Rapid screening of inorganic poisons by column-switching ion chromatography

1998年，和歌山发生了一起非同寻常的谋杀案；4人死亡。事件发生后，又发生了多起模仿中毒案件。一些无机化合物，如砷、氰化物或叠氮化物，被用于中毒案件。叠氮化钠在2000年被《有毒有害物质控制法》列为有毒物质。因此，用较少的人工快速筛选这些无机化合物是很重要的。离子色谱法（IC）已广泛应用于无机阳离子和阴离子的分离；虽然集成电路不能识别和指定这些无机离子，但它易于使用和高度定量。到目前为止，集成电路主要应用于环境样品，如地表水样品。在本项目中，我们试图建立一种简单、快速和可靠的方法来分析生物样品中的无机离子。叠氮化钠是广泛用于实验室试剂的防腐剂。然而，它是剧毒的，超过1克叠氮化钠就会致命。在大鼠中，其口服LD_<50>值估计为45 mg/kg，仅为氰化钾的5倍。因此，我们开发了一种简单的分析叠氮化钠的方法。我们尝试了几种从生物样品中纯化叠氮化物的方法；结果表明，Conway扩散法具有简便、快速的优点。采用康威微扩散池提取各种样品中的叠氮化物离子；1 mL样品（血浆或饮料）外槽中加入1 mL 5%硫酸汽化水合苯甲酸，在中央圆盆中加入250 μL 0.1 M NaOH溶液吸收。37℃下30分钟的孵育足以从生物样品中纯化叠氮化物。为了进行IC分析，将20 μ l的样品放入装有抑制器和电导率检测器的IC系统中（Dionex， DX 500系统）。柱前柱和分离柱为ag15 （20 mm × 2mm直径）和as15 （250 mm × 2mm直径）半微柱。流动相为38 mM NaOH，流速为0.4 mL/min。叠氮离子的停留时间约为10 mm。结合康威扩散法中NaOH溶液的还原和半微柱的使用，与以前报道的方法相比，灵敏度提高了4到5倍；血清样品的检出限约为30 ng/mL，在50 ng/mL和10 μg/mL血清范围内具有良好的线性关系，对该方法进行了验证；日间和日常测量的CV值分别小于6.8%和93%。以饮料为例，由于某些杂质峰的干扰，需要采用康威扩散法进行准确定量。口服给药（10 mg/kg） 1、4小时后，在大鼠血清中检测叠氮化物离子。该方法简便、灵敏，可应用于临床和法医毒理学。我们现在正在准备提交论文。在接下来的研究中，我们将获得不同样品在几种环境条件下叠氮化物离子衰变的数据。少

In 1998, an extraordinary murder incidence took place in Wakayama ; 4 victims were killed. After the incidence, a lot of imitative poisoning cases occurred. Several inorganic compounds, such as arsenic, cyanide or azides, were used in the poisoning cases. In the case of sodium azide, it was then regulated as a poison by the Poisonous and Deleterious Substances Control Law in 2000. It is thus important to screen these inorganic compounds rapidly with less labor. Ion chromatography (IC) has been widely used for the separation of inorganic cations and anions ; IC is easy to use and highly quantitative, although IC cannot identify and specify these inorganic ions. So far, IC has been applied mainly for environmental samples, such as surface water samples. In this project, we have tried to develop simple, rapid and robust methods for the analyses of inorganic ions in the biological samples by IC.Sodium azide is widely used as preservative for laboratory reagents. However, it is highly toxic … More and the intake of about I g sodium azide would be fatal. In rat, its oral LD_<50> value is estimated to be 45 mg/kg, which is only 5 times greater than that potassium cyanide. Thus we have developed a simple method for analysis of sodium azide. We tried several methods for purification of azide from biological samples ; it was revealed that Conway diffusion method would be simple and fast. Azide ion in various samples was extracted using a Conway microdiffusion cell ; hydrazoic acid was vaporized from 1 mL sample (plasma or beverages) by adding 1 mL of 5% sulfuric acid in the outer groove, and absorbed in 250 μL of 0.1 M NaOH solution in the central round basin. Incubation for 30 min at 37℃ was sufficient for the purification of azide from biological samples. For IC analysis, a 20-μL aliquot was subjected to IC system equipped with a suppressor and a conductivity detector (Dionex, DX 500 system). The precolumn and separation column used were an AG 15 (20 mm × 2 mm i.d.) and an AS 15 (250 mm × 2 mm i.d.) semimicrocolumns. The mobile phase was 38 mM NaOH and the flow rate was set at 0.4 mL/min. The retention time of azide ion was about 10 mm. Combination of the reduction of NaOH solution in the Conway diffusion method and the use of semimicrocolums, has enabled 4 to 5 times higher sensitivity compared to methods previously reported ; the detection limit for serum samples was about 30 ng/mL Its calibration curve showed good linearity in the range of 50 ng/mL and 10 μg/mL serum We have validated this method; the CV values for intra-day and day-to-day measurements were less than 6.8 % and 93 %, respectively. In the case of beverages, Comway diffusion method was needed for accurate quantitaion because of the interference of some impurity peaks. Azide ion was detected from rat serum samples 1 or 4 hours after its oral administration (10 mg/kg). Thus the present method can be applicable for clinical and forensic toxicology, because of its simplicity and sensitivity. We are now preparing a paper for submitting. In the next research, we are going to obtain data about the decay of azide ion of different samples under several environmental conditions. Less