本研究是利用固相微萃取法(簡稱SPME)來分析水中人工合成除蟲菊酯系殺蟲劑(Pyrethroids pesticides)。研究的對象有畢芬寧(Bifenthrin)、賽洛寧(λ-Cyhalothrin)、百滅寧(Permethrin) 、賽扶寧(Cyfluthrin) 、第滅寧(Deltamethrin)等五種除蟲菊酯殺蟲劑，此五種也是台灣目前最常用的殺蟲劑。分析方法是利用65 μm PDMS/DVB纖維針，以頂空萃取方式，結合氣相層析儀(GC)搭配電子捕獲偵測器(ECD)來進行人工合成除蟲菊酯殺蟲劑分析。實驗過程並探討SPME萃取之最佳化條件。
牛乳加熱時會放出揮發性硫化物，此硫化物即為加熱臭，並影響飲用牛奶的風味。硫化物的來源為β-乳球蛋白經熱裂解而產生。本研究利用頂空式固相微萃取(Headspace Solid phase microextraction, HS-SPME)和薄膜保護浸入式固相微萃取法(Hollow fiber membrane-protected solid-phase microextraction, HFM-SPME) 結合氣體層析儀/無火焰式硫化學發光偵測器(Gas chromatography/ Fameless Sulfur chemiluminescence detection) 來分析和偵測牛奶中揮發性的硫化物。此方法為一套快速、精確且有效的分析方法。
由實驗結果顯示，零脂牛奶中硫化物含量分別為甲硫醇3.06~4.11 ng/mL，二甲基硫0.05 ng/mL，二甲基二硫 0.01~0.02 ng/mL和二甲基三硫0.01 ng/mL；全脂牛奶中含甲硫醇0.45 ng/mL，二甲基硫0.08~0.11 ng/mL，二甲基二硫0.02ng/mL和 二甲基三硫0.01 ng/mL 。
A method for analyzing of pyrethroid pesticides in water solution by solid-phase microextraction (SPME) and gas chromatography (GC) is described. Five kinds of pyrethroid pesticides, including Bifenthrin, λ-Cyhalothrin, Permethrin, Cyfluthrin and Deltamethrin were determined. These were once widely used to control insects for crop production in Taiwan. Experimental design was achieved by using 65 μm polydimethylsiloxane-divinylbenzene (PDMS-DVB) SPME fiber and used the HS-SPME mode to extract the pyrethroid pesticides from water sample and determined by GC with ECD . The influence of the extraction process was also studied and optimized.
HS-SPME experimental parameters such as extraction temperature, extraction time, salt concertation and pH values were investigated and optimized. From our experimental results show that the optimized conditions were : 60 min extraction at 100℃, 1% NaCl content and pH 4 for pyrethroid pesticides in water solution.
Many volatile compounds generated during the thermal processing of milk have been related to stable, sulfurous and cooked flavor in milk. Volatile sulfides were derived from the sulfhydryl groups of β-lactoglobulin for the “cabbagey” and “cooked” flavor in heated milk; however, their analysis has been a challenge due to their high reactivity, high volatility, and low sensory threshold (sensitive limit). To quantitative determination of volatile sulfur compounds (VSCs) in milk by headspace (HS-SPME) and hollow fiber membrane-protected solid-phase microextraction (HFM-SPME) with Gas chromatography-Flameless Sulfur chemiluminescence detection (GC-Flameless SCD) was investigated in this study. This method provides a very simple and fast technique.
There are three parts to study in this research, including (1) The sulfur compounds generated during the thermal processing of skim and whole milk. (2) Calibration curves were established from standard solution for methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMDS). (3) HS-SPME experimental parameters such as extraction temperature, extraction time, salt concertation and pH value were investigated.
From our experimental results, the concentrations of sulfur compounds in skim milk were 3.06~4.11 ng/mL for MeSH, 0.05 ng/mL for DMS, 0.01~0.02 ng/mL for DMDS, 0.01 ng/mL for DMTS and the concentrations of sulfur compounds in whole milk were for 0.45 ng/mL MeSH, 0.08~0.11 ng/mL for DMS, 0.02 ng/mL for DMDS, 0.01 ng/mL for DMTS, respectively.