Ion formation of N-Methyl carbamate pesticides in thermospray mass spectrometry: The effects of additives to the liquid chromatographic eluent and of the vaporizer temperature.

The effects of three additives-ammonium acetate, ammonium formate, and nicotinic acid-to the liquid chromatographic (LC) eluent and of the vaporizer temperature on the ion formation of N-methyl carbamate pesticides in thermospray (TSP) mass spectrometry was investigated by using filament- or discharge-assisted ionization. Nineteen carbamates and 12 of their known environmental degradation products were used as model compounds. The additives cause a strong reduction in the abundance of the characteristic fragment ions [M + H - CH3NCO](+) and [M - H - CH3NCO](-) for some of the carbamates.

On-line post-column Diels-Alder derivatization for the determination of vitamin D3 and its metabolites by liquid chromatography/thermospray mass spectrometry.

Liquid chromatography/thermospray mass spectrometry (LC/TSP MS) has been used for the determination of vitamin D3 and some of its metabolites, i.e. 1 alpha(OH) vitamin D3, 25(OH) vitamin D3, 1 alpha,25(OH)2 vitamin D3 and 24,25(OH)2 vitamin D3, using positive and negative ion detection.

On-line diode array UV-visible spectrometry in screening for drugs and drug metabolites by high-performance liquid chromatography.

The direct coupling of a multi-channel diode array UV-visible spectrophotometer to a powerful reversed-phase HPLC separation system is considered, especially for use in qualitative analysis, e.g., screening/identification of drugs and drug metabolites.