Simple and sensitive method for determination of metronidazole in human serum by high-performance liquid chromatography.

A simple and sensitive HPLC method for determination of metronidazole in human plasma has been developed. A step of freezing the protein precipitate allowed an efficient separation of aqueous and organic phases minimizing the noise level and improved therefore the limit of quantitation (10 ng ml(-1) using 1 ml of plasma sample). The separation of compounds was performed on a RP 18 column with acetonitrile-aqueous 0.

Comparative study of the biotransformation of bepridil analogs in isolated liver cells from one rat. Relationships between structure and in vitro liver toxicity.

The biotransformation of several analogs of the anti-calcium agent bepridil was studied comparatively in liver cells isolated from one rat. Three types of metabolites were identified by mass spectrometry, resulting from three phase I reactions: hydroxylation, N-debenzylation and pyrrolidine ring opening. The amount of each bepridil analog untransformed after 18 h of incubation depended on its liver toxicity rather than on its concentration in the culture medium.

Gas chromatographic-mass spectrometric determination of isosorbide 5-mononitrate in human plasma.

A highly specific and precise method using gas chromatography-mass spectrometry was developed for the measurement of isosorbide 5-mononitrate in plasma using isomannide mononitrate as internal standard. With regard to the numerous analytical problems encountered when organic mononitrates were determined in plasma, such as thermal instability and adsorption, compounds were silylated before gas chromatography. In order to increase the specificity of the assay, two specific ions of the isosorbide 5-monitrate were simultaneously recorded.

Determination of oxeladin in human plasma by gas chromatography--mass spectrometry.

A capillary gas chromatographic method with mass-selective detection was developed for the determination of oxeladin in human plasma. Plasma samples (1 mL) were alkalinized and extracted using 5mL of hexane: isoamyl alcohol (99:1). The method was demonstrated to be sensitive (limit of quantitation at 1 ng/mL), linear between 1 and 150 mg/mL, accurate and precise enough (mean error and mean coefficient of variation at the limit of quantitation were 2.

Determination of phloroglucinol in human plasma by gas chromatography-mass spectrometry.

A specific and sensitive method has been developed for the determination of phloroglucinol in plasma; it involves an optimized procedure for blood sampling designed to minimize the in vitro oxidation of the molecule, and gas chromatography-mass spectrometry after silylation of the compound. The method allowed a reliable determination of phloroglucinol in plasma. The precision and accuracy of the assay, reported as coefficients of variation, were below 15%.