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A simple and sensitive gas chromatographic method has been developed for the determination of timolol in plasma using electron-capture detection and propranolol as internal standard. Timolol was extracted using butyl chloride and derivatized using trifluoroacetic anhydride in butyl acetate. The lower detection limit for the assay was found to be 1 ng/ml from 1 ml of plasma. Extracted standards gave within-day precision of 12.55, 9.68 and 3.78% for 1, 20 and 100 ng/ml plasma samples, respectively. A recovery of at least 80% of timolol was found using the extraction method described. The assay was used in a randomized cross-over bioequivalence trial using an oral administration of 20 mg of timolol. Pharmacokinetic parameters compare favourably with other literature values.

The N-acetylated metabolites of p-tyramine, p-octopamine and dopamine were identified unambiguously and quantitatively determined in a single ventral thoracic nerve cord of the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry (GC-NICIMS). Deuterium-labelled analogues of each compound were added to a single ventral thoracic nerve cord in acetonitrile: the tissue was homogenised and the suspension centrifuged. The solvent was removed from the supernatant and the resultant residue was derivatised with trifluoroacetic anhydride. Under negative-ion chemical ionisation conditions, the trifluoroacetyl derivatives produced ions which were sufficiently abundant to be suitable for selected-ion monitoring. This method is highly specific and gave a limit of detection below the picogram levels. N-Acetyl-5-hydroxytryptamine was determined using a previously published GC-NICIMS technique [S.P. Markey, R.W. Colburn and J.N. Johannessen, Biomed. Mass Spectrom., 7 (1981) 301]. The concentrations of N-acetyltyramine, N-acetyloctopamine, N-acetyldopamine and N-acetyl-5-hydroxytryptamine in locust thoracic nerve cords were, respectively, 1.86 +/- 0.71, 1.13 +/- 0.34, 6.77 +/- 8.48 and 0.07 +/- 0.02 ng per tissue.

A method based on whole-cell methanolysis and trifluoroacetic acid anhydride derivatization was developed for routine laboratory differentiation between isolates from the Actinobacillus--Haemophilus--Pasteurella group. All species, except Haemophilus aphrophilus, contained D-glycero-D-mannoheptose, although in varying concentrations. The distribution of this sugar could be used to distinguish H. aphrophilus from Actinobacillus actinomycetemcomitans, H. paraphrophilus, H. influenzae type b, Pasteurella haemolytica, P. multocida and P. ureae, and also H. influenzae type b from Pasteurellae. The pattern of major sugars in P. ureae and P. haemolytica resembled that of A. actinomycetemcomitans. Major fatty acids of the whole-cell methanolysates provided no basis of interspecies differentiation.

A sensitive gas chromatographic method for the quantitative analysis of atenolol in human plasma and urine is described. Atenolol is extracted with dichloromethane containing heptafluorobutanol to improve the extraction ability. Derivatization with trifluoroacetic anhydride in diethyl ether gives a bistrifluoroacetyl derivative which is more selectively detected by an electron-capture detector than is the corresponding heptafluorobutyryl derivative. The method allows determination down to 20 nmol/l (5 ng/ml) in 1 ml of sample with a relative standard deviation below 10%.

Chromatographic conditions for the determination of protein and non-protein amino acids as their N(O,S)-trifluoroacetyl n-propyl esters are given which allow the separation of about 30 amino acids within 19 min using nitrogen or within 17 min using helium as the carrier gas. Retention times and responses are given for 42 amino acids or related compounds. Only few of them elute together when using a 2 m x 2 mm I.D. glass column filled with 0.65% ethylene glycol adipate on Chromosorb W AW (80-100 mesh). The acylation of the n-propyl esters was investigated with respect to optimal reaction conditions and was found to be best performed at 150 degrees C for 5 min.

Gas chromatography with electron-capture detection was used to quantify the glucuronic acid conjugate of trichloroethanol, urochloralic acid. The conjugate was extracted into ethyl acetate--ethanol (19:1, v/v) under acidic conditions, and analyzed as its trifluoroacetylated methyl ester or as its acetylated methyl ester. As little as 0.2 microgram of the conjugate was quantified, and the method was applicable to urine, plasma and liver. The synthesis of urochloralic acid from trichloroethanol by rat liver microsomal fraction was demonstrated in the presence of uridine diphosphoglucuronic acid as coenzyme.