电感耦合等离子体质谱法同时测定食品中的铅、镉和总砷

建立了电感耦合等离子体质谱(ICP–MS)法同时测定食品中的铅、镉和总砷含量的分析方法。样品经消化后直接用ICP–MS分析,采用在线引入混合内标溶液校正基体干扰和仪器的信号漂移。铅、镉、总砷的质量浓度在0~50μg/L范围内与信号强度呈良好的线性,线性相关系数(r)均大于0.999 0。用该方法对标准物质进行测定,分别采用湿法、微波消解法对样品进行处理,两种前处理方式测定值无显著性差异,测定结果的相对标准偏差在0.45%~4.2%之间(n=6),检测结果均在参考值范围内。该方法可同时测定铅、镉和总砷含量,操作简便、重现性好、结果准确可靠,可以满足各种食品中铅、镉和总砷同时测定的要求。     

铋膜电极溶出伏安法测定食品中痕量重金属

以铋膜电极为工作电极,采用微分脉冲阳极溶出伏安法直接测定食品样品中痕量铅、镉和锌。在富集电位-1.4V,富集时间180s,铋膜质量浓度150μg·L-1的条件下,铋膜电极对铅、镉和锌的氧化溶出具有良好的电化学响应。铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)的质量浓度在5.0~40μg·L-1的范围内与其阳极溶出峰电流呈线性关系,铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)的检出限(3S/N)分别为0.80,0.65,0.58μg·L-1。对25μg·L-1铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)溶液用铋膜电极连续测定15次,相对标准偏差分别为6.2%,5.1%,7.1%。方法应用于食品中痕量重金属的测定,测定结果与石墨炉原子吸收光谱法的测定值相符。     

微波消解-ICP-AES测定食品塑料包装中钛、铅、铬和镉

采用微波消解技术,电感耦合等离子体原子发射光谱法(ICP-AES)同时测定食品塑料包装中钛、铅、铬和镉.研究了消解程序和消解试剂,建立了塑料样品的微波消解方法.测定了三种不同的食品包装用塑料,方法回收率为73.3%~101.7%,相对标准偏差为0.3%~10.7%,钛、铅、铬和镉在塑料中的检出限分别为1.50、7.38...     

北京市朝阳区食品污染物监测状况分析

为通过2008年北京市朝阳区食品污染物监测,了解辖区部分食品铅、镉、铝的污染现状,给食品风险评估和政府部门强化监管提供依据,按照国家标准方法GB／T5009对13种135件食品样品进行了铅、镉、铝含量的监测。结果表明,100件样品中铅超标率为6．O％,镉超标率为0;35件样品铝的超标率为65．71％。显示辖区经销的食品中重金属确有污染存在,而铝在油炸面制品和天然海蜇中超标率较高,仍对人体健康存在威胁。     

微波消解样品-石墨炉原子吸收光谱法测定食品添加剂中铅和镉含量

提出了石墨炉原子吸收光谱法测定食品添加剂中铅和镉含量的方法。样品用硝酸及过氧化氢作溶剂,使用微波消解的方法处理。以磷酸二氢铵为基体改进剂,铅和镉灰化温度分别为600℃和400℃,原子化温度分别为2 100℃和1 800℃。在优化的试验条件下,测得铅和镉相对标准偏差(n=6)分别为2.8%～6.5%和2.4%～5.3%,7种食品添加剂中铅和镉的回收率在94%～102%和96%～103%之间。     

SPCE-微型DPSA-1仪同步快速检测蔬菜中的铅、镉、铜

以优化的微波消解法进行样品预处理,用微型DPSA-1仪结合丝网印刷碳电极,通过微分电位溶出法对蔬菜中的铅、镉、铜进行同步快速检测。结果表明,在1～840μg/L(相当于蔬菜中铅、镉、铜含量为0.0125～10.5mg/kg)范围内呈现良好的线性关系,铅的相关系数为r=0.9977,检出限为0.42μg/L(S/N=3);镉的相关系数为r=0.9976,检出限为0.34μg/L(S/N=3);铜的相关系数为r=0.9958,检出限为1.36μg/L(S/N=3)。研究了检测过程中存在多种干扰离子对于铅、镉、铜检测的干扰情况。试验检测26种蔬菜,所得检测结果与国标检测法进行t检验,无显著差异。与常规的检测技术相比,本法同步检测蔬菜中的铅、镉、铜具有更经济、简便、快速等优点,可实现样品的高比例筛检,还有望作为推广应用于其它类型食品和环境样品中铅、镉、铜快速检测的基础模型,具有很好的应用潜力和广阔的应用前景。     

原子吸收光谱法测定益寿回春口服液中砷铅镉铬汞的含量

采用原子吸收光谱法测定了益寿回春口服液中砷、铅、镉、铬和汞的含量，并参照食品中重金属的限量规定进行了比较。结果表明，益寿回春口服液中的砷、铅、镉、铬和汞均低于限量标准，为该产品的质量控制提供了依据。     

示波极谱法快速同时测定矿石中铅镉锌

极谱法测定铅、镉、锌的报道颇多,不少已成功地得到了运用,例如盐酸底液法、氯化钙底液法、盐酸-柠檬酸氢铵法等测铅,盐酸-乙酸钠底液法、氨性底液法测锌,乙酸-乙酸钠底液法铅、锌连测,氨性底液法测镉等.通过试验发现在乙酸-吡啶-Br~- 组成的体系中,用Br~- -吡啶掩蔽铜,于-0.43V、-0.61V、-1.10V处测量铅、镉、锌峰高,在0～10mg/50ml范围内波高与浓度呈线性关系.方法简单、快速、准确度和精密度令人满意,用于矿石中铅、镉、锌同时测定,效果好.     

微波消解-溶出伏安法快速检测食品中的金属污染物——介绍一个创新性的仪器分析实验

采用微波消解作为样品前处理方法,结合阳极溶出伏安法,采用在线镀汞膜技术对食品中的铜、铅、镉等重金属同时进行定性和定量分析,以此替代传统的溶出伏安法验证性实验。     

分离富集-原子吸收光谱法测定锌锰电池中铅和镉

对用原子吸收光谱法测定锌锰电池中铅和镉结果的可靠性进行了研究。对于典型的4R25电池,试液中主要成分锌和锰总量超过40 g.L-1,直接用普通稀释法得不到准确的结果。采用CL-7301萃淋树脂微色谱柱将电池试液中铅和镉与基体快速分离,用火焰原子吸收光谱法测定铅和镉,当铅和镉的含量较高时,可以将样品预稀释后采用在线稀释技术直接测定铅和镉。     

镉基体分离及纯镉中杂质成分的ICP-MS法测定

研究了用阴离子交换树脂分离纯镉中铜、锌、铅、铁的条件，所得优化分离条件为：717型阴离子交换树脂柱，样品溶液为2mol/L HCl溶液；三段淋洗液依次为2mol/L HCl溶液、0．2mol/L HBr 0．25mol/L HNO3的混合酸溶液及3mol/L HNO3溶液。经ICP-MS测定证明，95％以上的镉得到分离，95％以上的铜、锌、铅、铁可以分离测定，有效地降低了ICP-MS测定纯镉中铜、锌、铅、铁时镉基体的干扰。     

1-(2-苯并噻唑)-3-(4-硝基苯)-三氮烯的合成及其与镉(Ⅱ)的显色反应研究

报道了１－（２－苯并噻唑）－３－（４－硝基苯）－三氮烯（ＢＴＮＰＴ）的合成及与镉（Ⅱ）的显色反应研究。在ＴｒｉｔｏｎＸ－１００的存在下,ｐＨ１１．６时,镉（Ⅱ）与ＢＴＮＰＴ形成摩尔比＝１∶２型黄色络合物,在４３５ｎｍ处有一最大正吸收,在５３０ｎｍ处有最大负吸收。以４３５ｎｍ为参比波长,５３０ｎｍ为测量波长进行双波长测定,表观摩尔吸光系数为２．５２×１０５Ｌ·ｍｏｌ－１·ｃｍ－１,线性范围为０～１０μｇ／２５ｍＬ。已用于测定地面水和人发中的镉含量。     

Preconcentration of trace elements in sea water with poly (acrylaminophosphonic – dithiocarbamate) chelating fiber for their determination by inductively coupled plasma mass spectrometry

A new ion exchange chelating fiber with aminophosphonic and dithiocarbamate groups based on polyacrylonitrile was used for the simultaneous preconcentration of beryllium, bismuth, cobalt, gallium, silver, lead, cadium, copper, manganese and indium in sea water. The optimum experimental parameters, such as fiber capacity, pH, sample flow rate and volume, eluant and effect of matrix ions on the preconcentration were investigated. The separation of analytes can be achieved from sea water with a concentration factor of at least 200 times. The method has been applied for the determination of trace elements in coastal sea water. The data obtained by this method agreed well with certified values.     

应用多元统计技术研究动物产品中重金属的分布特征

采用直方图频率说明、参数分布拟合假设检验、非参数密度估计等多元统计技术,研究了铅、镉、汞、砷在不同动物源性产品中的分布特征,通过非参数方法给出了4种元素在不同产品中的密度分布函数曲线和经验分布函数曲线,以此解释了元素的分布特征,掌握了重金属的累积富集规律。     

Preconcentration of trace elements in sea water with poly (acrylaminophosphonic – dithiocarbamate) chelating fiber for their determination by inductively coupled plasma mass spectrometry

A new ion exchange chelating fiber with aminophosphonic and dithiocarbamate groups based on polyacrylonitrile was used for the simultaneous preconcentration of beryllium, bismuth, cobalt, gallium, silver, lead, cadium, copper, manganese and indium in sea water. The optimum experimental parameters, such as fiber capacity, pH, sample flow rate and volume, eluant and effect of matrix ions on the preconcentration were investigated. The separation of analytes can be achieved from sea water with a concentration factor of at least 200 times. The method has been applied for the determination of trace elements in coastal sea water. The data obtained by this method agreed well with certified values. Received: 1 May 1998 / Revised: 30 July 1998 / Accepted: 8 August 1998     

Investigations of properties and binding forms of cadmium and nickel in protein extracts by ultra-/diafiltration, photometry and atomic absorption spectrometry

A combination of a special ultrafiltration procedure with photometry and atomic absorption spectrometry for application in the speciation analysis of protein containing solutions is described, allowing not only the determination of qualitative distribution patterns of metal species but also the quantitative characterization of metal species. According to these investigations, exemplified by cadmium and nickel species in protein extracts of bean seeds, it is demonstrated how to use this method. The results show that cadium and nickel have completely different binding mechanisms in these seeds. Furthermore, these investigations lead to the result that the application of membrane separation techniques in speciation analysis is not limited to the separation into molecular weight ranges only. Much more, they are useful techniques in combination with detection methods to obtain information about binding strength and the complexing ability of different matrices to bind heavy metals.     

丙氨酸二元和三元配合物的pH电位法研究

本文报导了用pH电位法在温度为37±0.1℃和离子强度为150mM/dm³下研究了丙氨酸与铜、锌、镍、镉的二元和三元配合物稳定常数,并确定了各体系中配合物粒子的正确组成.ΔlgK和lgX值表明混合配合物比较稳定。配位离子分布图指出在生理条件下,这些配合物主要是以中性配合物的形式存在。这对于金属离子的透膜传输有重要意义。     

石柱黄连及根际土壤中矿质元素特征分析

研究石柱黄连不同器官及其根际土壤中矿质元素特征,探究黄连根茎矿质元素间及其与土壤环境的相关性。采用电感耦合等离子体质谱法(ICP-MS)、电感耦合等离子体发射光谱法(ICP-OES)及原子荧光光谱法(AFS)测定了15组石柱黄连植株和根际土壤中18种矿质元素含量,所得数据运用SPSS 22.0统计软件分析。石柱黄连根际土壤中锰、磷、镁、镉、汞等元素含量的变异性较大,部分采样点土壤中镉含量超过农用地土壤污染风险筛选值。在检测的18种元素中,黄连植株中钙、镁、磷、钾含量最高,其次是铁、锰、锌,再次是锶、铜、镍,最后是铅、钒、钴、镉、钼、铬、砷、汞。须根对大部分矿质元素的富集能力强于根茎或地上部;黄连根茎对锌的富集能力强于须根或地上部;地上部对钙、磷、钾、铬的富集能力强于须根或根茎。Spearman分析表明黄连根茎矿质元素间、黄连根茎与土壤中矿质元素有一定相关性,部分具有统计学意义(P＜0.05)。石柱黄连不同器官中矿质元素含量有明显差异,以此建立的指纹图谱可用于区分黄连根茎及须根的粉末样品;黄连根茎中矿质元素间主要表现为协同作用,黄连根茎与土壤中矿质元素既有协同作用又有拮抗作用。     

Effect of reaction media on the growth and photoluminescence of colloidal CdSe nanocrystals

Using cadium oxide (CdO) as the Cd precursor and tri-n-octylphosphine selenide (TOPSe) as the Se source, TOP-capped and TOP/tri-n-octylphosphine oxide (TOPO)-capped CdSe nanocrystals were synthesized without the use of an acid. The synthetic approach involved the addition of a TOPSe/TOP solution into a CdO/TOP solution with or without TOPO at one temperature and subsequent growth at a lower temperature. The temporal evolution of the optical properties, namely, absorption and luminescence, of the growing nanocrystals was monitored in detail. A comprehensive examination on the control of the photoluminescence (PL) properties was performed by systematically varying the TOP/TOPO weight ratio of the reaction media. Surprisingly, a rational choice of 100% TOP or 80% TOP was found to produce "quality" nanocrystals when monitored under the present experimental conditions and growth-time scale. The term "quality" is mainly based on the sharp features and rich substructure exhibited in the absorption spectra of the growing nanocrystals, as well as the sharp features in the emission spectra with narrow full width at half-maximum (fwhm). There are two distinguishable stages of growth: an early stage (<5 min) and a later stage. TOP plays a major role in the control of a slow growth rate in the early stage, while TOPO controls slow growth in the later stage. The optical sensitivity of the growing nanocrystals when dispersed in nonpolar or polar solvents was studied, including two size-dependent parameters, namely, the solvent sensitivity (PL intensity) and nonresonant Stokes shift (NRSS). The insights gained from the present study enable a synthetic approach in which high-quality CdSe nanocrystals are achieved with high synthetic reproducibility.     

气相色谱-质谱法测定水中有机含磷农药前处理方法比较

用气相色谱-质谱法测定了水中6种有机含磷农药残留量,并比较了全自动固相萃取(方法1#)和全自动液-液萃取(方法2#)两种样品前处理方法。结果表明:从准确度方面,方法1#优于方法2#,所测得的方法1#的回收率在73.5%～92.0%之间,而方法2#的回收率在63.7%～89.7%之间;但方法2#耗时较方法1#少。