A high resolution headspace gas chromatography/selected ion monitoring analytical method has been developed for the quantitation of methanol in body fluids. The addition of tetradeuterated methanol as internal standard gives this method high accuracy and reproducibility. The high sensitivity of the mass spectrometer permits analysis of methanol in aqueous solutions at concentrations down to 0.012 mg/l. The analytical procedure described was used to measure serum methanol in rats given 5 mg/kg of this alcohol orally. The method proved suitable for analysis of endogenous levels of methanol and of variations close to endogenous levels.
Dibenzo [c,f]-[1,2] diazepine is a new compound with a tricyclic structure and a double bond between two nitrogen atoms in positions 1 and 2 of the molecule. Its in vitro metabolism has been studied, incubating the compound with rat liver microsomes. Two metabolites have been identified: dibenzo [c,f] - [1,2]diazepine-1-N-oxide and a monohydroxyderivative in the aromatic ring.
An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer.The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The "on-line" internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run.
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