以固相微萃取配合微波輔助技術發展室內灰塵中農藥之分析方法

Abstract

近年來內分泌干擾物質(endocrine disrupting chemicals; EDCs)對人體健康的可能影響普遍受到重視，即使是在住家環境中，許多被廣泛使用的化學物質被陸續被認定為EDCs，如:鄰苯二甲酸酯(塑化劑) 、多溴二苯醚(阻燃劑)、壬基苯酚(清潔劑代謝產物)及農藥等；而室內中的灰塵因較可免於風吹日曬，所以光解、微生物分解等降解作用也較緩慢，以致吸附於灰塵上的污染物於室內環境中可更持久的存在。 灰塵是住家環境中重要的污染暴露來源；尤其是嬰兒及剛學會走路的小孩，由於其行為的關係更可能攝入大量附著灰塵上的各種污染物質。另一方面，台灣的農藥使用一直非常普遍；而農藥除了被認定為EDCs外，研究更指出其暴露可能與癌症發生有關(例如：兒童於農藥的暴露被懷疑與白血病的罹患有關)。因此，評估兒童接觸家戶灰塵而暴露農藥的狀況，並進而推估其健康風險，將具有重要的公共衛生意義。 有鑑於現有暴露評估工具的不足，本研究嘗試以固相微萃取技術(solid-phase microextraction；SPME)配合微波輔助(microwave assisted；MAE)發展灰塵中農藥的分析方法，以解決傳統方法上需使用大量有機溶劑與耗時的問題。 本研究首先以吸塵器收集室內灰塵，接著以不銹鋼篩網選出粒徑小於150 μm的灰塵後，以索氏萃取技術並分別以正己烷與丙酮 (9:1)之溶液及甲醇進行各8小時的萃取，以洗淨灰塵。灰塵經洗淨後，秤取0.2 g並置入 4 mL的樣本瓶中、再加入已知量的農藥(包括：靈丹(lindane)，飛布達(heptachlor)，陶斯松(chlorpyrifos)，阿特靈(aldrin)，地特靈(dieldrin)，安特靈(endrin)，滴滴梯(4,4’-DDT) 和擬似標準品(2, 4, 5, 6-Tetrachloro-m-xylene))，並放置隔夜，之後進行萃取測試。 本研究所建立的MAE-HS-SPME最佳化萃取條件如下：首先將1 mL 的水加入灰塵樣本以微波加熱至80℃，接著以polydimethylsioxane (PDMS) 纖維進行20分鐘之頂空吸附；頂空萃取後則以攜帶式氣相層析儀搭配電子補捉偵測器分析(注射口溫度為250℃，脫附5分鐘可達100%脫附效率)。 本研究所建立之農藥分析方法的線性範圍在1.25~ 1250 ng/g dust之間(r=0.99)；分析之精確度(RSD)為4.08%~17.02%。而與傳統萃取方法比較，本研究同時結合了微波與固相微萃取的操作簡單、省時、及不需溶劑使用等優點。

Pesticides residuals are ubiquitous problems in the environment while household dust has been known as a sink for many semivolatile organic compounds such as phthalates (plasticizers), 4-nonylphenol (detergent metabolite), polybrominated diphenyl ethers (flame retardants) and pesticides. Since indoor environment can protect dust from sunlight, rain and biological degradation, pollutants then could be persistent and accumulated in the residential environment. Seeing that the activity of children, they are more vulnerable to the exposure and have more chances to intake pesticides from household dusts. Therefore, there is a need to determine the pesticides contained in household dusts to assess the possible health risks caused from the exposures. Up to now, the analysis of pesticides in dust is solvent and time consuming. The purpose of this research was then to develop a method for the determinations of different pesticides in dusts simultaneously by using microwave assisted headspace solid-phase microextraction (MAE-HS-SPME). Commercial vacuum cleaner was used to collect household dusts while particles with diameter smaller than 150μm were filtered out by stainless mesh. After cleaning by the Soxhlet extraction, the sample with known amounts of pesticides spiked was then put in a vial for the MAE-HS-SPME extraction. Several parameters affecting the SPME extraction efficiency were optimized. The results showed the best suitable fiber coating was 100μm PDMS and the optimum condition of MAE-HS-SPME for extraction of pesticides in dust was 20 minutes at 80℃ by the addition of 1 ml water. After headspace extraction, the sample was then analyzed by gas chromatograph with electron capture detector (GC-ECD). The desorption efficiency was found to be 100% when the desorption time was 5 min under 250℃. The linear range for the analysis was 1.25 ~ 1250 ng/g dust (r=0.99). On the other hand, precisions of the method were 4.08% to 17.02%. Furthermore, compared with tradition extraction methods, the MAE-HS-SPME provides a time saving, easy for operation and solvent-free procedure.