微波消解-扫描电镜联用检测脏器内硅藻

Using microwave digestion technique and scanning electron microscopy to detect diatoms in organs for the diagnosis of drowning

目的介绍一种微波消解-扫描电镜联用检测脏器内硅藻的新方法。方法大白兔30只,随机分为生前溺死组(n=15)和死后溺尸组(n=15)。提取兔肺、肝、肾、股骨骨髓和现场珠江水样,采用建立的微波消解-扫描电镜联用法检测脏器组织和水样中的硅藻,并与硝酸乙醇消解-扫描电镜联用的方法进行比较。结果生前溺死组的兔肺、肝、肾、股骨骨髓组织中大多数观测到与现场珠江水样一致的硅藻,微波消解-扫描电镜联用法检测脏器内硅藻的平均含量分别为:2505.2个/2g肺,18.7个/10g肝,6.5个/10g肾,6.3个/0.5g骨髓;肺与肝、肾、骨髓检出硅藻的阳性比例为86.7%,脏器硅藻检出含量和硅藻检验阳性比例均明显高于硝酸乙醇消解-扫描电镜联用法所测值。死后溺尸组的兔脏器组织均未观测到硅藻。结论微波消解-扫描电镜联用法检测脏器内硅藻,高效、安全、环保,硅藻检验灵敏度高,降低了劳动强度,提高了定性定量分析准确度,且能有效避免污染,在法医学溺死鉴定中具有良好的应用价值。

Objectives To present a novel method using microwave digestion technique and scanning electron microscopy （SEM） for diatom test in medicolegal diagnosis of drowning. Methods 30 white rabbits were divided randomly into two groups,i.e.,drowning group （n=15） and post-mortem immersion group. Lungs and closed organs （liver,kidney and femoral marrow） of the rabbits as well as the drowning medium were collected for diatom analysis with the established method using microwave digestion and SEM. And for the purpose of comparison,the method using conventional chemical digestion （nitric acid and ethanol digestion） and SEM was also used. Results For the drowning group：diatoms with a concordance of types were recovered in most organs and water. The average diatom concentrations in organs determined by the method using microwave digestion and SEM were 2505.2/2g of lung,18.7/10g of liver,6.5 /10g of kidney and 6.3/0.5g of bone marrow respectively and the ratio of positive diatom test with diatom present in lungs and closed organs was 86.7%,which were all significantly higher than the values determined by the method using conventional chemical digestion and SEM. For the post-mortem immersion group,no diatom was detected in the organs by the both methods. Conclusion The developed novel method using microwave digestion and SEM is high-efficiency,safe,environment-friendly,labor-saving,sensitive,accurate and contamination-free for qualitative and quantitative diatom analysis,thus is of prominent application value in forensic diagnosis of drowning.