Analysis of nitriles at low parts per million levels by capillary gas chromatography

Two methods have been developed for the determination of trace levels of acetonitrile and propionitrile in light naphthas. One involves clean-up and preconcentration by medium pressure liquid chromatography (MPLC) in which nitriles are concentrated ten-fold while the complex hydrocarbon matris is removed. The concentrated solution is then analyzed by high resolution GC with flame ionization detection. The second method involves direct injection of samples into a capillary GC equipped with chemiluminescence nitrogen detection. The results and repeatability obtained from both methods are comparable. Preconcentration enables identification by GC-MS and simultaneous analysis of other polar species, with no need for selective detectors. Direct analysis is, on the other hand, much less time-consuming and requires less sample.     

石墨炉原子吸收法测定石脑油中微量砷

试样用四氢呋喃（THF）有机溶剂稀释，以硝酸镍为基体改进剂，研究采用石墨炉原子吸收法直接进样测定石脑油中的砷量。研究表明，砷量在0～50μg／L范围内线性关系良好，回收率93％～104％。     

同步荧光光谱方法测定柴油中的溶剂油

同步荧光光谱方法与表面荧光技术结合,研究了柴油中混120#溶剂油的荧光光谱.通过佑发射峰位置蓝移程度可以快速分析出柴油中是否含有120#溶剂油,并发现含有120#溶剂油的柴油其发射峰相对纯柴油的发射峰偏移量与柴油中含有120#溶剂油的百分含量具有一定的关系.通过这种关系可以定性的判断出柴油中掺杂120#溶剂油的多少,这对于分析市场上柴油的真伪、维护市场稳定具有重要的意义.     

Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO₃, the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO₃ medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.     

Determination of manganese in diesel,gasoline and naphtha by graphite furnace atomic absorption spectrometry using microemulsion medium for sample stabilization

The determination of Mn in diesel, gasoline and naphtha samples at µg L^− 1 level by graphite furnace atomic absorption spectrometry, after sample stabilization in a three-component medium (microemulsion) was investigated. Microemulsions were prepared by mixing appropriate volumes of sample, propan-1-ol and nitric acid aqueous solution, and a stable system was immediately and spontaneously formed. After multivariate optimization by central composite design the optimum microemulsion composition as well as the temperature program was defined. In this way, calibration using aqueous analytical solution was possible, since the same sensitivity was observed in the optimized microemulsion media and 0.2% v/v HNO₃. The use of modifier was not necessary. Recoveries at the 3 µg L^− 1 level using both inorganic and organic Mn standards spiked solutions ranged from 98 to 107% and the limits of detection were 0.6, 0.5 and 0.3 µg L^− 1 in the original diesel, gasoline and naphtha samples, respectively. The Mn characteristic mass 3.4 pg. Typical relative standard deviation (n = 5) of 8, 6 and 7% were found for the samples prepared as microemulsions at concentration levels of 1.3, 0.8, and 1.5 µg L^− 1, respectively. The total determination cycle lasted 4 min for diesel and 3 min for gasoline and naphtha, equivalent to a sample throughput of 7 h^− 1 for duplicate determinations in diesel and 10 h^− 1 for duplicate determinations in gasoline and naphtha. Accuracy was also assessed by using other method of analysis (ASTM D 3831-90). No statistically significant differences were found between the results obtained with the proposed method and the reference method in the analysis of real samples.     

Identification of compounds in gasoline range mixtures using combined group-type and capillary GC separations

Summary A procedure is described to improve the identification of the hydrocarbon isomers separated on a single capillary column. Group-type PNA separation was combined with capillary GC analysis. Different paraffin and naphthene groups separated by carbon number on the 13X column of a PNA-analyzer were heart-cut and analysed off-line by capillary GC. Capillary GC chromatograms of the trapped groups compared to that of the original sample helped to identify the peaks (at least by group-type), to clear up mixed peaks and to find out the ratio of the compounds co-eluting in that particular peak. Results were used to create identification tables for different types of naphthas. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

石脑油样品的族组成分析

用气相色谱以程序升温方式分析了石脑油 ,并将各组分程序升温保留时间转换为恒温保留指数。以各组分在OV -1和SE -54固定相上、同一柱温下的保留指数差及在各柱上的温度系数为3因素进行斜交因子分析和本征矢量旋转 ,给出了石脑油样品的族组成值 ,经色谱 -质谱仪分析验证了结果的正确性 ,为石脑油样品的族组成分析提供了一种新方法。     

One-pot synthesis of 12H-benzo[b]xanthen-12-ones and naphtha[2,3-b]furans from non-naphthalene substrates

An efficient one-pot synthesis of 12H-benzo[b]xanthen-12-ones via an oxidant initiated and base promoted tandem reaction of 2-(4-(2-haloaryl)-4-hydroxybut-1-ynyl)benzaldehydes has been developed. By using similar strategy, a one-pot synthesis of naphtha[2,3-b]furans from the cascade reaction of 2-(4-hydroxy-but-1-ynyl)benzaldehydes with 2-bromoacetonitrile or α-bromocarbonyl compounds has also been achieved.     

应用ICP-MS测定石脑油中硅的方法研究

采用优化的微波消解条件进行石脑油样品处理,应用ICP-MS对石脑油中硅含量分析方法进行了探索研究.方法的检出限为0.007μg/mL,相对标准偏差≤3.56%,样品加标回收率在92.7%-106.3%之间.该方法简便、快速,准确度高,适用于批量轻质石油样品中硅的检测需求.