Using Gas Chromatography with Ion Mobility Spectrometry to Resolve Explosive Compounds in the Presence of Interferents*

Abstract: Ion mobility spectrometry (IMS) is a valued field detection technology because of its speed and high sensitivity, but IMS cannot easily resolve analytes of interest within mixtures. Coupling gas chromatography (GC) to IMS adds a separation capability to resolve complex matrices. A GC‐IONSCAN^® operated in IMS and GC/IMS modes was evaluated with combinations of five explosives and four interferents. In 100 explosive/interferent combinations, IMS yielded 21 false positives while GC/IMS substantially reduced the occurrence of false positives to one. In addition, the results indicate that through redesign or modification of the preconcentrator there would be significant advantages to using GC/IMS, such as enhancement of the linear dynamic range (LDR) in some situations. By balancing sensitivity with LDR, GC/IMS could prove to be a very advantageous tool when addressing real world complex mixture situations.     

Potency Trends of Δ9‐THC and Other Cannabinoids in Confiscated Cannabis Preparations from 1993 to 2008*

Abstract: The University of Mississippi has a contract with the National Institute on Drug Abuse (NIDA) to carry out a variety of research activities dealing with cannabis, including the Potency Monitoring (PM) program, which provides analytical potency data on cannabis preparations confiscated in the United States. This report provides data on 46,211 samples seized and analyzed by gas chromatography‐flame ionization detection (GC‐FID) during 1993–2008. The data showed an upward trend in the mean Δ⁹‐tetrahydrocannabinol (Δ⁹‐THC) content of all confiscated cannabis preparations, which increased from 3.4% in 1993 to 8.8% in 2008. Hashish potencies did not increase consistently during this period; however, the mean yearly potency varied from 2.5–9.2% (1993–2003) to 12.0–29.3% (2004–2008). Hash oil potencies also varied considerably during this period (16.8 ± 16.3%). The increase in cannabis preparation potency is mainly due to the increase in the potency of nondomestic versus domestic samples.     

Using Alkylate Components for Classifying Gasoline in Fire Debris Samples

The characteristic that discriminates gasoline from other ignitable liquids is that it contains high‐octane blending components. This study elaborates on the idea that the presence of gasoline in fire debris samples should be based on the detection of known high‐octane blending components. The potential of the high‐octane blending component alkylate as a characteristic feature for gasoline detection and identification in fire debris samples is explored. We have devised characteristic features for the detection of alkylate and verified the presence of alkylate in a large collection of gasoline samples from petrol stations in the Netherlands. Alkylate was detected in the vast majority of the samples. It is demonstrated that alkylate can be detected in fire debris samples that contain traces of gasoline by means of routine GC‐MS methods. Detection of alkylate, alongside other gasoline blend components, results in a more solid foundation for gasoline detection and identification in fire debris samples.     

肺气虚证与肺阳虚证大鼠血气分析及血液流变学比较

目的 探讨血气分析及血液流变学在肺气虚证和肺阳虚证大鼠中的变化及其作用.方法 将雌雄Wistar大鼠30只随机分为对照组、肺气虚组、肺阳虚组,其中肺气虚证组模型单纯烟熏(香烟、锯末,0.5 h/d),肺阳虚证组采用烟熏和寒冷刺激(0～2 ℃,每次2 h,每日2次),以上各组连续处理7周后取大鼠腹主动脉血,进行血气分析和...     

生血宝颗粒中何首乌苷的含量测定

目的 测定生血宝颗粒中何首乌苷（2,3,5,4′-四羟基二苯乙烯-2-O-β-D葡萄糖苷）的含量。方法 采用高效液相色谱法,色谱柱为Agilent HC-C18(4.6 mm×250 mm×5 μm）;流动相为乙腈-水（18∶82）;流速为1.0 ml/min,检测波长为320 nm。 结果 何首乌苷进样量在3.580～114.5 μg/ml范围内与峰面积呈良好的线性关系（r=0.999 94,n=6）,RSD=1.3%;平均回收率为100.3%,RSD=1.76%。结论 高效液相色谱法简便易行,结果可靠,可有效地控制生血宝颗粒的质量。     

文莱油气产业发展现状与转型评析——基于石油公司竞争力的分析视角

鉴于文莱油气产业的发展特征,本文从石油公司竞争力的分析视角评析文莱油气产业的发展现状与转型。通过采取油气产业本土化、扩张油气下游产业、开放油气上游产业准入以及加强国际合作等措施,文莱油气产业转型与升级取得一定效果,但这与该国政府既定的目标还有较大的距离。如何降低国民经济对油气产业的高度依赖、拓展油气产业的相关产业,仍将是今后一个时期文莱政府需要努力的方向。     

Analysis and Discrimination of Single‐Layer White Architectural Paint Samples,

Comparative analyses of 50 single‐layer white architectural paints were conducted to determine the discrimination power using standard techniques and to provide a basis for assessing significance when paints with limited features are not discriminated. Utilizing Fourier transform infrared spectroscopy (FTIR), 68 undifferentiated pairs resulted, yielding a discrimination of 94.45%. Adding stereomicroscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and backscatter electron (BSE) imaging, and pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), the overall discrimination was 99.35%. The study included blind verification replicates, which resulted in the only pairs without indications of physical or chemical differences. The remaining groups of undifferentiated samples contained subtle differences by at least one technique, but were considered undifferentiated for the discrimination power evaluations. This study demonstrates a high degree of discrimination of single‐layer white architectural paints using methods of analysis often encountered in forensic science laboratories.     

Methyl tert‐Butyl Ether (MTBE) Detected in Abnormally High Concentrations in Postmortem Blood and Urine from Two Persons Found Dead Inside a Car Containing a Gasoline Spill

Two deep frozen persons, a female and a male, were found dead in a car. There had been an explosive fire inside the car which had extinguished itself. On the floor inside the car were large pools of liquid which smelled of gasoline. The autopsy findings and routine toxicological analyses could not explain the cause of death. Carboxyhemoglobin levels in the blood samples were <10%. Analysis with a headspace gas chromatography revealed methyl tert‐butyl ether (MTBE) concentrations of 185 mg/L (female victim) and 115 mg/L (male victim) in peripheral blood. The urine MTBE concentrations were 150 mg/L and 256 mg/L, respectively. MTBE is a synthetic chemical which is added to gasoline as a fuel oxygenate. Gasoline poisoning is likely to be the cause of the death in these two cases, and MTBE can be a suitable marker of gasoline exposure, when other volatile components have vaporized.     

不同炮制温度和时间对炮姜中姜酮含量的影响

目的 考察不同炮制温度和时间对炮姜中姜酮含量的影响。方法 采用超高效液相色谱法对15份不同炮制温度和炮制时间的炮姜样品中姜酮含量进行测定。色谱条件：色谱柱为Acquity BEH C18（100 mm×2.1 mm,1.7 μm）;流动相为乙腈-水,梯度洗脱;流速0.3 ml/min,检测波长280 nm,柱温30 ℃。结果 姜酮进样量在0.073 2～0.366 0 μg时与峰面积呈良好的线性关系（r=0.999 8）,平均加样回收率为97.42%（RSD=2.35%）。炮姜中姜酮含量随着炮制温度和时间的变化明显,以炮制温度为200 ℃、炮制时间为6 min时样品中姜酮含量最高。结论 炮制过程中姜酮含量随着温度升高和时间延长呈现先升高后降低的趋势,所建立的超高液相色谱法简便、准确、重现性好,可用于炮姜中新生成分姜酮的测定。     

SPE-GC/MS 法分析鱼塘水中的5种农药

目的：建立鱼类中毒案件中鱼塘水5种农药的固相萃取（solid phase extraction,SPE）结合气相色谱－质谱联用仪（GC/MS）的检测方法。方法比较 Oasis HLB cartridge、Bond Elut C18和 SampliQ C183种固相萃取柱提取、净化鱼塘水中5种农药的提取回收率,并考察洗脱剂种类、洗脱剂用量对提取回收率的影响。结果利用 Bond Elut C18固相萃取柱,以3mL 苯作为洗脱剂,鱼塘水中5种农药质量浓度在1~50μg/mL范围内有良好的线性关系,相关系数为0．9962~0．9996,测得的检出限为3．4~26μg/L,提取回收率为61．49%~102．48%,相对标准偏差均≤3．01%。结论 SPE－GC/MS 法灵敏度高、准确度和精密度好,简单快速,溶剂消耗量少,适用于鱼塘水中5种农药的检测。