Surface chracteristics of treated glasses for the preparation of glass capillary columns in gas-liquid chromatography

Plasma lipoproteins and fatty acid composition after "minipill"

A study of the effect of a low-dose oral contraceptive, Adepal (ethinyl estradiol and levonorgestrel, 30 and 150 micrograms on the 5th to 12th, 40 and 200 micrograms on the 13th to 28th, respectively) on the blood lipids, lipoproteins and fatty acid composition has been conducted on 13 young women before and after six months of treatment. All together, total cholesterol concentration did not vary; however, the high cholesterol values decreased whereas the low cholesterol values increased with the pill. Triglyceride levels increased significantly (p less than 0.001). High density lipoprotein (HDL)-cholesterol decreased clearly (p less than 0.001) regardless of the cholesterol value at the beginning; low and very low density lipoprotein (LDL + VLDL)-cholesterol increased slightly, as well as the apoprotein B (Apo B) concentration (p less than 0.05). The lipoprotein electrophoresis showed intermediate bands (IDL) in 5/12 of the women after treatment. The three major classes of lipoprotein showed some variations in the fatty acid composition after the oral contraceptive; in any lipid class from any lipoprotein, the linoleic (18: 1 omega 6), arachidonic (20: 4 omega 6) and eicosapentaenoic (20: 5 omega 3) acids decreased whereas the palmitic (16: 0) and oleic (18: 1 omega 9) acids increased. Our results suggest that a low-dose contraceptive like Adepal produces, nevertheless, some significative modifications of plasma lipids and lipoproteins.

Quantitative determination of underivatized anti-convulsant drugs by high resolution gas chromatography with support-coated open tubular columns

A method is described to prepare routinely high resolution support-coated open tubular (SCOT) columns. A siliceous support material (Cab-O-Sil) is deactivated with benzyltriphenylphosphonium chloride and deposited on the inside wall of a glass capillary column. After additional coating with a polar stationary phase (OV-225) a number of anticonvulsant drugs can be analyzed without prior derivatization. The columns described show high plate numbers and do not deteriorate in use. The repeatability of the gas chromatographic analysis is better than 1.2% (Orel). The minimum detectable quantity is of the order of 10(-10) g. An improved procedure for isolating the drugs from serum is given, which results in an extraction recovery of better than 90% for the drugs of interest.

New method for the preparation of highly stable polysiloxane-coated glass open-tubular capillary columns and application to the analysis of hormonal steroids

A new approach to the preparation of methylsiloxane-coated glass open-tubular capillary columns is described. A siloxane polymeric mixture is first prepared by hydrolysis of dimethyldichlorosilane. The polymer is then coated on to the previously etched glass wall by a base-catalyzed reaction to yield a non-polar system of high stability and showing satisfactory chromatographic properties. This type of column has been used for the high-resolution separations of complex hormonal steroid mixtures. The flexibility of this method should permit the preparation of capillary systems with a wide range of polarity.

Organic micropollutants in air and water. Sampling, gas chromatographic-mass spectrometric analysis and computer identification

Organic micropollutants are sampled by dynamic enrichment on a porous polymer column and subsequently thermally eluted in a flow of helium. The eluted compounds enter gas chromatograph inlet and then pass into two parallel glass capillary columns with different stationary phases, in which they are separated. The separated compounds are detected by gas chromatographic (GC) detectors and by a mass spectrometer that is connected to one or other of the two capillary columns by "heart cutting" systems. The GC and mass spectrometric (MS) signals are fed via interfaces into a minicomputer which controls the MS scan and performs data acquisition, reduction and treatment on-line and off-line. The resulting GC and MS data are displayed on a line printer or a visual display unit. The minicomputer is connected by a telephone line to an IBM 370/165 computer, where a library search system has been implemented. Some difficulties encountered, data on the sampling recovery of model compounds and the identification of compounds in air and water samples by GC-MS data and library searches are discussed.

Study on the efficiency of support-coated open-tubular columns for steroid analysis

Glass support-coated open-tubular columns for the analysis of steroids in biological samples were prepared with varous support materials. The reproducibility of the procedure of preparing the column was investigated and some fundamental chromatographic properties were studied.