Transition from CLSA to SPME for the Analysis of Taste Odor Compounds in Water

摘要

Although very sensitive, CLSA is labor intensive and more technique-dependent than many other methods. Some of the reluctance from switching to SPME included concerns about a loss of sensitivity, the ability to operate the mass selective detector in the full scan mode for the analysis of unknowns, ability to determine analytes other than the 3 listed in Standard Method 6040D, and the reliability of SPME fibers. Once the decision was made to purchase the necessary components to adapt the existing instrumentation to handle SPME, the transition was smooth. Within two weeks of installation of a SPME-capable autosampler, field samples were being analyzed. Within three weeks, parameters had been optimized and all six analytes were being monitored in water supplies. Method Detection Limit (MDL) studies were conducted in a way that was never attempted with CLSA. Studies with a variety of spiking concentrations were completed with SPME. Based on these studies, Minimum Reporting Levels (MRLs) were developed for each target analyte (2,4,6 Trichloroanisole (TCA), 2-^sIsopropyl-3-methoxypyrazine (IPMP), trans-2,cis-6,nonadienal (T2C6N), and 2,4,6 Tribromoanisole (TBA), MIB, Geosmin). The MRL for IPMP, MIB, Geosmin, and TCA were each 2 ng/L. The MRL for TBA and T2C6N were 5ng/L and 25 ng/L, respectively. Calibration curves consisted of 7 standards with a correlation coefficient >0.995 for linear fit. Advantages became apparent after using SPME for only two months. These advantages included: increased productivity, automated operation, easier preparation of samples, improved Quality Control, equivalent sensitivity for 4 of 6 analytes, and minimized use of organic solvents.