石墨炉原子吸收光谱法测定麦麸颗粒中镉

为消除石墨炉原子吸收光谱法测定麦麸中镉时基体产生的背景干扰,在消解液中加入镉标准溶液配制基体匹配工作曲线进行测定,对灰化温度、原子化温度及基体改进剂等条件进行优化,确定最佳分析方法。结果表明：在选定条件下镉在0.0~3.0 μg/L范围内工作曲线相关系数为0.9991,检出限为0.027 μg/L,定量限为0.091 μg/L,加标回收率为89.50%~104.12%,精密度为1.64%~4.30%,质控物质测定结果准确。该方法操作简便,快速准确,精密度良好,适用于麦麸中镉元素的测定。     

塞曼效应无火焰原子吸收法直接测定化探样品中痕量镉

地球化学样品中痕量镉(0.0Xppm)不经分离富集直接用无火焰原子吸收法测定是困难的。现有文献多采用分离富集后才能测定,或加入基体改进剂,我们曾在此基础上进行试验与探讨,但基体干扰仍未能消除。我们发现,用硫脲-EDTA盐-磷酸二氢铵作为基体改进剂,能消除基体干扰且提高了镉的原子化效率,无需分离富集可直接测定地球化探样品中痕量镉。用拟定的方法测定地球化学标准样中镉的结果与可用值相符,本法灵敏,快速、能满     

平台及基体改进效应石墨炉原子吸收测定尿中镉

为研究工业环境中镉对人体的危害,迄今为止都以尿中镉含量的多少来诊断其受害程度。然而尿基体复杂多变,严重干扰ppb级镉的测定,所以一直是临床分析工作者所要研究解决的课题。石墨炉原子吸收法测定尿中镉,多采用平台原子化、基体改进剂及表面活性剂等方法。平台原子化和基体改进剂在方便性和数据的稳定性方面都是可取的。氟化铵和硝酸铵作为基体改进剂可使稀释一倍的尿样中尿素、柠檬酸钠、肌酸酐等所产生的     

塞曼石墨炉原子吸收法直接测定海水镉

本文介绍用塞曼石墨炉原子吸收法直接测定海水样品中的痕量镉。通过实验发现,抗坏血酸和硝酸混和或者酒石酸与硝酸混和使用都可有效地消除海水基体的干扰,考虑到酒石酸较稳定,因此选用酒石酸为基体改进剂。无需灰化而直接原子化。对Z180-80型仪器,原子化温度为700℃,对Z3030型仪器,原子化温度为950℃。仪器用单纯标准溶液校准。通过与极谱法比较及对标准海水样的测定,表明该法准确可靠。     

电热原子吸收光谱法测定钢中铅

钢中痕量铅的测定,基体干扰严重。本文用镧作基体改进剂,能消除5mg/ml基体铁的干扰,同时2mg/ml钙、镁、钴、镍、铜、铝、铬、锌和0,2mg/ml锰、镉均无明显干扰。方法具有灵敏度高、重现性好等优点。仪器及工作条件:岛津AA-650型原子吸收分光光度计,GFA-2型石墨炉原子化器。分析波长283,3nm,灯电流8mA,光谱通带0.3nm,干燥15A、50s,灰化55A、30s,原子化160A、5s。进样体积20μl。氘灯扣背景。     

氮、氩在5分子筛上的低温吸附分离

测定了不同温度下氮、氩在5分子筛上的吸附等温线,其中三参数的Langmuir-Freundlich方程和Toth方程在不同温度下都能获得较好的拟合结果;计算了不同温度下氮、氩在5分子筛上吸附的亨利常数,获得了氮、氩选择性和温度的关系。测定了125K温度下氮、氩混合气体在5分子筛吸附柱上的穿透曲线。结果表明:最先流出的5L气体中含有约70%的氩,通过收集5L气体即可实现混合气体中氩的初步分离。     

氮、氩在5A^。分子筛上的低温吸附分离

测定了不同温度下氮、氩在5分子筛上的吸附等温线,其中三参数的Langmuir-Freundlich方程和Toth方程在不同温度下都能获得较好的拟合结果;计算了不同温度下氮、氩在5分子筛上吸附的亨利常数,获得了氮、氩选择性和温度的关系.测定了125K温度下氮、氩混合气体在5分子筛吸附柱上的穿透曲线.结果表明:最先流出的5L气体中含有约70%的氩,通过收集5L气体即可实现混合气体中氩的初步分离.     

石墨炉原子吸收光谱分析中钯基体改进剂对微量镉测定的影响

对石墨炉原子吸收法和钯基体改进剂测定微量镉的实验方法进行了研究,讨论了钯用量对镉测定灵敏度的影响,根据实验结果及Ｘ光电子谱分析,提出了钯存在下镉在石墨管内的原子化过程是一个以物理作用为主,同时伴有钯的催化还原作用的复杂的物理－化学过程的观点。     

石墨炉原子吸收法测定食品中痕量铅、镉

本文研究了巯基棉富集分离及基体改进剂与石墨炉原子化法相结合的铅、镉连续检测法,并对几种类型的食品进行了试验。该法可准确测定多种类型食品中痕量铅、镉。一、仪器与试剂     

电热蒸发进样微波诱导等离子体原子吸收光谱法测定银和镉的研究

研究了以常压低功率氩微波诱导等离子体（ＭＩＰ）为原子化器的原子吸收光谱法（ＡＡＳ）测定银和镉。采用电热蒸发（ＥＴＶ）,浓Ｈ２ＳＯ４吸收去溶的进样方法。考察了微波前向功率,载气流量,去溶电压,去溶时间,蒸发电压,酸度对银,镉测定的影响。方法已用于试样分析。     

Electrothermal behavior of sodium,potassium, calcium and magnesium in a tungsten coil atomizer and review of interfering effects

The electrothermal behavior of Na, K, Ca and Mg in a 150-W tungsten coil atomizer was investigated in order to gather information about the atomization processes and the underlying factors responsible for chemical interferences of them on atomization of Al, Ba, Cd, Co, Cr, Pb and Yb. The interference effects were discussed considering the thermal stability of the species that could be formed in the condensed phase, the effect of protective gas composition in the atomization process and the pyrolysis temperature curves. Ca is the most serious interferent due to its high thermal stability (up to 1600°C) and to the possibility of double oxides formation. As hydrogen is decisive for the atomization of Na, K, Ca and Mg, some interference processes caused by these elements seem to be related to the competition towards hydrogen present in the protective gas composition. The knowledge of the correct temperature of the tungsten coil surface shows that most strategies for overcoming interferences based on chemical modifiers will fail for Cd and Pb, because tungsten acts as a natural permanent chemical modifier. It seems that in many applications previous separation and masking will be necessary.     

Determination of bismuth in river sediment by electrothermal atomic absorption spectrometry with low-temperature atomization in argon/hydrogen

A method is described for the direct determination of bismuth (1–5 μg g^?1) in river sediments by graphite-furnace atomic absorption spectrometry in 90% argon/10% hydrogen with low-temperature atomization. The presence of 10% hydrogen in the argon sheath gas promotes atomization; the bismuth absorption reaches a maximum at 850–950°C, which allows better discrimination of the atomic signal from the background absorption. The use of trisodium phosphate as the matrix modifier further decreases the interference effects from the matrix components and increases the sensitivity. The results, obtained by direct calibration with aqueous standards, are in good agreement with certified values.     

Atomic absorption spectrometry of tin with electro-thermal atomization in a molybdenum microtube

The atomic absorption spectrometry of tin with atomization in a molybdenum microtube is described. The addition of hydrogen to the argon purge gas improves the efficiency of atomization of tin; measurements are best done at 224.61 nm. Phosphoric acid lowers the atomization temperature of tin, and depresses the interferences from diverse elements. Tin in canned foods (fruit juices and drinks) can be determined by direct atomization after dilution with phosphoric acid. Prior extraction is necessary for analysis of geological materials.     

Organic solvents as interferents in arsenic determination by hydride generation atomic absorption spectrometry with flame atomization

Interference effects of various organic solvents miscible with water on arsenic determination by hydride generation atomic absorption spectrometry have been studied. Arsine was chemically generated in continuous flow hydride generation system and atomized by using a flame atomizer able to operate in two modes: miniature diffusion flame and flame-in-flame. The effects of experimental variables and atomization mode were investigated: tetrahydroborate and hydrochloric acid concentrations, argon, hydrogen and oxygen supply rates for the microflame, and the distance from the atomization region to the observation zone. The nature of the species formed in the flame due to the pyrolysis of organic solvent vapors entering the flame volume together with arsine is discussed. The observed signal depression in the presence of organic solvents has been mainly attributed to the atomization interference due to heterogeneous gas–solid reaction between the free arsenic atoms and finely dispersed carbon particles formed by carbon radicals recombination. The best tolerance to interferences was obtained by using flame-in-flame atomization (5–10 ml min^− 1 of oxygen flow rate), together with higher argon and hydrogen supply rates and elevated observation heights.     

The influence of atomization pressure on the behaviour of aluminium in electrothermal atomic-absorption spectrometry

Pressurized atomization in argon purge gas considerably enhances the peak area in AAS determination of aluminium, owing to the decrease in the diffusion rate of atoms with increasing pressure. If lower heating rates are used, the diffusional loss mechanism becomes more important. Thus pressure then has an even more pronounced influence on signal strength. Atomization under pressure in argon purge gas is shown to be beneficial only for light elements. It can be expected that if instrumental matrix modification is made by using hydrogen as purge gas, increasing the atomization pressure may prove beneficial for all elements.     

Atomic absorption spectrometry of tellurium with electrothermal atomization in a molybdenum microtube

Hydrogen, added to argon purge gas, is necessary to protect the molybdenum microtube atomizer from oxidation, but it increases the atomization temperature and decreases the maximum absorbance of tellurium. A mixture of thiourea and copper removes the interfering effects of diverse elements and counteracts the effect of hydrogen. Tellurium (20–200 ppm) in copper can be determined after extraction as a chloride complex.     

Influence of graphite furnace tube design on vapour temperatures and chemical interferences in ETA-AAS

A two-line atomic absorption method for determination of lead was used for calculation of the temperatures experienced by analyte atoms in the gas phase after wall atomization with modified Philips SP-9 graphite tubes. For each tube, the influence of the temperature gradient on the vapour phase temperature and chemical interferences experienced by Cd, Mn and Pb in ETA-AAS was investigated. A higher vapour temperature and lower chemical interference by chlorides were observed when the tube temperature gradient was reversed through a reduction in the wall thickness towards the ends of the tube.     

The determination of atom vapor diffusion coefficients by high temperature gas chromatography with atomic absorption detection

A method of measuring diffusion coefficients of several metal vapors is described using a high temperature gas Chromatographic technique with atomic absorption detection. Diffusion coefficients were determined for Ag, Cd, Cu, Mg, and Mn in argon containing 12% hydrogen at temperatures from 1890 to 2460 K. Diffusion coefficients increased with temperatures at a slightly higher rate than theoretically predicted. However, there was generally good agreement between our experimental values, theoretical values and a previously measured experimental value for Cd in Ar.     

Optical emission spectroscopy diagnostics of inductively-driven plasmas in argon gas at low pressures

An optical emission spectroscopy method for determination of electron temperature, electron density and gas temperature is developed and applied for diagnostics of inductively-driven argon discharges in a cylindrical geometry. The discharges are maintained at frequency 27 MHz, applied power varied in the limits P = (90 – 160) W and gas pressure in the range p = (1.1 – 117.3) Pa. The method combines measurements of emission spectral line intensities and profile broadenings with a collisional-radiative model of argon plasma at low pressure. The model is employed for investigation of the plasma kinetics governing the population densities of 3p⁵4s and 3p⁵4p argon configuration levels, treated separately. In the numerical calculations the electron density and electron temperature are varied whereas the values of the third plasma parameter — the gas temperature — are involved as obtained data from the experiments. Comparison of the experimental results of the line-intensity ratios with those calculated by the model yields the values of the electron density and temperature. The dependence of the electron temperature, electron density and gas temperature on the discharge conditions is obtained and discussed in the study.