Resarch On The Identification And Traceability Of Benzene Series

Benzene series (BTEX) are widely used in many organic and chemical plant. Theycan easily enter into environment by many ways, and pollute water, soil and airseriously. Due to the harm of human and organisms, BTEX has been in the lists ofpriority pollutants in China. Therefore all over the word pay much attention to this issue.In recent years, marine accidents occur frequently, especially hazardous chemicalsleakage and oil spill, that make serious damage for halobios and natural resources.Harmful chemicals are needed to determine the accurate components as well as thepollution sources in the process of accident emergency treatment and responsibility formarine monitoring law enforcement. Therefore, it is very necessary to develop the rapiddetermination and traceability technology research for BTEX of coastal leak, and it alsohas a wide range of demand in our country. It has important practical significance forsettling legal disputes logically, establishing supervisory laws regulations of marineenvironment and improving emergency system of the hazardous chemical.In this paper, the rapid determination of BTEX in seawater and study on differentsource of toluenes were studied in detail. Two sample devices were applied to developmethods for the determination of BTEX in seawater and for the determination of BTEXby Headspace (HS) and solid phase microextraction (SPME) coupled to GasChromatography-Mass Spectrometry (GC-MS). Through the study of the trace featureelements in toluene of the typical BTEX, we discussed the different sources of toluenetraceability technology preliminarily. The main research contents are as follows:Firstly, outlined the uses, harm and source of BTEX in the ocean; briefly describedthe literature concerning the traditional and up-to-date methods for sample pretreatmenttechnology and analysis of BTEX in the environment, respectively introduced theprinciple and application of these technologies; summarized the research progress ofBTEX in the environment; briefly introduced the importance of traceability for BTEX.On the base of these, the innovation and significance of this paper were explicit.Secondly, a method for the simultaneous determination of13BTEX in seawater using Gas Chromatography-Mass Spectrometry with Static Headspace extraction(HS-GC/MS) was developed in the paper. To carefully characterize the performance ofthis method, several factors affecting parameters were studied in detail, such as the typeof column, heating procedure, equilibration temperature, equilibration time and thevolume ratio of gas phase to liquid phase. The optimized conditions were as follows: thepolar column of DB-WAX; heating procedure,40℃kept for4min, then raised to120℃at10℃/min, to180℃at25℃/min; equilibration temperature,80℃;equilibration time,10min; and the volume ratio of gas phase to liquid phase,1:1. Underthe optimized conditions, the linear equations were obtained in the concentration range0.16~320μg/L. The coefficients of linear equation for BTEX were greater than0.9990.The limits of detection (S/N=3) were0.057~0.099μg/L. The recoveries at the threespiked levels of1.6,16, and160μg/L ranged from81.25%to103.73%. The relativestandard deviations were from1.1%to4.4%(RSD, n=6). Through analysis of thepractical seawater samples of Shanghai Huangpu District, the result was satisfactory.The determination of13BTEX can be finished in12min. The method is simple,accurate, efficient and environmental–friendly.Gas Chromatography-Mass Spectrum method with Headspace Solid PhaseMicroextraction (HS-SPME-GC/MS) was established to analysis of13BTEX inseawater. BTEX was extracted by100μm polydimethylsiloxane (PDMS) fiber anddeterminated by GC-MS with selective ion mass mode and external standardquantitative method. In this method, several factors affecting the parameters ofextraction were optimized in detail. The optimized conditions were as follows: thecolumn of DB-WAX;100μm PDMS fiber; extraction temperature,30℃; extractiontime,20min; desorption time,3min; and sample volume,10mL Under optimizedconditions, the linear equations were obtained in the concentration range of0.16~16μg/L with correlation coefficient (r:0.9990~1.000), the limits of detection (S/N=3) were0.006~0.043μg/L. The recoveries at the three spiked levels of0.16,1.6and16μg/Lranged from80%to116.56%with the relative standard deviation (RSD, n=6) from2.00%to5.56%. The analytical results of the real samples from Zhapu District inHangzhou were satisfactory. HS-SPME-GC/MS, a simple, sensitive, rapid and greenproposed method, was suitable for determination of13BTEX in seawater.At last, traceability technology for toluene from different sources was establishedpremininarily. Harmful chemicals from different sources because of the difference of raw materials, production process cause different characteristics of the types of tracefeature elements and content. Therefore, identification of BTEX was based on thetrace feature elements. Referring to identification methods of spilled oil, the formationof trace feature elements in toluene was used, and the diagnostic ratios of the tracefeature elements of toluene was gained. After t-test analysis, these diagnostic ratios (DR)can be used for source identification. T-test analysis was introduced in detail, includingthe principle, the evaluation for DR and identification principle. Taking identification ofsix samples of toluene from five manufacturers for an example, it illustrates theeffectiveness for identifying of different toluene with the selected DR.Through the above research, this paper was established two methods that thedetermination of BTEX in seawater. And an identification method was built for toluenesbased on the DR of trace feature elements. Using the DR of trace feature elements oftoluenes is a new attempt. I hope that can give some reference for further explanationfor BTEX of traceability, and these dates will contribute to study for BTEX in seawater.