發(fā)布時(shí)間：2018-09-11 11:51

【摘要】：尿素絡(luò)合法和5A分子篩法是常用的分離富集環(huán)境樣品中正構(gòu)烷烴的方法。尿素絡(luò)合法步驟多、流程長(zhǎng),每部分處理流程中都可能損失部分正構(gòu)烷烴,5A分子篩法受環(huán)境影響較大,兩種方法對(duì)于低含量正構(gòu)烷烴的回收率普遍較低。本研究通過優(yōu)化尿素絡(luò)合法的絡(luò)合條件(尿素用量、絡(luò)合反應(yīng)時(shí)間、絡(luò)合反應(yīng)溶劑、萃取溶劑等),減小了前處理流程中正構(gòu)烷烴的損失,較大幅度提高了正構(gòu)烷烴的回收率,建立了尿素絡(luò)合法分離-氣相色譜/同位素質(zhì)譜分析樣品中低含量正構(gòu)烷烴單體碳同位素的方法。優(yōu)化的實(shí)驗(yàn)流程為:采用正己烷-丙酮溶解樣品,加入2ml尿素-甲醇飽和溶液,放置于4℃冰箱中反應(yīng)48h;制備的尿素絡(luò)合物用去離子水溶解,加入正己烷后分離出有機(jī)相和水相,分別用正己烷、丙酮-正己烷萃取有機(jī)相和水相中的正構(gòu)烷烴,氣相色譜法(GC)測(cè)定正構(gòu)烷烴含量,氣相色譜-氣體同位素質(zhì)譜法(GC-C-IRMS)測(cè)定正構(gòu)烷烴單體碳同位素。低含量中長(zhǎng)鏈正構(gòu)烷烴(C19~C40)的回收率達(dá)79%~104%,高于5A分子篩法和已有尿素絡(luò)合法分離富集低濃度中長(zhǎng)鏈正構(gòu)烷烴的回收率;正構(gòu)烷烴單體碳同位素的分析精度為0.09%~0.63%(1σ)。利用建立的尿素絡(luò)合法分析實(shí)際樣品,能大幅降低未分峰和共流出的干擾,獲得良好的凈化效果,提高了實(shí)際樣品中低含量正構(gòu)烷烴的回收率,尤其能夠滿足環(huán)境樣品中的低含量中長(zhǎng)鏈正構(gòu)烷烴的單體碳同位素分析要求。
[Abstract]:Urea complexation method and 5A molecular sieve method are common methods for separation and enrichment of normal alkanes in environmental samples. There are many steps in urea complexation process and the process is long. The partial loss of n-alkane and 5A molecular sieve process may be affected by the environment in each part of the process. The recovery rate of the two methods for low-content n-alkanes is generally low. By optimizing the complexation conditions of urea complexation (urea dosage, complexation time, complexation solvent, extraction solvent, etc.), the loss of n-alkanes in the pretreatment process was reduced, and the recovery rate of n-alkanes was greatly increased. A method for the determination of carbon isotopes of low and low content n-alkane monomers by urea complexation and gas chromatography / isotope mass spectrometry was established. The optimized experimental process was as follows: the sample was dissolved with n-hexane-acetone, the saturated solution of 2ml urea-methanol was added, and the prepared urea complex was dissolved in deionized water at 4 鈩，

本文編號(hào)：2236613