J. L. Gu

Simple HPLC Method for Simultaneous Determination of Acetaminophen, Caffeine and Chlorpheniramine Maleate in Tablet Formulations

SummaryA simple, rapid and accurate, routine-HPLC method is described for simultaneous determination of acetaminophen, caffeine and chlorpheniramine maleate in a new tablet formulation Chromatographic separation of the three pharmaceuticals was achieved on a Hypersil CN column (150×5.0 mm, 5 μm) using a mobile phase comprising a mixture of acetonitrile, an ion-pair solution and tetrahydrofuran (13:14:87, v/v,pH4.5). The flow-rate was changed from 1.0 mL min−1 (in 0≈7.5 min) to 1.8 mL min−1 (after 3.5 min). was complete in <10 min. The method was validated for system suitability, linearity, accuracy, precision, limits of detection and quantitation, and robustness. Linearity, accuracy and precision were found to be acceptable over the ranges 31.6≈315.8 μg mL−1 for acetaminophen, 9.5≈94.6 μg mL−1 for caffeine and 1.4≈13.8 μg mL−1 for chlorpheniramine maleate.

Capillary zone electrophoretic separation of proteins using a column coated with epoxy polymer

Abstract Fused-silica capillaries used in capillary zone electrophoresis were covalently coated with epoxy polymer and then cross-linked with ethylenediamine to form a stable layer. This coating was of sufficient thickness and hydrophilicity to reduce both protein adsorption and electroosmotic flow. The electroosmotic flow-rate showed about a twofold decrease but was still sufficient to carry both positive and negative species to the detector. As a consequence, high separation efficiencies were obtained in the pH range 2–10. The coatings were stable after more than 350 injections in 2 months. Further, reproducible separations were achieved from run to run and day to day.

Epoxy resin coatings for capillary zone electrophoretic separation of basic proteins

Abstract Epoxy resins, combining with a cross-linker, were coated on organosilanes modified fused-silica capillaries. After cross-linking, a tough three-dimensional network was attached to capillary surface via SiOSiC bonds. The most effective coating consisted of epoxy resins cross-linked with diaminodiphenylmethane, which was stable over the pH range 2–12 and suppressed protein adsorption effectively. The electroosmotic flow was also greatly reduced and maintained constant over the pH range 6–10. High resolutions and separation efficiencies for basic proteins were obtained in the pH range 3–10 and reproducible separations were achievedafrom run to run and day and day.

Resorcarene derivative used as a new stationary phase for capillary gas chromatography

Abstract Resorcarene derivative, 2,8,14,20-tetraphenyl-4,6,10,12,16,18,22,24-octapentyloxy-pentacyclo-[19.3.1. 3.7 .1 9.13 .1 5.19 ] octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecene (phenyl-pentyloxy-resorcarene) was synthesized and used as a new stationary phase for capillary gas chromatography. The results showed that it had high column efficiency, medium polarity and excellent selectivity, especially for the separation of substituted benzenes. In the separation, strong retention ability for naphthalene and its analogs was observed. The thermal stability of this new stationary phase was also tested.

Synergistic effect of resorcarene and cyclodextrin mixed stationary phase in gas chromatography

SummaryA new resorcarene derivatives, ethylhexylresorcarene, was synthesized and used as stationary phase in opentubular (capillary) columns. It was combined with heptakis(2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD and coated on fused-silica capillary tubes. By studying the chromatographic properties of the mixed stationary phase and its selectivity for different isomers, as well as comparing with the resorcarene and the CD used as individual stationary phases, a synergistic effect was observed on the mixed stationary phase.

Cyclodextrins With Heterocyclic Substitution as GC Stationary Phases

SummaryTwo new cyclodextrin (CD) derivatives, heptakis{2,6-di-O-pentyl-3-O-[3′-(2″-chloro-4″,5″-dioxylmethene)-phenyl-5′-iso-oxazolylmethyl]}-β-CD (CD I) and heptakis{2,6-di-O-methyl-3-O-[3′-(2″-chloro)-phenyl-5′-iso-oxazolylmethyl]}-β-CD (CD II) were synthesized and coated on fused-silica capillary columns. Their chromatographic characteristics, including column efficiency, polarity, selectivity and phase transition were studied and compared with similar β-CD stationary phases. It was found that the heterocycle group has a significant effect on the selectivity of the CD stationary phases. Both stationary phases can be successfully used to separate many di- and trisubstituted benzene positional isomers and show stronger separation ability in separating low-polarity benzene positional isomers than other β-CD stationary phases.

Separation of chiral isomers of p-nitrophenyl-2-amino-3-hydroxypropanone by capillary zone electrophoresis using cyclodextrins as chiral selector

Chiral isomers of p-nitrophenyl-2-amino-3-hydroxypropanone (NPAP) were separated by capillary zone electrophoresis in a background electrolyte containing β-cyclodextrin as stereospecific selector. In order to improve the resolution, three soluble cellulose derivatives as modifiers of the background electrolyte were studied. The operating conditions of capillary zone electrophoresis, such as concentrations of β-cyclodextrin and Tris, pH of buffer solution and applied voltage, were investigated. Under the optimized condition the NPAP optical isomers could be successfully separated.

Simultaneous determination of acetaminophen, dextromethorphen hydrobromide and pseudoephedrine hydrochloride in a new drug formulation for cold treatment by HPLC

SummaryA rapid and accurate HPLC method is described for the simultaneous determination of acetaminophen, dextromethorphen hydrobromide and pseudoephedrine hydrochloride in a new cold formulation. Chromatographic separation of the three pharmaceuticals was performed on a Hypersil CN column (150×5.0 mm, 5 μm) with a mobile phase mixture of an ion-pairing solution, methanol and acetonitrile (25:57:18, v/v), at a flow rate of 1.0 mL min−1, with detection at 220 nm. Separation was complete in less than 10 min. The method was validated for linearity, accuracy, precision, limit of quantitation and robustness. Linearity, accuracy, and precision were found to be acceptable over the ranges of 2.06∼20.6 μg·mL−1 for acetaminophen, 0.202∼2.02 mg·mL−1 for pseudoephedrine hydrochloride and 0.042∼1.06 mg·mL−1 for dextromethorphen hydrobromide.

A new gas chromatographic stationary phase: Polysiloxane with β-cyclodextrin side chain for the separation of chiral and positional isomers

SummaryA new stationary phase [bikis(2,6-di-O-pentyl-3-O-hex-6-enyl)-pentakis(2,6-di-O-pentyl-3-O-methyl)-β-CD-polysiloxane] was synthesized and successfully applied in GC for the separation of chiral and achiral isomers. It possesses high column efficiency and exhibits excellent separation ability for disubstituted benzenes. Some typical enantiomers and optical isomers are well separated. The separation behavior of this new phase is characterized and discussed.

Investigation into the separation of achiral and chiral molecules on fused-silica capillary columns coated with three peralkylated cyclodextrins

SummaryThree peralkylated β-cyclodextrins (CD), perethylated β-CD, perbutylated β-CD and peroctylated β-CD have been coated on to untreated fused-silica capillary tubing and used to separate some achiral and chiral compounds. The separation mechanism is discussed in the paper.