Determination of biogenic amines by capillary electrophoresis.

A method for determining biogenic amines in food using micellar electrokinetic capillary chromatography has been developed. Derivatization of the amines was performed with AccQ (6-aminoquinolyl-N-hydroxysuccinimidyl carbamate; Waters, Milford, MA, USA) reagent. The influence of buffer composition on the separation (including pH, SDS concentration and various additives) was investigated. The separation of seven biogenic amines (histamine, tyramine, tryptamine, spermine, spermidine, cadaverine and putrescine) could be achieved within 25-30 min with good repeatability. The biogenic amine profiles in three different food samples (wine, salami and chive) were determined and quantitated.

Characterization of a basement membrane protein (BM180) using capillary electrophoresis.

Coeliac disease (gluten intolerance) is a genetically based autoimmune disease that becomes evident following ingestion of cereal prolamins such as the wheat gliadins. The process of this disease is not yet thoroughly understood. Purification of basement membrane protein-180 (BM180) (a basement membrane protein with a potential autoantigen role) and multiple analysis of the purified protein can lead to a better understanding of this disorder, which affects millions of people worldwide. Our preliminary work on the purification and characterization of this protein is presented in this paper. BM180 proteins were expressed in mouse EHS (Engelberth-Holm-Swarm) tumor cells. A crude purification process (see "Methods") was performed and the purified fractions were analyzed by capillary gel electrophoresis (CGE) for determination of the apparent molecular weight of the protein components in each fraction. The fractions, which contained compounds of the expected molecular weight, were further analyzed using a capillary zone electrophoresis (CZE) method developed for the routine analysis of wheat gliadins. Using the two CE methods, we were able to compare BM180 with certain gliadin fractions. Additional information on the protein stability was also obtained.

Effect of the degree of substitution of cyclodextrin derivatives on chiral separations by high-performance liquid chromatography and capillary electrophoresis.

Optical isomers of some basic racemic drugs (oxprenolol, AMEBD, ephedrine) were separated by high-performance liquid chromatography (HPLC) and/or capillary electrophoresis (CE) using carboxymethyl-beta-cyclodextrin (CMBCD) with various degree of substitution (DS). The effects of the separation conditions (pH, concentration and DS of CMBCD) were studied and compared using CE and HPLC. The degree of substitution had a significant effect on the resolution of the optical isomers and the ionic strength of the separation media, hence the use of well characterized CD derivatives is crucial. Different optimum DS values for the same test samples were obtained when HPLC or CE was used.

High-performance capillary electrophoresis of SDS-protein complexes using UV-transparent polymer networks.

This paper demonstrates the use of UV-transparent replaceable polymer networks for the separation of SDS-protein complexes on the basis of molecular weight. First, the use of linear (i.e. non-cross-linked) polyacrylamide is shown to provide molecular separation of SDS-protein complexes. A study reveals such columns to yield significantly greater lifetime than cross-linked gels because of the flexibility of the noncovalently attached polymer chains. However, column lifetime was still found to be limited (approximately 20-40 injections), and detection at 214 nm was problematical because of the absorbance of polyacrylamide. UV-transparent polymer networks of dextran and PEG were substituted for polyacrylamide with successful molecular weight sieving of SDS-protein complexes at 214 nm. Due to their low to moderate viscosities, these networks could be routinely replaced leading to the possibility of hundreds of injections with a single column. Migration time reproducibilities of 0.5% RSD or less were found with replacement of the network. Using dextran, calibration plots of peak area vs concentration of standard protein were linear over the range of 0.5 microgram/mL up to at least 0.25 mg/mL. Furthermore, plasma samples could be directly utilized because of the strong solvating power of SDS. Rapid separation of protein mixtures are demonstrated with these UV-transparent polymer networks.

Metabolism of anti-herpes agent 5-(2-chloroethyl)-2'-deoxyuridine in mice and rats.

The enzymatic splitting and metabolic elimination of anti-viral agent 5-(2-chloroethyl)-2'-deoxyuridine [CEDU] have been studied. For elucidation of structures of metabolites, several different kinds of extraction, purification and spectroscopic methods were used (Extrelut LC, TLC, HPLC, MS, NMR, IR, UV and CD). For mass spectral analysis, various ionization techniques (EI, CI and FAB-MS) were performed as complementary methods. After oral administration of [14C]-CEDU to mice and rats, the parent compound, 5-(2chloroethyl) uracil [CEU] and hydroxylated CEU metabolites were isolated and identified from urine and faeces by the above mentioned methods. The CEDU showed rapid phosphorolysis in vitro with thymidine phosphorylase Km 41.0 +/- 5.0; and uridine phosphorylase Km 10.0 +/- 1.5. The cleavage of the N-glycosidic bond of the nucleoside analogue and a new metabolic pathway of CEDU [stereoselective oxidation of 5-(2-chloroethyl) uracil] was observed in both species.

Effective sample preparation method for extracting biologically active compounds from different matrices by a microwave technique.

A method is described for extracting lupin alkaloid (sparteine) and drug metabolites from different matrices (seeds and rat faeces) using microwave energy and for checking the homogeneity of the electric field in the microwave oven. The high-performance liquid chromatographic separation and determination of the extracted compounds showed that the microwave extraction method is more advantageous than other traditional extraction methods with regard to the yield of extraction and the time and cost of the procedure. The potential degradation of the extracted compounds may be considerably reduced.

Microwave extraction. A novel sample preparation method for chromatography.

The applicability of microwave irradiation to the extraction of various types of compounds from soil, seeds, foods and feeds as a novel sample preparation method for chromatography was investigated. Samples were ground and mixed with an appropriate solvent, methanol or methanol-water for polar compounds and hexane for non-polar compounds. The suspensions were irradiated for 30 s, but they were not allowed to boil. After cooling, the irradiation was repeated several times. The samples were then centrifuged, and aliquots of the supernatant were injected into a chromatographic column. The yields of the extracted compounds obtained by microwave irradiation were compared with those obtained by the traditional Soxhlet or shake-flask extraction methods. The microwave extraction method was more effective than the conventional methods. Due to the considerable savings in time and energy, this novel method is suitable for fast extractions of large sample series.