A modification of the soxhlet apparatus for drug extraction from biological fluids.

The authors suggest a method to isolate drugs and toxic substances from biological fluids which appears to be of easier and better applicability than other systems, because it allows the extraction by means of a hot solvent, reduces manual operations and the waste of solvent, and shortens the time of execution for the researchers. A mathematical formula is proposed in order to evaluate the recovery-time curves of any drug shortly and with better accuracy.

High-performance liquid chromatography for the quantitative determination of the urinary metabolites of toluene, xylene, and styrene.

A new high-pressure liquid chromatography (HPLC) method for simultaneous quantitative determination of the urinary metabolites of toluene, m-xylene, and styrene (hippuric acid, m-methylhippuric acid, phenylglyoxylic acid, mandelic acid) is described. The extraction procedure was performed on acidified urines, after addition of 4-hydroxybenzoic acid as internal standard, using a butylchloride/isopropanol mixture and drying 0.5 ml of the organic layer under nitrogen flow. The residue obtained was dissolved in 0.1 ml water/acetonitrile and 5 microliters were injected into an HPLC apparatus equipped with a 0.26 X 25 cm HC ODS SIL X column. Absorbance measures were performed at 225 nm throughout the investigation. All metabolites were clearly separated in a short time (12 min) and the amounts of other urinary compounds affecting the analysis were so small that the measurement of low concentrations of the urinary metabolites could be easily performed. Linear calibration curves were obtained from 0.1 to 3 mg/ml and a correlation coefficient greater than 0.99 was found between concentrations of the standards and areas of the peaks. Statistical analysis confirms that this method, which has a high reproducibility, is simple, reliable, and useful for the biologic monitoring of industrial exposure to aromatic compounds.

Distribution and fate of alpha-naphthl-isothiocyanate (ANIT) in the organs and body fluids of the rat.

alpha-Naphthyl-isothiocyanate (ANIT) is a well known toxic substance which induces characteristic hepatic lesions. Its distribution in some organs and body fluids was investigated by using spectrophotometry, gas-chromatography and thin-layer chromatography. The results indicate that ANIT concentrates in the liver, kidneys and blood but not in the brain, urine and bile. Another five ANIT-like substances have also been examined, but no trace of them has been found in these organs and body fluids. The authors suppose that ANIT is metabolized to an unknown metabolite which is responsible for the toxic action of ANIT. None of the ANIT-like substances examined by us can be indentified with this metabolite.