| 摘要: | 直鏈式烷基苯基二甲基銨鹽類(Alkylbenzyldimethyl ammonium chloride，ABDACs)為主要陽離子型界面活性劑之一，在臺灣的年生產量大約8000噸，且有逐年增加的趨勢，最常被使用作殺菌劑，其同系物有C12-，C14-，C16-BDACs ，另有C18-BDAC被用做潤髮劑。由於臺灣廢水處理廠的使用率不過5%而已，大部分ABDACs將直接被排放至河川或海洋中，且此類有機污染物在水環境中具有毒性與持久性，因此有必要發展一套方便的分析檢測方法，來探討ABDACs在水環境中的來源與宿命。 本研究主要是改善先前分析水中和土壤中ABDACs的方法，藉加入直鏈式烷基苯磺酸鹽類(Linear alkylbenzenesulfonates，LAS)形成親油性的離子對錯合物，以增加ABDACs 在固相萃取管中的萃取效果，利用甲醇-乙酸乙酯混合液沖提後，再行Hofmann degradation ，衍生化成直鏈式烷基二甲基胺(Alkyldimethyl amine )，並以GC-MS作定性與定量。結果顯示，此方法具有高精確性和靈敏度，在500 ml水樣中的偵測極限達0.1μg/L ; ABDACs的平均回收率分別為:89%、104%、98%、90%，相對標準偏差(RSD)分別為4.4%、12%、12%、7%。而台灣各河水中偵測ABDACs的總含量約為2.5~65μg/L。 Alkylbenzyldimethyl ammonium chlorides (ABDACs) are widely used cationic surfactants, which is the mixture of unbranched alkyl homologues of dodecyl- (C12-), tetradecyl- (C14-), hexadecyl- (C16-) and octadecyl (C18-) benzyldimethyl ammonium chlorides. In Taiwan, more than 8,000 metric tons of cationic surfactants are produced and consumed each year. Here, C12-, C14- and C16-ABDACs are applied as bactericides, disinfectants and sanitizer in sanitary products, and antistatic agents in textile-softener formulation. For C18-ABDAC, it is applied mostly as a major ingredient in hair conditioners, which imparts softness, manageability and antistatic properties to hair. However, less than 5% of all wastewater is treated by wastewater treatment plants in Taiwan. Large quantities of these surfactants in wastewaters are discharged into the rivers and ocean directly. Due to the toxicity and their persistence, it is vital to develop a convenient analytical technique to study the occurrence and fate of cationic surfactants in the aquatic environment. This work presents a modified method to analyze ABDACs residues in the samples of river water and sewage effluent. The method involves mixed sample with linear alkylbenzenesulfonates (LAS) as a counter-ion to enhance extraction of native ABDACs residues from RP-18 solid-phase cartridge by formation of hydrophobic ion-pair complexes. The ABDACs were then eluted by methanol-ethyl acetate, and formed to their corresponding alkyldimethylamines by the Hofmann degradation with potassium tert.- butoxide. The products were then identified and quantitated by GC-MS. The technique provides high precision and sensitivity for ABDACs, to quantitation at < 0.1 ?g/L in 500 ml of water samples. The effect of the temperature for alkyldimethylamine formation was examined. The results indicate that the debenzylation of ABDACs proceeds selectively at higher than 90?C to produce the corresponding alkyldimethylamines when LAS presents. The average recovery of ABDACs spiked water samples was 95% with relative standard deviations (RSD, n=7) 9%. The RSDs of three replicate environmental sample analyses ranged from 5 to 11%. The analytical procedure developed herein demonstrated that the RP-18 SPE and GC-MS methods with the Hofmann degradation reaction are reliable, sensitive and offer a convenient analytical technique for trace determination of ABDACs residues in complex environmental samples. The present method reveals that ABDACs residues are widespread in Taiwanese rivers. |
