Metabolism of free fatty acids（FFAs） is related to several important physiological events and therefore their quantitaion in biological samples arouses extensive interest and efforts.Existing gas chromatography with...Metabolism of free fatty acids（FFAs） is related to several important physiological events and therefore their quantitaion in biological samples arouses extensive interest and efforts.Existing gas chromatography with flame ionization detector（GC-FID） methods for the analysis of FFAs normally require derivatization of them in order to lower boiling points.But this extra procedure tends to induce additional error and it is laborious and time-consuming.A derivatization-free method was therefore established in the present investigation to determine FFAs in human plasma by capillary（GC-FID）.After extraction of FFAs from plasma,a highly polar FFAP（free fatty acid in plasma） column was employed to directly quantitate FFAs concentration,free from derivatization reaction.All sample pretreatments were carried out at room temperature,improving recovery of short-chain FFAs.Heptadecanoic acid（C17：0） was employed as internal standard,and the proposed method was validated for recovery,precision,sensitivity,stabi-lity,and linearity.Validation data show that it is suitable for clinical study that has been applied to the evaluation of FFAs levels in plasma of diabetic nephropathy（DN） patients during the course of treatment.Forty-seven patients diagnosed with DN were admitted to the double-blind experiment.Control group（n=17） underwent solely basic treatment and the patients did not show significant change in FFAs concentration during six months of treatment.Experiment group（n=30） was supplied with traditional Chinese medicine besides basic treatment.After six months of medication,their plasma concentration of palmitic acid（C16：0）,stearic acid（C18：0） and oleic acid（C18：1n-9） decreased while linolenic acid（C18：3n-3） increased significantly（P〈0.05）.These four compounds could be served as biomar-kers in the evaluation of drug efficacy,and their quantitation in plasma may provide additional information for disease progression in DN patients.展开更多
A method involving Headspace solid-phase microextraction (HS-SPME) fiber combined with gas chromatography (GC) coupled with flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) was de...A method involving Headspace solid-phase microextraction (HS-SPME) fiber combined with gas chromatography (GC) coupled with flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) was developed and optimized to investigate volatile organic compounds (VOCs) from different tissues (flowers, leaves, stems, rhizosphere and whole plants) of Floribunda and Hybrid Tea roses (intact and cut). Three-phase fiber 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) was used. Two types of chambers (Tedlar bag and glass jar) were evaluated for collection of VOCs and glass jar was selected. Absorbed compounds on the fiber were completely desorbed in the GC injector port at three desorption times (5, 10 and 15 min), and 5 min at 250?C was used. The maximum extraction efficiency for flowers tissues (equilibrium absorption) was achieved 2 h after fiber exposure in the headspace for intact and cut Floribunda and Hybrid Tea flowers. Under the optimized HS-SPME and GC-FID/MS conditions, 1h extraction time was chosen for intact and cut Floribunda and Hybrid Tea leaves and stems. The results demonstrated that 5 cm depth was selected for root and soil part (rhizosphere) for both rose cultivars, and 6 h and 12 h extraction time of VOCs from rhizosphere was achieved for Floribunda and Hybrid Tea, respectively. One hour was chosen for VOCs released from whole rose plants for both cultivars. In this study, the VOC profiles of two rose cultivars were characterized by the optimized HS-SPME-GC method. The different tissues of rose plants gave wide range of the VOCs;also the chromatograms of different cultivars were quite different and the specific VOC pattern of rose types depends on the species. Results from this study demonstrate the feasibility of this method for identifying VOCs from two rose cultivars and the potential use of this method for physiological studies on rose plants or on other floriculture plants.展开更多
The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chr...The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chromatographic conditions of the two methods were optimized and the samples were determined. The recovery, precision, correlation coefficient, detection limit and quantitative limit of the two methods were compared. The results showed that the linear relationship between the two methods was good. The percentage recovery of standard addition by HPLC-DAD was 92.20%~102.80%, by RSD was 0.77%~2.00%;the detection limit was 0.05 mg/kg, the quantitative limit was 0.17 mg/kg. The percentage recovery of standard addition by GC-FID was 97.30%~103.28%, by RSD was 0.47%~4.87%;the detection limit was 1.3 mg/kg, the quantitative limit was 5.0 mg/kg. The detection limit by HPLC-DAD was lower and more sensitive than that by GC-FID , which also shows that HPLC-DAD has more advantages for the detection of low content samples.展开更多
The determination of the ethanol content in food products is of fundamental importance for HALAL certification. In this work, an analytical method for the determination of ethanol in water by headspace gas chromatogra...The determination of the ethanol content in food products is of fundamental importance for HALAL certification. In this work, an analytical method for the determination of ethanol in water by headspace gas chromatography with flame ionization detector (HS-GC-FID) has been developed and validated for the use in characterization of ethanol reference materials. The validation study was carried out in the linear calibration range 100 - 1500 mg/kg using the NIST SRM 2900, nominal 95.6%. The studied performance characteristics of the method were the limit of detection, LOD, the limit of quantification LOQ, selectivity, linearity, precision, recovery and bias. The validation results showed that the method is selective, precise, accurate and free from any significant bias. The LOD and LOQ were 1.27 and 3.86 mg/kg respectively and the estimated expanded uncertainty was 2% indicating that the method is fit for the purpose of certification of ethanol in water reference materials.展开更多
基金Supported by the National Basic Research Program of China(Nos.2007CB511903,2005CB523503)the International Cooperation Project of Ministry of Science and Technology of China(No.S2010GR0583)the National Natural Science Founda- tion of China(Nos.90709045,20805026)
文摘Metabolism of free fatty acids（FFAs） is related to several important physiological events and therefore their quantitaion in biological samples arouses extensive interest and efforts.Existing gas chromatography with flame ionization detector（GC-FID） methods for the analysis of FFAs normally require derivatization of them in order to lower boiling points.But this extra procedure tends to induce additional error and it is laborious and time-consuming.A derivatization-free method was therefore established in the present investigation to determine FFAs in human plasma by capillary（GC-FID）.After extraction of FFAs from plasma,a highly polar FFAP（free fatty acid in plasma） column was employed to directly quantitate FFAs concentration,free from derivatization reaction.All sample pretreatments were carried out at room temperature,improving recovery of short-chain FFAs.Heptadecanoic acid（C17：0） was employed as internal standard,and the proposed method was validated for recovery,precision,sensitivity,stabi-lity,and linearity.Validation data show that it is suitable for clinical study that has been applied to the evaluation of FFAs levels in plasma of diabetic nephropathy（DN） patients during the course of treatment.Forty-seven patients diagnosed with DN were admitted to the double-blind experiment.Control group（n=17） underwent solely basic treatment and the patients did not show significant change in FFAs concentration during six months of treatment.Experiment group（n=30） was supplied with traditional Chinese medicine besides basic treatment.After six months of medication,their plasma concentration of palmitic acid（C16：0）,stearic acid（C18：0） and oleic acid（C18：1n-9） decreased while linolenic acid（C18：3n-3） increased significantly（P〈0.05）.These four compounds could be served as biomar-kers in the evaluation of drug efficacy,and their quantitation in plasma may provide additional information for disease progression in DN patients.
文摘A method involving Headspace solid-phase microextraction (HS-SPME) fiber combined with gas chromatography (GC) coupled with flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) was developed and optimized to investigate volatile organic compounds (VOCs) from different tissues (flowers, leaves, stems, rhizosphere and whole plants) of Floribunda and Hybrid Tea roses (intact and cut). Three-phase fiber 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) was used. Two types of chambers (Tedlar bag and glass jar) were evaluated for collection of VOCs and glass jar was selected. Absorbed compounds on the fiber were completely desorbed in the GC injector port at three desorption times (5, 10 and 15 min), and 5 min at 250?C was used. The maximum extraction efficiency for flowers tissues (equilibrium absorption) was achieved 2 h after fiber exposure in the headspace for intact and cut Floribunda and Hybrid Tea flowers. Under the optimized HS-SPME and GC-FID/MS conditions, 1h extraction time was chosen for intact and cut Floribunda and Hybrid Tea leaves and stems. The results demonstrated that 5 cm depth was selected for root and soil part (rhizosphere) for both rose cultivars, and 6 h and 12 h extraction time of VOCs from rhizosphere was achieved for Floribunda and Hybrid Tea, respectively. One hour was chosen for VOCs released from whole rose plants for both cultivars. In this study, the VOC profiles of two rose cultivars were characterized by the optimized HS-SPME-GC method. The different tissues of rose plants gave wide range of the VOCs;also the chromatograms of different cultivars were quite different and the specific VOC pattern of rose types depends on the species. Results from this study demonstrate the feasibility of this method for identifying VOCs from two rose cultivars and the potential use of this method for physiological studies on rose plants or on other floriculture plants.
文摘The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chromatographic conditions of the two methods were optimized and the samples were determined. The recovery, precision, correlation coefficient, detection limit and quantitative limit of the two methods were compared. The results showed that the linear relationship between the two methods was good. The percentage recovery of standard addition by HPLC-DAD was 92.20%~102.80%, by RSD was 0.77%~2.00%;the detection limit was 0.05 mg/kg, the quantitative limit was 0.17 mg/kg. The percentage recovery of standard addition by GC-FID was 97.30%~103.28%, by RSD was 0.47%~4.87%;the detection limit was 1.3 mg/kg, the quantitative limit was 5.0 mg/kg. The detection limit by HPLC-DAD was lower and more sensitive than that by GC-FID , which also shows that HPLC-DAD has more advantages for the detection of low content samples.
文摘The determination of the ethanol content in food products is of fundamental importance for HALAL certification. In this work, an analytical method for the determination of ethanol in water by headspace gas chromatography with flame ionization detector (HS-GC-FID) has been developed and validated for the use in characterization of ethanol reference materials. The validation study was carried out in the linear calibration range 100 - 1500 mg/kg using the NIST SRM 2900, nominal 95.6%. The studied performance characteristics of the method were the limit of detection, LOD, the limit of quantification LOQ, selectivity, linearity, precision, recovery and bias. The validation results showed that the method is selective, precise, accurate and free from any significant bias. The LOD and LOQ were 1.27 and 3.86 mg/kg respectively and the estimated expanded uncertainty was 2% indicating that the method is fit for the purpose of certification of ethanol in water reference materials.
