A new and simple procedure for the determination
of parathion in human whole blood and urine using
direct immersion (DI) solid-phase microextraction (SPME)
and gas chromatography/mass spectrometry (GC/MS) is
presented. This technique was developed using only
100 ìL of sample, and ethion was used as internal standard
(IS). A 65-ìm Carbowax/divinylbenzene (CW/DVB)
SPME fibre was selected for sampling, and the main
parameters affecting the SPME process such as extraction
temperature, adsorption and desorption time, salt addition,
agitation and pH effect were optimized to enhance the
sensitivity of the method. This optimization was also
performed to allow the qualitative determination of parathion’s
main metabolite, paraoxon, in blood. The limits
of detection and quantitation for parathion were 3 and
10 ng/mL for urine and 25 and 50 ng/mL for blood,
respectively. For paraoxon, the limit of detection was
50 ng/mL in blood. The method showed linearity between
the LOQ and 50 ìg/mL for both matrices, with correlation
coefficients ranging from 0.9954 to 0.9999. Precision and
accuracy were in conformity with the criteria normally
accepted in bioanalytical method validation. The mean
absolute recoveries were 35.1% for urine and 6.7% for
blood. Other parameters such as dilution of sample and
stability were also validated. Its simplicity and the fact that
only 100 ìL of sample is required to accomplish the analysis make this method useful in forensic toxicology laboratories
to determine this compound in intoxications, and it can be
considered an alternative to other methods normally used for
the determination of this compound in biological media