DETERMINATION OF METHYLISOBORNEOL IN CHANNEL CATFISH POND WATER BY SOLID-PHASE EXTRACTION FOLLOWED BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Several compounds exist which are responsible for unwanted taste and o dor characteristics that have been found in the edible tissue of the c hannel catfish (Ictalurus punctatus). Methylisoborneol (MIB), one comp ound responsible for these off-flavors, is produced through the metabo lism of cyanobacteria in aqueous systems such as reservoirs and ponds. The channel catfish accumulates MIB in its tissues from the intake of its culture-pond water. Current methods of analysis for MIB, such as closed- and open-loop stripping, and liquid-liquid extraction, are tim e-consuming and labor-intensive. A method for the analysis of MIB in c atfish culture-pond water is described which, unlike other methods, is rapid, inexpensive, and does not require specialized sample preparati on equipment. This method utilizes C-18 solid-phase extraction followe d by capillary gas chromatography with detection by mass spectrometry. Standard MIB and the internal standard, butylisoborneol (BIB), were p repared from the reaction of D-camphor with methylmagnesium chloride a nd n-butyllithium, respectively. Extraction efficiencies for MIB in ch annel catfish pond water averaged 89% at 101 parts per trillion (ppt) and 84% at 202 parts per billion (ppb). The detection limit of the met hod was calculated to be 11.5 ppt. Copyright (C) 1996 Elsevier Science Ltd