THE STABILITY OF GEOSMIN AND MIB AND THEIR DEUTERATED ANALOGS IN SURFACE WATERS AND ORGANIC-SOLVENTS

Deuterated geosmin [trans-1,10-[H-2(3)]-dimethyl-9-alpha-decalol] and deuterated methylisoborneol [2-exo-hydroxy-2-[H-2(3)]-methylborane] were synthesised and evaluated as alternatives to 1-chloroalkanes as internal standards in the determination of geosmin and MIB in surface waters. Geosmin and MIB were stored as dilute solutions in methanol, ethanol, acetone, hexane or carbon disulfide for > 6 months without deterioration. Dichloromethane caused substantial decomposition of MIB. When added at the time of sampling, the labelled standards compensated for losses of analyte by physical, chemical and biological processes during sample storage. The labelled compounds were effective internal standards for the determination of other odorous metabolites such as the carbonyl compounds beta-cyclocitral, beta-ionone, geranylacetone and 6-methylhept-5-en-2-one.