论文标题:以铅笔芯为吸咐基质的固相微萃取研究及应用
Studies on sing Pencil Lead as Solid Phase Microextraction Sorbent and Its Application
论文作者 詹彤
论文导师 陆光汉,论文学位 硕士,论文专业 分析化学
论文单位 华中师范大学,点击次数 613,论文页数 53页File Size1487k
2001-05-01论文网 http://www.lw23.com/lunwen_219887/ 固相微萃取;铅笔芯;异戊醇;乙酸乙酯;顶空-固相微萃取; 甲醇
solid phase microextraction (SPME),alcohol,acetic ester,headspace (HS)-SPME,methanol
在众多的样品预处理法中，固相微萃取法（Solid PhaseMicroextraction-SPME）是一种非溶剂型萃取法，它是90年代初由Pawliszyn发展起来的。这种技术具有装置简单，分析时间短，灵敏度高，无需有机溶剂的优点。至今，SPME技术已成功的应用于许多领域，如：农药残留分析，酒的分析甚至生物样品的分析。在SPME装置中，石英表面的高分子涂层是决定萃取和富集能力的关键。近年来随着SPME技术的不断完善和发展，针对不同的分析物，新的固定相，吸附基质不断出现。但涂层不耐高温，易脱落，使用寿命短（30次），价格昂贵，限制了方法的应用范围。鉴于这些原因，近一步开发研制出适用性好，价廉易得的新型萃取介质和涂层对于SPME技术的发展有着极其重要的意义。本论文中我们使用了经物理及化学方法处理的铅笔芯作为SPME吸附基质，分析了的水中的有机物，克服了以上缺点得到了满意的结果，证明这种固相微萃取探头有着良好的应用前景。 （1）首先制备了铅笔芯探头：砂纸打磨后用氢氟酸浸泡一段时间，高温焙烧5-6小时，经此方法处理得到的吸附探头，去除了铅笔芯中会对分析造成影响的杂质，而且使探头对水中的有机化合物有着很好的吸附作用。使用次数更达到了80-90次。 （2）分别实验了甲醇，正丙醇，叔丁醇，正丁醇，异戊醇五种醇，实验数据表明，该探头对异戊醇的吸附最好。在选择的最佳萃取时间，解吸温度，解吸时间条件下，测定了该探头对异戊醇的富集率（10倍）。方法的线性范围是5×10~(-6)g/mL-2.5×10~(-8)g/mL，线性相关系数r=0.999。萃取30min时，最低检出限可达到1×10~(-8)g/mL。如果将萃取富集的时间延长至1小时其余条件不变，方法的检出限可以降低到5ng/mL。精密度RSD=5.9％。并与气相色谱仪联用测定了模拟样品中异戊醇的含量，加标回收率为107.5％和97％。 （3）使用经过处理的铅笔芯替代原商品化固相微萃取装置的涂有一定固定相的纤维测定了乙酸乙酯水溶液，优化了萃取条件，如：搅拌速度，萃取温度，解吸温度和时间，pH值，氯化钠的浓度等等，实验表明适当的升高温度，使用高速搅拌有利于萃取平衡。而溶液的pH值，氯化钠的浓度对萃取的影响则可以忽略。方法有较宽的线性范围（5 μg/ml-0.05μg/ml）和理想的检测限（1ng/ml），平均标准偏差小于6％，并测定了废 卜自霎霎。1 故＋堂a个寸 ＼“、一W ＼lASTERS TH日SIS 水中的乙酸乙酯，回收率为 96．3％。 N）顶空一固相微荤取的探头停留在溶液上方的顶空体积中，大大 减少和降低了样品基质对苹取的影响，而且革取平衡的时间更短。实验 中我们使用自制的铅笔芯吸附基质与顶空SPME联用测定了水中的的甲 醇。在选好的革取条件：水浴30C，高速搅拌，富集20min，170t解吸 2．smlll下，在5 x 10“‘一2x10－仑／mL范围内有很好的线性关系。线性相关。 系数 r＝0．9975。富集 30min，检出限为 0．5 X 10b／ml。
In the procedure of organic analyses, it is necessary to prepare the sample in order to pure and concentrate the analyte. Pawliszyn and co-workers recently introduced the new extraction technique, solid-phase microextraction (SPME). Solid-phase microextraction (SPME) preserves all the advantages such as simplicity, low cost, easy automation, and on-site sampling. SPME has been used in environmental, drug studies, food, pesticides and so on. The crucial part of the SPME device is the cover of the fiber. But to date these coating can"t stand high temperature, easy to drop off, the longevity of usage is short (SOtimes) and too expansive. The shortcoming limits the range of SPME usage. Pencil lead, a very convenient choice was used. As a new sorbent used in SPME, pencil lead has already showed a good characteristic.(1) We used commercial SPME handle, removed the silica fiber. First the pencil lead was ground thinner to fit the syringe needle using a piece of sandpaper. After that dipped the pencil lead in HF for 20h. And then baked at 290癈 for 5h before use. In general, the involved exposing it to the hot GC injection port (200癈) for at least 30mins until no peaks were detected in blank analyses. This kind of sorbent conquered the shortcomings of commercial SPME coating. The longevity of usage is (80-90times).(2) We used pencil lead as a new sorbent to analyze methanol, n-propanol, tertiary butyl alcohol, isoamyl alcohol, n-butanol in water. Among these five alcohols, isoamyl alcohol is the best analyte to pencil lead, The enrichment ratio of isoamyl alcohol is about 10 times. Under the optimum conditions, the linear is 5xlO-6--2.5*10VmL. The detection limit is SxW"g/mL. We also used this method to determine the concentration of alcohol in environment water. The recoveries are 107.5% and 97%. The RSD is 5.9%. So we can know that the pencil lead is a very good material of solid-phase microextrction (SPME).(3) Using pencil lead as a new sobent of solid-phase microextraction to analyze the acetic ether in aqueous sample. Optimized the extraction conditions: speed of agitation, temperature, pH and so on. This method has good precision (RSD<6%), wide linear relationship (5 ng/ml ? 0.05 ng/ml) , low detection limit (Ing/mL). This all facts proved that pencil lead has excellent future of application.(4) We used pencil lead as a new sorbent of HS-SPME to analyze the methanol in water. Optimize conditions like extraction time, stirring speed, headspace volume and so on. The linear is 5x10-6-2x10-7g/mL. The detection limit is 5xl0-8g/mL. We also used this method to determine the concentration of methanol in the wine. The recovery is 92.1-110%. The RSD is 5.4%.
|
