Fast gas chromatography of explosive compounds using a pulsed-discharge electron capture detector

The detection of a mixture of nine explosive compounds, including nitrate esters, nitroaromatics, and a nitramine in less than 140 sec is described. The new method employs a commercially available pulsed-discharge electron capture detector (PDECD) coupled with a microbore capillary gas chromatography (GC) column in a standard GC oven to achieve on-column detection limits between 5 and 72 fg for the nine explosives studied. The PDECD has the benefit that it uses a pulsed plasma to generate the standing electron current instead of a radioactive source. The fast separation time limits on-column degradation of the thermally labile compounds and decreases the peak widths, which results in larger peak intensities and a concomitant improvement in detection limits. The combination of short analysis time and low detection limits make this method a potential candidate for screening large numbers of samples that have been prepared using techniques such as liquid-liquid extraction or solid-phase microextraction.     

Police officers’ judgements of veracity,tenseness, cognitive load and attempted behavioural control in real-life police interviews

Abstract

The present experiment examined the apparently incongruent findings that police officers (i) believe that suspects show nervous behaviour when they lie but (ii) seem able to detect deceit in suspects who do not show nervous behaviours. It was hypothesized that police officers’ judgements about whether a suspect is lying would not be correlated with their judgements regarding whether the suspect is tense, but, instead, would be correlated with their judgements regarding whether suspects are having to think hard or attempting to control their behaviour.

Each of 84 police officers saw seven truths and seven lies told by suspects during their police interviews. Participants in Condition 1 were asked to indicate after each clip whether the suspect was lying, whereas participants in Condition 2 were asked to note after each clip to what extent the suspect appeared to be tense, having to think hard or attempting to control their behaviour. Condition 3 was a combination of Conditions 1 and 2 and participants were asked all the above questions. The findings support the hypotheses and therefore negate the assumption that police officers primarily look for cues of nervousness when they attempt to detect deceit.     

Effectiveness of deception detection training: a meta-analysis

Abstract

A meta-analysis was conducted to determine the overall effectiveness of deception detection training and to identify conditions that may moderate training effectiveness. The analysis was based on a total of 16 studies with 30 separate hypothesis tests, representing the behavior of 2847 trainees. Results indicated that the effect of deception detection training on detection accuracy was positive, significant, and of medium magnitude. Moreover, training effectiveness was moderated by the type of training implemented, training content, trainee expertise, and the type of lie told. Discussion centers on implications for training design and implementation.     

Elaborations on credibility judgments by professional lie detectors and laypersons: strategies of judgment and justification

Abstract

Laypersons and professional lie detectors differ in biases of credibility judgment. The former are biased toward the truth, whereas the latter are biased toward lies. In an attempt to further understand these differences, the present study focused on the process of credibility judgment, rather than on its outcome. Forty-nine professionals (27 officers, 11 interrogators, 11 intelligence and secret services agents) and 40 laypersons (students) read an account of an event, and judged the credibility of the narrator; namely, the likelihood that he had actually experienced the event. Laypersons tended to believe the narrator more than professionals. The two groups also differed from each other in judgmental strategy (heuristic versus systematic) and justification (of either believing or disbelieving the narrator), and in the interpretation of the very same heuristics. Overall, the data showed that in credibility judgment laypersons and professionals process information differently: analyzing the very same statement, the former tended to consider it as true, whereas the latter tended to consider it as false. These data may partially account for the observed biases in credibility judgment of laypersons and professionals.     

Differential effectiveness of the cognitive interview in a simulation of testimony

The cognitive interview (CI) is a set of forensic evaluation procedures that has proven its efficiency. Nevertheless, little investigation has been made into its usage on witnesses with the intention of lying. With the aim of proving whether the efficiency of the CI is maintained where the witness is lying we carried out two experiments and we included instructions to tell the truth or to lie as independent variables. We used a 2 Type of interview (SI/CI)×2 Statement Condition (True/False)×2 Interviewee Gender (Male/Female) design with 18 interviewers in a sample group of 240 gender-matched university students being interviewed and the classic measures from the CI as dependent variables: the total number of details, details of actions, details about people and details concerning objects. In a first experiment, participants who lied exculpated the protagonist of a film fragment from rape, whereas in a second, those who lied accused an innocent protagonist. The results, in accordance with previous studies, showed a globally better efficiency for CI. Nevertheless, analysing the material based on type of details, this efficiency is only found in details concerning actions and objects. We discuss the forensic importance of these findings.     

基于眼动追踪测量认知负荷变化的犯罪心理测试

目的探索可用于认知犯罪心理测试的眼动指标及测试方法。方法对被测人进行视觉、听觉双通路-双任务模拟案件犯罪心理测试,要求被测人对相同问题分别进行诚实回答和欺骗回答,对不同眼动数据和行为数据进行分析。结果注视点离靶、眼跳次数、眨眼间隔随认知负荷（实施欺骗时）增加而增大,并未发现瞳孔变化与答题策略间存在特定关系。结论注视点、离靶距离等眼动指标能有效分析认知负荷变化且应用于认知犯罪心理测试。     

高效液相色谱-蒸发光散射法检测芪白平肺胶囊中3种人参皂苷含量

目的 采用高效液相色谱仪-蒸发光散射检测器(high performance liquid chromatography-evaporative light scattering detector, HPLC-ELSD)建立芪白平肺胶囊中人参皂苷Rg1、Re和Rb1的含量测定方法。方法 采用色谱柱为Hypersil ODS XB-C8柱(4.6 mm×250 mm,5 μm)和Hypersil ODS XB-C18柱(4.6 mm×250 mm,5 μm),以乙腈为流动相A、以水为流动相B进行梯度洗脱;洗脱程序(0～40 min,A 19%;40～55 min,A 19%～40%),流速为1.2 ml/min,柱温为30 ℃。ELSD参数优化：漂移管温度分别设为50、70、90、110 ℃,载气流量分别为1.0、1.2、1.4、1.6 L/min。结果 通过对比研究,最终采用Hypersil ODS XB-C8柱作为分析柱,漂移管温度为90 ℃,载气流量为1.2 L/min时,3种人参皂苷的含量检测结果最佳。人参皂苷Rg1、Re和Rb1的加样回收率分别为98.3%、99.1%、101.8%,RSD分别为0.67%、1.03%、1.22%。结论 所选择的色谱柱和优化的ELSD参数可准确测定芪白平肺胶囊中3种人参皂苷的含量,且重现性好。     

高效液相色谱-蒸发光散射法测定黄芪中单糖和双糖的含量

目的 采用高效液相色谱-蒸发光散射法建立黄芪中单糖和双糖含量的测定方法。方法 色谱柱为Waters X BridgeTM氨基柱（250 mm×4.6 mm,5 μm）,流动相为乙腈-水（70∶30）,流速为1.0 mL/min,柱温为30 ℃。蒸发光散射检测器参数：雾化器温度为50 ℃,漂移管温度为90 ℃,气体流量为1.60 L/min,增益值为1.0。结果 果糖、蔗糖和麦芽糖分别在0.10~0.90 μg（r=0.999 9）、1.00~9.00 μg（r=0.999 6）、0.25~2.25 μg（r=0.999 4）范围内其对数值与峰面积的对数值呈良好的线性关系;平均回收率分别为97.97%（RSD=1.56%）、97.82%（RSD=1.53%）、97.36%（RSD=1.59%）。结论 所建立的高效液相色谱-蒸发光散射法简单、准确、重复性好,可用于黄芪中单糖和双糖的含量测定。     

高效液相-二极管阵列法检测当归芍药散中主要化学成分

［摘要］目的 定性分析中药复方当归芍药散中的主要化学成分。方法 采用高相液相 二极管阵列检测法（high performance liquid chromatography-diode array detector, HPLC-DAD），色谱柱为Welchrom XB C18 (250 mm×4.6 mm，5 μm)，流动相为乙腈-0.05%磷酸水溶液（梯度洗脱）。二极管阵列扫描范围：200~400 nm。结果 通过实验并与已有文献的比较，利用HPLC-DAD检测后的三维图谱可找出中药复方当归芍药散中所含的主要化学成分川芎嗪、芍药内酯苷、芍药苷、阿魏酸、白术内酯Ⅰ、藁本内酯、23-乙酰泽泻醇B醋酸酯等。结论 HPLC-DAD可以对当归芍药散中主要化学成分做出准确定性，为其药效学研究提供依据。