ANALYSIS AND OCCURRENCE OF TRICHLOROACETONITRILE AND TRICHLOROACETALDEHYDE IN DRINKING WATER
Report No FR0414

C P James

Sept 1993

EXECUTIVE SUMMARY

Trichloroacetonitrile (TCAN) and trichloroacetaldehyde (TCAL) may be produced as disinfection by-products during drinking water treatment. The provisional WHO guideline value for the maximum concentration of these two compounds in drinking water is 1 g 1-1 for TCAN and 10 g l-1 for TCAL. However, since a satisfactory validated analytical method for these substances in drinking water does not exist there is little good quantitative data on their levels in UK water supplies. Consequently, a sensitive method for their analysis is required.

An analytical method for TCAN and TCAL was developed and its performance validated. The limits of detection are 0.08 g l-1 for TCAN and 0.5 g l-1 for TCAL. The performance of the method has been shown to be satisfactory for the purpose of monitoring drinking water supplies. Laboratory chlorination experiments demonstrated the formation of TCAL but not TCAN. Results from analysis of samples of chlorinated drinking water indicated that levels of TCAL were below the WHO guideline. TCAN was, however, not detected.

Further monitoring at different sites is needed to confirm these indications.

SUMMARY

I BENEFITS

A sensitive method for determining tricloroacetonitrile (TCAN) and trichloroacetaldehyde (TCAL) in water will allow levels in chlorinated drinking water to be monitored and provide a comparison with the provisional WHO guideline values for these disinfection by-products.

II OBJECTIVES

The objectives of the work are, i, to develop and test the performance of an analytical method for the analysis of TCAN and TCAL in treated waters and then, ii, to investigate the potential formation of TCAN and TCAL from the laboratory chlorination of raw waters, and finally, iii, to apply the method developed to UK drinking waters.

III REASONS

TCAN and TCAL may be produced as disinfection by-products during drinking water treatment. The provisional WHO guideline values for the maximum concentration of these two by-products in drinking water are 1 g l-1 for TCAN and 10 g l-1 for TCAL. A sensitive method for their analysis is required to see if the values are exceeded in practice.

IV CONCLUSIONS

An analytical method for TCAN and TCAL has been developed and its performance validated. The limits of detection are 0.08 g l-1 for TCAN and 0.5 g l-1 for TCAL. The performance of the method has been shown to be satisfactory for the purpose of carrying out a survey of drinking water supplies. Laboratory chlorination experiments demonstrated the formation of TCAL but not TCAN. Results from a small survey indicate that while TCAL is probably commonly present in drinking water its level is normally below the WHO guideline value. TCAN was not detected. A wide survey would be needed to confirm these findings.

V RECOMMENDATIONS

The analytical method presented in this report should be used to carry out a more extensive survey of drinking water supplies to confirm the indications from the small survey.

VI RESUME OF CONTENTS

The development and validation of a method for determining TCAN and TCAL in drinking water are described. The method is detailed in an appendix. Laboratory chlorination experiments are described which demonstrate the formation of TCAL but not TCAN. A small survey of drinking waters has been carried out.

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