Determination of 2-methylisoborneol and geosmin in drinking water using headspace solid phase micro-extraction coupled with gas chromatography-mass spectrometry

Abstract

The odorous compounds of 2-methylisoborneol (2-MIB) and geosmin (GSM) heavily produced and released in water source are one of the most important factors leading to off-flavor emergencies and resident water consumption panic in drinking water. A headspace solid phase micro-extraction ( HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of these two trace earthy and musty compounds in reservoir water, reservoir soil and tap water. The conditions of HS-SPME, such as salt amount, extraction time and extraction temperature, were optimized based on orthogonal analysis. The qualitative and quantitative analyses of 2-MIB and GSM were carried out in the electron impact (EI) -selective ion scanning mode. The results showed that the linear relationship between peak area and concentration of 2-MIB and GSM was good enough (r2 0.998) from 5 to 1 000 ng/L, the limits of detection were 0.72 ng/L for 2-MIB, 0.34 ng/L for GSM and the limits of quantification were 2.40 ng/L for 2-MIB, 1.13 ng/L for GSM. When the target samples spiked in the range of 10-600 ng/L, the average recoveries of the target compounds were 93.6% - 107.7% ( RSD ≤ 6.1%, n = 6). Based on the above method, the target compounds in reservoir water, reservoir soil and tap water in a certain region of Liaoning Province were analyzed. The results showed that the two target odors in reservoir water were 3.0 -3.6 ng/L. As for the extract of the soil around the reservoir, 2-MIB was 8.1 ng/L and GSM was 17.8 ng/L. The odorous substances were not detected in the tap water. This method is simple, accurate, reliable, highly sensitive and no need of organic solvents. And it is suitable for the detection of 2-MIB and GSM in drinking water.

Analysis of Three Dimethyl Sulfides in Freshwater Lakes Using Headspace Solid-Phase Microextraction-Gas Chromatography with Flame Photometric Detection

“…The DMTS fitted curve image shows that the peak area of DMTS was more in equilibrium and stable until the ion concentration reached 20%, after which it began to decline. Numerous researchers have chosen a 20% ion concentration as the extraction condition in single-variable optimization experiments [18,20], and the results in this study were similar; that is, the maximum extraction peak area of DMSs was found at a 20% ion concentration. Based on the fitting results of the three DMSs, 16%, 18%, and 20% were selected as the three ion concentrations in the orthogonal optimization experiments to further refine the optimal ion concentration.…”

“…The fitted DMDS curve showed that the peak area of DMDS exhibited a roughly parabolic trend with the increase in extraction temperature, and reached the maximum value when the extraction temperature was 55 • C. The curve fitting of DMTS showed that the DMTS peak area increased logarithmically with an increase in the extraction temperature, the growth rate increased, and the effect of the extraction temperature on the peak area of DMTS was most significant. The extraction temperature should not be too high, or it will cause water vapor to attach to the extraction fiber, affecting the extraction and adsorption of the target analytes [20]. In this study, the optimal extraction temperatures for DMS and DMDS were not excessively high.…”

“…Most current optimizations of HS-SPME conditions use a single factor as a variable to investigate the optimal conditions for the variation of this single factor when other factors are fixed [18][19][20][21]. This method often ignores the influence of interactions between multiple factors on target extraction.…”

“…However, both PFPD and SCD are specific detectors that require sophisticated measurement techniques and are not commonly configured in laboratories, whereas MSD detectors are more expensive. Previous studies have shown that for the determination of DMSs in different environmental media, despite the use of expensive MSD detectors, the detection limit is of the same order of magnitude as other detectors and does not reflect a better quantitative advantage [20]. Compared to other detectors, FPD detector has better selectivity for the small molecules of sulfides and phosphides.…”

“…In recent years, headspace solid-phase microextraction (HS-SPME) pretreatment technique has been widely applied to the analysis of trace-level volatile or semi-volatile odorants in water. Cheng et al used HS-SPME-GC-MS to detect geosmin in drinking water, which improved the limit of quantification of the assay [20]. When using HS-SPME for the pretreatment of solid and liquid samples, the selection of the surface coating of the extraction fibers and fiber specifications are very important for the extraction process, while the extraction conditions are also critical for the sensitivity of the detection.…”