Studies On Sing Pencil Lead As Solid Phase Microextraction Sorbent And Its Application

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%.