Isolation of drugs from blood by column chromatography on Amberlite XAD-2

Solid-phase extraction procedures in systematic toxicological analysis

In systematic toxicological analysis (STA) the substance(s) present is (are) not known at the start of the analysis. In such an undirected search the extraction procedure cannot be directed to a given substance but must be a general procedure where a compromise must be reached in that the substances of interest are isolated at a yield as high as possible and the interfering substances from the biological material are removed. When using solid-phase extraction (SPE) it is desirable to have procedures using just one column. An overview of screening procedures using diatomaceous earth, polystyrene-divinylbenzene copolymer and mixed-mode bonded silica as column material in SPE is given. The latter type of sorbent is most popular at the moment and the critical steps in the procedure are outlined in more detail. Recent developments of SPE disks look very promising for STA.

Analysis of tricyclic antidepressant drugs in plasma and serum by chromatographic techniques

A review of methods for the determination of tricyclic antidepressants in plasma or serum, based on the application of chromatographic techniques, is presented. A general discussion of the techniques in terms of their precision, accuracy, sensitivity and selectivity, with respect to parent drug and metabolites, is used to facilitate a comparison of methods. No one technique can be claimed as the method of choice for these drugs, although gas-liquid chromatography with nitrogen selective detection has some strong claims, viz. generally good sensitivity and reproducibility of assays and ready availability of equipment in most laboratories. The ultimate choice of a method for determining tricyclics will be determined more by the clinical application (routine monitoring versus pharmacokinetics) than by other factors.

Evaluation of Amberlite XAD-2 as the extractant for carbamate insecticides from natural water

A rapid and sensitive analytical technique to quantify carbamate insecticides at nanogram levels is reported using resin column and sorption, and desorption followed by N-P gas-liquid chromatography (GLC) analysis. The carbamates were extracted from natural water by percolation through a column of Amberlite XAD-2, followed by elution with ethyl acetate. The carbamate residues were directly analyzed by GLC with a Tracor Model 702 N-P detector. The recoveries for several carbamates including aminocarb, mexacarbate, carbaryl, propoxur, carbofuran, pirimicarb and methiocarb were from 86 to 108% at 1.0 and 0.01 ppm levels. Only 41 to 58% was recovered for methomyl. The extraction efficiency of Amberlite XAD-2 was pH-dependent as indicated in the extraction of aminocarb. More than 90% of the added aminocarb was recovered from phosphate buffer by the described method at pH 5.0 to 7.5 at 5.0 and 0.5 ppm levels.

Isolation and determination of quaternary ammonium compounds by means of amberlite XAD-columns and thin layer chromatography

The potentials of XAD-columns for the isolation of quaternary ammonium compounds from aqueous media have been investigated. When adequate amounts of counter ions (perchlorate, chloride, phosphate, nitrate) were added to the aqueous sample, to the column pretreatment fluid and to the aqueous washing fluid, most quaternary compounds investigated were retained on the column and could be recovered by elution with methanol. This approach proved also suitable for urine. Quantitation of quaternaries isolated in this way from urine samples could be performed on silicagel thin layer plates through visualization with iodine, followed by densitometric evaluation. For decamethonium detection limits were 0.1 micrograms/ml. Recoveries at the 1 micrograms/ml level were between 80--90% with variation coefficients of less than 10%.

Isolation of drugs from blood and tissues with XAD-2 bags

Nylon bags containing 2-g portions of Amberlite XAD-2 resin were used for systematic analysis of drugs in biosamples. The procedure requires 10 or less grams of material, two XAD-2 bags, and enables rapid and economical isolation of most common drugs. The method was demonstrated on autopsy blood spiked withe 19 of the most common drugs, and was routinely used in cases of fatal and non-fatal poisoning. The eluates were clean and suitable for direct gas chromatographic and ultraviolet spectrophotometric analysis. The procedure used appeared more convenient than XAD-2 column extraction procedures. Classic solvent extraction methods were usually less efficient.