The Establishment Of Multi-component Analysis Method Of Volatile Organic Compounds In Drinking Water And Orange Juice

Volatile organic compounds(VOCs)are chemicals with boiling point below 250 ? under 101.3kpa such as aliphatic hydrocarbon,aromatic hydrocarbons,halogenated hydrocarbons,aldehyde,ketone etc.Some VOCs are used as solvent and also can be found in fuel,paint,adhesive,deodorant,cryogen,another VOCs comes from chemical reaction.Some VOCs have characteristic of migrate,vitality and toxicity which cause them to be environmental pollutants.Drinking water may have potential risk because its source comes from nature water which may be polluted by VOCs,so it is necessary to establish high efficient and sensitive method to detect VOCs in dring water and beverage.In this paper,two pretreatment methods of VOCs in drinking water and orange juice had been developed,respectively.Infulencing factors of Head space and Purge&trap were optimized.Also,a method of determination of 55 kinds of VOCs in water was established by GC/MS with both Scan and SIM mode,this method was applied to determinate VOCs in dring water.The main results were as follows:1?Pretreatment methods of Head space and Purge&trap were researched and established respectively.The former was applied to detect drink water and the latter was used to monitor orange juice which has complex matrix.2?Method was established to determine 55 kinds of VOCs in water by GC/MS using capillary chromatographic column DB-624(30m×0.25mm×1.4?m).Separation time was within 28 min.The following factors such as type of capillary chromatographic column,column temperature,quantative ion of SIM mode etc were optimized.Compare GC/MS with GC,the former can qualitative and quantitative analysis more compounds simultaneously.Method of GC/MS can avoid false positive effectively and inproves the reliability of analysis results.3?Influencing factors of Head space pretreatment method were discussed as following:vapour-liquid ratio,equilibrium temperature,equilibrium time,salting-out effect,adding volumn of methanol.Using GC/MS coupled with HS,in Scan mode,good linearity was obtained in the range from 20 ug/L to 400ug/L,average recoveries ranged from 86.8%?112%at spiked levels of 20?g/L,50?g/Land 200?g/L with RSD(n=6)in the range of 0.4%?14.4%.In SIM moed,average recoveries ranged from 89.1%?107%%at spiked levels of 2?g/L with RSD(n=6)in the range of 0.4%?6.5%.Method was applied to detect VOCs in orange juice,trichlormethane and benzene were checked out.4?Influencing factors of Purge&trap pretreatment method were discussed as following:purge time,desorption temperature,desorption time.Using GC/MS coupled with purge&trap,good linearity was obtained in the range from 0.5 ug/L to lOug/L,average recoveries ranged from 68.7%?123%with RSD(n=6)less than 10%.Method was applied to detect VOCs in drinking water.Results shows:concentration of trichloromethane(one of the major disinfection by-products in tap water)in mineral water which comes from tap water is higher than spring water which comes from nature water.All concentrations of compounds which were checked out were far below the limit value of drinking water.