SOFT/TIAFT 98 - Improved Solid Phase Extraction Method for Systematic Analysis...

SOFT - TIAFT 1998

Poster Session 4

Friday October 9, 1998

IMPROVED SOLID PHASE EXTRACTION METHOD FOR SYSTEMATIC ANALYSIS IN BIOLOGICAL FLUIDS

Teresa Soriano, Carmen Jurado, Manuel Menéndez, Manuel Repetto

Instituto Nacional de Toxicología, P.O. Box 863, 41080 Sevilla, Spain

A method for the simultaneous qualitative and quantitative determination of drugs of abuse (opiates, cocaine or amphetamines), as well as prescribed drugs (tricyclic antidepressants, phenotiazines, benzodiazepines, etc.) in biological fluids (including blood and urine) was developed. Other matrices, such as bile and gastric content, can also be analyzed by this procedure. It involves solid-phase extraction with Bon-Elut Certify columns followed by GC/NPD and/or HPLC/UV analyses and confirmation by GC/MS, after derivatization -- if necessary.

A pretreatment was performed in all samples: sonication for 15 min. in blood and enzymatic hydrolysis with b-glucuronidase in urine. With respect to the internal standards: nalorphine and trihexylamine were used for basic substances and allobarbital for acidic drugs and prazepam for benzodiazepines. Acidic and basic compounds were extracted from different aliquots of samples at different pH: 5-7 for the acidic and neutral ones and 8-9 for the basic ones and the benzodiazepines.

In order to obtain a better recovery in extraction, some modifications have been performed, such as:

Benzodiazepines, because of their particular behavior, are separated in the washing fraction previous to the elution of basic substances.
Blood and urine were sonicated before and after pH adjustment and the addition of internal standard in order to improve the homogenization.
Acetonitrile was used to wash the column before eluting the basic compounds to obtain cleaner extracts and a higher recovery of benzoylecgonine.

In the previously described conditions, the recovery for 40 compounds tested was always higher than 71%.

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