气相色谱法测定海洛因含量的测量不确定度评定

目的探讨气相色谱法测定海洛因含量的测量不确定度评定。方法从测定程序分析不确定度来源,并计算各不确定度分量及合成不确定度,得出总不确定度。结果重复性测定不确定度分量最大,气相色谱仪误差次之,而玻璃容量器具天平及对照品所引起的不确定度分量对总不确定度的影响可忽略不计。结论气相色谱法测定海洛因含量的测量不确定度主要来源于重复性测定的误差及气相色谱仪的误差。     

The indirect detection of bleach (sodium hypochlorite) in beverages as evidence of product tampering

Bleach (sodium hypochlorite) has been identified as the adulterant in a relatively large number of product tamperings that have been investigated by the Forensic Chemistry Center (FCC) of the U.S. Food and Drug Administration. In this work, household bleach was added to 23 different beverages at each of three levels. The impact of sodium hypochlorite on these beverages over a 13-day study period was evaluated using the following techniques: diphenylamine spot test for oxidizing agents, potassium iodide-starch test paper for oxidizing agents, pH, iodometric titration for quantitating hypochlorite, ion chromatography for chloride and chlorate quantitation, automated headspace sampling with gas chromatography-flame ionization detection (GC-FID) for determination of chloroform, and visual and organoleptic observations. This study has shown that hypochlorite is fragile when added to most common beverages and typically breaks down either partially or completely over time. In cases where a beverage is suspected of being adulterated with bleach but tests for hypochlorite are negative, it is still possible to characterize the product to demonstrate that the results are consistent with the addition of bleach. An adulterated product will give a positive test for oxidizing agents using the diphenylamine spot test. It is likely that the pH of the adulterated product will be higher than a control of that product. Ion chromatographic analysis shows elevated chloride and chlorate as compared with a control. And, chloroform may also be detected by GC-FID especially if the beverage that was adulterated contains citric acid.     

Review of analytical techniques for arson residues

Arson is a serious crime that affects society through cost, property damage, and loss of life. It is important that the methods and technologies applied by fire investigators in detection of evidence and subsequent analyses have a high degree of reliability, sensitivity, and be subject to rigorous quality control and assurance. There have been considerable advances in the field of arson investigation since the 1950s. Classification of ignitable liquids has been updated to include many new categories due to developments in the petroleum industry. Techniques such as steam or vacuum distillation and gas chromatography (GC) with flame ionization detection that may have been considered acceptable--even a benchmark--40 years ago, are nowadays generally disfavored, to the extent that their implementation may almost be considered as ignorance in the field. The advent of readily available mass spectrometric techniques has revolutionized the field of fire debris analysis, increasing the degree of sensitivity and discrimination possible considerably. Multi-dimensional GC--particularly GC x GC--while not yet widely applied, is rapidly gaining recognition as an important technique. This comprehensive review focuses on techniques and practices used in fire investigation, from scene investigation to analysis.     

猪肺炎霉形体膜蛋白抗体间接ELISA检测方法的建立

通过提取猪肺炎霉形体ATCC25095株膜蛋白,并用免疫亲和层析柱对膜蛋白进行纯化,经SDS-PAGE分析得到了分子质量分别为66、50、46、42、32和24 ku的6种膜蛋白。以纯化的膜蛋白为包被抗原,建立了检测猪肺炎霉形体抗体的间接ELISA检测方法。结果显示,纯化的抗原具有更好的重复性和敏感性,对临床检测样品的检出率高于IDX ELISA试剂盒。     

Simultaneous Quantitative Determination of Amphetamines,Opiates, Ketamine,Cocaine and Metabolites in Human Hair: Application to Forensic Cases of Drug Abuse

A method using liquid chromatography–tandem mass spectrometry (LC–MS/MS) to simultaneously quantify amphetamines, opiates, ketamine, cocaine, and metabolites in human hair is described. Hair samples (50 mg) were extracted with methanol utilizing cryogenic grinding. Calibration curves for all the analytes were established in the concentration range 0.05–10 ng/mg. The recoveries were above 72%, except for AMP at the limit of quantification (LOQ), which was 48%. The accuracies were within ±20% at the LOQ (0.05 ng/mg) and between −11% and 13.3% at 0.3 and 9.5 ng/mg, respectively. The intraday and interday precisions were within 19.6% and 19.8%, respectively. A proficiency test was applied to the validated method with z-scores within ±2, demonstrating the accuracy of the method for the determination of drugs of abuse in the hair of individuals suspected of abusing drugs. The hair concentration ranges, means, and medians are summarized for abused drugs in 158 authentic cases.     

Fast Discrimination of Marijuana using Automated High-throughput Cannabis Sample Preparation and Analysis by Gas Chromatography–Mass Spectrometry

In the United States, federal law and many state laws differentiate between marijuana and industrial hemp through delta-9-tetrahydrocannabinol (THC) levels, whereby the latter is defined as ≤0.3 percent THC on a dry weight basis. Many traditional cannabis identification methods employed by crime laboratories cannot accurately determine total THC quantities in accordance with federal and state regulations, or do so with increased time, labor, and risks of instrument damage. In order to quickly distinguish positive marijuana samples, a method was developed to identify plant material with a total THC level >1%. This novel, automated dispersive pipette extraction (DPX) method uses tip-based technology and an automated liquid handler to enable fast, hands-free selective isolation of THC and its precursors for downstream gas chromatography–mass spectrometry (GC-MS) analysis. The workflow proceeds with no repetitive manual effort and reduced need for instrument maintenance while enabling crime labs to legally identify marijuana through the detection of total THC above 1%. Recovery of THC using the DPX extraction method was 93% at 30 µg/mL and 78% at 500 µg/mL. Similarly, THCA-A recovery was 100% at 30 µg/mL and 74% at 500 µg/mL. Samples evaluated in a blind study (proficiency, hemp, and nonprobative case samples) were all accurately identified as greater than or less than 1% THC, with samples containing <1% THC being identified as “cannabis” and subjected to more discriminative analysis as needed.     

Characterization of Algerian-Seized Hashish Over Eight Years (2011–2018). Part II: Chemical Categorization

In Algeria, large quantities of hashish are seized every year. This study aimed to investigate the total content of major cannabinoids in the illicit seized hashish in Algeria over an 8-year period (2011–2018) in order to establish the chemical profile of North African hashish. A total of 3265 hashish samples were analyzed using a validated high-performance liquid chromatography–diode array detection (HPLC-DAD) method, allowing the simultaneous quantification of both the acidic and the neutral forms of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN). The results revealed a slight upward trend in the mean THC content, from 7.0% in 2011 to 9.4% in 2018, with an overall mean value of 8.4%. The overall means of CBD and CBN content were 3.5% and 0.8%, respectively. The number of high-potency hashish samples gradually increased to reach 6% in 2018. Two distinct hashish chemotypes were identified: the highly populated chemotype II, corresponding to the traditional medium-potency hashish ([THC + CBN]/CBD ~ 2.16), and chemotype I, containing hashish samples of relatively high THC levels and low levels of CBD (ratio ~ 4.90). Both chemotypes I and II were characterized in the ternary plot, and the proportions (THC:CBD:CBN) were about 85%:13%:2% and 60%:35%:5%, respectively.     

绿萼梅药材超高效液相色谱指纹图谱研究

目的 采用超高效液相色谱法（ultra performance liquid chromatography,UPLC）建立绿萼梅药材的指纹图谱,为有效控制绿萼梅药材的质量奠定基础。方法 采用CORTECS C18色谱柱（2.1 mm×100 mm,1.6 μm）,以乙腈（A）-0.1%甲酸水（B）溶液为流动相进行梯度洗脱,进样量为1 μL,流速为0.3 mL/min,检测波长260 nm。结果 通过相似度分析确定19个色谱峰构成绿萼梅药材指纹图谱的特征峰。结论 采用UPLC方法建立的指纹图谱具有精密度、稳定性、重复性良好的特点,可为绿萼梅化学成分的进一步提取分离和药效物质基础的研究提供科学依据。     

苦地胆内酯类化合物的制备及其体外抑菌效果研究

为探讨中药苦地胆有效成分苦地胆内酯的抗菌效果,用浓度为800mL/L的乙醇溶液进行热回流浸提,制备苦地胆内酯的粗提物,经硅胶柱层析分离、纯化,再结晶,制得苦地胆内酯类化合物,用薄层层析法进行苦地胆内酯检测与鉴定,并进行了苦地胆内酯类化合物的体外抑菌试验。结果显示,当浓度为2.0mg/mL时,苦地胆内酯类化合物对巴氏杆菌、蜡状芽孢杆菌具有明显的抑制作用(P0.05),对金黄色葡萄球菌、肠炎沙门氏菌和鸡大肠杆菌呈现极明显的抑制作用(P0.01);浓度分别为50、10mg/mL时,苦地胆内酯类化合物对5种供试菌均有极明显的抑制作用(P0.01)。苦地胆内酯类化合物对供试金黄色葡萄球菌、肠炎沙门氏菌、巴氏杆菌、鸡大肠杆菌、蜡状芽孢杆菌的最小抑菌浓度分别为0.313、0.313、0.156、0.625mg/mL和1.25mg/mL;对蜡状芽孢杆菌的最小杀菌浓度为2.5mg/mL,对其他4种供试菌的最小杀菌浓度均为0.625mg/mL。表明,苦地胆内酯类化合物具有很好的体外抗菌效果。     

人血、尿中富马酸喹硫平的气相色谱分析

目的建立人血、尿中富马酸喹硫平的气相色谱分析方法。方法用乙醚提取血、尿中的富马酸喹硫平，直接对其进行定性、定量分析。以正常人血、尿为空白样本，分别添加标准富马酸喹硫平，确定检材的前处理方法、色谱分析条件、工作曲线、线性范围、方法的精密度、回收率等，并对1例大剂量服用富马酸喹硫平中毒死者的体液浓度进行测定。结果该方法分析血、尿中富马酸喹硫平的线性范围分别为8．0～800．0μg／ml和20．0—800．0μg/ml；最低检测限分别为0．04μg／ml和0．10μg／ml（S／N≥3），日内、日间精密度均小于4％，回收率在97．08％-101．42％之间。结论该分析方法操作便捷、实用、准确度高，适用于富马酸喹硫平的临床血药浓度快速监测和法医毒物鉴定。