Chelex 100树脂固相萃取-电感耦合等离子体原子发射光谱法测定高氯高盐废水中6种重金属元素

用Chelex 100树脂固相萃取法分离高氯高盐废水中的铜、铅、锌、镍、镉和锰等6种目标元素,用电感耦合等离子体质谱法(ICP-MS)优化固相萃取条件,用电感耦合等离子体原子发射光谱法(ICP-AES)测定目标元素的含量。高氯高盐废水样品经硝酸消解后,用乙酸盐缓冲溶液(pH 6.5)定容。预先填充好Chelex树脂的固相萃取小柱,用0.5 mol·L~(-1)乙酸铵溶液活化,以1 mL·min~(-1)速率加入样品溶液10 mL后,用0.5 mol·L~(-1)乙酸铵溶液和水淋洗柱子,用5%(体积分数)硝酸溶液以1 mL·min~(-1)速率洗脱柱子,收集10 mL洗脱液,在检测波长214.439,257.610,231.604,206.200,327.395,220.353 nm处测定其中镉、锰、镍、锌、铜、铅含量。结果显示:目标元素标准曲线的线性范围为0.1～10.0 mg·L~(-1),检出限(3s)为4.0×10~(-4)～3.0×10~(-2) mg·L~(-1)。对含氯化钠废水、含氯化铵废水、含氯化钠和氯化铵的废水进行加标回收试验,目标元素的检出量在1.600 mg·L~(-1)以下,回收率为92.2%～102%,测定值的相对标准偏差(n=9)为0.50%～3.5%。     

电感耦合等离子体质谱法测定土壤中镉和总汞

建立电感耦合等离子质谱法测定土壤中镉和总汞的方法。土壤样品在电热板上用盐酸和硝酸于100℃低温消解,重量法定容,取上清液上机测定。镉和总汞含量分别在0.502~10.20 ng/g,0.212~5.010 ng/g范围内线性良好,相关系数(r2)大于0.999,土壤中镉和总汞的检出限分别为0.021,0.002μg/g,测定结果的相对标准偏差分别为1.99%,5.57%(n=6),加标回收率分别为97.5%~101.1%,87.5%~92.9%。该方法样品处理简单快捷,检出限低,准确度和精密度高,适合土壤中镉和总汞含量的测定。     

不同前处理方法测定银锡焊料中3种重金属元素

选用银含量为3%、30%和70%的银锡焊料样品,分别经过三种不同前处理方法,采用硝酸、盐酸消解,应用电感耦合等离子体发射光谱法(ICP-OES)同时测定锡铅合金中镉、铅、汞3种重金属元素含量。实验研究了不同前处理方法对银锡合金中重金属测定的影响。实验表明消解实验中的共沉淀现象会对3种重金属元素的测定产生不利的影响,回收率不能满足要求;采用硝酸消解,过滤残渣经王水消解的方法,镉、铅、汞的7次测定重复性相对标准偏差在2.7%~5.5%、加标回收率在85.6%~103%,能够满足RoHS测试要求。     

微波消解–ICP–MS法测定话梅中的二氧化钛

建立了微波消解–电感耦合等离子体质谱仪(ICP–MS)测定话梅中二氧化钛的方法。话梅样品用硝酸及过氧化氢经微波消解仪消解,将消解液除酸定容后用电感耦合等离子体质谱仪测定,以内标法测得钛的含量,并转换成样品中的二氧化钛含量。钛含量在0~500μg/kg范围内与信号强度呈良好的线性,线性相关系数r=0.999 9,检出限为0.04μg/kg。在0.06,0.15,0.30μg/kg的添加水平下,加标回收率为80%~100%,相对标准偏差为3.2%~3.9%(n=6)。该法稳定性好,测定结果准确、可靠。     

二苯硫脲-醋酸丁酯萃取-石墨炉原子吸收法测定地球化学样品中痕量银

对石墨炉原子吸收光谱法测定地球化学样品中痕量银进行了研究。样品经盐酸、硝酸、硫酸、高氯酸溶解,在盐酸(1.2mol/L)介质中用醋酸丁酯萃取银与二苯硫脲螯合物,用石墨炉原子吸收光谱法测定地球化学样品中痕量银,方法检出限为0.011ng/mL,相对标准偏差(RSD,n=11)为6.0%~12.2%,加标回收率为96.00%~105.00%。能满足地球化学样品中银含量为0.02~5μg/g范围内银测定的准确度和精密度的要求。     

微波消解-石墨炉原子吸收法测定酵母粉中的微量铅和镉

本文采用微波消解-石墨炉原子吸收法直接测定酵母粉中微量铅和镉的含量。利用硝酸和过氧化氢消解样品,对微波消解的条件,基体改进剂的选择,铅原子化温度的效果以及常见元素对测定的干扰进行了研究。在优化的实验条件下,方法对铅和镉的检出限(3σ)分别为0.062 ng/mL和0.013 ng/mL,相对标准偏差(RSD)分别为0.64%~1.11%、0.75%~4.70%,加标回收率在95.00%~102.0%之间。本法已用于酵母粉中微量铅和镉的测定,分析结果与电感耦合等离子体-质谱(ICP-MS)法具有良好的一致性。     

原子吸收光谱法测定水生生物体内铜、锌、镍、铬、铅、镉

用硝酸-高氯酸体系消解螺蛳和水葫芦样品,采用火焰原子吸收光谱法测定铜、锌、镍、铬,用石墨炉原子吸收光谱法测定铅、镉。铜、锌、镍、铬、铅、镉的检出限分别为0.328、0.126、0.271、0.416、0.006 64、0.001 15 mg/kg,线性相关系数不小于0.999 0,测定结果的相对标准偏差为1.1%~3.7%,加标回收率为86.0%~94.2%。     

电感耦合等离子体原子发射光谱法测定植物中钾、钠、钙和镁

采用硝酸–高氯酸湿法消解或硝酸–双氧水微波消解植物样品,以电感耦合等离子体原子发射光谱法同时测定样品溶液中钾、钠、钙和镁含量。用该法测定灌木枝叶和茶叶标准样品,测定值均在标准值范围内,测定结果的相对标准偏差为0.45%~4.05%(n=8)。钾、钠、钙、镁的加标回收率分别为94.4%~107.6%,92.6%~107.9%,93.7%~105.4%,92.9%~107.2%。该方法操作简便,测量精密度和准确度完全满足植物中钾、钠、钙和镁含量的测定要求。     

测定食品及生物样品中微量锡的消化方法探讨

采用干灰化、硝酸-高氯酸、硝酸-硫酸-高氯酸和用硝酸过氧化氢微波消解4种消化方法消化样品,氢化物发生-原子荧光光谱法测定食品及生物样品中微量锡。方法线性范围为20.0μg.L-1以内,相关系数为0.999 8,经过比较,微波消解和硝酸-硫酸-高氯酸消解方法较理想,回收率分别为98.2%~101.4%和97.4%~102.8%,相对标准偏差分别为2.39%~3.85%和3.25%~3.82%。只测定锡时,微波消解和硝酸-硫酸-高氯酸消解法均可,但如锡与其他微量元素需要同时测定,为避免引入有干扰的硫酸根,以用硝酸-过氧化氢微波消解为好。     

萃取光度法测定电镀废水中微量镉

采用双硫腙-TBP萃取光度法快速测定电镀废水中微量镉。在磷酸盐的中性缓冲溶液中,双硫腙-TBP显绿色,与镉离子生成橙红色配合物。镀镉废水中的干扰离子用钛铁试剂-酒石酸钾钠-碘化钾联合掩蔽。镉-双硫腙配合物萃取至有机相直接进行光度法测定。试验结果表明,在500 nm波长处,表观摩尔吸光系数为6.0×104L.mol-1.cm-1,Sandell灵敏度为0.001 9μg.cm-2;5 mL有机萃取相中镉含量在0~8.0μg/5 mL符合比耳定律。应用电镀废水样品中微量镉的直接萃取测定,分析结果的相对偏差小于2.8%,回收率为99.5%。     

Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples

A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO₂ (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L⁻¹ (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples.     

液/液界面萃取循环伏安法测定Pb2+离子研究

本文利用吡咯烷二硫代氨基甲酸铵（APDC）作为螯合剂,甲基异丁酮（MIBK）作为萃取剂,将水相中的Pb2+萃取到有机相中,利用经典的三电极系统研究该有机相在液/液界面的伏安特性。实验结果表明,该电化学过程是一个由扩散控制的不可逆过程,Pb2+的萃取物从有机相转移到水相。铅萃取物的转移峰在0.16V vs.SCE处,并且在1.0×10-5~ 9.0×10-5mol/L范围内与峰电流大小成正比。这一方法为工业废水中铅的在线、现场测定提供了可靠、灵敏的监测方法。     

Determination of trace cadmium in waters by flame atomic absorption spectrophotometry after preconcentration with 1-nitroso-2-naphthol-3,6-disulfonic acid on Ambersorb 572

A procedure for the determination of trace amount of cadmium after adsorption of its 1-nitroso-2-naphthol-3,6-disulfonic acid chelate on Ambersorb 572 has been proposed. This chelate is adsorbed on the adsorbent in the pH range 3-8 from large volumes of aqueous solution of water samples with a preconcentration factor of 200. After being sorbed, cadmium was eluted by 5 mL of 2.0 mol L(-1) nitric acid solution and determined directly by flame atomic absorption spectrophotometery (FAAS). The detection limit (3sigma) of cadmium was 0.32 microg L(-1). The precision of the proposed procedure, calculated as the relative standard deviation of recovery in sample solution (100 mL) containing 5 microg of cadmium was satisfactory (1.9%). The adsorption of cadmium onto adsorbent can formally be described by a Langmuir equation with a maximum adsorption capacity of 19.6 mg g(-1) and a binding constant of 6.5 x 10(-3) L mg(-1). Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for the preconcentration and determination of cadmium in water samples. This procedure was applied to the determination of cadmium in tap and river water samples.     

Simultaneous determination of four heavy metal ions in tobacco and tobacco additive by online enrichment followed by RP-HPLC and microwave digestion

A new method for the simultaneous determination of tin, lead, cadmium, and mercury in tobacco and tobacco additive by reversed-phase high-performance liquid chromatography combined with microwave digestion and an online enrichment technique is developed. The tin, lead, cadmium, and mercury ions are precolumn derivatized with tetra-(4-dimethylaminophenyl)-porphyrin (T(4)-DMAPP) to form color chelates. The Sn-T(4)-DMAPP, Hg-T(4)-DMAPP, Cd-T(4)-DMAPP, and Pb-T(4)-DMAPP chelates are absorbed onto the front of the enrichment column using a buffer solution of 0.05 mol/L pyrrolidine-acetic acid (pH = 10.0) as the mobile phase. After the concentration is finished (by switching the six-port switching valve) the retained chelates are back-flushed by the mobile phase and move to the analytical column. The chelate separation on the analytical column is satisfactory using gradient elution with methanol (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0) and tetrahydrofuran (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0). The linearity range is 0.01-120 micro g/L for each metal ion. The detection limits (S/N = 3) of tin, lead, cadmium, and mercury are 0.6, 0.8, 0.5, and 0.6 ng/L, respectively. This method is applied to the determination of tin, lead, cadmium, and mercury in tobacco and it's additive with good results.     

Ionic liquid as a complexation and extraction medium combined with high-performance liquid chromatography in the evaluation of chromium(VI) and chromium(III) speciation in wastewater samples

A simple method has been proposed for the determination of chromium species by high-performance liquid chromatography (HPLC) after preconcentration by the ionic liquid, 1-butyl-3-methyimidazolium hexafluorophosphate ([C₄MIM][PF₆]). The simultaneous preconcentration of Cr(VI) and Cr(III) in wastewater was achieved with ammonium pyrrolidinedithiocarbamate (APDC) as the chelating agent and the ionic liquid [C₄MIM][PF₆] as the extractant. Baseline separation of the APDC chelates of Cr(III) and Cr(VI) was realised on a RP-C18 column using a mixture of methanol–acetonitrile–water (53:14:33, v/v) as the mobile phase at a flow rate of 1.0 mL min^{− 1}. The influences of several variables on the complexation and extraction were evaluated: pH, reaction time, APDC concentration and metal ion interference. Our results showed that when the linear concentration of Cr(VI) and Cr(III) ranged from 25 to 200 μg L^{− 1}, their linear correlation coefficients were between 0.9977 and 0.9978, their recoveries ranged from 91.8% to 95.8% and their relative standard deviations (n = 3) were between 0.31% and 1.8%. Common metal ions in water did not interfere with the determination. This method is a simple, fast, accurate, highly stable and selective method and has successfully been applied to the speciation of chromium in wastewater.     

Cloud point extraction–thermospray flame quartz furnace atomic absorption spectrometry for determination of ultratrace cadmium in water and urine

A simple, low cost and highly sensitive method based on cloud point extraction (CPE) for separation/preconcentration and thermospray flame quartz furnace atomic absorption spectrometry was proposed for the determination of ultratrace cadmium in water and urine samples. The analytical procedure involved the formation of analyte-entrapped surfactant micelles by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution and a Triton X-114 solution. When the temperature of the system was higher than the cloud point of Triton X-114, the complex of cadmium-PDC entered the surfactant-rich phase and thus separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, the limit of detection was 0.04 μg/L for cadmium with a sample volume of 10 mL. The analytical results of cadmium in water and urine samples agreed well with those by ICP-MS.     

Determination of cadmium and lead in aqueous environmental samples after complexation and microextraction onto the surface of an empty solvent-impregnated polypropylene fibre coupled with electrothermal AAS

A procedure based on polypropylene hollow-fibre preconcentration coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed for the determination of cadmium and lead in seawater, wastewater, tap water and lake water samples. The n-octanol was immobilised in the pores of the polypropylene hollow fibre, which was used as the liquid sorption membrane negating the need for acceptor liquid phase in the lumen. The metal ions were extracted from water samples onto the impregnated fibre, as ammonium pyrrolydine dithiocarbamate (APDC) complexes, and then back-extracted into a small volume of 0.1?mol?L^?1 HNO₃. The main extraction-related parameters were properly evaluated and an interference study was carried out. Linear regression lines were plotted and replicate analyses of real samples revealed that the proposed method is precise and accurate, able to be applied in routine analysis with detection limits of 4?ng?L^?1 and 12?ng?L^?1 for Cd and Pb, respectively.     

Development of an automated sequential injection on-line solvent extraction-back extraction procedure as demonstrated for the determination of cadmium with detection by electrothermal atomic absorption spectrometry

An automated sequential injection (SI) on-line solvent extraction-back extraction separation/preconcentration procedure is described. Demonstrated for the assay of cadmium by electrothermal atomic absorption spectrometry (ETAAS), the analyte is initially complexed with ammonium pyrrolidinedithiocarbamate (APDC) in citrate buffer and the chelate is extracted into isobutyl methyl ketone (IBMK), which is separated from the aqueous phase by means of a newly designed dual-conical gravitational phase separator. A metered amount of the organic eluate is aspirated and stored in the PTFE holding coil (HC) of the SI-system. Afterwards, it is dispensed and mixed with an aqueous back extractant of dilute nitric acid containing Hg(II) ions as stripping agent, thereby facilitating a rapid metal-exchange reaction with the APDC ligand and transfer of the Cd into the aqueous phase. The aqueous phase is separated in a second dual-conical gravitational phase separator, and 30 μl of it is entrapped and metered in a sample loop (SL) and subsequently introduced via air segmentation into the graphite tube for analyte quantification. The ETAAS determination is performed in parallel with the separation/preconcentration process of the ensuing sample. An enrichment factor of 21.4, a detection limit of 2.7 ng l⁻¹, along with a sampling frequency of 13 h⁻¹ were obtained at a sample flow rate of 6.0 ml min⁻¹. The precision (R.S.D.) at the 0.4 μg l⁻¹ level was 1.8% as compared to 3.2% when quantifying the organic extractant directly. The applicability of the procedure is demonstrated for the determination of trace levels of cadmium in three certified reference materials.     

冷原子荧光法测定水中汞

研究了以高锰酸钾消化,冷原子荧光法测定水质中汞的最佳测定条件。汞含量在0.0025~0.075μg范围内呈线性关系,相关系数为0.99993,检出限为0.026μg.L-1。方法应用于水样中汞的测定,样品加标回收率在97.6%~117.0%之间,相对标准偏差在1.7%~5.7%之间。     

A rapid, sensitive and effective quantitative method for simultaneous determination of cationic surfactant mixtures from river and municipal wastewater by direct combination of single-drop microextraction with AP-MALDI mass spectrometry

A rapid, simple, sensitive, and effective quantitative method for simultaneous determination of cationic surfactants (CS(+)) from river and municipal wastewater by direct combination of single-drop microextraction (SDME) with atmospheric pressure (AP)-MALDI mass spectrometry has been successfully demonstrated without the requirements of tedious sample pre- or post-treatment or separation by high-performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE). This quantitative method can greatly enhance the signal-to-noise ratio for analysis of small molecules of CS(+) owing to the strong suppression of matrix ions by the analytes. In addition, SDME assisted in the isolation and preconcentration of CS(+) from water samples, which could effectively reduce the background interferences from the matrices present in waste and river water. The SDME conditions were optimized for achieving high extraction efficiency of CS(+) from aqueous samples, in terms of solvent selection, stirring speed, extraction time, exposure volume of acceptor phase, and salt addition. The enrichment factors for CS(+) were found to be 40-64-folds for 7 min of extraction time with no salt addition and at room temperature. This method was found to yield a linear calibration curve in the concentration range from 50 to 1500 microg/l CS(+) with a limit of detection (LOD) of 10 microg/l. The relative recoveries in river and municipal wastewater were found to be 93.8-103.6% and 91.0-98.7%, respectively. These results indicate that the combination of SDME with AP-MALDI/MS is effective for the simultaneous determination of CS(+) from river and municipal wastewater. In addition, a comparison of enrichments and LOD values for this method with hollow-fiber liquid phase microextraction (HF-LPME) was also demonstrated. The present approach is easy to operate, rapid, sensitive, and suitable for high-throughput of analysis.