipens, G I

    1983-07-01

    The influence of acetonitrile concentration in the eluent and of the peptide hydrophobicity on the capacity factors has been studied. The equation is proposed that describes retention as a function of the eluent characteristics and the peptide composition. The hydrophobicity increments for -COOH, -NH2, and greater than CHCONH-fragments in the studied chromatographic system have been determined. The proposed model of peptide retention is useful for a prior evaluation of the eluent composition that is necessary to elute a compound at a given capacity factor. It can be also used for the qualitative interpretation of peptide chromatograms.

  18. Sequential injection chromatography for separation and quantification of chlorpromazine in human urine and pharmaceutical formulations.

    PubMed

    Idris, Abubakr M; Elgorashe, Rafea E E

    2013-01-01

    Sequential injection chromatography (SIC) is a recent, simple, and inexpensive green miniaturized separation technique. In the current study, SIC was exploited for the first time for biochemical analysis. A new SIC method for the separation and quantification of chlorpromazine in human urine, as well as pharmaceutical formulations, was developed and validated. Clozapine was used as an internal standard. Chlorpromazine was successfully separated on a C18 monolithic column (25x4.6 mm id). The UV detection was carried out at 250 nm using miniaturized fiber optic spectrometric devices. The optimum mobile phase composition was 30 mmol/L phosphate-acetonitrile-methanol (55.0 + 31.5 + 13.5, v/v/v) at pH 3.0. The sample volume was 40 microL and flow rate was 40 microL/s. Acceptable chromatographic results were obtained. The resolution was 2.7, peak symmetry was 1.1, and number of theoretical plates was more than 1 x 10(6). Good linearity (r = 0.9997) in the range of 25-100 microg/mL was also obtained. The method offered acceptable recovery for both human urine (89.6-93.1%) and pharmaceutical formulations (96.9-98.5%), which was sensitive enough to detect chlorpromazine. The LOD and LOQ in human urine were 61 and 204 ng/mL, respectively. The method was rapid and reagent-saving, and hence safe for the environment. The sample throughput was 26.3 samples/h and the total volume of consumed reagents was 4.0 mL.

  19. Development and validation of a reversed-phase liquid chromatographic method for analysis of estradiol valerate and medroxyprogesterone acetate in a tablet formulation.

    PubMed

    Segall, A; Hormaechea, F; Vitale, M; Perez, V; Pizzorno, M T

    1999-04-01

    A simple and accurate liquid chromatographic method was developed for estimation of estradiol valerate and medroxyprogesterone acetate in pharmaceuticals. Drugs were chromatographed on a reverse phase C18 column, using a mixture (30:70) of ammonium nitrate buffer and acetonitrile and eluants monitored at a wavelength of 280 nm. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision and selectivity. Due to its simplicity and accuracy, the authors believe that the method may be used for routine quality control analysis. It does not require any specific sample preparation except the use of a column guard before the analytical column and suitable prefilter attached to the syringe prior to injection.

  20. Chromatographic determination of Fe chelated by ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid in commercial EDDHA/Fe3+ fertilizers.

    PubMed

    García-Marco, Sonia; Torreblanca, Ana; Lucena, Juan J

    2006-02-22

    EDDHA/Fe3+ chelates are the most common fertilizers used to solve Fe chlorosis in established crops. Commercial products contain two regioisomers, ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA)/Fe3+ and ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA)/Fe3+. Although several chromatographic methods exist for the determination of Fe3+ chelated by the o,o-EDDHA isomer, no method has been described for the quantification of Fe3+ chelated by o,p-EDDHA. In this work, factors that affect the behavior of o,p-EDDHA/Fe3+ in ion pair chromatography are reviewed: pH, ion pair reagent, and organic modifier. The best chromatographic performance was obtained with an aqueous mobile phase at pH 6.0 containing 35% acetonitrile and 5 mM tetrabutylammonium hydroxide under isocratic elution conditions. This method was applied to the quantification of commercial samples.