高效液相色谱-电感耦合等离子体质谱联用测定生物样品中无机汞和甲基汞

建立了高效液相色谱(HPLC)和电感耦合等离子体质谱(ICP-MS)联用测定多种生物样品中的无机汞和甲基汞的方法,并对比了提取生物样品中无机汞和甲基汞的不同前处理方法。实验使用5 mol/L的盐酸超声波提取样品中的无机汞和甲基汞。高效液相色谱流动相为含有0.06 mol/L醋酸氨,20μg/L B i,0.1%(V/V)2-巯基乙醇的5%(V/V)甲醇-水溶液,色谱柱为C18反相柱(5μm,3.9 mm×150 mm)。提取液在液相色谱中分离后,进入电感耦合等离子体质谱检测其中无机汞和甲基汞的浓度。测定了人发(GBW 07601),对虾(GBW 08572),鱼肉组织(IAEA MA-B-3/TM)和牛肝(GBW 080193)4种生物标准参考物,结果与标准参考物的标准值相符。无机汞和甲基汞检出限分别为0.3和0.2μg/L。     

利用AFS和LC-AFS测定鱼肉中的总汞与甲基汞

建立了以微波消解和微波萃取实现对鱼肉组织快速高效前处理的方法,对萃取剂的组成及萃取条件进行了优化。使用原子荧光光谱和液相色谱-原子荧光联用仪分析鱼肉组织中总汞(Hg)、无机汞(Hg2+)和甲基汞(CH3Hg+)含量,并研究了流动相对分析测试效果的影响。经过优化实验,在以0.5%(V/V)2-巯基乙醇、5%(V/V)CH3OH和0.15%(m/V)KCl混合溶液作为萃取剂、萃取温度125℃、萃取时间15 min条件下对鱼肉中甲基汞萃取效率最高。流动相最佳组成为5%(V/V)HCl、5%(m/V)KBH4和0.15%(m/V)KCl溶液。分析结果表明,样品鱼肉中的汞形态可分为无机汞和甲基汞,但主要以甲基汞的形式存在。总汞与甲基汞重复测定结果 RSD5%。微波消解处理样品总汞的加标回收率达到94%~106%,微波萃取样品甲基汞的加标回收率达到90%~109%。     

高效液相色谱与原子荧光光谱联用分析海产品中的甲基汞

建立了高效液相色谱-紫外消解-氢化物发生-原子荧光光谱联用测定海产品中甲基汞的方法, 比较了不同溶剂对海产品中甲基汞提取效率的影响. 实验采用质量分数25% (m/V) KOH甲醇溶液, 室温振荡10 h消解样品, CH2Cl2萃取, 再以0.01 mol/L Na2S2O3水溶液反萃取, 并采用HPLC-UV-HG-AFS测定鱼和扇贝萃取液中的甲基汞的含量. 在优化分离和前处理条件下, 平行进样5次10 ng/mL的汞混合标准溶液, 甲基汞、无机汞和乙基汞的色谱峰面积的相对标准偏差(RSDs)分别为4.4%、 3.9%和4.3%, 甲基汞、无机汞和乙基汞的检出限分别为0.069、 0.15和0.046 ng/mL;鱼和扇贝的甲基汞的加标回收率为96±5%和95±5%.     

水产品中甲基汞测定的液相色谱-原子荧光光谱联用方法的改进

对本实验室前期建立的食品中甲基汞的液相色谱-原子荧光光谱联用测定方法进行了改进。采用无毒的半胱氨酸代替有毒试剂巯基乙醇作为流动相中的配位剂,流动相组成为5%(v/v)乙腈-1 g/L半胱氨酸-50 mmol/L乙酸铵水溶液,使汞化合物分离时间缩短至8 min。在优化条件下,甲基汞标准曲线的线性范围为1～50 μg/L,检出限(S/N=3)为0.3 μg/L。采用超声波辅助5 mol/L HCl提取样品中的甲基汞,提取液经C18固相萃取小柱净化后进样。鱼、虾、贝等不同种类水产动物样品以及水产类膳食样品的甲基汞加标回收率为89%～112%。对标准参考物质NIST1566b、BCR464和GBW10029以及英国食品分析水平评估计划(Food Analysis Performance Assessment Scheme, FAPAS)的罐装鱼肉样品(样品编号07115)的测定结果与参考物定值相符,验证了该方法的可靠性与准确性。本方法可满足食品中甲基汞检测的需要。     

微波萃取高效液相色谱-冷原子荧光光谱法测定沉积物中甲基汞和无机汞

建立了微波萃取高效液相色谱-冷原子荧光光谱法(MAE-HPLC-CVAFS)测定沉积物中甲基汞(MeHg+)和无机汞(Hg2+)的方法。以0.1%(V/V)2-巯基乙醇为萃取剂,用于沉积物样品中汞形态的萃取,在80℃下萃取8 min,萃取液直接注入HPLC-CVAFS系统分析。在优化条件下,MeHg+和Hg2+的检出限分别为0.58和0.48 ng/g;加标回收率分别为96.2%和95.8%;RSD(n=6)分别为5.7%和4.1%。对标准参考物质(IAEA-405和ERM-CC580)的分析结果与推荐值一致。本方法简单、快速、准确、检出限低,抗干扰能力强,具有很好的实用性和推广价值。     

稳定同位素稀释-气相色谱质谱联用法测定水产品中甲基汞和乙基汞

建立了测定水产品中甲基汞和乙基汞的气相色谱质谱联用分析方法。采用6.0 mol/L HCl超声辅助提取,在NaCl存在下,提取液中甲基汞和乙基汞可被甲苯萃取,再用半胱氨酸反萃取,加入CuSO4释放出的甲基汞和乙基汞与四苯硼钠反应,生成甲基苯基汞和乙基苯基汞,经DB-5MS毛细柱分离,选择离子监测方式(SIM)质谱检测,以d3-甲基汞作为内标的稳定同位素稀释法定量。甲基汞和乙基汞标准曲线的线性范围均为1~500μg/L,国家标准参考物质(GBW 10029)6次测定的甲基汞(以汞计)平均值为0.828 mg/kg,相对标准偏差为3.2%,与证书参考值(0.84±0.03)mg/kg(以汞计)一致。鱼、虾和贝类等不同种类水产品中甲基汞和乙基汞的平均加标回收率分别为94%~101%和81%~104%,相对标准偏差在1.9%~4.7%和3.1%~8.2%范围内(n=6),样品的检出限为0.1~0.3μg/kg(S/N=3)。方法灵敏,准确,可用于水产品中甲基汞和乙基汞的测定。     

高效液相色谱-原子荧光光谱法测定化妆品中的无机汞、甲基汞、乙基汞

建立高效液相色谱–原子荧光光谱法对化妆品中无机汞、甲基汞、乙基汞进行测定。优化后的实验条件:负高压为300 V,灯电流为50 mA,炉温为200℃,还原剂为20 g/L硼氢化钾–5 g/L氢氧化钠溶液,流动相为5%甲醇–60 mmol/L乙酸铵–0.1%L-半胱氨酸溶液,载液为10%的盐酸。结果表明,无机汞、甲基汞、乙基汞的质量浓度在0～10μg/L范围内与色谱峰面积呈良好的线性关系,相关系数分别为0.999 7,0.998 3,0.999 3,方法的检出限均为0.067 mg/kg。测定结果的相对标准偏差为3.6%～4.8%(n=6),样品加标回收率为80.0%～97.3%。该方法快速、准确,灵敏度高,检测成本低,适用于化妆品中无机汞、甲基汞、乙基汞的测定。     

毛细管气相色谱法测定生物样品中痕量甲基汞

建立了以5 g·L-1L-半胱氨酸为萃取溶剂,采用改装的家用微波炉微波辅助加热提取分离,所得溶液用盐酸酸化后用苯反萃取后用毛细管气相色谱(电子捕获器)测定甲基汞的新方法测定甲基汞的线性范围为0．1～1．0 ng,检出限为0．064 ng对0．80 ng甲基汞进行7次测定,其RSD为4．58%,应用于实际样品中甲基汞的测定,回收率在95．5％-102．3％之间。     

高效液相色谱-原子荧光光谱法测定海产品中甲基汞

为调查渤海海域海产品中甲基汞的污染情况,建立了高效液相色谱-原子荧光光谱法测定海产品中甲基汞的分析方法。样品中甲基汞经提取剂磁力搅拌提取20min,0.1μm有机系尼龙微孔滤膜过滤,以10%甲醇+0.04mol/L乙酸铵+0.1%L-半胱氨酸为流动相,用HC-C18 0.5um色谱柱分离,原子荧光光谱法进行测定。甲基汞在2-40ng/mL范围内线性关系良好,相关系数r＞0.999,方法检出限为0.02ng/mL,回收率在97.2-99.2%之间,相对标准偏差为3.7%。首次采用0.1%L-半胱氨酸+10%甲醇作为提取剂,该方法操作简单,精密度高,干扰少,可用海产品中甲基汞的测定。     

柱前衍生反相高效液相色谱分离和测定氨基酸--用N-羟基琥珀酰亚胺-α-萘乙酸酯作衍生试剂

以N-羟基琥珀酰亚胺-α-萘乙酸酯(SINA)为氨基酸的柱前衍生试剂,反相高效液相色谱分离测定了15种氨基酸.采用含10 mmol/L pH 5.0的乙酸-乙酸钠缓冲溶液的甲醇-乙酸乙酯-水(10/2/88,V/V/V)溶液为流动相体系,分离测定了7种氨基酸;用甲醇-乙酸乙酯-水(26/2/77,V/V/V)分离测定了5种氨基酸;用甲醇-乙酸乙酯-水(45/2/53,V/V/V)分离测定了3种氨基酸.检测限均达到pmol级,且重现性好.     

甲基汞检测研究进展

汞是常见的一种污染物,它可以在微生物的甲基化作用下转化为甲基汞.甲基汞是汞形态中最具毒性的一种,通过食物链可以危害人体健康,对人体中枢神经系统造成不可逆的损害.环境与生态问题使得检测甲基汞迫在眉睫,近年来分析检测甲基汞的手段显著发展,光谱法、色谱法尤其是仪器联用技术,例如GC-MS、GC-ICP-MS和HPLC-ICP...     

Inorganic and methylmercury speciation in environmental samples

The different strategies for mercury species analysis in environmentally-related samples are reviewed. After consideration of the main different steps involved in the speciation of mercury, such steps are discussed with more extension for mercuric ion and methylmercury. The different approaches for preservation of these mercury species during the storage of samples are considered. Different ways for the extraction of mercury species from the several possible environmental compartments and the possibilities for preconcentration of such species after previous derivatization reactions are discussed. Mercuric ions and methylmercury chromatographic and non-chromatographic separations along with different techniques used for sensitive and selective detection of mercury are also critically reviewed. Ranges of published detection limits achievable for such species determination, by using hyphenated techniques between a chromatographic separation and a specific atomic detector are also given.     

Direct evidence for the presence of methylmercury bound in the thyroid and other organs obtained from mice given methylmercury; differentiation of free and bound methylmercuries in biological materials determined by volatility of methylmercury

Peroxidase in mouse thyroid was inhibited by mercuric chloride but not by methylmercury in in vivo and in vitro systems (Nishida, et al., J. Histochem. Cytochem., 37, 723 (1989)). To identify the reason for the difference, the present study was conducted to examine whether methylmercury is indeed bound within cells or tissues. Mice were given radioactive methylmercury by intubation for 18 d and the tissues were dissected out and vacuum-dried. With this procedure, free methylmercury was evaporated off and the bound mercury remained. The thyroid, liver, kidney and fats examined showed no loss of radioactivity under the vacuum, indicating that the mercury was bound to the thyroid, as well as the other tissues. Radioactive mercuric chloride was nonvolatile regardless of the presence or absence of the tissues. The preferential affinity of methylmercury for SH-containing materials was re-confirmed by this method.     

Improvements of reliability for methylmercury determination in environmental samples

The determination of methylmercury (MeHg) in environmental samples by ethylation derivation-gas chromatography-atomic fluorescence spectrometry (ED-GC-AFS) is associated with an intimate problem of water moisture accumulation introduced in the ethylation step, which enters the detection system and cause a spectroscopic interference. With a simple modification on the GC-AFS system, this problem was eliminated and the analytical quality of the measurements was significantly improved. The presence of dissolved sulfide in samples can also cause serious chemical interference in the ethylation step resulting in lower or total loss of the MeHg signal. It was found that a masking system of CuSO₄-Na₂C₂O₄ was able to eliminate this interference. With this system, the accurate determination of trace amount of MeHg in high dissolved sulfide containing samples was achieved. Satisfactory analytical results were obtained with the certified reference sediment IAEA405, sulfate reducing bacteria culture and sulfide containing water samples. The limit of detection and quantitation of this masking system is 0.01 and 0.04 ng L⁻¹ respectively. Other factors affecting ethylation are also discussed.     

An international intercalibration for methylmercury in biological tissue

An intercalibration exercise between 13 laboratories from seven countries was conducted for comparing the methylmercury measurement techniques for marine biological tissues. Analyses have been conducted on two sets of samples: a fish muscle and a mussel soft tissue. Most of the participating laboratories performed six replicate analyses, allowing statistical comparisons. Various analytical techniques have been used, including cold vapour atomic absorption spectrophotometry (CVAA), electron capture gas liquid chromatography (GCEC), neutron activation (NAA), and inductively coupled plasma–isotopic dilution mass spectrometry (ICPIDMS). All of these methods offer similar results. They allow us to define consensus values which seem good estimates of the real concentrations. In addition the results show, for most of the participating laboratories, good accuracy and precision in the determination.     

Comparative studies of methylmercury determination in biological and environmental samples

Some parameters affecting the accuracy of various approaches to methylmercury (MeHg) determination in biological and environmental samples were studied. Different isolation techniques (ion-exchange, extraction, volatilization, distillation) and final measurement via cold vapour atomic absorption spectroscopy (CV AA) or gas chromatography (GC) were compared. Results obtained by the various isolation techniques are comparable for almost all biological and environmental samples, except for soils and some sediments, where disagreement between the results obtained by GC and CV AA was found. In order to resolve these problems, a new separation technique based on distillation of MeHg from the sample followed either by CV AA or GC was developed. The new method results in very good recovery and reproducibility (95 ± 2%) for all samples examined (fish, mussel, shrimp, blood, hair, algae, sediment, etc.), is specific for MeHg and provides for its differentiation from other species by an indirect CV AA determination. Gas-chromatographic measurement of the isolated MeHg using different packings and conditioning of the columns is also discussed. The distillation method with GC detection is advantageous in producing cleaner chromatograms and in prolonging the life-time of the packing and the intervals between reconditioning.     

Storage and stability of mercury and methylmercury in sea water

The long-term storage behavior of mercury and methylmercury at ng 1^?1 levels in sea water was studied at pH 4.0, 6.0, 8.0 and 10.0, and with 2% (v/v) hydrochloric or nitric acid added. Partial complexation and disappearance of mercury and methylmercury were observed; some of the lost mercury became detectable (by cold-vapour atomic absorption spectrometry) after prolonged storage.     

Effects of sample preparation on methylmercury concentrations in Arctic organisms

The biogeochemical cycling of mercury (Hg) in the marine environment is an issue of global concern, as consumption of marine fish is a major route of human exposure to the toxic specie methylmercury (MeHg). The most widely utilised and accepted technique for preparing biological tissue samples for the analysis of MeHg involves an alkaline digestion of the sample. Recent studies suggest, however, that this technique is inadequate to produce satisfactory recoveries for certain biological samples, including fish, fur, feathers and other ‘indicator’ tissues which contain relatively high levels of MeHg. Thus an improved acidic extraction method has been proven to produce more satisfactory results for a wide range of biological tissues. The present study compares the two methods on real sample material from different organisms of an Arctic marine food chain, and shows how this could lead to misinterpretation of analytical results. Results show significantly (p < 0.05) lower concentrations for alkaline digestion for large parts of the food chain; especially in fish and birds. The mean differences in concentrations found between the two different methods were 28, 31 and 25% for fish (Polar and Atlantic cod), Little Auk and Kittiwake, respectively. For samples lower in the food chain (i.e. zooplankton and krill) no significant differences were found. This leads to a clear underestimation of the levels of MeHg found higher up in these food chains; the ratio of MeHg to Hg in biological samples; and thus potentially erroneous conclusions drawn from these results concerning the biological cycling of mercury species. We hypothesise that the main reasons for these differences are poor extraction efficiency and/or matrix effects on the ethylation step prior to analysis. This is the first study to examine the effects of these artefacts on real environmental samples covering a complete food chain.