NEW ANALYTICAL TECHNIQUES FOR PESTICIDES
Report No FR0187

K Moore, S Gibby, S Shurvell, S Jones and C James

Mar 1991

SUMMARY

I OBJECTIVES

To develop new analytical methods for pesticides in raw and treated waters.

II REASONS

The Water Supply (Water Quality) Regulations (1989) impose a duty on water undertakers in England and Wales to take regular samples of drinking water from consumer's taps or supply points in order to analyse them for various parameters. The regulations embrace the EC Drinking Water Directive parameter 55 which states that the maximum admissible concentration (MAC) for pesticides and related products is 0.1 g/l. Water undertakers ideally need to be able to analyse for pesticides down to a detection limit of one-tenth of the MAC for individual pesticides, ie 0.01 g/l in order to monitor compliance with the Regulations. Also the maximum tolerable error should not exceed one-tenth of the prescribed concentration or 20% of the result, whichever is the greater. These are demanding performance characteristics which are not achievable for many pesticides using present methods of analysis.

There are many pesticides which could possibly find their way into drinking water. Since it would be too costly to monitor for each pesticide individually, there is a need for multi-residue analytical methods.

Thus a need exists for multi-residue analytical methods for pesticides in drinking water that are sufficiently sensitive and accurate.

III CONCLUSIONS Further work had shown that the analytical methods reported in progress report UM 1048 needed improvement. However, it has been found that the performance of the analytical method for neutral/basic pesticides could be improved using graphitised carbon black cartridges for the extraction. The performance of the analytical method for uron and carbamate pesticides was improved by changing from Thermospray LC-MS to Plasmaspray LC-MS, and by washing inorganic impurities from the C18-bonded silica SPE cartridges using deionised water. Thus modified, the analytical methods are now capable of better overall sensitivity and accuracy.

IV RECOMMENDATIONS

The two modified multi-residue analytical methods developed need further performance-testing before they can be used routinely.

V RESUME OF CONTENTS

The literature review of potentially suitable multi-residue analytical methods presented in progress report UM 1048 has been updated.

Two multi-residue analytical methods - one for neutral/basic pesticides and another for uron and carbamate pesticides have been improved. Limited development work has been carried out on an analytical method for phenoxy acid and phenolic pesticides.

Copies of the Report are available from FWR, price 15.00 less 20% to FWR Members