液相色谱–原子荧光光谱法检测水产品中汞形态

建立了液相色谱–原子荧光光谱联用测定水产品中无机汞和甲基汞含量的方法。对影响测定结果的分析条件,如流动相组成、载流、还原剂、氧化剂、载气和屏蔽气进行了研究和优化,同时考察了该方法的有效性。结果表明:无机汞和甲基汞在质量浓度1~20 ng/m L范围内线性关系良好,相关系数分别为0.999 4,0.999 1;检出限分别为0.19,0.17 ng/m L;色谱峰面积的相对标准偏差分别为3.16%,2.16%(n=7);加标回收率分别为74%~100%,71%~91%。该方法可用于水产品中汞元素的形态分析。     

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。     

液相色谱-电感耦合等离子质谱联用技术测定水产品中汞化合物形态分析方法探讨

建立了高效液相色谱与电感耦合等离子体质谱联用技术测定水产品中汞化合物形态的分析方法。采用盐酸提取样品,C18柱(4.6 mm×150 mm)分离,流动相为5%甲醇-0.06 mol/L乙酸铵-0.1%半胱氨酸,3种汞化合物的线性范围均为0~100μg/L,相关系数(r)均大于0.999 0,检出限为0.5~0.8μg/L;汞化合物各形态的RSD均小于5%;不同质量浓度下无机汞、甲基汞、乙基汞的加标回收率分别为72%~90%、99%~118%、93%~111%;鱼肉标准物质(GBW 10029)、人发标准物质(GBW 09101B)中汞形态的测定值均在标准值范围内,甲基汞的FAPAS国际比对结果Z评分为1.0。该方法前处理简便、线性范围宽、精密度高、准确性好,适用于水产品中汞化合物的形态分析。     

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%.     

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%。     

微波消解-液相色谱-原子荧光光谱联用(LC-AFS)法测定稻米样品中砷形态

建立了稻米中4种砷元素形态的液相色谱-原子荧光光谱联用法(LC-AFS),样品用0.15mol/L的硝酸溶液微波提取50min,提取液经离心分离后,采用Hamilton PRP-X100色谱柱,45mmol/L KH2PO4-5mmol/L Na2HPO4缓冲液为流动相,砷形态4个组分能够在7min内达到基线分离,且无需调pH。优化了氢化物发生条件,使用了更低浓度的载流和还原剂。方法学实验结果表明,各组分在2~10ng/mL范围内线性关系良好,相关系数为0.9988~0.9998,各组分的检出限分别为0.29 ng/mL、0.47 ng/mL、0.62 ng/mL和1.16 ng/mL;各组分峰面积的相对标准偏差均低于3.11%;加标回收率为85.3%～112.8%;对稻米标准物质的分析测定结果表明该方法定值准确。最后,与GB 5009.11-2014中使用的提取及测量条件进行对比,表明该方具备法快速、环保、高效的特点。     

低压液相色谱-原子荧光快速测定鱼肉和土壤样品中汞形态

使用最新的低压液相整体柱与原子荧光联用及控温混旋提取技术,建立了鱼肉样品中汞形态分析的快速前处理及测定的方法。称取适量鱼肉样品,打成泥状,加入提取液(10%HCl,1%硫脲,和0.15%KCl),置于恒温混旋仪上,2000 r/min混旋提取,整个前处理和分析过程在30 min内可完成。样品的提取液先经过分离,然后经形态管内紫外消解,使用氢化物发生原子荧光的方法检测,得到各形态组分。本方法采用Merck整体柱分离,通过流速梯度淋洗将色谱分离和检测时间缩短到10 min之内。对流动相的配比和组分进行优化,确定了流动相的组成为3%(V/V)乙腈,30 mmol/L乙酸铵和0.03%(V/V)2-巯基乙醇。在样品分离后,选用灯内紫外消解方式,再进行检测,获得更高的检测灵敏度。本方法得到甲基汞和无机汞的检出限(DL)分别为0.15和0.14μg/L;相对标准偏差(RSD)<5%;线性相关系数(R)>0.999;用本方法检出了实际鱼肉和土壤样品中的汞形态,加标回收率在85%~110%之间。本方法快速、简单、准确可靠,可用于鱼肉样品中的汞形态的日常检测。     

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...     

加速溶剂提取-液相色谱-原子荧光光谱法测定对虾饲料中5种形态的汞北大核心CSCD

称取经粉碎的样品1.000 0g,置于加速溶剂提取池中,加入10mL的5mol·L-1盐酸溶液、1mL的5mol·L-1氯化钾溶液和2mL的10mol·L-1半胱氨酸溶液;在8.0MPa和70℃下,预加热2min,加热5 min,静态提取5min,分离,重复上述提取过程2次,合并提取液;加入0.2mL的0.5mol·L-1半胱氨酸溶液、1.5mL的6mol·L-1氢氧化钠溶液,以10 000r·min-1离心5min,将上清液氮吹浓缩并用硝酸(5+95)溶液定容至1mL,过0.45μm尼龙滤膜后,采用Eclipse XDB-C18反相色谱柱(150mm×4.6mm,5.0μm)分离溶液中的甲基汞、乙基汞、无机汞、硫柳汞和苯基汞,流动相为50g·L-1乙腈溶液+5g·L-1乙酸铵溶液+1g·L-1半胱氨酸溶液(体积比为1∶1∶1),用原子荧光光谱仪进行测定。5种形态的汞的质量浓度在一定范围内与其荧光强度呈线性关系,测定下限(10S/N)在1.0~2.5μg·kg-1之间。加标回收率在91.0%~98.3%之间,测定值的相对标准偏差(n=6)在0.94%~2.7%之间。     

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。     

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.     

Speciation analysis of mercury in sediments, zoobenthos and river water samples by high-performance liquid chromatography hyphenated to atomic fluorescence spectrometry following preconcentration by solid phase extraction

A high-pressure microwave digestion was applied for microwave-assisted extraction (MAE) of mercury species from sediments and zoobenthos samples. A mixture containing 3 mol L⁻¹ HCl, 50% aqueous methanol and 0.2 mol L⁻¹ citric acid (for masking co-extracted Fe³⁺) was selected as the most suitable extraction agent. The efficiency of proposed extraction method was better than 95% with R.S.D. below 6%. A preconcentration method utilizing a “homemade” C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the mercury species determination using on-column complex formation of mercury-2-mercaptophenol complexes. Methanol was chosen for counter-current elution of the retained mercury complexes achieving a preconcentration factor as much as 1000. The preconcentration method was applied for the speciation analysis of mercury in river water samples. The high-performance liquid chromatography-cold vapour atomic fluorescence spectrometric (HPLC/CV-AFS) method was used for the speciation analysis of mercury. The complete separation of four mercury species was achieved by an isocratic elution of aqueous methanol (65%/35%) on a Zorbax SB-C18 column (4.6 mm × 150 mm, 5 μm) using the same complexation reagent (2-mercaptophenol). The limits of detection were 4.3 μg L⁻¹ for methylmercury (MeHg⁺), 1.4 μg L⁻¹ for ethylmercury (EtHg⁺), 0.8 μg L⁻¹ for inorganic mercury (Hg²⁺), 0.8 μg L⁻¹ for phenylmercury (PhHg⁺).     

Arsenic speciation in edible alga samples by microwave-assisted extraction and high performance liquid chromatography coupled to atomic fluorescence spectrometry

Twelve commercially available edible marine algae from France, Japan and Spain and the certified reference material (CRM) NIES No. 9 Sargassum fulvellum were analyzed for total arsenic and arsenic species. Total arsenic concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) after microwave digestion and ranged from 23 to 126 μg g⁻¹. Arsenic species in alga samples were extracted with deionized water by microwave-assisted extraction and showed extraction efficiencies from 49 to 98%, in terms of total arsenic. The presence of eleven arsenic species was studied by high performance liquid chromatography–ultraviolet photo-oxidation–hydride generation atomic–fluorescence spectrometry (HPLC–(UV)–HG–AFS) developed methods, using both anion and cation exchange chromatography. Glycerol and phosphate sugars were found in all alga samples analyzed, at concentrations between 0.11 and 22 μg g⁻¹, whereas sulfonate and sulfate sugars were only detected in three of them (0.6-7.2 μg g⁻¹). Regarding arsenic toxic species, low concentration levels of dimethylarsinic acid (DMA) (<0.9 μg g⁻¹) and generally high arsenate (As(V)) concentrations (up to 77 μg g⁻¹) were found in most of the algae studied. The results obtained are of interest to highlight the need to perform speciation analysis and to introduce appropriate legislation to limit toxic arsenic species content in these food products.     

Selenium speciation by high-performance liquid chromatography with on-line detection by atomic absorption spectrometry

Several approaches to the determination of selenomethionine, selenocystine, selenite and selenate by high-performance liquid chromatography with online detection by atomic absorption spectrometry are described. The N?2,4-dinitrophenyl derivatives of selenomethionine, selenoethionine, selenocystine and phenylmercury(II) cystineselenoate were recovered from aqueous solution, separated on a Nucleosil 5-NO₂ reversed-phase HPLC column with a methanolic mobile phase containing acetic acid and triethylamine, and detected with a quartz thermochemical hydride-generating interface–atomic absorption spectrometry (AA) system. The restriction of having to perform chromatography with an organic mobile phase (to support the combusion process) was overcome with a new interface design capable of operation with either organic or aqueous HPLC mobile phases. Using aqueous acetic acid (0.015% v/v) containing 0.1% (w/v) ammonium acetate delivered at 0.5cm³ min^?1, selenate, selenite, selenomethionine, selenocystine and selenoethionine were separated virtually to baseline on a cyanopropyl-bonded phase HPLC column. Other selenium compounds which were investigated included methane seleninic and methane selenonic acids as well as the crude oxidation product mixtures resulting from the treatment of selenomethionine and selenocystine with hydrogen peroxide. A procedure for extracting selenate, selenite, selenomethionine, selenocystine and selenoethionine from spiked water or ground feed supplement into liquefied phenol resulted in acceptable recoveries for the latter four analytes but was unacceptably low for selenate.     

液相色谱-双通道原子荧光检测联用法同时测定砷和硒的形态

建立了一种利用高效液相色谱-双通道原子荧光检测联用同时进行砷和硒形态分析的方法。以10 mmol/L NH4H2PO4溶液(pH 5.6)(添加2.5%(体积分数)的甲醇)为流动相,在12 min内同时分离了三价砷(As(III))、一甲基砷(MMA)、二甲基砷(DMA)、五价砷(As(V))、硒代胱氨酸(SeCys)、硒代蛋氨酸(SeMet)和四价硒［Se(IV)］等化合物。As(III)、DMA、MMA、As(V)、SeCys、SeMet和Se(IV)的检出限分别为1,3,2,3,4,18和3 μg/L (进样量为200 μL),5次测定的相对标准偏差为1.9%～6.1%(As 100 μg/L, Se 300 μg/L)。应用该方法对人体尿样及硒酵母片中砷和硒的形态进行了分析,目标物在尿样中的加标回收率为83%～108%,在硒酵母片中的加标回收率为88%～105%。实验结果表明,该方法可用于尿样及药品中砷和硒形态的日常分析。该方法减少了样品的分析时间和试剂用量,降低了工作强度,提高了工作效率。     

Mercury speciation in thawed out and refrozen fish samples by gas chromatography coupled to inductively coupled plasma mass spectrometry and atomic fluorescence spectroscopy

Different sub-sampling procedures were applied for the determination of mercury species (as total mercury Hg, methylmercury MeHg⁺ and inorganic mercury Hg²⁺) in frozen fish meat. Analyses were carried out by two different techniques. After the sample material was pre-treated by microwave digestion, atomic fluorescence spectroscopy (AFS) was used for the determination of total Hg. Speciation analysis was performed according to the following procedure: dissolution of sample material in tetramethylammonium hydroxide (TMAH), derivatisation with sodium tetraethylborate (NaBEt₄), extraction into isooctane and measurement with gas chromatography inductively coupled plasma mass spectrometry (GC-ICPMS) for the identification and quantification of methylmercury (MeHg⁺) and inorganic mercury (Hg²⁺). The concentration range of total Hg measured in the shark fillets is between 0.9 and 3.6 g g^–1 thawed out shark fillet. Speciation analysis leads to 94% Hg present as MeHg⁺. Homogeneity, storage conditions and stability of analytical species and sample materials have great influence on analytical results. Sub-sampling of half-frozen/partly thawed out fish and analysis lead to significantly different concentrations, which are on average a factor of two lower.     

Sequential injection analysis implementing multiple standard additions for As speciation by liquid chromatography and atomic fluorescence spectrometry (SIA-HPLC-AFS)

An analytical procedure for multiple standard additions of arsenic species using sequential injection analysis (SIA) is proposed for their quantification in seafood extracts. SIA presented flexibility for generating multiple specie standards at the ng mL⁻¹ concentration level by adding different volumes of As(III), As(V), monomethylarsonic (MMA) and dimethylarsinic (DMA) to the sample. The mixed sample plus standard solutions were delivered from SIA to fill the HPLC injection loop. Subsequently, As species were separated by HPLC and analyzed by atomic fluorescence spectrometry (AFS). The proposed system comprised two independently controlled modules, with the HPLC loop acting as the intermediary device. The analytical frequency was enhanced by combining the actions of both modules. While the added sample was flowing through the chromatographic column towards the detection system, the SIA program started performing the standard additions to another sample. The proposed method was applied to spoiled seafood extracts. Detection limits based on 3σ for As(III), As(V), MMA and DMA were 0.023, 0.39, 0.45 and 1.0 ng mL⁻¹, respectively.     

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.     

Non-chromatographic speciation analysis of arsenic and antimony in milk hydride generation atomic fluorescence spectrometry

A rapid, high sensitivity method has been developed for the determination of As(III), As(V), Sb(III) and Sb(V) in milk samples by using hydride generation atomic fluorescence spectrometry. The method is based on the leaching of As and Sb from milk through the sonication of samples with aqua regia followed by direct determination of the corresponding hydrides both before and after reduction with KI. It was confirmed by recovery experiments on spiked commercially available samples that neither the reduced nor the oxidized forms of the elements under study or mixtures of the two oxidation states were modified by the room temperature sample treatment with aqua regia. The methodologies developed provided 3σ limit of detection values of 8.1, 10.3, 5.4 and 7.7 ng l⁻¹ for As(III), As(V), Sb(III) and Sb(V) in the diluted samples. Average relative standard deviation values of 5.7, 5.5, 8.2 and 4.7% were found for determination of As(III), As(V), Sb(III) and Sb(V) in commercially available samples of different composition and origin containing from 3.5 to 13.6 ng g⁻¹ total As and from 4.9 to 11.8 ng g⁻¹ total Sb, it being confirmed that As(V) and Sb(V) are the main species present in the samples analyzed (62±5 and 73±5%, respectively). The time required to determine As and Sb species in milk involves 10 min sonication and 30 min prereduction but these steps can be carried out for several sample simultaneously. Additionally the fluorescence measurement step involves less than 20 min for three replicates of all the four measurements required. So, in less than 2 h it is possible to determine the content of As(III), As(V), Sb(III) and Sb(V) in four samples.