|SOFT - TIAFT 1998||Poster Session 4||Friday October 9, 1998|
METHODS FOR THE QUANTIFICATION OF PARATHION IN TISSUES A COMPARISON BETWEEN TWO CLEAN-UP PROCEDURES|
Estela G. Pinho Marques, Angelines Cruz Landeira*, D.N.Vieira, Maria Margarida F. Oliveira, Paula C. V. Monsanto, Alice M. Castanheira, and Paula Proença
Laboratory of Forensic Toxicology of the Institute of Legal Medicine of Coimbra, University of Coimbra, 3000 Coimbra, Portugal
|Acute intoxications by organophosphate pesticides are frequent in Portugal. Parathion (C10H14NO5PS) is the product responsible for the greatest number of lethal cases studied (> 50%) in the Laboratory of Toxicology of the Institute of Legal Medicine of Coimbra. Blood is the sample most used in toxicological analysis, because it shows a better correlation with the symptomatology and also it is one of the simplest matrices, with the exception of urine. However, in some fatal cases it is not possible to collect blood samples and urine is seldom present. Thus, the toxicological tests in such cases must be undertaken on organs of the cadaver.
The authors describe two methods of parathion determination in liver, kidney and heart from analyte-free tissues and compared their accuracy and precision. All tissue samples were fortified to parathion concentrations of 0.01, 0.1, 1.0 and 10.0 mg/g. The extraction was carried out by hexane. In one of the methods (Method A), the clean-up was performed by solvent partitioning and by column chromatography with florisil. In the other (Method B), the clean-up was carried out by thin-layer chromatography. Gas chromatography was used in the identi-fication and quantification of parathion in both methods.
In method A a higher recovery rate (70.2 % to 79.0%) than in method B was generally obtained. However, in the latter one the lowest concentration presented better results in all the tissues, specially in the liver (80.4%). In the remaining concentration levels the recoveries vary from 68.7% to 78.1%. The coefficients of variation were 8.2% and 8.7% with ranges of 4.3% to 11.1% and 4.5% to 10.0% for methods A and B, respectively.
Although, in general, method A presents better results, method B, being simpler, is the one used in undertaking routine analyses for parathion determination, except in cases where the samples have a great deal of fat, since the insecticide may not be well differentiated from the fat in these cases.