柯衣定褪色光度法测定食盐中碘

建立了加碘盐中碘含量测定新的光度分析法, 借助于在H2SO4介质中碘酸根氧化柯衣定使其褪色, 褪色前后的吸光度之差ΔA与碘含量成正比进行测量的. 柯衣定在波长455 nm处有强吸收, 碘含量在0～50 μg/mL范围内呈线性关系, 方法的相对标准偏差小于0.84%, 回收率为101.7%～105.7%.     

加碘食盐中微量碘的离子选择性电极测定

在加碘食盐中加入还原剂将KIO3中的IO3^-还原为I^-,使用碘离子选择性电极技术,采用标准曲线法直接测定了溶液中的I-量.并引入表面活性剂作为增敏剂,降低了检测下限,提高了检测的灵敏度.实际测定3种食盐样品,取得了较好的效果.     

基于反射式光度传感器的自动光度滴定仪的研制及应用

研制了一种以颜色变化为滴定终点的自动光度滴定仪,仪器以光度传感器为核心,包括光度探头、滴定装置、AT89S52单片机、电磁阀、二极管和磁力搅拌器等部件。传感器采用开放设计,对溶液吸光度变化反应迅速。仪器用于红醋酸度的测定,所得结果与电位滴定分析法结果相符。     

原子吸收分光光度计上采用连续光源用于光度分析的研究

探讨了应用连续光源和双光束原子吸收分光光度计用于光度分析的可行性。     

Catalytic Photometric Determination of Selenium by Flow Injection Analysis

A method is developed for the determination of trace amounts of selenium by flow injection analysis based on the catalytic effect of this element. Catalytic enhancement by selenium for the reduction of picrate ion by sodium sulfide was used and photometrically measured at the wavelength, 470nm. Optimum conditions were determined for temperature, pH, the concentrations of picrate and sodium sulfide, and also the conditions of the flow system; injection of sample volume, flow rate and mixing coil length. With these conditions a good linear relationship was obtained for selenium in the range from 0.1 ppm to 1.0ppm and the detection limit was about 5ppb (two times of the noise). Interference by the diverse ions can be avoided with the use of a precolumn cation exchanger (Dowex 50) and by masking with EDTA in the conditional stream.     

Molecular iodine selective membrane for iodate determination in salt samples: chemical amplification and preconcentration

A molecular iodine selective membrane has been used for preconcentration of I₂ generated in situ by iodometric reaction of with excess I⁻ in acidic medium (pH 1–2). This iodometric reaction amplifies the iodine content six times resulting in enhancement of analytical response ranging from three times for molecular methods to six times for elemental methods. The chemical conditions of this iodometric reaction were optimized for quantitative generation and subsequent sorption of I₂ in the membrane samples (96 ± 3%). The homogeneous transparent membrane was prepared by immobilizing I₂-complexing polyvinylpyrrolidone (PVP) in the plasticized cellulose triacetate matrix. Four different analytical methods were examined for quantitative determination of in iodized salt samples by preconcentrating it as I₂ in the membrane matrix. These methods were: (1) spectrophotometry of the PVP-I₂ complex formed in the membrane matrix, (2) a radiotracer method using I⁻ tagged with ¹³¹I radiotracer, (3) instrumental neutron activation analysis (INAA), and (4) energy-dispersive X-ray fluorescence (EDXRF) analysis. The contents thus determined in the iodized salt samples by the membrane-based radiotracer method were compared with the total iodine determined in salt samples by epithermal instrumental neutron activation analysis (EINAA). The membrane-based method for iodate determination in salt samples has advantages over conventional analytical methods, for example preconcentration and chemical amplification, and is free from interference from anions. Figure A molecular iodine selective membrane was used for the quantitative preconcentration of I₂ generated in situ by iodometric reaction of with excess I^aˆ’ in acidic medium, which amplifies iodine content six times     

铋盐-钼蓝示差光度法测定磷矿石中五氧化二磷

采用硝酸、盐酸溶矿,用高氯酸将偏磷酸氧化为正磷酸,在铋盐催化下磷与钼酸铵反应生成黄色磷钼酸铵,此磷钼酸铵能被抗坏血酸还原为磷钼蓝,以示差光度法直接测定.其最大吸收波长为700nm,表观摩尔吸光系数为1.60×10⁵L/(mol·cm),磷在3～5μg/mL范围内符合比耳定律,试样加标回收率为97.10%～100.86%,9次测定的相对标准偏差为1.08%～4.66%.适用于磷矿石中5%～38%五氧化二磷的测定.     

A cleaner and simple spectrophotometric micro-fluidic procedure for copper determination using nitroso-R salt as chromogenic agent

A cleaner and simple spectrophotometric method using microflow analysis (muFA) was performed. It consisted of a T-junction with microcoil on a polymethyl methacrylate (PMMA) chip which was fabricated by laser ablation and a molded polydimethylsiloxane (PDMS) as top plate. The fabricated PMMA chip was integrated with light emitting diode (LED) as light source and spectrometer as detector. The proposed device was applied to determining copper in water samples using nitroso-R salt as chromogenic reagent at 495nm. It was found that the proposed muFA system was with less reagents and samples consumption with tiny waste generation. The relative standard deviation (R.S.D.) was less than 2% (n=11) with the percentage recovery of 98.0+/-1.7% (n=7). The linear range for determination of copper in water samples was over the range of 0.05-3.0mugmL(-1) with a correlation coefficient (r(2)) of 0.999. The limit of detection (3sigma) was 47ngmL(-1) with a sample throughput of 30h(-1).     

甲基红氧化褪色光度法测定食盐中碘

基于在盐酸介质中 ,碘酸根在溴化钾的催化作用下使甲基红氧化褪色的反应 ,建立了测定微量碘的新方法。方法的线性范围为 8μg/2 5mL～ 2 2 μg/2 5mL ,表观摩尔吸收系数为 6 .5× 1 0 4 L·mol- 1 ·cm- 1 ,已用于食盐中碘的测定。     

Photometric Flow Injection Determination of Psychotropic Drugs: Brotizolam and Midazolam

Abstract

Brotizolam and Midazolam, psychotropic drugs belonging to thienotriazolodiazepine and imidazobenzodiazepine families, have been determined by flow injection analysis with photometric detection. At pH 7, signals showed to be rectilinear from 1.27 × 10^?6M to 1.07 × 10^?4 M for brotizolam and from 1.53 × 10^?6 M to 1.07 × 10^?4M for midazolam. Methods developed were applied to the determination of both drugs in their formulations (Lendormin and Dormicum).     

Reverse flow injection spectrophotometric determination of iodate and iodide in table salt

A very simple and sensitive reverse flow injection method is described for the determination of iodate and iodide. The iodate reacts with excess iodide in acidic medium to form tri-iodide, which can be spectrophotometrically monitored at 351 nm, and the absorbance is directly related to the concentration of iodate in the sample. The determination of iodide is based on oxidizing iodide to iodate. The calibration curve is linear in the range of 0.02-3.0 μg ml⁻¹ I with r²=0.9998, and the limit of detection is 0.008 μg ml⁻¹ I. The chemical and flow injection variables were studied and optimized to make the procedure suitable for quantitating iodate and iodide in table salts. It is shown that the reverse flow injection analysis could greatly improve the sensitivity and precision for determination of iodate with a relative standard deviation of 0.9%. A complete analysis, including sampling and washing, could be performed in 35 s. The procedure was applied successfully to the determination of iodate and iodide in table salts, and the results were statistically compared with results determined by standard iodometry method.     

水相中丁基锡化合物同时衍生／萃取气相色谱／火焰光度检测方法研究

本文建立了水相中丁基锡化合物的衍生／萃取一步进行气相色谱／火焰光度检测的方法，探讨了溶剂，氮气流速，温度及火焰条件对分离及测定的影响，获得了理想的分离及检测条件。检出限分别为一丁基锡（ＭＢＴ）及二丁基锡（ＤＢＴ）０．２５ｎｇ，三丁基锡（ＴＢＴ）及四丁基锡（Ｂｕ４Ｓｎ）０．５ｎｇ；线性范围０－８ｎｇ，相对标准偏差小于４％。     

Spectrophotometric determination of iodine species in table salt and pharmaceutical preparations

A sensitive spectrophotometric method for the determination of iodine species like iodide, iodine, iodate and periodate is described. The method involves the oxidation of iodide to ICl(2)(-) in the presence of iodate and chloride in acidic medium. The formed ICl(2)(-) bleaches the dye methyl red. The decrease in the intensity of the colour of the dye is measured at 520 nm. Beer's law is obeyed in the concentration range 0-3.5 microg of iodide in an overall volume of 10 ml. The molar absorptivity of the colour system is 1.73 x 10(5) l mol(-1) cm(-1) with a correlation coefficient of -0.9997. The relative standard deviation is 3.6% (n=10) at 2 microg of iodide. The developed method can be applied to samples containing iodine, iodate and periodate by prereduction to iodide using Zn/H(+) or NH(2)NH(2)/H(+). The effect of interfering ions on the determination is described. The proposed method has been successfully applied for the determination of iodide and iodate in salt samples and iodine in pharmaceutical preparations.     

Photometric detection of cyclodextrins in liquid chromatography by using iodine generated electrochemically in-situ

A method has been developed for photometric detection of cyclodextrins (CD) in liquid chromatography using iodine (I₂) generated electrochemically in-situ. Iodide ion in the mobile phase was electrochemically oxidized to I₂ which was subsequently reacted with I^–, in an electrochemical flow cell, forming I₃^–. The absorbance of I₃^– was found to be greatly enhanced when CD were present in the mobile phase. The absorbance enhancement was caused by the change in the mole fraction of I₃^–, because of the inclusion reaction of I₃^– with CD. On the basis of this phenomenon, CD were detected by means of a photodiode-array UV–visible detector positioned downstream of the electrochemical flow cell. The signals were found to be linearly dependent on CD concentration. Because the formation constants of I₃^– with CD decrease in the order -CD>-CD>-CD, -CD was most detectable by the method. Detection limits were 1.0 mol L^–1 for -CD, 65 mol L^–1 for monoG1--CD, 100 mol L^–1 for -CD, and 200 mol L^–1 for -CD.     

苯胺蓝增色光度法测定食盐中的碘

在H2SO4介质中,KIO3与苯胺蓝反应增色程度与IO3-量在一定范围内呈线性关系,从而建立了增色光度法测定碘的新方法.实验结果表明,该体系最大吸收波长为603 nm,IO3-在0.91～4.55 μg/L范围内符合比耳定律,表观摩尔吸光系数为5.00×105 L·mol-1·cm-1.本法可直接测定食盐中的碘.     

Photometric Endpoint Detection in the Edta Titration of Zinc in the Presence of Manganese

Abstract

A method has been developed for the simultaneous determination of manganese and zinc or just zinc in the presence of manganese using a photometric technique for determination of the zinc end-point. The accuracy of the results is comparable to that obtained with conventional methods but, in most cases, there is a slight increase in precision. The endpoint is much easier to determine photometrically.     

Selective preconcentration and determination of iodine species in milk samples using polymer inclusion sorbent

A method to determine low levels of iodine species namely I⁻ and IO₃⁻ in aqueous samples was developed and applied to milk and milk powder samples. It is based on selective preconcentration of I⁻ in polymer inclusion sorbent (PIS) and neutron activation analysis (NAA) of I⁻ sorbed in PIS. The PIS was found to be highly selective for I⁻ in presence of IO₃⁻ and other anions commonly present in the milk samples. In order to preconcentrate total I⁻ + IO₃⁻ content in the PIS, IO₃⁻ was reduced to I⁻ using a mixture of acetic acid and ascorbic acid. It was found that total iodine content in milk could be determined with epithermal neutron activation analysis (ENAA). A scheme was developed to determine I⁻, IO₃⁻ and total iodine. The developed method was applied to milk reference materials (NIST SRM-1549 and IAEA-RM-153 milk powder) and a commercially available milk powder. The scheme for estimation of iodine in different forms was validated by using reference material NIST SRM-1549.     

Photometric determination of molybdenum in iron and steels using tin(II) chloride in nonaqueous solvent

Summary A new procedure is proposed for the photometric determination of molybdenum in iron and steels using thiocyanate and tin(II) chloride solution [in glycerol-ethannol (31) or in diethylenglycol] as a reducer and extraction with n-butyl acetate. Beer's law is obeyed between 0.2 and 80 g Mo/ml. The minimum photometric error is 3.2%, the molar absorptivity is 15640 at 470 nm and the best concentration range for determination is between 0.6 and 6 g Mo/ml.

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Photometrische Bestimmung von Molybdän in Eisen und Stahl mit Hilfe von Zinn(II)-chlorid in nichtwärigem Medium

Zusammenfassung Das vorgeschlagene Verfahren beruht auf Bildung des Thiocyanatkomplexes unter Verwendung von Zinn(II)-chlorid als Reduktionsmittel [in Glycerin/Äthanol (31) oder Diäthylenglykol]. Als Extraktionsmittel dient n-Butylacetat. Das Beersche Gesetz wird im Bereich 0,2–80 g Mo/l befolgt. Der kleinste photometrische Fehler beträgt 3,2%, die molare Extinktion 15640 bei 470 nm und der optimale Konzentrationsbereich 0,6–6 gMo/l.

Lecture presented at Euroanalysis I Conference, 28. 8. –1. 9. 1972 in Heidelberg, Germany.     

硅钼蓝光度法测定碳化硅中二氧化硅的含量

采用氯化钠-盐酸-氢氟酸溶解碳化硅样品,加钼酸铵使硅酸离子形成硅钼杂多酸,然后用1-氨基-2-萘酚-4-磺酸还原剂将其还原成硅钼蓝,在700nm波长处测定其吸光度,从而测得碳化硅中的二氧化硅含量。考察了称样量、水浴温度、水浴加热时间、样品储存容器、显色反应时间等因素对测定结果的影响,优化了测试条件。二氧化硅的质量浓度在0．25-12．5mg／（100mL）的范围内与吸光度呈良好的线性关系,线性相关系数r=0．99986。加标回收率为99．2％～100．9％,测定结果的相对标准偏差为0．76％（n=6）。     

Speciation Analysis of Butyltin Species in Water by Gas Chromatography with Flame Photometric Detection Using Quartz Surface-induced Tin Emission

A flame photometric detector using quartz surface-induced tin emission was designed and evaluated for quantification analysis of butyltin species. It has been demonstrated that this quartz surface-induced tin emission, centred at 390 nm, is more sensitive than the commonly used gas-phase emission at 610 nm. The dependence of detector response on quartz enclosure was studied. The operational variables such as hydrogen–air flow rate, carrier-gas flow rate and purge-gas flow rate were optimized. An analytical procedure for speciation analysis of butyltin species in water using simultaneous hydride generation with sodium borohydride and extraction into dichloromethane was established. The detection limits (defined as the signals that equal three times the deviations of the noise) were 0.3 pg of Sn for tetrabutyltin (TeBT), 5 pg of Sn for monobutyltin (MBT), 18 pg of Sn for dibutyltin (DBT) and 2 pg of Sn for tributyltin (TBT), which are approximately 10- to 30-fold better than those reported for using more commonly used gas-phase emission centred at 610 nm.