Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-kno...Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.展开更多
In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methyl...In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methylisoborneol （2-MIB）, 2,4,6-trichloroanisole （TCA）, 2-isopropyl-3-methoxy pyrazine （IPMP）, 2-isobutyl-3- methoxy pyrazine （IBMP）, and trans-l,lO-dimethyl- trans-9-decalol （geosmin, GSM）. The mass spectrometry was operated in selective ion monitoring （SIM） mode. Three kinds of SPE columns and three eluting solvents were compared, the C 18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1-200 ng.L^-1 and gave detection limits of 0.5 1.5 ng.L^-1 for individual compounds. Good recoveries （93.5%-108%） and relative standard deviations （1.58%-7.31%） were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan＇s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan＇s raw water.展开更多
A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavo...A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavor/odor compounds, included geosmin, 2- methylisobomeol （MIB）, 2-isobutyl-3-methyoxypyrazine （IBMP）, and 2-isopropyl-3-methoxypyrazine （IPMP）. Using this method, a single sample can be extracted within minutes using only 1 mL of organic solvent. The ion transitions for IPMP, IBMP, MIB, and geosmin were 153 〉 121, 167 〉 125, 152 〉 95, and 165 〉 109, respectively. The linearity of this method for analyzing MIB ranged from 4 to 200ng·L^-1, and from 0.8 to 200ng·L^-1 for the other analytes. Method recoveries ranged from 97% to 111% and percent relative standard deviations ranged from 3% to 9%, indicating that the method is accurate, precise, and reliable.展开更多
Manure odor, which results in the increasing complaints and lawsuits, has increased the tension among swine producers and surrounding residents. The effects of Lactobacillus plantarum and different rates of soluble ca...Manure odor, which results in the increasing complaints and lawsuits, has increased the tension among swine producers and surrounding residents. The effects of Lactobacillus plantarum and different rates of soluble carbohydrates additions to swine manure on odorous compounds, chemical compounds and indigenous flora were evaluated. Additions were calculated on dried manure weight basis. Variables monitored included ammonia （NH3）, hydrogen sulfide （H2S）, odor offensiveness, pH, ammonium nitrogen（NH4^＋-N）, volatile fatty acids （VFAs）, urease and indigenous flora. The results indicated that the combination of L. plantarum and soluble carbohydrates dramatically reduced manure pH. Lower pH resulted in the reduction of NH3 volatilization （34.6%-92.4%, P〈0.01）, the increases of H2S （P〈 0.05） and NH4^＋-N （5.3%-17.5%, P〈0.05）. In addition, L. plantarum and soluble carbohydrates additions significantly reduced odor offensiveness, those VFAs related to malodor indicators（valeric acids, 12.3%-47.7%, P〈 0.05; iso-valeric, 3.5%-23.8%） and the main microorganisms responsible for odor production, with the number of Eubacteria in swine manure reducing by 4.9%, 11.6%, 17.4%, 34.1% and 32.2% respectively.展开更多
基金supported by the National Natural Science Foundation of China(No.21007077,51290283)the Ministry of Water Resources’ Special Funds for Scientific Research on Public Causes(No.201201032)
文摘Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.
文摘In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methylisoborneol （2-MIB）, 2,4,6-trichloroanisole （TCA）, 2-isopropyl-3-methoxy pyrazine （IPMP）, 2-isobutyl-3- methoxy pyrazine （IBMP）, and trans-l,lO-dimethyl- trans-9-decalol （geosmin, GSM）. The mass spectrometry was operated in selective ion monitoring （SIM） mode. Three kinds of SPE columns and three eluting solvents were compared, the C 18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1-200 ng.L^-1 and gave detection limits of 0.5 1.5 ng.L^-1 for individual compounds. Good recoveries （93.5%-108%） and relative standard deviations （1.58%-7.31%） were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan＇s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan＇s raw water.
文摘A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavor/odor compounds, included geosmin, 2- methylisobomeol （MIB）, 2-isobutyl-3-methyoxypyrazine （IBMP）, and 2-isopropyl-3-methoxypyrazine （IPMP）. Using this method, a single sample can be extracted within minutes using only 1 mL of organic solvent. The ion transitions for IPMP, IBMP, MIB, and geosmin were 153 〉 121, 167 〉 125, 152 〉 95, and 165 〉 109, respectively. The linearity of this method for analyzing MIB ranged from 4 to 200ng·L^-1, and from 0.8 to 200ng·L^-1 for the other analytes. Method recoveries ranged from 97% to 111% and percent relative standard deviations ranged from 3% to 9%, indicating that the method is accurate, precise, and reliable.
文摘Manure odor, which results in the increasing complaints and lawsuits, has increased the tension among swine producers and surrounding residents. The effects of Lactobacillus plantarum and different rates of soluble carbohydrates additions to swine manure on odorous compounds, chemical compounds and indigenous flora were evaluated. Additions were calculated on dried manure weight basis. Variables monitored included ammonia （NH3）, hydrogen sulfide （H2S）, odor offensiveness, pH, ammonium nitrogen（NH4^＋-N）, volatile fatty acids （VFAs）, urease and indigenous flora. The results indicated that the combination of L. plantarum and soluble carbohydrates dramatically reduced manure pH. Lower pH resulted in the reduction of NH3 volatilization （34.6%-92.4%, P〈0.01）, the increases of H2S （P〈 0.05） and NH4^＋-N （5.3%-17.5%, P〈0.05）. In addition, L. plantarum and soluble carbohydrates additions significantly reduced odor offensiveness, those VFAs related to malodor indicators（valeric acids, 12.3%-47.7%, P〈 0.05; iso-valeric, 3.5%-23.8%） and the main microorganisms responsible for odor production, with the number of Eubacteria in swine manure reducing by 4.9%, 11.6%, 17.4%, 34.1% and 32.2% respectively.
