Accurate analysis of trace earthy‐musty odorants in water by headspace solid phase microextraction gas chromatography‐mass spectrometry

Abstract

A simple and sensitive method was developed for the simultaneous separation and determination of trace earthy-musty compounds including geosmin, 2-methylisoborneol, 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,3,4-trichloroanisole, 2,4,6-trichloroanisole, and 2,3,6-trichloroanisole in water samples. This method combined headspace solid-phase microextraction (HS-SPME) with gas chromatography-mass spectrometry and used naphthalene-d(8) as internal standard. A divinylbenzene/carboxen/polydimethylsiloxane fiber exposing at 90°C for 30 min provided effective sample enrichment in HS-SPME. These compounds were separated by a DB-1701MS capillary column and detected in selected ion monitoring mode within 12 min. The method showed a good linearity from 1 to 100 ng L(-1) and detection limits within (0.25-0.61 ng L(-1)) for all compounds. Using naphthalene-d(8) as the internal standard, the intra-day relative standard deviation (RSD) was within (2.6-3.4%), while the inter-day RSD was (3.5-4.9%). Good recoveries were obtained for tap water (80.5-90.6%), river water (81.5-92.4%), and lake water (83.5-95.2%) spiked at 10 ng L(-1). Compared with other methods using HS-SPME for determination of odor compounds in water samples, this present method had more analytes, better precision, and recovery. This method was successfully applied for analysis of earthy-musty odors in water samples from different sources.

Development of Models for Predicting the Predominant Taste and Odor Compounds in Taihu Lake, China

“…Second, previous models were developed without distinguishing the different algal growing seasons [14], [24], which are important to distinguish because the blooming and nonblooming seasons in many eutrophic waters like Taihu Lake differ markedly in both the composition and the abundance of the phytoplankton community. Third, most studies have examined only the well-known earthy-musty algal metabolites, GEO and MIB, and just a few have studied other algal metabolites or derivatives, such as β-ionone [25], [26], β-cyclocitral [25], [27], 2-isobutyl-3-methoxypyrazine (IBMP) [28], [29], 2-isopropyl-3-methoxypyrazine (IPMP) [29], [30], dimethyl trisulfide and related alkyl sulfide compounds [31].…”

Trace analysis of off-flavor/odor compounds in water using liquid-liquid microextraction coupled with gas chromatography—positive chemical ionization-tandem mass spectrometry

“…Strong matrix effects on the peak intensity of the compounds were observed, requiring use of matrixmatched standards. Due to the use of matrix calibration techniques, recoveries were much higher than those reported in many studies [3,16,18,19]. Relative standard deviations (%) were similar ( < 10%) between both studies [16].…”

“…Major contributors to the earthy-musty odors include geosmin, 2-methylisoborneol (MIB), 2-isobutyl-3-methyoxypyrazine (IBMP), and 2-isopropyl-3-methoxypyrazine (IPMP) [1][2][3]. Odors of these compounds are perceptible at low levels (in the order of 10 ng$L -1 or less) [4,5].…”

“…These chemicals can also cause significant economic losses in the aquaculture industry due to their partitioning into fish flesh. Several studies have documented the transfer of these compounds from water into the marketable flesh of catfish [3,6,7]. When released into the culture water within aquaculture facilities, geosmin and MIB are absorbed by lipid-rich fish tissues, which often render the fish unmarketable due to the smell and taste [8,9].…”

Determination of Musty-Odor Compounds in Water by Gas Chromatography–Mass Spectrometry with a Needle-Type Sample-Preparation Device

“…[5][6][7][8][9][10][11] In these studies, MOCs were detected at approximately 1 ng L -1 , and satisfactory sensitivities were reported.…”