Pesticides In Environmental Waters Research Articles

Method development for monitoring pesticides in environmental waters: liquid-solid extraction followed by liquid chromatography

Our recent method based upon liquid-solid extraction of pesticides from drinking water followed by high-performance liquid chromatography (HPLC) was modified tomake it suitable for monitoring 89 pesticides in ground-water and river water. The modified method involved passing 2, 1.5, and 0.5 L, respectively, of drinking water, groundwater, and river water through a 300-mg Carbopack cartridge at 120-130 mL/min. The complete separation of base-neutral pesticides from acidic ones was accomplished by a stepwise elution. After concentration of the two extracts, pesticides were separated and quantified by reversed-phase HPLC with UV detection

Study of pesticides in waters from a chalk catchment, cambridgeshire

AbstractWRc are undertaking a long term study of pesticides in the aquatic environment. A study of the pesticides in the rain, river water and groundwater of the Granta catchment in Cambridgeshire is now in its fourth year. Preliminary results are presented and the concentrations of agricultural pesticides in environmental waters are related to the land‐use within the catchment.The Granta study is incomplete but certain anomalies in pesticide occurrence can be identified. In particular, the triazines are much more prevalent in the groundwaters than their agricultural usage would lead one to expect.The limited data base gives problems with modelling the contaminant transport in groundwater. The present situation is reviewed and areas of future work necessary to fulfil the modelling needs identified. These areas of study.The historical land‐use and pesticide usage; the groundwater quality data base; the pesticide transport in the unsaturated zone.

An Evaluation of High Performance Liquid Chromatography-UV for the Multi-Residue Analysis of Organophosphorous Pesticides in Environmental Water

Abstract In this study isocratic high performance liquid chromatography in the reversed-phase mode (RP-8 or RP-18 column) with UV-detection (254 nm), was evaluated for the analysis, directly or after extraction, of organophosphorous pesticides in environmental water. Fifteen pesticides were studied and good resolution was obtained for eight by direct analysis of a multi-residue water sample. Reproducibility in terms of retention times was found to be very good. Linear calibration curves were obtained down to 0.5ng/μL (3 ng injected) with a coefficient of variation near 10%. The limit of quantitation for direct analysis was found to be 0.5mg/L (3ng) in water. However, by extraction with methylene chloride or ethyl acetate and concentration of the extract some of the pesticides could be determined at 0.5 μg/L (ppb) in water.

Conversion of a conventional packed-column gas chromatograph to accommodate megabore columns : II. Determination of organophosphorus pesticides in environmental water

Several methods involving solvent extraction or solid extraction (Amberlite XAD resins) were studied for the multi-residue recovery of fourteen organophosphorus compounds in water. It was found that extraction with ethyl acetate in a salted medium provided the most consistent data, both in terms of number of compounds recovered and percentage recovery. Amberlite XAD resins gave consistently high recoveries, and this was attributed to a matrix effect upon the particular nitrogen-phosphorus detector. The evaluation was made using a megabore column installed in a conventional packed-column chromatograph, and the results show that such a system is amenable to the multi-residue analysis of organophosphorus pesticides at very low cost.

Conversion of a conventional packed-column gas chromatograph to accommodate megabore columns : I. Evaluation of the system for organophosphorus pesticides

A conventional packed-column chromatograph was modified for use with a megabore column using a commercial conversion kit, with the intention of developing a multi-residue method for organophosphorus pesticides. The results indicate that the conversion does not affect the resolving power of the megabore column, since fourteen organophosphorus pesticides could be separated in a single injection. The megabore column in such a system proved to be much more efficient than a packed column in terms of resolution and qualitative reproducibility, and comparable with a similar column in a dedicated chromatograph. However, the conversion did affect the quantitative reproducibility of the system to some degree, as indicated by coefficients of variation between 5 and 27%, although it was determined that the particular nitrogen—phosphorus detector system (filament bead) used in this study was partly responsible for the variation. Nevertheless, calibration curves were obtained down to 0.1 ng per component, and a limit of quantitation of 1.0 ng was established for each component in a sample containing fourteen organophosphorus compounds. The results indicate that the system is sufficiently reproducible to develop a multi-residue method for organophosphorus pesticides in environmental waters.