六氯丁二烯分析方法研究进展

六氯丁二烯是一种持久性有机污染物,于2015年和2017年分别被列入《斯德哥尔摩公约》附件A和附件C的受控污染物名单中。六氯丁二烯的来源、环境赋存和影响等研究对控制该新增受控持久性有机污染物污染具有重要意义,而灵敏可靠的六氯丁二烯分析方法是开展相关研究的前提和基础。近年来已有不少学者将六氯丁二烯作为分析目标物之一进行了检测或方法学研究。基于这些研究成果,该文综述了六氯丁二烯分析方法的研究进展,其中重点介绍了空气、水体、土壤、污泥、生物组织等多种介质中六氯丁二烯的样品前处理方法,并比较了各方法的优缺点,以期为该领域的进一步研究提供参考。空气中六氯丁二烯主要由泵抽气通过吸附管而采集,再经热脱附后进行仪器分析,检出限在ng/m³水平。也有研究应用聚氨酯泡沫被动采样器和吸附剂填充聚氨酯泡沫被动采样器采集大气中六氯丁二烯及其他污染物。基于吸附剂填充聚氨酯泡沫被动采样器的分析方法灵敏度较高,其对六氯丁二烯的检出限低至0.03 pg/m³。然而目前被动采样体积仅根据六氯丁二烯的log K_OA系数估算,未来仍需进一步实验校正。水体样品前处理通常也较简单,通过吹扫捕集、液-液萃取或固相萃取目标物后进行仪器分析。固相萃取法能够同步实现目标物的提取、净化和浓缩,在水样中六氯丁二烯分析方面具有明显优势。固相萃取柱类型以及干燥步骤中柱中残留水分去除率均会影响六氯丁二烯的回收率。灰尘、土壤、沉积物、污泥和生物组织等固体介质样品基质最为复杂,需联合多种方法进行前处理。固体样品中六氯丁二烯提取方法包括索氏提取,加速溶剂萃取和超声萃取,其中超声萃取法应用最为广泛。固体基质净化方面主要采用层析柱色谱法,多根净化柱联用或多层复合柱能够提升净化效果。仪器分析方面,六氯丁二烯主要采用气相色谱和质谱联用检测,高性能质谱检测器如串联质谱能够大大提高六氯丁二烯的检测灵敏度,具有较大的应用潜力。

Research progress on analytical methods for the determination of hexachlorobutadiene

Hexachlorobutadiene(HCBD) is one of persistent organic pollutants(POPs) listed in Annex A and Annex C of the Stockholm Convention in 2015 and 2017, respectively. Research on the sources, environmental occurrences, and biological effects of HCBD has a great significance in controlling this newly added POPs. Sensitive and credible methods for the determination of HCBD are preconditions and form the basis for related research work. In recent years, many researchers have included HCBD as one of the analytes in monitoring or methodological studies. Based on the results of these studies, this paper reviews the research progress on analytical methods for the determination of HCBD and focuses on sample pretreatment methods for the analysis of HCBD in various matrices such as air,water,soil,sewage sludge,and biological tissues. The advantages and disadvantages of the methods are also compared to provide reference for further research in this field.For air samples,HCBD was usually collected by passing air through sorbent cartridges. Materials such as Tenax-TA,Carbosieve,Carbopack,Carboxen 1000,or their mixtures were used as the sorbent. HCBD was thermally desorbed and re-concentrated in a trap and finally transferred for instrumental analysis. Limits of detection(LODs)for HCBD in these methods were at the ng/m3 scale. Compared to sampling using pumps,passive air samplers(PAS)such as polyurethane foam PAS(PUF-PAS)do not require external power supply and are more convenient for sampling POPs in air at a large scale. The LOD of the sorbent-impregnated PUF PAS(SIPPAS)method was much lower(0. 03 pg/m3)than that of the PUF-PAS method(20 pg/m3).However,the sampling volumes in the SIP-PAS and PUF-PAS methods(-6 m3)calculated from the log KOAvalue of HCBD have significant uncertainty,and this must be confirmed in the future.For water samples,HCl or copper sulfate was added to the sample immediately after sampling to prevent any biological activities. HCBD can be extracted from water using methods such as the purge and trap method,liquid-liquid extraction(LLE)method,and solid phase extraction(SPE)method. Among these methods,SPE enabled the simultaneous extraction,purification,and concentration of trace HCBD in a single step. Recoveries of HCBD on Strata-X and Envi-Carb SPE cartridges(63%-64%)were higher than those on Envi-disk,Oasis HLB,and Strata-C18 cartridges(31%-46%). Drying is another key step for obtaining high recoveries of HCBD. Disk SPE involving the combination of a high-vacuum pump and a low-humidity atmosphere is an effective way to eliminate the residual water. In addition,a micro SPE method using functionalized polysulfone membranes as sorbents and employing ultrasonic desorption was developed for extracting HCBD from drinking water. The recovery of HCBD reached 102%,with a relative standard deviation(RSD)of 3. 5%.For solid samples such as dust,soil,sediment,sewage sludge,fly ash,and biota tissue,multiple pretreatment methods were used in combination,owing to the more complex matrix.Freeze or air drying,grinding,and sieving of samples were commonly carried out before the extraction. Soxhlet extraction is a typical extraction method for HCBD;however,it requires many organic reagents and is time consuming. The accelerated solvent extraction(ASE)method requires a small amount of organic reagent,and the extraction can be performed rapidly. It was recently applied for the extraction of HCBD from solid samples under 10. 34 MPa and at 100 ℃ . Purification could be achieved simultaneously by mixing florisil materials with samples in the ASE pool. Nevertheless,employing the ASE methods widely is difficult because of their high costs. Ultrasonic-assisted extraction(UAE)has the same extraction efficiency for HCBD,with much lower costs compared to ASE,and is therefore adopted by most researchers.The type of extraction solvent,solid-to-liquid ratio,ultrasonic temperature,and power affect the extraction efficiency. Ultrasonic extraction at 30 ℃ and 200 W using 30 mL dichloromethane as the extraction solvent resulted in acceptable recoveries(64. 0%-69. 4%)of HCBD in 2 g fly ash. After extraction,a clean-up step is necessary for the extracts of solid samples. Column chromatography is frequently used for purification. The combined use of several columns or a multilayer column filled with florisil,silica gel,acid silica gel,or alumina can improve the elimination efficiency of interfering substances.Instrumental analysis for HCBD is mainly performed with a gas chromatograph equipped with a mass spectrometer operating in selected ion monitoring mode. DB-5 MS,HP-5 MS,HP-1,ZB-5 MS,and BP-5 can be used as the chromatographic columns. Qualification ions and quantification ions include m/z 225,223,260,227,190,and 188. GC-MS using an electron ionization(EI)source was more sensitive to HCBD than GC-MS using a positive chemical ionization source(PCI)and atmospheric pressure chemical ionization source(APCI). Gas chromatography-tandem mass spectrometry(GC-MS/MS),gas chromatography-high-resolution mass spectrometry(GC-HRMS),and high-resolution gas chromatography-high-resolution mass spectrometry(HRGC-HRMS)have recently been used for the separation and determination of HCBD and various other organic pollutants. Instrumental detection limits for HCBD in GC-MS/MS,GCHRMS,and HRGC-HRMS were more than ten times lower than that in GC-MS,indicating the remarkable application potential of these high-performance instruments in HCBD analysis.