Determination of aldicarb, aldicarb sulfoxide, aldicarb sulfone and carbofuran residues in water using high-performance liquid chromatography

Extraction of aldicarb and its metabolites from excreta and gastrointestinal tissue

Carbamate insecticide screens often include aldicarb and its oxidative metabolites, aldicarb sulfoxide (ASX), and aldicarb sulfone (ASN). The rapid hydrolysis and thermal cleavage of the C-N bond within the carbamate functional group of these compounds produces nitrile transformation products. Nitriles are primary transformation products from aldicarb, its sulfoxide, or its sulfone. However, these nitriles are infrequently monitored. The method reported used acetonitrile/water extraction and HPLC postcolumn derivitization to determine aldicarb, ASX, and ASN from avian excreta and from gastrointestinal (GI) tissue. Recoveries of aldicarb, ASX and ASN from excreta were of 79% +/- 5.4, 120% +/- 7.7, and 93% +/- 6.2, respectively. Recoveries from tissue were 70% +/- 5.0, 80% +/- 12.1, and 85% +/- 6.7, respectively. The same extraction procedure and a GC-FPD analysis were used to determine nitrile metabolites from the same tissues. Aldicarb nitrile, ASX nitrile, and ASN nitrile recoveries from excreta were 42% +/- 2.3, 65% +/- 3.6, and 79% +/- 3.3, respectively. Overall recoveries from tissue were 29% +/- 3.4, 72% +/- 8.3, and 83% +/- 11.4, respectively. Since aldicarb, ASX, and ASN are normally detectable in organ tissues for 1-2 days following exposure, determining the presence of nitrile cleavage products provides an important forensic tool for evaluating aldicarb exposures.

Strategies for chromatographic analysis of pesticide residues in water

A review is presented of the modern techniques and approaches in methods for pesticide residue analysis in water matrices. The state of the art of the individual steps (extraction, clean-up, separation, identification, quantitation) of the chromatographic methods is reviewed with emphasis laid on emerging techniques which have gained popularity. The new approaches are discussed with respect to their relevancy to the requirements for increasing the sensitivity of detection and reliability of identification and quantitation at low levels of concentrations, arising from the European Community Drinking Water Directive.

High-performance liquid chromatographic analysis of carbofuran residues in tomatoes grown in hydroponics

Tomato plants grown in hydroponics were irrigated three times on alternate days with nutrient solutions fortified with carbofuran at levels of 36, 111 and 222 mg 1-1, and carbofuran residues were analysed in tomato fruits. Residues were found to be below the maximum residue level set up by Codex Alimentarius Mundi (0.1 mg kg-1) 6, 11 and 18 days after the third irrigation with nutrient solutions fortified with carbofuran. Consequently, the withholding period of 60 days may be reduced to allow continuous harvest of tomatoes under the conditions used in this experiment.

Determination of carbofuran by GLC/NPD and HPLC in tomato fruits

Two analytical methods, using GLC/NPD and HPLC to analyse carbofuran residues in tomatoes, are described. Both methods have shown a high recovery rate, up to 90%, and their detection limits are below the maximum residue limit set by Codex Alimentarius Mundi for carbofuran in tomatoes. Therefore, both methods may be of use in routine analysis of this pesticide in those fruits.

Isocratic high-performance liquid chromatographic separation and multiple-wavelength ultraviolet detection of aldicarb and its soil degradation products. Optimization of stationary phase selectivity

The unique selectivities which can be generated through optimization of stationary/mobile phase combinations have been applied to the development of an isocratic, reversed-phase high-performance liquid chromatographic method for the separation of aldicarb and its primary soil degradation products. The method utilizes a cyanopropyl bonded stationary phase and water-acetonitrile mobile phase and is capable of separating aldicarb and its various sulfoxide, sulfone and oxime derivatives in less than 10 min. When combined with multiple-wavelength UV detection and an appropriate preconcentration step, this method can in principle be applied to the routine monitoring of aldicarb and its soil derivatives in water at concentrations less than 1 microgram/l.

[Application of electrochemical detection to the analysis of some residues of carbamate insecticides by high performance liquid chromatography]

A new high-performance liquid chromatographic determination of residues of some carbamate insecticides with electrochemical detection after degradation of molecules as the phenols is described. Residues of carbamate insecticides in vegetables can be quantified with high sensitivity.