CHARACTERISATION OF TWO COMMON BUT UNIDENTIFIED ORGANIC CONTAMINANTS IN WATER SUPPLIES
Report No DWI0175

Oct 1987

SUMMARY

It is our opinion that the two major components of interest do not exist in natural waters. However we suggest that acetone (and possibly acetaldehyde) are concentrated from water by the extraction procedure and that this process produces conditions which promote the aldol condensation of acetone (and possibly the incorporation of acetaldehyde as well if present in a sufficient quantity) to produce compounds such as mesityl oxide and diacetone alcohol. These compounds are effectively dimers of acetone. A third possible dimer of acetone is iso-mesityl oxide but an authentic sample was not available for testing. The presence of acetaldehyde will complicate the process. The presence of extraneous sources of acetone (laboratory contamination is a likely possibility here) will serve only to enhance this process. The presence of acetone in natural waters has been established. The conditions for the aldol condensation reaction to occur are present in the sample extraction procedure. Two of the primary products of the aldol condenstion reaction of acetone have been confirmed as present in water extracts.

Co-injection of mesityl oxide with the sample sent on 14-4-87 (ex-Anglian Water) indicated that the first of the two major peaks (FIGURE 4) was mesityl oxide. The second correlates with diacetone alcohol.

Our current knowledge of the chemistry of acetone, mesityl oxide and diacetone alcohol would indicate that these findings have no serious toxicological implications.

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