石墨炉原子吸收法测定人参样品中微量锗的方法探讨

本研究以Ｍｇ、Ｐｄ为基体改进剂，提高了对人参样品中微量锗的分析灵敏度，消除了干扰和记忆效应，并研究人参样品的前处理方法。所建立的方法具有简单、快速、灵敏的特点，适应于测定某些生物样品中的痕量锗。     

超声波溶样、APDC-MIBK萃取石墨炉原子吸收法测定土壤中有效钼的研究

研究石墨炉原子吸收法测定土壤中有效钼,采用超声波溶样,APDC-M IBK萃取,抗坏血酸作基体改进剂.实际样品加标回收率为95%~105%,相对标准偏差为:1.35%.与其他方法比较具有快速、准确、灵敏、干扰小、操作简单、重现性好等特点,结果令人满意,值得推广。     

基体改良效应石墨炉原子吸收法直接测定植物样品中微量钼

本文研究利用460μg/mlNa_2CO _3—1000μg/mlCa_(2+)复合溶液作石墨炉原子吸收法(GFAAS)直接测定植物样品中微量钼的基体改良剂,详细讨论了该改良剂的作用、特性、钼原子化条件和基体干扰情况。使用本试验推荐的基体改良剂,在一定的浓度范围内能彻底消除钼的记忆效应,大大提高测定灵敏度,钼的原子吸收信号增加104.6％,特征性浓度为0.5ng/mlMo,相对偏差(RSD)为2.4％。     

塞曼石墨炉原子吸收法直接测定硼的方法研究

采用 Sr-Ni-Al-Mg 混合液为基体改进剂,研究了塞曼石墨炉原子吸收法直接测定硼的方法.试验表明,使用本混合基体改进剂,抗干扰能力强,大大挺高硼的吸收信号,线性范围较宽(0.2～10μg/mLB),并且在线性范围内彻底消除了硼的记忆效应.方法的特征量为100pg/0.0044A·S.     

平台石墨炉原子吸收光谱法测定土壤保水剂中铅镉

提出了在不用任何基体改进剂的条件下,用平台石墨炉原子吸收法测定土壤保水剂中铅、镉的方法。加标实验结果表明:铅、镉平均回收率分别为101%、98.4%。本方法切实可行。     

石墨炉原子吸收光谱法测定土壤铝的条件优化

酸性土壤中的活性Al是影响作物生长发育的主要因子之一,土壤Al的测定一直是人们关注的问题。石墨炉原子吸收光谱法测土壤Al所需的样品量少、灵敏度高、离子干扰小,目前在国内外应用较为广泛。由于其测试条件多是应用单因素轮换法来确定,存在实验量大且未考虑交互作用的影响等缺点。采用双因素重复实验及正交实验可显著降低确定最佳测试条件的工作量,且实验条件代表性强,对于准确快捷测定土壤Al具有重要意义。通过双因素（波长和灯电流）重复试验对石墨炉原子吸收光谱仪测定土壤Al的波长和灯电流进行了优化选择,确定最佳波长为309.3nm,最佳灯电流为14mA;应用L2（556）正交试验法对控温程序及基体改进剂、基体酸度条件进行了优化,得出最佳的灰化温度为1400℃、灰化时间为10s,原子化温度为2300℃、原子化时间为5s,最佳基体改进剂为0.1%NH4H2PO4、最佳基体酸度为0.2%硝酸。优化后的方法检出限为1.14μg.L-1,加标回收率达到93.6%~104.1%,相对偏差均小于8%。     

硝酸一次消解同时测定土壤中Cd、As、Hg的方法研究

硝酸在水浴中一次性消解土壤样品,用石墨炉原子吸收测定镉、原子荧光光谱法同时测定砷和汞。其检出限镉为0.053 ng m l-1、砷为0.011 ng m l-1、汞为0.008 ng m l-1,线性范围镉为0~4 ng m l-1、砷为0~40ng m l-1、汞为0~2 ngm l-1。回收率在93.0~104.0%。本方法简便了消煮过程,一次消解能同时测定土壤中的多种重金属。     

微波消解塞曼火焰原子吸收法测定土壤中重金属元素的方法研究

利用光纤压力自控密闭微波消解系统和采用正交实验等方法,优选了微波消解土壤的酸用量、微波时间及压力强度等项指标。实验结果表明,在供试条件下,以HNO33ml、HClO42ml、HF3ml混合酸作消解液,采用0.5MPa3min、1 5MPa5min二段微波消解方式,可获得满意的检测结果,其准确度和精密度均符合土壤环境样品分析要求,具有操作简便、快速、经济的特点,并可在同一消解液中分别测定土壤Cu、Zn、Pb、Cd、Cr、Ni等重金属元素,是测定土壤重金属元素含量的有效方法。     

Chromium Speciation in Water by Sorption on Calcite and Determination by Electrothermal Atomic Absorption Spectrometry

Abstract

A rapid, sensitive, and accurate method for the separation and speciative determination of chromium (Cr)(VI) and Cr(III) in water samples has been developed using sorption as the separation technique in conjunction with final determination by electrothermal atomic absorption spectroscopy (ETAAS). The present method, where granular calcite is used as selective sorbent, separates Cr(III) with retention values up to 99%, resulting in high accuracy determination of Cr(VI). Total Cr was likewise determined by ETAAS after an efficient reduction of Cr(VI) to Cr(III) using ascorbic acid as reducing agent, deriving Cr(III) concentration from the difference between total Cr and Cr(VI). The parameters of the separation technique, solution pH (4.5–5.5), solution flow rate through the calcite column (0.14–0.42 mL min^?1), and calcite column internal diameter (1.5–3.0 cm), were evaluated. Best results were achieved with pH of 5.5, flow rate of 0.42 mL min^?1, and column internal diameter of 1.5 cm. Optimum determination conditions were found using magnesium nitrate [Mg(NO₃)₂] as chemical modifier, pyrolysis, and atomization temperatures of 1400 and 2200°C, respectively. In such conditions, the detection limits (n=10) were 1.5 and 0.8 µg L^?1 for Cr(III) and Cr(VI), respectively.     

Selective Determination of Chromium(VI) in Industrial Wastewater Samples by Micro-Electromembrane Extraction Combined with Electrothermal Atomic Absorption Spectrometry

This study describes application of free liquid membrane (FLM) in micro-electromembrane extraction (μ-EME) of Cr(VI) from wastewater samples. Amount of Cr(VI) was quantified by electrothermal atomic absorption spectrometry. The transportation of Cr(VI) across the FLM was explored by electrokinetic migration and ion-exchange process. FLM and acceptor solution types, pH of donor and acceptor solutions, applied electrical potential, as well as FLM thickness were optimized. Presence of an anion exchange carrier (methyl trialkyl-ammonium chloride, Aliquat 336) in FLM facilitated Cr(VI) transportation. The best performance was observed for 1-octanol (containing 5% Aliquat 336) with thickness of 1 mm used as FLM, under applied electrical potential of 75 V, when 0.5 M NaClO₄ and 0.1 M HCl were used as the acceptor and donor phases, respectively; and the extraction time was set to 5 min. Linearity was obtained in the working range of 0.5–14.0 ng mL^?1 Cr(VI) (R²?>?0.98). The calculated limit of detection was below 0.06 ng mL^?1. Application of this method to wastewater samples showed that relative recoveries of the spiked Cr(VI) in the samples were in the range of 73.8–85.1%, based on the standard addition method.     

Sequential Injection Determination of Nitrate in Vegetables by Spectrophotometry with Inline Cadmium Reduction

Abstract

A sequential injection system for the determination of nitrate (NO₃ ^?) in vegetables was developed to automate this determination, allowing for substantially reduced reagent consumption and generated waste using low‐cost equipment. After extraction with water and filtration, the extracted nitrate is reduced inline to nitrite in a copperized cadmium (Cd) column and determined as nitrite. According to the Griess–Ilosvay reaction, nitrate is diazotized with sulfanilamide and coupled with N‐(1‐naphtyl)‐ethylenediamine dihydrochloride to form a purple‐red azo dye monitored at 538 nm.

Nitrate can be determined within a range of 1.35–50.0 mg L^?1 of NO₃ ^? (corresponding to 0.270–10.0 g of NO₃ ^? per kg of vegetable), with a conversion rate of nitrate to nitrite of 99.1±0.8%. The results obtained for 15 vegetable extracts compare well with those provided by the classical procedure, with a sampling throughput of 24 determinations per hour and relative standard deviations better than 1.2%.     

原子吸收次灵敏线法直接测定土壤中Fe、Mn

用原子吸收次灵敏线法塞曼效应扣除背景测定土壤中Fe、Mn,实验结果表明:此方法有较好的准确度,精密度,操作简单,适合一般土壤中Fe、Mn的测定。     

4种蔬菜对硒酸盐的吸收、富集与转运特征的研究

用盆栽试验研究了不同含量硒酸钠对4种蔬菜（小白菜、芥菜、生菜和菠菜）生长、硒吸收及转运特征的影响,为富硒蔬菜的开发和硒污染土壤的植物修复提供理论依据。结果表明,低含量的硒酸钠态硒（〈1.45mg·kg-1）可促进4种蔬菜的根和茎的生长,增加其生物量,但过量硒酸态硒（〉2.04mg·kg-1）对蔬菜有明显的毒害作用。供试的4种蔬菜地上、地下部硒含量均随外源硒含量的增加显著增大（P〈0.01）,其中小白菜和芥菜地上硒含量是生菜和菠菜的5.8～8.5倍;4种蔬菜地下部硒含量的大小依次为芥菜〉小白菜〉菠菜〉生菜。所有施硒处理小白菜、芥菜和生菜地上硒含量约是地下硒含量的1～2倍,菠菜地上与地下硒含量与土壤硒含量高低有关,当土壤硒含量〈5.02mg·kg-1时,菠菜的地下硒含量大于地上部,当土壤中硒含量〉5.02mg·kg-1时,地上部硒含量大于地下部。4种蔬菜相比较,地上部硒富集系数（BCFshoot/soi）l值的大小依次为小白菜≈芥菜〉菠菜〉生菜,地下部富集系数（BCFroot/soi）l值的大小依次为芥菜〉小白菜〉菠菜〉生菜;以小白菜对硒的转运系数（TF）值最大,菠菜最小。供试的4种蔬菜中,小白菜因具有较高的将六价硒从地下转运到地上的能力,且拥有较高的地上生物量,可作为富硒蔬菜和硒污染土壤修复植物。     

Determination of Water-Soluble and Acid-Soluble Zinc in Soils by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of water-soluble and acid-soluble zinc (Zn) in soils by flame atomic absorption spectrometry. Deionized water and 0.1 mol L^–1 hydrochloric acid (HCl) were selected as extracting agents. In the proposed approach, 2-(5-bromo-2-pyridylazo)-5-diethylam-inophenol (5-Br-PADAP) was used as a chelating agent, and polyethylene glycol octyl phenyl ether (OP) was selected as the surfactant. Some factors including the pH of analytical solution, concentrations of the chelating agent and surfactant, equilibration temperature and time, and salt effect, which would affect the extraction efficiency and subsequent determination of Zn, were studied and optimized. Under the optimized conditions, the calibration graph was linear in the range of 5.0?×?10^–3 to 0.5 μg mL^–1, and preconcentration of 20 mL sample solution gave an enhancement factor of 25. The detection limit was 4.93?×?10^–3 μg mL^–1. Recoveries in the range of 95.0–110% were obtained. Some metal ions including iron (Fe²⁺), cobalt (Co²⁺), and manganese (Mn²⁺) would interfere with the determination of Zn. The interference from these ions can be eliminated using thiourea (0.5% w/v) and triethanolamine (0.5% w/v) as masking agents. The proposed method was applied to the determination of water-soluble and acid-soluble Zn in soils, which were collected from the suburbs of Zhengzhou, and satisfactory results were obtained. To have more understanding of the soils, we determined the total content of Zn in soils. The results showed that the water-soluble and acid-soluble Zn contents in different soils are not correlated with the total content. For example, the total content of Zn for the soil from a farm in north loop was very low, but the percentage of water-soluble Zn was very high.     

Determination of Available Cadmium and Lead in Soil by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of available cadmium (Cd) and lead (Pb) in soil by flame atomic absorption spectrometry. The proposed method was based on the CPE of a complex from ammonium pyrrolidine dithiocarbamate (APDC) and metal Cd and Pb using emulsifier octyl polyethylene glycol phenol ether (OP) as surfactant. Conditions that would affect the complex formation and separation were researched in detail, including extraction conditions as well as pH, amount of the chelating agent, concentration of the surfactant, equilibration temperature and time, and salt effect. Under the optimized conditions, both of the calibration graphs were linear in range of 0–1.0 μg mL^?1 with detection limits of 0.29 ng mL^?1 for Cd and 2.10 ng mL^?1 for Pb. The relative standard deviation (RSD) for 11 replicate measurements at 0.10 μg mL^?1 of Cd and Pb were 2.18% and 4.04%, respectively. The enhancement factors were 48.8 and 61.6 for Cd and Pb, respectively. The recoveries of Cd and Pb at the spiking level of 0.10 μg g^?1 in soil samples were from 91.7% to 115% and from 91.0% to 115%, respectively. The proposed method has been applied to the determination of available Cd and Pb in soil.