高效液相色谱-电感耦合等离子体质谱(ICP-MS)法测定中药材中无机汞、甲基汞、乙基汞

为准确测定中药材中不同形态的汞含量,通过选用人工胃液作为提取液,经水浴加热提取后,以甲醇-乙酸铵为流动相,采用C18反相色谱柱对样品溶液进行分离,最后经电感耦合等离子体质谱(ICP-MS)法测定3种汞形态化合物的含量。建立了中药材中无机汞、甲基汞、乙基汞的高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)法的测定方法,结果表明,3种汞形态化合物在0.5～5 ng/mL范围内均获得良好的线性关系,相关系数均大于0.999。通过加标回收的方法进行准确性评价,加标回收率为75.5%～118%,相对标准偏差RSD为2.4%～9.7%。测定的106批次中药材中,均未检出甲基汞、乙基汞。无机汞检出率为88.7%,合格率为100%。方法能够准确、高效地测定中药材中3种汞形态化合物的含量。106批次中药材中的汞存在形态主要是以无机汞为主。考察的106批次根及根茎类中药材中3种汞形态化合物的含量,积累了基础数据,为中药饮片的质量安全性监管提供技术支撑。     

冷蒸气发生-原子荧光光谱法测定化工废水中的无机汞和总有机汞

用氢化物发生－原子荧光光谱法测定了化工废水中的无机汞和总有机汞。无机汞可以直接测定;用过硫酸钾在沸水浴中加热20min即可把有机汞转化为无机汞,实现总汞的测定,二者之差为总有机汞。对影响测定灵敏度的一些实验参数进行了优化,汞的检测限为8．2ng/L。     

水中微量汞的快速测定

本文提出了一种快速测定水中微量汞的新方法。采用KBrO_3-HCl-HNO_3体系在室温下破坏水样中的有机汞,产生的无机汞用自制的KBH_4片剂还原,用测汞仪测定。此法具有简便、快速、精密度和灵敏度较好等优点,适合大批量水样的分析。     

电磁感应加热与原子荧光光谱联用测定海产品中的无机汞和有机汞

研制了电磁感应加热装置和磁感应加热柱,并将其应用于有机汞的在线氧化。与冷蒸汽发生-原子荧光光谱法联用,在线测定了海产品中的无机汞和有机汞。样品溶液与K2S2O8在线混合后流经磁感应加热柱,在较低功率(15W)时快速升温将有机汞氧化为无机汞,测定总汞含量;加热柱为室温时,测定无机汞含量,二者之差为有机汞。对各种实验参数和干扰情况进行了详细研究。无机汞的检出限为0.036μg/L;样品分析精密度(RSD)为2.4%(n=11);有机汞的检出限为0.043μg/L,样品分析精密度(RSD)为3.6%(n=11)。     

天然水中痕量无机汞和有机汞的氢化物原子荧光光谱法分析

建立了天然水中溶解的痕量无机汞和有机汞的氢化物原子荧光光谱法分析方法,该方法经标准物质(PACS-1)和加标回收实验研究表明重现性好、准确度高。在此基础上,应用该方法分析了该校人工湖水中的无机汞和有机汞,发现无机汞和有机汞的含量均低于0.1 礸/L。     

汞在人体中累积情况的调查（一）

自五十年代初,日本水俣湾发生汞中毒事件以来,人们已经了解到汞的许多化合物是剧毒物质,这些物质对人体健康有极大危害。为了弄清楚汞在人体中是否会产生储集,我们对某体温计厂职业性汞接触工人进行了汞中毒情况的调查。１材料和方法人体中的含汞量一般是以尿液、血液或者毛发中含汞的多少来表示。此次调查采用的是人发中汞的含量测定分析。我们对该厂两大不同工种的不同工龄的工人进行头发的采集。对发中汞的测定采用的是氧瓶燃烧——无焰原子吸收法。即人发在充氧条件下充分燃烧,使有机汞无机化,然后用高锰酸钾一一硫酸吸收液进行吸…     

汞的形态分析研究：Ⅱ.固相萃取预富集—液相色谱分离测定不同形态…

本文报道了固相萃取预富集处理样品继以液相色谱分离测定不同形态痕量有机汞的方法。二乙基二硫代氨基甲酸钠作络合剂及甲醇作洗脱液的预富集系统能在线富集甲基汞、乙基汞和苯基汞。     

高效液相色谱与原子荧光光谱联用分析汞化合物形态的研究

建立了高效液相色谱与原子荧光光谱联用测定汞化合物形态的分析方法。实验对淋洗液组分浓度、氧化剂和还原剂浓度、载气流速及紫外消解管长度等操作条件进行了优化,获得了令人满意的分析结果。在优化的分离检测条件下,20μg/L的汞化合物标准溶液平行7次进样分析,甲基汞、无机汞和乙基汞的色谱峰高的相对标准偏差(RSD)分别为2.0%、2.9%和2.4%;3种汞化合物的线性范围为10~1000μg/L,25μL进样检出限分别为3、2和4μg/L。用建立的方法测定了脉红螺样品中甲基汞的含量,甲基汞和乙基汞的加标回收率分别为90%和92%。     

冷原子吸收光谱法结合热解-原子吸收光谱法快速测定废水样中痕量无机汞和总有机汞

提出以冷原子吸收光谱法结合热解-原子吸收光潜法测定废水样中的痕量无机汞和总有机汞、水样经0．45μm膜过滤后不需消化处理,直接用冷原子吸收光谱法测定无机汞含量．用热解法测定总汞含量,二者之差为总有机汞含量。方法简便快速,干扰少．经加标回收实验验征,回收率为90％～103％．相对标准偏差(n=11)为3．8％。     

汞的形态分析研究：（Ⅰ）萃取—液相色谱分离测定不同形态汞

本文报道了有机汞及无机汞与二乙基二硫代氨基甲酸盐形成络合物，经氯仿萃取后用反相高效液相色谱法进行分离测定的方法，对实验的最佳条件进行了探讨，用于测定加标西湖水样和海水中不同形态的汞含量，回收率为９３．２％－１１４％，相对标准偏差为甲基汞３．７％，乙基汞３．６％，苯基汞３．２％和无机汞３．０％，检测下限为０．２５、０．２１、０．１９和０．７２ｎｇ。     

Speciation analysis of mercury in seafood by using high-performance liquid chromatography on-line coupled with cold-vapor atomic fluorescence spectrometry via a post column microwave digestion

An automatic system, based on the on-line coupling of high-performance liquid chromatography (HPLC) separation, post column microwave digestion, and cold-vapor atomic fluorescence spectrometry (CVAFS) detection, was proposed for the speciation analysis of four mercury compounds. Post column microwave digestion, in the presence of potassium persulfate (in HCl), was applied in the system to improve the conversion efficiency of three organic mercury compounds into inorganic mercury. Parameters influencing the on-line digestion efficiency and the separation effect were optimized. To avoid water vapor and methanol entering into the atomic fluorescence detector, ice-water mixture bath was used to cool the microwave-digested sample solution. Four mercury species including inorganic mercury chloride (MC), methylmercury chloride (MMC), ethylmercury chloride (EMC) and phenylmercury chloride (PMC) were baseline separated within 13 min by using RP C₁₈ column with a mobile phase of 50% (v/v) methanol containing 10 mmol l⁻¹ tetrabutyl ammonium bromide and 0.1 mol l⁻¹ sodium chloride pumped at 1.2 ml min⁻¹. Seafood samples, composed of three gastropod species and two bivalve species from Yantai port, China, have been analyzed by the proposed method. Dogfish muscle (DORM-2) was analyzed to verify the accuracy of the method and the result was in good agreement with the certified value.     

A high performance liquid chromatographic post-column fluorescent ion pair extraction system: application to physostigmine and its metabolite eseroline in human serum

A high performance liquid chromatographic post-column fluorescent ion pair extraction system was developed for the analysis of quaternary ammonium and amine drugs in serum. A new fluorescent ion pair reagent, sodium alpha-(3,4-dimethoxyphenyl) cinnamonitrile-2'-sulfonate (DPS), was synthesized and characterized. The post-column extraction system consisted of a three-dimensional knitted teflon mixing coil and a membrane phase separator which was modified from an original literature design. Physostigmine and its metabolite eseroline were used as model cations. A solid phase extraction procedure using octadecylsilane columns was developed to extract the compounds and neostigmine bromide (internal standard) from human serum. The compounds were chromatographed on a diol column using a 80:20 aqueous phosphate buffer pH 4 absolute methanol mobile phase at a flow rate of 1 mL/min. Methylene chloride was used as the on-line extraction solvent for the DPS ion pairs formed. Fluorescence of the extracted ion pairs was measured using an excitation of 243 nm and an emission cut-off filter at 418 nm. Linearity was in the 2-100 ng/mL and 5-100 ng/mL ranges for physostigmine and eseroline, respectively. Detection limits based on a signal-to-noise ratio of 2, were 2 and 5 ng/mL, respectively. Precision of the method was found to be in the 1.5-3% range and percentage error in the 1.5-7% range for both compounds.     

Liquid chromatographic determination of cobalt(II), copper(II) and iron(II) using 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone as derivatizing reagent

The complexing reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) was examined for high performance liquid chromatographic (HPLC) separations of cobalt(II), copper(II) and iron(II) or cobalt(II), nickel(II), iron(II), copper(II) and mercury(II) as metal chelates on a Microsorb C-18, 5-mum column (150x4.6 mm i.d.) (Rainin Instruments Woburn, MA, USA). The complexes were eluted isocratically with methanol:acetonitrile:water containing sodium acetate and tetrabutyl ammonium bromide (TBA). UV detection was at 254 nm. The solvent extraction procedure was developed for simultaneous determination of the metals, with detection limits within 0.5-2.5 mug ml(-1) in the final solution. The method was applied for the determination of copper, cobalt and iron in pharmaceutical preparation.     

Simultaneous separation of organomercury species by nonaqueous capillary electrophoresis using methanol containing acetic acid and imidazole

A simple and rapid nonaqueous capillary electrophoresis method for simultaneous separation of four kinds of mercury species, namely inorganic mercury, methylmercury, ethylmercury, and phenylmercury, is reported. The effective mobilities of organomercury in aqueous and nonaqueous electrolytes were compared. Imidazole was confirmed not only as a co-ion for the separation but also as an online complexing reagent for mercury species. The optimum conditions for separation were achieved by using methanol solvent containing 0.15 M acetic acid and 15 mM imidazole as electrolyte. The sensitive detection of mercury species was accomplished at 191 nm.     

Critical review of analytical methods for determination of inorganic mercury and methylmercury compounds

This review describes determinations of mercury compounds under three categories: total mercury; separate determinations of inorganic mercury(II) and organomercury compounds by selective reduction; and speciation of inorganic mercury(II), monomethylmercury cation, and dimethylmercury. Topics described for each category include sample treatment, separation, detection, and limit of detection. Finally, we note that most methods would not detect dimethylmercury if it were present.     

Dual Effect of Organomercury Compounds on Peroxide Oxidation of Oleic Acid

Oxidation of oleic acid with atmospheric oxygen in the presence of HgCl₂ and various organo- mercury compounds (methylmercury iodide, isopropylmercury bromide, n-hexylmercury bromide, phenylmercury bromide, diphenylmercury, p-tolylmercury bromide, bis-p-tolylmercury) was studied. Mercury compounds exert a dual effect on accumulation of oleic acid hydroperoxide in the temperature range 20-90°C. Below 50°C, the concentration of the hydroperoxides formed in the presence of mercury compounds is lower, and at higher temperatures, higher than in the experiments performed without mercury compounds. Comparison of the concentrations of oleic acid hydroperoxides with those of their transformation products, carbonyl compounds, determined spectrophotometrically, shows that actually organomercury compounds and HgCl₂ accelerate peroxide oxidation at all the studied temperatures. Decreased accumulation of peroxides below 50°C is apparently due to the fact that the rate of their reaction with organomercury compounds is higher than the rate of their formation.     

Phase-transfer-mediated electrochemical reaction: anodic disulfide bond formation under biphasic condition

The use of bromide ion as a redox mediator promotes electrochemical reactions in the non-conductive cyclohexane phase. Anodically oxidized species of bromide ion in the conductive methanol phase can bring oxidizing power across phases to induce oxidative disulfide bond formation of a hydrophobically-tagged tripeptide, which is located predominantly in the cyclohexane phase. In addition to commonly used tetraalkylammonium salts, inorganic sodium salt can also be effective alternatives for the bromide source.     

GC-MIP-PED as an element-specific system for the determination of organomercury compounds

The application of the combination of gas chromatography and a self-developed plasma emission detector for organomercury speciation is presented. The system, basing on interference filter technology, is described briefly. The plasma and the optical system have to be optimized to reach highest sensitivity for mercury detection. Dimethyl-, methyl- and inorganic mercury as selected compounds have been separated on a GC column and calibrated to obtain the analytical performance data of the system used. Finally, the analysis of some real samples has been performed.     

Gas-chromatographic determination of organomercury(II) compounds

Gas chromatography has proved to be an invaluable technique not only for the identification and determination of organomercury(II) compounds but also for differentiating inorganically bound from organically bound mercury. It also offers a possible route for determining various inorganic species through their conversion into organomercury(II) compounds. These procedures and the chemical and instrumental problems associated with them are reviewed.     

Dithizone derivatives as sensitive water soluble chromogenic reagents for the ion chromatographic determination of inorganic and organo-mercury in aqueous matrices

Water-soluble sulfonate and the novel carboxylate analogues of dithizone, combined with ion interaction chromatography on a Dionex Acclaim 120 C18 silica column (250 x 4.6 mm id) with an eluent consisting of 10 mM tetrabutylammonium bromide and 60:40 methanol:water, have been developed as highly sensitive chromogenic ligands for the quantitative isocratic determination of inorganic and organo-mercury compounds in aqueous matrices in under 12 min. Using an optimised post column reagent system containing 0.65 mM dye, 0.5% Triton X-100 and 50 mM sodium hydroxide, good linearity (0-7.5 mg L(-1) R2 > 0.999), reproducibility using peak area measurements (RSD 0.69-1.38%, n = 8), and limits of detection (4-12 microg L(-1)) were achieved for methyl mercury, inorganic mercury and phenyl mercury.