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
An optimum method has been developed for extracting volatile organic compounds (VOCs) which contribute to the aroma of different species of citrus fruit (orange, lemon, lime, and mandarin). Headspace solid phase micro...An optimum method has been developed for extracting volatile organic compounds (VOCs) which contribute to the aroma of different species of citrus fruit (orange, lemon, lime, and mandarin). Headspace solid phase microextraction (HS-SPME) combined with gas chromatography (GC) coupled with flame ionization detection (FID) is used as a very simple, efficient and non-destructive extraction method. A three phase 50/30 μm PDV/DVB/CAR fibre was used for the extraction process. The optimal sealing time for volatiles reaching equilibrium from whole fruit in the headspace of the chamber was 20, 16, 8 and 16 hours for lemon, lime, mandarin, and orange respectively. Optimum fibre exposure times for whole fruit were 2, 4, 2 and 2 hours for lemon, lime, mandarin, and orange respectively. Three chamber volumes (500, 1000 and 2000 ml) were evaluated for the collection of VOCs with the 500 ml chamber being selected. The 500ml chamber produced the highest quality peak areas and quantity of extracted volatiles. As a result of fruit respiration, the percentage of oxygen (O2) of all citrus fruit species in 500 ml chamber decreased from 21.8% to 18.8% in the 20 hours sealing time, while carbon dioxide (CO2) contents increased to 2.9% also in the 20 hours sealing time. The results of this study showed the feasibility of this technique for identifying VOCs from four of the citrus fruit species and its potential as a routine method for physiological studies on citrus fruit or on other fruit species.展开更多
Despite the worldwide increase in the consumption of PET-bottled mineral waters compared to tap waters encouraged by its microbiological and chemical safety for public health, contaminants could migrate from the plast...Despite the worldwide increase in the consumption of PET-bottled mineral waters compared to tap waters encouraged by its microbiological and chemical safety for public health, contaminants could migrate from the plastic packaging into the water and induce adverse effects on human health. Volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, ortho, meta, and para-xylenes (BTEX), styrene, chlorobenzene and benzaldehyde are among the potential contaminants of bottled waters. This study aimed to assess Lebanese PET-bottled waters, in respect of VOCs contents, with comparison to polycarbonate-bottled and tap waters. Both HS-SPME-GC/FID and SPE-GC/FID were optimized and validated for VOCs determination in the waters, and their performances were compared. The HS-SPME-GC/FID was valid (Afnor NF T 90-210 (May 2009)) for all the studied molecules with limits of quantifications (LOQ) far lower the maximum contaminants levels (MCLs) set by both US-EPA and WHO. SPE-GC/FID was valid only for ethylbenzene, m/p-xylenes, o-xylene, and styrene, with poorer LOQs. HS-SPME-GC/FID was used therefore for VOCs monitoring in studied water samples showing the safety of the Lebanese bottled-water. The effects of bottles storage conditions (time, and exposure to sunlight) on VOCs migration were also studied.展开更多
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.
文摘An optimum method has been developed for extracting volatile organic compounds (VOCs) which contribute to the aroma of different species of citrus fruit (orange, lemon, lime, and mandarin). Headspace solid phase microextraction (HS-SPME) combined with gas chromatography (GC) coupled with flame ionization detection (FID) is used as a very simple, efficient and non-destructive extraction method. A three phase 50/30 μm PDV/DVB/CAR fibre was used for the extraction process. The optimal sealing time for volatiles reaching equilibrium from whole fruit in the headspace of the chamber was 20, 16, 8 and 16 hours for lemon, lime, mandarin, and orange respectively. Optimum fibre exposure times for whole fruit were 2, 4, 2 and 2 hours for lemon, lime, mandarin, and orange respectively. Three chamber volumes (500, 1000 and 2000 ml) were evaluated for the collection of VOCs with the 500 ml chamber being selected. The 500ml chamber produced the highest quality peak areas and quantity of extracted volatiles. As a result of fruit respiration, the percentage of oxygen (O2) of all citrus fruit species in 500 ml chamber decreased from 21.8% to 18.8% in the 20 hours sealing time, while carbon dioxide (CO2) contents increased to 2.9% also in the 20 hours sealing time. The results of this study showed the feasibility of this technique for identifying VOCs from four of the citrus fruit species and its potential as a routine method for physiological studies on citrus fruit or on other fruit species.
文摘Despite the worldwide increase in the consumption of PET-bottled mineral waters compared to tap waters encouraged by its microbiological and chemical safety for public health, contaminants could migrate from the plastic packaging into the water and induce adverse effects on human health. Volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, ortho, meta, and para-xylenes (BTEX), styrene, chlorobenzene and benzaldehyde are among the potential contaminants of bottled waters. This study aimed to assess Lebanese PET-bottled waters, in respect of VOCs contents, with comparison to polycarbonate-bottled and tap waters. Both HS-SPME-GC/FID and SPE-GC/FID were optimized and validated for VOCs determination in the waters, and their performances were compared. The HS-SPME-GC/FID was valid (Afnor NF T 90-210 (May 2009)) for all the studied molecules with limits of quantifications (LOQ) far lower the maximum contaminants levels (MCLs) set by both US-EPA and WHO. SPE-GC/FID was valid only for ethylbenzene, m/p-xylenes, o-xylene, and styrene, with poorer LOQs. HS-SPME-GC/FID was used therefore for VOCs monitoring in studied water samples showing the safety of the Lebanese bottled-water. The effects of bottles storage conditions (time, and exposure to sunlight) on VOCs migration were also studied.
