Use of 4-chloro-7-nitrobenzofurazane as a derivative reagent for the determination of amino acids by cathodic stripping square wave voltammetry in biological fluids

The rapid and simple reaction of 4-chloro-7-nitrobenzofurazane with amino acids allows the determination of amino acids in urine using cathodic stripping square wave voltammetry. The obtained compounds are adsorbed on a hanging mercury drop electrode for determination by voltammetric methods using phosphate buffer at pH 2.0 as supporting electrolyte. The proposed method allows determination with an error of 5.68%. A limit of detection (3sigma) of 3.64 nM (0.766 ng ml(-1)) and a limit of determination (10sigma) of 12.12 nM (2.55 ng ml(-1)) are obtained for arginine determination. The proposed method has been applied to the determination of amino acids in urine.     

人体内酮体检测技术的研究进展

论述了检测人体内酮体浓度的重要意义和酮体的代谢过程，对各种检测技术的发展过程、检测原理、操作步骤及各自的优缺点进行了比较分析，着重探讨了对血液中β-羟丁酸的检测，并对各种技术的发展方向作了进一步的展望。     

关于单离子活度的测定

论述了测定单离子活度的困难及其为何不能用严格的热力学方法处理的原因。以pH电动势法测定为例，详述了测定单离子活度αH 的原理、方法和其中存在的问题。     

大气及污染源排放气体中苯系物气相色谱测定

建立了气体样品中不同浓度的苯系物的分析方法,优化了测定的操作条件,提出了保证测定质量的技术关键。方法已用于污染源及环境空气中苯系物的气相色谱测定。     

溴酸钾滴定法测定铜冶炼烟尘中的砷含量

研究了测定铜冶炼烟尘中砷含量的溴酸钾滴定方法。对测定体系中的各共存元素进行研究,探讨了测定方法的各项测定条件,方法的相对标准偏差RSD为0.13%～0.61%,样品加标回收率在99.5%～100%,方法精密度高,准确度好,适用于铜冶炼烟尘中砷含量为1.00%～50.00%的测定。     

Determination of uranium by fluorescence method

The paper describes a procedure for the determination of uranium in dilute solutions by fluorescence method. Factors influencing the determination in a phosphoric acid medium were studied. The detection limit of uranium determination is 0.04–0.05 ppm.     

Determination of trace elements in metals and alloys by atomic-absorption spectroscopy using an induction-heated graphite well furnace as atom source

An induction-heated graphite furnace, coupled to a Unicam SP 90 atomic-absorption spectrometer, is described for the direct determination of trace elements in metals and alloys. The furnace is capable of operation at temperatures up to 2400 degrees , and has been used to obtain calibration graphs for the determination of ppm quantities of bismuth in lead-base alloys, cast irons and stainless steels, and for the determination of cadmium at the ppm level in zinc-base alloys. Milligram samples of the alloys were atomized directly. Calibration graphs for the determination of the elements in solutions were obtained for comparison. The accuracy and precision of the determination are presented and discussed.     

Die selektive invers-voltammetrische Bestimmung des Antimons in salzsauren L?sungen nach L?sungswechsel in einer einfachen Durchflu?zelle

Summary The selective invers-voltammetric determination of antimony in a simple flow-through cell in hydrochloric acid solutions is described. After double medium exchange for post-electrolysis and inverse-voltammetric determination, the determination of antimony is possible in the presence of a large excess of copper, bismuth and other elements. The limit of determination is 0.2–0.3 ppb Sb, the reproducibility 1.5% (10 ppb Sb).     

火焰原子吸收光谱法测定水中锰的不确定度评定

为建立并运用火焰原子吸收光谱法测定生活饮用水中锰的不确定度评定方法,根据《不确定度评定与表示》,并参考《化学分析测量不确定度的评定指南》,对火焰原子吸收法测定生活饮用水中锰进行了不确定度的分析和评价。结果表明,合成不确定度0.006 7 mg/L,扩展不确定度0.013 mg/L。运用该不确定度评定分析方法对测量过程中的关键环节进行重点质量控制,可有效降低引入的不确定度,保证测定结果准确。     

分光光度法测定微量炔烃的研究

叙述了利用生成炔亚铜的反应来定量测定微量炔烃的分光光度法。研究表明，在严格控制氨的浓度、保持足量的还原剂的条件下，可以有效地消除反应介质、反应时间、反应物的浓度、空气中的氧等对测定的影响，获得满意的定量结果。该方法已在实际生产中得到应用。     

分光光度法同时测定多元素的研究(Ⅱ)——以CPA-矩阵法计算混合体系中微量锆和铪

本文将m-NPF+CTMAB体系用于锆、铪混合物中微量锆、铪的同时测定。确定了同时测定锆,铪的最佳实验条件。通过使用CPA-矩阵法计算解决了混合体系中锆、铪分量的测定;对光度分析中应用CPA-矩阵法的关键——选择适宜的测定波长问题作了进一步讨论,提出了“相关波长”和“相关组份”的概念。     

原子光谱法测定润滑油中金属

评述了近年来原子光谱法测定润滑油中金属含量技术的沿革、方法及进展。着重介绍了原子光谱法测定润滑油中金属含量的样品前处理方法及原子光谱法测定技术。     

Determination of platinum and iridium in reforming catalysts by second derivative and absorptiometric spectrophotometry

Summary Investigations on the spectrophotometric determination of platinum as a complex formed by tin(II)chloride in hydrochloric acid are reported. The determination of platinum was found to be interfered with by iridium, because it also forms a complex with tin(II) chloride. The features of the derivative absorption spectrophotometry for the quantitative determination of platinum and iridium was also studied. The analytical application of the method for the determination of platinum and iridium in catalysts was investigated.     

Electrothermal atomic absorption spectrometric determination of chromium,iron and nickel in lithium metal

Graphite-furnace atomic absorption spectrometry is applied to the determination of traces of Cr, Fe and Ni in lithium metal, after dissolution as lithium chloride. Direct determination is applied to lithium samples containing higher levels of impurities, but determination in pure lithium samples requires preliminary separation by lanthanum hydroxide coprecipitation. With this enrichment, detection limits of 0.02–0.25 μg g^-1 are obtained using 0.5-g samples of lithium. The accuracy of the procedure was checked by analysis of lithium samples by the proposed coprecipitation method, by direct determination, and by determination after extraction, atomic absorption spectrometry being used in all cases.     

Determination of diacetyl with spectrophotometry and thermal-lens spectrometry

The conditions for the spectrophotometric and thermal-lens determination of diacetyl with creatine and 2-naphthol are proposed. The obtained value of the detection limit for spectrophotometry (at 527 nm), which amounts to 10 ng/mL, is fivefold lower than the existing values of the spectrophotometric determination of diacetyl. The conditions for the thermal-lens determination of diacetyl (λ = 514.5 nm, strength of the inducing radiation: 40 mW) based on the unmodified procedure of spectrophotometric determination were proposed. Along with a fivefold (down to 2 ng/mL) decrease in the detection limit, which is comparable with that for the determination of diacetyl by means of gas chromatography with mass spectrometric detection (detection limit of 0.7 ng/mL), thermal-lens determination is characterized by the enhancement of other performance parameters of the determination. It was shown that, contrary to the case when gas chromatography is used, ethanol does not interfere with both the spectrophotometric and the thermal-lens determination of acetyl.     

Determination of soluble styphnate and nitrate in waste-water from lead styphnate primer plants

Methods are proposed for the determination of soluble styphnate and nitrate in waste-water from lead styphnate primer plants. The styphnate is extracted from the waste-water with methylene chloride and is determined by measurement of the absorbance of the methylene chloride solution at 273 nm. The nitrate is determined in the aqueous solution left after the methylene extraction by measurement of the absorbance at 220 nm. For complete extraction of the styphnate by the methylene chloride, the solution must be moderately acidic (about 6% perchloric acid). The acidity for the determination of the nitrate is not critical. Before the determination of the nitrate in the aqueous extract, it is necessary to boil the solution to eliminate residual methylene chloride which would interfere with the determination of nitrate. PETN is extracted by the methylene chloride but does not interfere with the determination of the styphnate, since it shows no interfering peaks. Chloride, sulphate, phosphate, fluoride and carbonate do not interfere with the determination of styphnate or nitrate.     

原子荧光光谱法测定煤中砷含量

主要研究了原子荧光光谱法测定煤中砷含量的方法,该法回收率为(95.75~98.34)%,RSD2.36%。通过与砷钼蓝分光光度法测定煤中砷含量比较,和对该法的精密度和准确度进行探讨,结果表明,该法操作简单,快速,灵敏度高,测定砷浓度范围大,适用于煤中砷含量测定。     

Quantitative infrared analysis of 2,4-tolylene diamine and 2,4-tolylene diurea mixtures

A rapid method is described for the simultaneous determination of 2,4-tolylene diamine and 2,4-tolylene diurea by infrared spectroscopy. The method is satisfactory for the diurea determination but gives rather large errors in the diamine determination.     

Computer aided exploitation of mathematical models of processes. A general description of the approach

An approach is described which helps the experimenter in: (a) selecting the most appropriate method of determination of physicochemical or technical parameters, (b) optimization of analytical procedures or of determination of physicochemical parameters, (c) indication of the possible improvements of the experimental technique applied, (d) diagnosis of the model and the data handling scheme applied in the determination of parameters, and other. The examples presented are based on simulated experiments. They concern selection of the best method for determination of an equilibrium constant and for determination of two analytes from a single instrumental (photometric, potentiometric) titration curve.     

Determination of glucose in alcoholic beverages by flow injection with two internally coupled injection valves and an enzyme reactor

Two new flow configurations are described for the determination of a component in samples for which the matrix provides varying blank values. They are applied to the determination of glucose in alcoholic beverages, by using immobilized hexokinase and glucose-6-phosphate dehydrogenase, and spectrophotometric determination of the NADPH formed.