摘要:

A MEKC method has been developed for the simultaneous determination of guaifenesin (GF), pseudoephedrine (PE), and dextromethorphan (DM) in capsule dosage form using 50 mM sodium dodecyl sulfate (SDS) added to a pH 8.5 100mM Tris run buffer at a voltage of 25 kV. The method utilized UV detection at 220nm and a 72 cm × 50 μm i.d. uncoated fused-silica capillary. The detection limits for GF, PE and DM were 1000, 500, and 500 ng/mL, respectively for a 5 s injection. The calibration curves were linear over ranges of 100–1000 μg/mL, 15–150 μg/mL and 5–50 μg/mL for guaifenesin, pseudoephedrine and dextro-methorphan, respectively, with sodium benzoate (SB) as internal standard. Coefficients of determination were greater than 0.9989 (n = 12). Precision and accuracy of the method were 0.60–2.18% and 0.44–4.20%, respectively for GF, 1.62–3.15% and 0.33–2.98%, respectively for PE, and 0.19–4.36% and 1.77–6.92%, respectively for DM. In comparison to high-performance liquid chromatography, the MEKC method is simple, capillary columns are low-cost, and there is high-resolution efficiency with a minimal consumption of environmentally friendly chemicals.

ISSN:1082-6076    

DOI:10.1081/JLC-100101431

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Integration of 1-nL sampling vials with a capillary sample introduction ultrathin slab gel electrophoresis system is described here. The low-volume sampling capabilities of capillary electrophoresis (CE) along with the small structural size make it an ideal sampling technique for these vials. A DNA restriction enzyme digest has been sampled and separated from these vials. A comparison of the nanovial DNA separation and a separation from a larger vial are virtually identical.

ISSN:1082-6076    

DOI:10.1081/JLC-100101432

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Classical (haloperidol and chlorpromazine) and atypical neuroleptics (olanzapine, clozapine, loxapine, and risperidone) were quantified in pharmaceutical formulations (tablets, capsules, and oral solutions) by capillary zone electrophoresis. The simple sample pretreatment consists of a one-step extraction, filtration, and dilution. The electrophoretic conditions were as follows: uncoated fused-silica capillary (28.3 cm total length, 22.0 cm effective length, 50 μm I.D.), phosphate buffer (pH 2.5, ionic strength 35 mmol/L). The separation voltage (15 kV) results in a current lower than 50 μA. UV detection was performed at 214 nm. Calibration curves were linear in the 5–50 μg/mL range for all tested drugs (rbetter than 0.999). The repeatability (or intra-day precision), expressed by the relative standard deviation, was better than 2% (6 measurements). The accuracy, resulting from recovery studies, was between 98 and 105 %. The amount of drug found agreed with the declared contents within the limits specified by U.S.P. (1995).

ISSN:1082-6076    

DOI:10.1081/JLC-100101433

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Three different glycosidic surfactants, namely cyclohexyl-butyl-β-D-maltoside (CYMAL-4), cyclohexyl-pentyl-β-D-maltoside (CYMAL-5), and cyclohexyl-hexyl-β-D-maltoside (CYMAL-6), were compared in the enantioseparation of some dansyl amino acids and methylated tryptophans. The three CYMAL surfactants have the same chiral maltoside head group but differ in the length of the hydrophobic tail. Increasing the length of the hydrophobic tail seems to shift the optimum surfactant concentration for maximum enantioresolution towards lower concentration values. In order to extend the range of optimum surfactant concentration over which maximum enantioresolution can be achieved, mixed CYMAL surfactant systems were introduced and evaluated. They consisted of mixing CYMAL-6 with either cyclohexyl-methyl-β-D-maltoside (CYMAL-1) or cyclohexyl-ethyl-β-D-maltoside (CYMAL-2).

ISSN:1082-6076    

DOI:10.1081/JLC-100101434

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We describe the use of a micro system for dielectrophoretic field flow fractionation (DFFF) of particles and cells. Micro-objects are separated on the basis of differences in size and/or passive dielectric properties, respectively. Bow-like strip electrode pairs have been proven to be the most effective separation systems.

ISSN:1082-6076    

DOI:10.1081/JLC-100101435

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Protein adsorption onto the inner walls of capillaries is a widely recognized problem in the separation of proteins by capillary electrophoresis. Chemical modification of the wall has been an effective method for suppressing this effect. The performance of an epoxy based hydrophilic coating has been evaluated under different experimental conditions. High efficiency separation of proteins (up to 200,000 theoretical plates per meter) was achieved using this coating. The recoveries of both cationic and anionic proteins were very high (over 90% for several positively charged proteins) on this capillary coating. The influence of both pH and potential on efficiency, resolution and peak capacity were examined.

ISSN:1082-6076    

DOI:10.1081/JLC-100101436

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

As an analytical tool, CE offers several advantages in the clinical laboratories. In addition to high resolution of the CE, the ease of modifying the selectivity by simple additives to the buffer allows complex mixtures of analytes in biological samples to be resolved easily. The driving forces for the widespread use of CE at the present time are simplicty, speed, high resolution, and low operating costs. Four general application areas were identified which are expected to have a great impact on the routine clinical analysis by CE. These areas are proteins (serum, CSF, urine), ions, drug screening, and DNA analysis. The analysis of these compounds is rapidly expanding and it is mature enough for bringing them into the routine work. The DNA applications for sequencing and PCR analysis have progressed to the extent that few specialized instruments dedicated to these analyses are on the market. Proteases as well as other enzymes can be analyzed conveniently by CE. The CE can offer also basic physical and structural information for the peptides and proteins such as charge (pI), size, and isoforms. The application of capillary electrophoresis in clinical analysis is expected to become more widespread in the near future with the introduction of more commercial instruments designed for specific applications.

ISSN:1082-6076    

DOI:10.1081/JLC-100101437

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Fused silica capillaries with an i.d. of 50 and 75 μm are chemically modified by the silanization/hydrosilation method to attach organic moieties for use in electrokinetic chromatography. An etching process was utilized to increase the surface area of the capillary inner wall. A comparison of Si-C bonded capillary columns to those obtained by conventional organosilanization (Si-O-Si-C) bond was performed. The etched capillaries after chemical modification are shown to have an anodic electroosmotic flow (EOF) below pH 4.5 while the bare modified capillaries show a cathodic EOF at all pH's studied.

ISSN:1082-6076    

DOI:10.1081/JLC-100101438

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The interactions of bilirubin, biliverdin, xanthobilirubin, biliverdin dimethyl ester, and xanthobilirubin methyl ester with unconjugated and glyco-conjugated bile salt solutions were investigated by micellar electrokinetic chromatography (MEKC). The capacity factors were measured in solutions of the different bile salts over the pH range of 6.5 to 8.5. The bile salts investigated were deoxycholic, chenodeoxycholic, glycocholic, glycodeoxycholic, and glycochenodeoxycholic acid. These results were compared to previous results in cholic, taurocholic, taurodeoxycholic, and taurochenodeoxycholic acids. Typically, the nature of the bile salt, trihydroxy versus dihydroxy, has a greater effect on the resulting capacity factors than does the nature of the conjugation. The influence on capacity factor of such features as molecular size, shape, and charge are revealed with this group of analytes.

ISSN:1082-6076    

DOI:10.1081/JLC-100101439

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Separations of five synthetic heptadecapeptides from the p-loop region of p21 Ras proteins, differing mostly in a single amino acid at the same position, were investigated. The studies were performed at low pHs in polyacryamide-coated capillaries, where the peptides were slightly positively charged. CZE, without surfactants, failed to separate all the peptides. Separations by MEKC employing an anionic surfactant sodium dodecyl sulfate (SDS), a neutral surfactant Tween 20 and a cationic surfactant cetyltrimethylammonium bromide (CTAB) provided results with varying degrees of success. Tween 20, slightly improved the separation while CTAB resulted in almost baseline separation of all the peptides.

ISSN:1082-6076    

DOI:10.1081/JLC-100101440

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor