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%。     

高效液相色谱-原子荧光光谱联用测定土壤中3种痕量汞形态

建立了高效液相色谱-原子荧光法测定土壤中二价汞、甲基汞、乙基汞3种汞形态的分析方法。对提取溶液、液相色谱柱、流动相及其pH值、载流HCl、还原剂KBH₄溶液及氧化剂K₂S₂O₈溶液等条件进行了优化。实验表明：在以10%HCl+10.0 g/L硫脲+15.0 g/L KCl为提取溶液，反相C18柱(150 mm×4.6 mm, 5μm)为色谱柱，5%甲醇+60 mmol/L乙酸铵+1.0 g/L L-半胱氨酸溶液为流动相(pH=6.00±0.02),10%HCl溶液为载流，5.0 g/L KOH+15.0 g/L KBH₄溶液为还原剂，5.0 g/L KOH+10.0 g/L K₂S₂O₈溶液为氧化剂等条件下，二价汞、甲基汞、乙基汞3种汞形态在10 min内可完全分离；校准曲线线性相关系数均大于0.999;方法检出限分别为0.01 mg/kg、0.006 mg/kg、0.008 mg/kg;实验室内相对标准偏差范围...     

高效液相色谱-氢化物发生-原子荧光光谱法检测紫菜中的砷形态

测定了4种中国紫菜样品的总砷含量并且分析了紫菜中的砷形态。紫菜经电热消解、ICP-AES测定,总砷含量为14.0～42.1 mg/kg。以高效液相色谱-氢化物发生-原子荧光光谱法(HPLC-(UV)-HG-AFS)测定紫菜中的5种砷形态。紫菜样品都检测出了DMA(0.196～0.668 mg/kg),但没有检测出As(III),As(V),MMA和AsB,紫菜砷的形态主要是砷糖。     

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。     

离子色谱-氢化物发生原子荧光光谱联用技术在砷形态分析中的应用

建立了离子色谱-氢化物发生原子荧光光谱联用分离4种常见有毒砷化合物的方法. 二者通过内径0.25 mm的PEEK管直接相连. 实验对影响分离度和测定灵敏度的参数进行了优化. 在优化条件下, 质量浓度均为50 μg/L的4种砷化合物混合标准溶液平行7次进样, 得到DMA、 As(Ⅲ)、 MMA和As(Ⅴ)的色谱峰面积的相对标准偏差(RSD)为2.8～3.0%. 250 μL进样的线性范围为5～1000 μg/L, 检出限为0.8～1.2 μg/L (三倍基线噪音峰高). 用建立的方法测定了砷处理后的水稻木质部伤流液中的砷量, 4种砷化合物的加标回收率为89%～105%. 该装置接口简单, 方法分离度好, 灵敏度高, 可用于实际样品中痕量砷化合物的形态分析.     

盐酸提取-液相色谱-原子荧光联用技术检测水产品中甲基汞等汞化合物

建立了HCl提取,高效液相色谱与原子荧光联用技术测定水产中无机汞、甲基汞、乙基汞形态的分析方法。对前处理方法和液相色谱的最佳参数进行优化,实验表明,3种汞化合物的线性范围为0~100μg/L,相关系数(r)均优于0.9990,检出限在0.3~0.6μg/L之间,汞化合物各形态的RSD均小于5%,加标回收率在78.8%~116.8%之间,标准物质(GBW10029),(GBW09101B)中汞形态的测定值均在标准值范围内,参加甲基汞FAPAS国际比对,测定结果的Z比分数为1.0,故本方法适用于水产品中汞化合物形态的分析测定。     

高效液相色谱-氢化物发生-原子荧光光谱在线联用系统分析中成药中砷化合物形态

建立了高效液相色谱-氢化物发生-原子荧光光谱砷形态分析在线联用系统,考察了不同实验条件对4种砷形态化合物（As^Ⅲ,DMA^Ⅴ,MMA^Ⅴ和As^Ⅴ）分离分析的影响,优化了实验条件.在优化的实验条件下,采用pH 5.8的磷酸盐缓冲溶液为流动相,梯度洗脱,10 min之内4种砷形态达到基线分离.进样20μL,测定4种形态的检出限分别为：As^Ⅲ2.76 ng/mL,DMA^Ⅴ7.37 ng/mL,MMA^Ⅴ2.86 ng/mL和As^Ⅴ5.22 ng/mL,相对标准偏差RSD在2.9%～4.2%之间.该联用系统灵敏度高,准确性好,分离分析了部分市售中成药中的不同砷形态化合物.     

高效液相色谱及其联用技术在汞形态分析中的应用

本文对近二十年来高效液相色谱及其联用技术在汞的形态分析中的应用进行了综述，着重讨论了样品的前处理方法，高效液相色谱用于汞化合物的形态分离以及检测器的选择。     

高效液相色谱-电感耦合等离子体质谱联用同时检测海产品中的多种有机锡

利用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP/MS)联用技术对5种有机锡[三甲基氯化锡(TMT)、二丁基氯化锡(DBT)、三丁基氯化锡(TBT)、二苯基氯化锡(DPhT)和三苯基氯化锡(TPhT)]进行了分离,采用Agilent TC-C18柱进行有机锡的形态分析,流动相为V(乙腈)∶V(H2O)∶V(乙酸)=65∶23∶12,0.05%的三乙胺,pH=3.0,流速为0.4mL/min,测定了0.5~100μg/L范围内5种有机锡化合物的混合标准工作曲线,其相关系数优于0.998(R2),方法的检出限均小于0.5μg/L。采用流动相对菲律宾蛤(Ruditapes Philippi-narum,R.P.)及毛蛤(Ark Shell,A.S.)样品进行超声萃取及高速离心后,用上述方法进行了分析。结果表明,海产品含有4种有机锡,其中TBT和TPhT的含量最高,为14.38~104.7μg/L(干重)。TMT、TBT和TPhT的加标回收率均优于80%。DPhT和DBT可能存在吸附或降解问题,因而回收率仅为37.3%~75.2%。     

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。     

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.     

Determination of methylmercury in environmental samples using static headspace gas chromatography and atomic fluorescence detection after aqueous phase ethylation

A rapid and automated method for the determination of monomethylmercury (MMHg) in environmental samples was developed using headspace gas chromatography with atomic fluorescence detection in combination with aqueous phase ethylation. Sample preparation steps were optimized for sediments, biological samples, and water samples using certified reference materials and real samples with a broad range of MMHg concentrations. Different extraction procedures were compared for both sediments and biological samples. The methods were applied in the intercomparison exercises for the certification of MMHg in sediments (IAEA 405) and in Oyster tissue (BCR 710) and the results were accepted for certification. The detection limits for MMHg are 0.002 ng Hg/g for sediments and biological samples and 0.01 ng Hg/L for water samples. The method was tested for methylation artifacts; no artifact was observed in the sediment samples and CRMs tested.     

Inorganic selenium speciation in environmental samples using selective electrodeposition coupled with electrothermal atomic absorption spectrometry

Speciation analyses are of increasing interest in the environmental, toxicological and analytical fields, because the toxicity and reactivity of trace elements depend strongly on the chemical forms in which they are present. A simple electrodeposition–electrothermal atomic absorption spectrometry method for speciation analysis of some organic and inorganic selenium species in typical environmental water and agricultural soil samples has been developed. The method is based on the selective reduction of water-soluble Se(IV) and selenocystine (Se–Cys) species by an uncontrolled applied potential (1.8 V) on a mercury-coated electrode. In acidic media (1.0 M HCl solution) the only inorganic selenium species electrodeposited was Se(IV), and, of the water-soluble organic selenium species Se–Cys and Se–Met only Se–Cys was electrodeposited onto the mercury electrode surface. The proposed methodology was successfully applied to the speciation and determination of selenium in a few environmental samples. The spiked recovery value varied between 91% and 99%. The suggested method has been shown to have a characteristic mass (m₀) of 25 pg, a limit of detection (LOD) of 1.0 μg L^− 1 and a relative standard deviation (RSD%) of 3.5% for 6 measurements at a concentration of 100 μg L^− 1 Se(VI).     

Determination of inorganic and methylmercury in fish by cold vapor atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry

Simple and rapid analytical procedures for the determination of Hg²⁺ and methylmercury in fish were proposed after careful optimization of chemical and instrumental parameters for Hg measurement by cold vapor (CV)/hydride generation (HG) atomic absorption spectrometry (AAS) and CV/HG inductively coupled plasma atomic emission spectrometry (ICP-AES). Quantitative extraction of Hg species avoiding any inter-species conversion was achieved by fast microwave assisted solubilization of fish tissue with relatively low amount of tetramethylammonium hydroxide (TMAH) or 6 mol L^− 1 HCl. After careful optimization of chemical parameters selective determination of Hg²⁺ in the presence of excess of methylmercury is attained by using continuous flow CV AAS, 1% m/V SnCl₂ as reductant and 0.1 mol L^− 1 HCl as reaction medium. Simple calibration curve prepared with aqueous standard of Hg²⁺ is recommended for its quantification. Both Hg²⁺ and methylmercury could be determined simultaneously with equal sensitivity by CV/HG ICP-AES directly in the diluted TMAH solution obtained after extraction with 1% m/V NaBH₄ as reductant. Quantification of the sum of Hg²⁺ and methylmercury against calibration curve prepared with aqueous standard of methylmercury is suggested. It should be mentioned that batch hydride generation system with quartz tube heated in air/acetylene flame could also be used for simultaneous determination of both Hg species in fish extracts, with standard additions calibration. The validity of the developed analytical procedures for selective determination of Hg²⁺ and methylmercury (by difference between the total Hg and Hg²⁺) is confirmed by the analyses of certified reference material DOLT-1 and reference material IMEP-20. Very close agreement between certified values and analytical results was found.     

Determination of hexavalent chromium in traditional Chinese medicines by high‐performance liquid chromatography with inductively coupled plasma mass spectrometry

An analytical method that combined high‐performance liquid chromatography with inductively coupled plasma mass spectrometry has been developed for the determination of hexavalent chromium in traditional Chinese medicines. Hexavalent chromium was extracted using the alkaline solution. The parameters such as the concentration of alkaline and the extraction temperature have been optimized to minimize the interconversion between trivalent chromium and hexavalent chromium. The extracted hexavalent chromium was separated on a weak anion exchange column in isocratic mode, followed by inductively coupled plasma mass spectrometry determination. To obtain a better chromatographic resolution and sensitivity, 75 mM NH₄NO₃ at pH 7 was selected as the mobile phase. The linearity of the proposed method was investigated in the range of 0.2–5.0 μg L^?1 (r² = 0.9999) for hexavalent chromium. The limits of detection and quantitation are 0.1 and 0.3 μg L^?1, respectively. The developed method was successfully applied to the determination of hexavalent chromium in Chloriti lapis and Lumbricus with satisfactory recoveries of 95.8–112.8%.     

Speciation of mercury compounds in waste water by microcolumn liquid chromatography using a preconcentration column with cold-vapour atomic absorption spectrometric detection

A microcolumn liquid chromatographic method with cold-vapour atomic absorption spectrometric detection was developed for the speciation of mercury compounds in waste water. The sample solution containing mercury at the 4-ng level was injected onto a preconcentration column (27 mn × 0.51 mm i.d.) packed with Develosil-ODS (30 μm) and eluted with cysteine-acetic acid through a separation column (125 mm × 0.5 mm i.d.) packed with STR-ODS-H (5 μm). After oxidation, tin(II) chloride in sodium hydroxide solution was used to reduce mercury compounds to mercury. The generated mercury vapour was swept from a gas-liquid separator by argon into the detector cell and monitored at 253.7 nm. Mercury(II) chloride, methylmercury chloride and ethylmercury chloride, were well resolved and the determination was completed in less than 16 min. The method was successfully applied to the speciation of mercury compounds in waste water.     

On-line coupling of flow injection displacement sorption preconcentration to high-performance liquid chromatography for speciation analysis of mercury in seafood

A simple and cost-effective method for speciation analysis of trace mercury in seafood was developed by on-line coupling flow injection microcolumn displacement sorption preconcentration to high-performance liquid chromatography (HPLC) with UV detection. The methodology involved the presorption of the Cu-PDC (pyrrolidine dithiocarbamate) chelate onto a microcolumn packed with a cigarette filter sorbent, simultaneous preconcentration of Hg(II), methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg) onto the microcolumn through a displacement reaction with the presorbed Cu-PDC, and their subsequent elution from the microcolumn for on-line HPLC separation. Interferences from heavy metal ions with lower stability of their PDC chelates relative to Cu-PDC were minimized without the need of any masking agents. With the consumption of 4.0 ml of sample solution, the enrichment factors were about 80. The detection limits were 10-25 ng g(-1) (as Hg) in fresh tissue. Precision (R.S.D. (%), n = 5) ranged from 2 to 3% at the 500 microg l(-1) (as Hg) level. The developed technique was validated by analyzing a certified reference material (DORM-2, dogfish-muscle), and was shown to be useful for mercury speciation in real seafood samples.     

Determination of mercury and methylmercury in seafood by ion chromatography using photo-induced chemical vapor generation atomic fluorescence spectrometric detection

A novel method based on photo-induced chemical vapor generation (CVG) as interface to on-line coupled Hg-cysteine ion chromatograpy (IC) with atomic fluorescence spectrometry (AFS) was developed for rapid determination of methylmercury (MHg) in seafood. Separation of inorganic mercury (Hg²⁺) and methylmercury(CH₃Hg⁺) was accomplished on a Hamilton PRP X-200 polymer-based exchange column with a mobile of 3% acetonitrile, 1% (w/w) L-cysteine and 20 mmol L^{− 1} pyridine and 160 mmol L^{− 1} formic acid, at pH 2.4 within 7 min. Once separated, both species are reduced by formic acid in mobile phase under UV radiation to convert Hg⁰ on-line, which is subsequently swept (by argon carrier gas) into an atomic fluorescence spectrometry (AFS) for measurement. Under the optimized experiment conditions, the detection limits (as Hg), based on three times the standard deviation of a standard solution, were found to be 0.1 ng mL^{− 1} for mercury and 0.08 ng mL^{− 1} for methylmercury, with an injection volume of 100 μL. The developed method was validated by determination of certified reference material DORM-2 and was further applied in determination of seafood samples.