【作者】 宋志敏；

【导师】 姜素霞； 单宝田；

【作者基本信息】 中国海洋大学 ， 分析化学， 2009， 硕士

【摘要】 目前,血样中汞的分析预处理方法主要采用常压湿法消化和微波消解法。分析过程中,先对血样进行预处理,再通过分析仪器测定汞含量。样品预处理方法耗时长,浓酸和血样用量大,而且由于汞易挥发、吸附,其在样品消解处理过程中极易损失,导致分析方法的回收率低,测定结果不够准确。本文针对常规分析方法存在的不足,研究建立了硫脲混合液提取测定血样中汞的新方法,样品预处理不需要加热消解,且由于硫脲混合液与汞生成稳定化合物,可有效地减少常规预处理方法在样品预处理和测定过程中汞的吸附和挥发损失,方法的回收率高、重现性好、简便、快速、分析费用低。本文主要研究内容如下:1.研究建立了硫脲混合液提取-原子荧光光度法测定血样中汞的检测方法。利用正交试验确定了硫脲混合提取液的最佳配方为:0.20%硫脲、0.10%柠檬酸、0.10%乙二铵四乙酸二钠盐、0.15%氯化钾的混合溶液。该方法回收率为95.0%～99.7%,检出限0.06μg/L,RSD<5%,完全满足血样中汞的测定。2.考察了静置时间、硝酸浓度、离心时间、过氧化氢用量等因素对回收率的影响,研究确定的最佳实验条件为:取血样0.5mL置于10mL离心管中,加入7mL硫脲混合提取液,静置反应5min后,加入40%硝酸1mL产生沉淀,经离心机3500rpm离心10min后,移取上清液,加入50μL过氧化氢氧化至溶液接近无色,加水定容至10mL,原子荧光仪测定。3.比较了常压湿法消化法、微波消解法、巯基乙醇提取法、硫脲提取法和本文研究建立的硫脲混合液提取法测定血样中汞的准确度和精密度,并考察了常压湿法消化法、微波消解法和硫脲混合液提取法处理后样品的稳定性。结果表明,常压湿法消化法、巯基乙醇提取法和硫脲提取法回收率都小于90%,RSD>5%,微波消解法回收率为91.0%～92.7%,RSD为4.4%～5.0%,硫脲混合液提取法克服了常规分析方法存在的缺点,无论准确度还是精密度都比其它四种方法要高,且用硫脲混合液提取法处理的血样比用常压湿法消化、微波消解法处理的血样更稳定,放置两天样品中汞含量不变,而用常压湿法消化、微波消解法处理的血样不稳定,必须二十四小时内进行测定。更多还原

【Abstract】 At present, the classical analytical methods of mercury in blood are mainly wet digestion and microwave digestion. These methods have the disadvantages of tedious workup, large amounts of thick acid and blood usage and so on. Moreover, because of characteristics of volatilization and adsorption mercury can easily be lost in sample pretreatment, resulting in low recovery rate and inaccurate determination result. A method for determination of mercury in blood using a thiourea mixed extraction method has been put forward in the present paper. Not using the heating the loss of the mercury volatilization can be commendably reduced. Because of stable mercury compounds the absorption loss can be effectively prevented. The method has the advantages of simple operation, high sensitivity, good repeatability and so on.1. A method for determination of mercury in blood using a thiourea mixed extraction method by atomic fluorescence spectrometry has been developed. Using orthogonal test the optimum formula of the thiourea mixed extraction is 0.20% thiourea, 0.10%citric acid, 0.10%EDTA, 0.15% potassium chloride. The detection of limit is 0.06μg/L.The recovery of Hg has been proved to be 95.0%~99.5%. The RSD is less than 5%. The method is suitable for the determination of Hg in blood.2. Extraction time, the concentration of nitric acid, centrifugal time and the volume of hydrogen peroxide are optimized. The experiments show that the appropriate experimental conditions are as follows: optimal time of standing 5 min, concentration of nitric acid 5%, centrifugal time 10min, volume of hydrogen peroxide 50μL.3. The precisions and accuracies of these methods such as wet digestion, microwave digestion, thiourea extraction method, mercaptoethanol extraction method and thiourea mixed extraction method are compared. The stability of the treated samples is discussed. The recovery of these methods such as wet digestion, thiourea extraction method, mercaptoethanol extraction method has been proved to be less than 90%, and the RSD is more than 5%. The recovery of microwave digestion is 91.0%～92.7%. The RSD of microwave digestion is 4.4%～5.0%.The experiment showed that no matter whether precision or accuracy, thiourea mixed extraction method is most highest. The accuracy of thiourea mixed extraction method is 5% higher than the other methods at least. The precision is 0.3% higher than the other methods. Thiourea mixed extraction method overcomes the disadvantages of the classical analytical methods. The mercury content of the sample which is treated by thiourea mixed extraction method keeps invariant for two days,but the blood samples which are treated by wet digestion and microwave digestion must be determined in twenty-four hours.更多还原