Detection limits for GC/MS analysis of organic explosives

Method detection limits are determined and compared for analysis of liquid injections of organic explosives and related compounds by gas chromatography-mass spectroscopy utilizing electron impact (EI), negative ion chemical ionization (NICI), and positive ion chemical ionization (PICI) detection methods. Detection limits were rigorously determined for a series of dinitrotoluenes, trinitrotoluene, two nitroester explosives, and one nitramine explosive. The detection limits are lower by NICI than by EI or PICI for all explosives examined, with the exception of RDX. The lowest detection limit for RDX was achieved in the PICI ionization mode. Judicious choice of the appropriate ionization mode can enhance selectivity and significantly lower detection limits. Major ions are reported for each analyte in EI, PICI, and NICI detection modes.     

Trace analysis of urea nitrate in post-blast debris by GC/MS

Urea nitrate (uronium nitrate, UN) is an improvised explosive that looks very much like sugar and is easily made from accessible starting materials, urea and nitric acid. During the last decade it has been frequently used by terrorists in the Israeli arena and in other countries as well. It is difficult to identify urea nitrate in post-explosion debris, since only a very small fraction survives the blast. Also, in the presence of water, it readily decomposes to its original components, urea and nitric acid, two ubiquitous substances with relatively low evidential value. By further modifying McCord's recent version of Clark's method for the detection of minute amounts of urea, we were able to identify with high degree of certainty traces of uronium ion, the main characteristic factor of urea nitrate, in post-blast residues by GC/MS. The analytical process is based on the initial formation of xanthenyl urea by the reaction of uronium cation with xanthydrol, followed by reaction with alcohol to form xanthylurethane, which is readily identified by GC/MS. The reaction mechanism was corroborated by the use of labeled ¹⁵N-urea. By applying the technique to residues collected from scenes of controlled firing experiments, 4 out of 16 samples showed the presence of uronium cation as indicated by the formation of the corresponding xanthylurethane. Potential interferences such as urea and ammonium nitrate did not respond under standard conditions. However, under strongly acidic conditions (pH < 2), urea is converted into uronium ion, which is a nuisance, since it behaves as an authentic uronium cation. Such conditions, however, do not prevail at common crime scenes.     

生物试样中巴比妥类药物固相提取柱上衍生化GC/MS分析

建立生物试样中常见巴比妥类药物的固相提取和柱上衍生化GC／MS分析法。将预制的血或肝分别在pH6．0和pH2.2的条件下过预活化的GDX－403吸附小柱，再用缓冲浪和蒸馏水各4ml顺序洗柱。最后用4ml丙酮／氯仿（1：1）溶剂洗脱样品，离心弃除水相，80℃挥至近干，用50μl乙醇定溶、取净化的样品2～4μl挥至近干，加20μl0．2molTMAH衍生化试剂，直接进样0.5μl，柱上衍生化GC／MS（GC）分析。在试验条件下，当血和肝分别添加2．0μg和5．0μg混合药物，回收率≥80％，相对标准差（RSD）优于±10％，检测限优于5ng（信／噪比≥2）。该法能有效地排除类脂物和组胺的干扰，可用于治疗量级药物分析和婴幼儿中毒案检验。     

快速溶剂萃取-气相色谱/质谱法分析血液中的4种滥用药物

目的 建立生物检材血液中滥用药物的快速溶剂萃取（ASE）方法.方法 通过优化快速溶剂萃取各参数,提取血液中的滥用药物进行GC/MS定性定量分析.结果 血液中美沙酮、可卡因、蒂巴因、海洛因4种滥用药物的平均回收率在87.8％～97.5％之间,滥用药物在0.4μg/mL～4.0μg/mL的浓度范围内线性良好.结论 该方法具有操作简便快捷,回收率高、重现性好等特点,可广泛应用于生物检材血液中滥用药物的检验鉴定.     

HS/GC/ECD分析生物检材样品中的氰化物

目的 建立生物样品中氰化物的衍生化定性定量分析方法。方法 用氯胺T衍生化,HS/GC/ECD分析衍生物CICN。结果 在1ml血中,添加0.2μg氰化钾,回收率为84.6％,RSD为6.39％;在1g肝中添加0.5μg氰化钾,回收率为67.3％,RSD为5.05％;血中检出限为5ng/ml。结论 所建方法能定性定量分析生物样品中的氰化物。     

分散固相萃取-GC/MS法测定人血中啶虫脒的含量

目的建立人血中新型农药啶虫脒的检验方法。方法用分散固相萃取法提取人血中啶虫脒,GC/MS/SIM法进行测定。结果在0.02μg/mL～2μg/mL添加水平范围内,线性关系良好,啶虫脒的平均添加回收率在76.4%～89.8%之间,相对标准偏差在1.3%～8.3%之间,啶虫脒的检出限为0.0075μg/mL。结论该方法操作简便,结果准确,适用于人血中啶虫脒的检验。     

血中毒鼠强的固相萃取和GC-NPD法测定

目的 研究人全血中毒鼠强的固相革取(SPE)。方法 用Bond Elute C18固相萃取柱萃取,GC-NPD检测,以甲基对硫磷为色谱内标(CS)。结果 全血中加标0.5μg/ml,毒鼠强回收率为92.5％,变异系数2.3％(CV,n=4)。在0.5～10μg/ml的浓度范围内,线性相关系数为0.9994。检出限(S/N=3)和定量限(S/N=10)分别为6ng/ml和20ng/ml。同一根萃取柱连续使用6次未见性能明显下降(CV=3.6%)。结论 本文方法适用于毒鼠强中毒的全血测定。     

Novel technique for the combined recovery, extraction and clean-up of forensic organic and inorganic trace explosives samples.

This paper describes a simple processing and analysis scheme for explosives trace swab samples which deals both with organic and inorganic materials. Swabs, wetted with ethanol or ethanol/water mixture, were extracted with ethanol/water mixture. The extract was passed directly through a simple column containing an acrylonitrile/styrene copolymer adsorbent. The adsorbent retained common organic explosives, which were recovered with an efficiency of 30-50% as a relatively clean ethyl acetate solution. The concentrated ethyl acetate eluate was analysed using gas chromatography with chemiluminescence or mass spectrometric detection. The unretained inorganic ions and sugars, which were recovered with generally high efficiency as an ethanol/water solution, could be directly analysed using ion chromatography and/or capillary electrophoresis. Minor difficulties encountered in the analysis of sugars, fluoride and phosphate were examined.     

SPME与GC/MS相结合检验尿液中的氯胺酮

目的应用固相微萃取与气相色谱-质谱联用技术分析尿液中的氯胺酮。方法对影响SPME萃取效果的萃取头类型、萃取时间、解析时间、离子强度等因素条件进行优化,分析尿中氯胺酮。结果在0.5~2.5μg/m l范围内线性关系良好,线性相关系数为0.995 6;最小检出限为2.5μg/L。结论该方法具有预处理简单、分析速度快、灵敏度高等优点,适合实际案件尿样的检验。     

快速溶剂萃取-GC／MS法测定全血中沙蚕毒素

目的采用快速溶剂萃取-GC／MS分析方法检验血液中杀虫双代谢产物沙蚕毒素。方法样本用硅藻土、中性三氧化二铝处理，用乙酸乙酯：环己烷：丙酮（2：2：1）进行萃取，GC／MS方法进行测定，并考察实验最佳条件。结果沙蚕毒素在50～2000ng／mL范围内线性关系良好，相关系数为0．999，检测限为15ng／mL，平均回收率为98．22％，相对标准偏差为4．6％。结论速溶剂萃取-GC／MS分析方法简便，快速，准确、灵敏度高，可在血中沙蚕毒素检验中选用。     

Evaluation of extraction techniques for the forensic analysis of human scalp hair using gas chromatography/mass spectrometry (GC/MS)

Preliminary research using on-line supercritical fluid extraction/gas chromatography-mass spectrometry (SFE/GC-MS) has shown that the natural and artificial surface components of human scalp hair are reproducible and differentiable. Therefore, these components may be useful for individualization or determining demographic characteristics or both. However, it is not known how the efficiency and selectivity of on-line SFE/GC-MS compares to other extraction methods. In this study, ultrasound, Soxhlet, and pressurized-fluid extraction were used to extract 1 mg to 1.3 g portions of a composite hair sample taken from an Asian male between the ages of 10 and 18. Percent extractables ranged from 0.9% to 5.6%, depending on the solvent used, and tended to increase with solvent polarity. Chemical analysis using GC/MS showed that the extracts contained large proportions of free fatty acids, squalene, cholesterol, and various wax esters. Finally, comparisons to SFE/GC-MS showed that this method possesses adequate efficiency, no observable differences in selectivity, and greater potential for miniaturization.     

Simple analysis of arylamide herbicides in serum using headspace-solid phase microextraction and GC/MS

A simple and sensitive method for analysis of four arylamide herbicides (butachlor, propanil, diphenamide and propyzamide) in serum was developed using a headspace–solid phase microextraction (SPME) and a gas chromatograph–mass spectrometer (GC–MS). A vial containing a serum sample and sodium chloride was heated at 90°C. The extraction fiber of the SPME was exposed for 45 min in the headspace of the vial. The compounds adsorbed on the fiber were desorbed by exposing the fiber in the injection port of the GC–MS. The calibration curves, using an internal standard method, demonstrated good linearity throughout the concentration range from 0.25 to 10.0 μg/ml. Propyzamide was used for an internal standard. The limit of detection was 0.10, 0.05, and 0.25 μg/ml for butachlor, diphenamide, and propanil, respectively. No interferences were found, and the time for analysis was 60 min for one sample. In addition, this proposed method was applied to a suicide case in which the patient ingested Kusanon A^®, a herbicide. Propanil, which was the main ingredient in the herbicide, was detected in the eight serum samples collected from the patient during the hospitalization at the concentration range from 26.7 to 1.1 μg/ml.     

Optimization of the separation of organic explosives by capillary electrophoresis with artificial neural networks

The separation of 12 explosives by capillary electrophoresis was optimized with the aid of artificial neural networks (ANNs). The selectivity of the separation was manipulated by varying the concentration of sodium dodecyl sulfate (SDS) and the pH of the electrolyte, while maintaining the buffer concentration at 10 mM borate. The concentration of SDS and the electrolyte pH were used as input variables and the mobility of the explosives were used as output variables for the ANN. In total, eight experiments were performed based on a factorial design to train a variety of artificial neural network architectures. A further three experiments were required to train ANN architectures to adequately model the experimental space. A product resolution response surface was constructed based on the predicted mobilities of the best performing ANN. This response surface pointed to two optima; pH 9.0-9.1 and 60-65 mM SDS, and pH 8.4-8.6 and 50-60 mM SDS. Separation of all 12 explosives was achieved at the second optimum. The separation was further improved by changing the capillary to an extended cell detection window and reducing the diameter of the capillary from 75 microm to 50 microm. This provided a more efficient separation without compromising detection sensitivity.     

固根萃取技术在系统药、毒物分析中的应用

根据反相色谱法及离子交换色谱法的原理,研制了一种固相萃取小柱,建立了筛分系统,可以同时完成对复杂体系中酸性、中性及碱性药、毒物的一次革取净化及富集,适应于系统毒物及药物筛分工作的需要。并对筛分柱的草取机理进行了初步的实验论证。     

固相微萃取结合气质联用测定血浆中敌草快

目的采用固相微萃取结合气相色谱-质谱联用方法快速测定血浆中的敌草快含量。方法采用硼氢化钠/氯化镍还原反应和顶空固相微萃取处理样本,气质联用检测方法,以乙基百草枯为内标,检测血浆中敌草快的含量,对还原反应和萃取的温度、时间等实验条件进行优化,并对方法学进行评价。结果采用m/z 194作为定性定量离子,在0.1~50μg/mL浓度范围内线性关系良好（Y=0.076 9X＋0.274 8,r2=0.997 5）,日内和日间精密度分别小于3.99%、5.64%。回收率为92.59%~101.27%,最低定量限为50ng/mL。敌草快还原产物1,1’-乙基-2,2’-联哌啶存在顺式和反式两种同分异构体,两者比率为1∶5.3,相对标准偏差为13.1%（n=17）。结论本文方法准确、快速、重现性好,可以在血浆等生物样品敌草快含量测定中选用。     

生物检材中巴比妥类药物固相萃取及分析方法

目的建立生物检材中巴比妥类药物的提取净化和定性定量分析方法；方法应用固相萃取法提取生物检材中巴比妥类药物，比较了巴比妥类药物固相萃取的最佳pH值、固相吸附柱等提取条件；结果确定了巴比妥类药物的GC／NPD线性范围和GC／MS检出限；结论该方法实用，提取率高，杂质干扰少，为实际案件中巴比妥类药物的提取净化和定性定量分析提供了方法和依据。     

血尿肝中毒鼠强硅藻土提取GC／NPD检测法

目的建立硅藻土提取气相色谱测定血、尿、肝中毒鼠强的方法。方法原尿液、血液用水稀释、肝匀浆用6％高氯酸沉淀蛋白的上清液倒入硅藻土小柱中，血和尿用苯洗脱，肝用三氯甲烷洗脱，挥干洗脱液，用甲醇定容至0．1ml。结果血提取率98．4％，尿提取率95．6%，肝提取率98．1％。相对标准偏差低于3．2％，检出限低于20ng／ml（g）。结论该法简便、快速，提取率高，适合作为常规毒物分析方法。     

Solid phase extraction method for rapid isolation and clean-up of some synthetic pyrethroid insecticides from human urine and plasma.

A simple and rapid method for the isolation of seven synthetic pyrethroid insecticides (methothrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fenvalerate, deltamethrin) with a solid phase extraction (SPE), utilizing Sep-Pak C18 cartridges, from human urine and plasma is presented. The detection of the insecticides was performed using a wide bore capillary gas chromatograph (GC) with flame ionization detection (FID). The insecticide-containing samples mixed with 70% methanol were directly applied to the cartridges and eluted with 2 ml chloroform. The recoveries using the cartridges were between 90-102% for urine and 81-93% for plasma. Mixing samples with 70% methanol prior to extraction, seems very useful for the screening of synthetic pyrethroid insecticides.     

有机爆炸物的现场非介入性检测——顶空固相微萃取一真空气相色谱质谱法

本文考察了顶空固相微萃取在有机爆炸物现场非介入性检测中的适用性。由固相萃取（SPME）纤维头吸附的有机爆炸物用真空气相色谱一质谱联用仪进行检测。该方法所需的洗脱温度低,色谱分离时间短。SPME适用于提取蒸汽压不低于2．4,6-三硝基甲苯（TNT）的挥发性和半挥发性有机爆炸物,如较易挥发且不稳定的化合物三过氧化三丙酮（TATP）的非介入性检测就可以应用该方法。本研究使用静态顶空,尽可能地减少顶空体积,实现了较高的灵敏度。在现场,SPME方法的灵敏度受环境温度的影响较大：由于样品的蒸汽压未达到平衡,在固定顶空体积和萃取时间的条件下,SPME纤维头萃取的样品总量随温度的提高而增加。在有合适容器的情况下SPME纤维头上萃取的样品在取样3天后仍然能顺利检测。