Identification and quantification of dehydroepiandrosterone sulphate in saliva.

3 beta-Hydroxy-5-androsten-17-one (dehydroepiandrosterone) sulphate has been separated from an extract of human saliva by ion exchange gel chromatography and identified by high resolution gas chromatography-high resolution mass spectrometry of the tert-butyldimethylsilyl derivative of the neutral steroid obtained by enzymic hydrolysis. Quantitative analyses, employing 7,7-2H-dehydroepiandrosterone sulphate as the internal standard, have indicated concentrations in the saliva of young adult subjects to be generally in the range 0.9-5.7 nmol/l, though concentrations as high as 10.7 nmol/l have been observed.

Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring.

Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. [2H3]Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r = 0.997; y = 1.008x + 0.564 nmol/L).

Analyses of steroids in saliva using highly selective mass spectrometric techniques.

Highly selective techniques of gas chromatography mass spectrometry have been used in the unequivocal identification of salivary steroids at concentrations ranging from 20 pg ml-1 to 20 ng ml-1. Oestradiol-17 beta, for example, has been identified in pregnancy saliva by gas chromatography high resolution mass spectrometry selected ion monitoring of the bis-TMS ether and by gas chromatography mass spectrometry metastable peak monitoring of the bis-tert-butyldimethylsilyl ether. Dehydroepiandrosterone sulphate has been identified in saliva, following enzymic hydrolysis, by gas chromatography high resolution mass spectrometry selected ion monitoring of the tert-butyldimethylsilyl ether and methyloxime tert-butyldimethylsilyl ether. These initial analyses have been designed to guide the development of routine immunoassay procedures which may subsequently be validated by comparison with reference gas chromatographic mass spectrometric methods.

Screening, confirmation, and quantification of sulphonamide residues in pig kidney by tandem mass spectrometry of crude extracts.

Collisionally activated dissociation mass spectra, observed with a hybrid tandem instrument, of the chemical ionization protonated molecular ions of sulphonamide drugs have been used as the basis of a rapid screening procedure for these drugs in crude extracts of pig's kidney by scanning to detect the parents of a characteristic daughter fragment. Extracts were introduced without chromatography by a moving belt interface. Detection limits of 0.1 mg/kg were achieved. Confirmation was made by obtaining daughter ion spectra of the protonated molecular ions. Multiple reaction monitoring with a stable isotope analogue as internal standard permitted the quantification of targeted compounds with high sensitivity and precision.