奋乃静的流动注射分光光度分析

基于在H2SO4介质中，K2S2O8氧化奋乃静生成红色中间产物的原理，建立了流动注射分光光度法测定药物中奋乃静含量的新方法。利用单纯形优化法选择了最佳实验条件。方法的线性范围为20-170μg/mL，检出限为0．46μg/mL，进样频率为150h。该方法用于奋乃静片剂中奋乃静含量的测定，其测定结果与药典法对照，无显著性差异。     

流动注射分光光度法测定亚硝酸根氮

使用北京吉天仪器有限公司水质分析仪样机建立了测定水中痕量亚硝酸根氮的流动注射光度方法,以先进的光纤光谱仪CCD作为检测器,亚硝酸盐与对氨基苯磺酰胺重氮化,再与盐酸N-（1-萘基）乙二胺偶合,形成玫瑰红色的偶氮染料,用分光光度法测定,其最大吸收峰在540nm处;最佳的显色管路长度1．5m;最佳的对氨基苯磺酰胺质量浓度为1.0g／L;最佳的N-（1-萘基）乙二胺质量浓度为60g／L,亚硝酸根氮的线性范围为0．002～1．0mg／L,检出限0．37μg／L,RSD0．2％,实际样品的加标回收率均在96.5％～101．2％之间,测定频率60样／h。     

基于不稳定反应的流动注射催化光度法测定铁

近年来,由于含铁水处理剂的广泛应用,水体中铁含量逐渐增高.含铁量高的水在管道内易生长铁细菌,增加水的浑浊度,使水产生特殊的色、嗅、味,易污染衣物、器皿,影响某些工业产品的质量.因此,研究准确快速测定水中铁的分析方法具有重要意义.     

流动注射催化光度法测定微量钒

采用流动注射与催化动力学光度法相结合,研究了在H3PO4介质中微量钒(Ⅴ)催化溴酸钾氧化吡啶偶氮变色酸试剂-2-(5-硝基-2-吡啶偶氮)-1,8-二羟基萘-3,6二磺酸(简称5-NO2-PACA)褪色反应,建立了测定微量钒的新方法。该方法线性范围为0.02~0.20μg/mL,线性回归方程为:ΔA=-0.004 2.63ρ(μg/mL),相关系数r=0.9988,检出限为:4.1×10-6g/L。方法已用于水样中微量钒的测定。     

流动注射光度法测定药物中的盐酸氯丙嗪

在pH 4.04的HAc-NaAc缓冲液中, 刚果红与盐酸氯丙嗪在室温下迅速结合生成缔合物, 且缔合物在480 nm处有最大吸收. 基于此建立了流动注射光度法测定药物中盐酸氯丙嗪的含量. 方法线性范围为0.25～50.0 μg/mL, 检出限为0.082 μg/mL, 测定频率达80次/h.     

流动注射褪色光度法测定食品中的亚硫酸盐

基于亚硫酸盐在碱性条件下与碱性品红的褪色反应,建立了流动注射光度分析测定食品中亚硫酸盐的新方法.在38样/h采样频率下检出限为0.016μg/mL,SO32-质量浓度在0.04～1.5 μg/mL范围符合朗伯比耳定律,测定1.2μg/mL SO32- 11次,相对标准偏差为0.41%.该法可用于食品中亚硫酸盐的测定.     

Determination of ethanol in liquor by near-infrared spectrophotometry with flow injection

A simple procedure for the determination of ethanol in a liquor by near-infrared (NIR) spectrophotometry with flow injection (FI) is proposed. A liquor sample is equilibrated off-line with dried chloroform to extract ethanol into the organic phase. The extract is injected into a carrier stream of dried chloroform passing through a home-made flow through cell (1 mm path length) sitting in a NIR spectrophotometer for continuous monitoring of absorbance at 2305 or 2636 nm. The ethanol content can be evaluated from a calibration established by a plot of change in absorbance versus concentration of ethanol standard solutions. Optimization of the system will be discussed. A calibration is linear in the range of 20–50% (v/v) ethanol. A throughput of 240 injections h⁻¹ can be obtained. The procedure is validated by comparing the results with an analysis using gas chromatography.     

Determination of nitrite in environmental waters by flow injection catalytic spectrophotometry

ABSTRACT

The flow injection catalytic spectrophotometry is proposed for the determination of nitrite based on the catalytic effect on the redox reaction between methylene blue and potassium bromate in acidic medium. The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of methylene blue at the maximum absorption wavelength of 664 nm. The method is characterised by low solvent consumption and easy automatic continuous analysis. It has higher sensitivity and lower detection limit. Experimental analysis conditions of the flow injection-catalytic photometry are optimised, and the best analysis conditions are: the concentration of the potassium bromate is 0.068 mol L^?1; the concentration of the phosphoric acid in oxidation liquid is 0.045 mol L^?1; the concentration of the methylene blue in colour-substrate solution is 2.4 mg L^?1, the volume of sample ring is 200 μL; the reaction coil is around 7 m in length; the inject time is 50 s and analysis time is 70 s. Under the optimal conditions, the linear range is from 10 to 500 μg L^?1 and the detection limit is 1 μg L^?1. The nitrate standard solution is continuously determined with a mass concentration of 300 μg L^?1. The RSD is determined to be 1.41% (n = 10). The nitrite in water samples, which were from the Half Acre pond, the Ink River and the Small West lake in a campus, was determined respectively by this method. A satisfactory standard addition recovery of 96.7%–103.9% was obtained.     

流动注射分光光度法快速测定水样中的铬

建立了用流动注射分光光度法快速检测水样中铬含量的方法.测定耗时140 s,测定频率25样/h.本法利用Cr(Ⅵ)和二苯碳酰二肼显色反应,Cr(Ⅵ)标准溶液的质量浓度在0.05～0.8 mm/L之间与吸光度呈线性.该法的检出限是4.0 μg/L,低于国家对Ⅰ类水的相关标准.应用此法分别测定了北京城区一些地表水中铬的含量,加标回收率在90.1%～113%之间.     

KMnO4分光光度法测定葡萄籽原花青素

建立了葡萄籽提取物中原花青素测定的新方法-KMnO4分光光度法.基于原花青素结构中含有还原性基团,能在强酸性介质中与KMnO4发生氧化还原反应,在545 nm吸光度值减少而在310 nm处吸光度值增加,通过A310/A545的比值来测定原花青素.该方法的线性范围为1.6～3.6 μg/mL,RSD为0.13%～0.4%,回收率为95.2%,相关系数r=0.9996,检出限为0.03 μg/mL.     

Determination of nitrite by flow injection spectrophotometry using a home-made flow cell detector.

A simple, rapid, low cost and accurate determination using flow injection spectrophotometry with a home made flow cell detector, in combination with green LED and photodiode, had been developed for nitrite based on the Griess-Saltzman reaction, measuring the absorbance at 525 nm. The proposed system is able to monitor nitrite in freshwater samples at a throughput of 60 samples per hour with a relative standard deviation (%RSD) of less than 2.4% and a detection limit of <7 microg dm(-3). The calibration graph was linear between 0.010 - 1.0 mg dm(-3).     

Determination of formaldehyde in foodstuffs by flow injection spectrophotometry using phloroglucinol as chromogenic agent

A spectrophotometric method for the determination of formaldehyde in foodstuffs was described by using phloroglucinol as the chromogenic agent. The reaction between formaldehyde and phloroglucinol could occur rapidly at room temperature under mild conditions. The spectrophotometric measurements were conducted at 474nm of an unstable intermediate orange product of the reaction, which greatly increased the sample throughput. Flow injection technique was used to control the merging and reaction timing of the reagents and sample. A detection limit (3sigma) of 0.023microg ml(-1) was achieved. The relative standard deviation was 0.29% for the determination of 7microg ml(-1) formaldehyde (n=11). The proposed method was applied to the analyses of formaldehyde in several preserved foodstuffs and the results were in good agreement with those obtained by a standard method.     

Simultaneous determination of silicate and phosphate in boiler water at power plants based on series flow cells by using flow injection spectrophotometry

A new flow injection spectrophotometric method is described for the simultaneous determination of silicate and phosphate. Effects on the sensitivity of the method of the wavelength, temperature, length of reaction coils, pump rates, acidity, sampling volume, concentration of the chromogenic reagent, etc. were also investigated. The optimum conditions were ascertained.The principle of the method is that total concentration of silicate plus phosphate is determined when a injected sample plug is passing through the first flow cell and then the concentration of silicate is serially) determined at a second flow cell of the same detector after continuously masking the yellow molybdophosphate in the sample zone. Finally, the concentration of phosphate is obtained by difference.Silicate and phosphate are determined in boiler water at power plants; 60-120 samples h⁻¹ be analyzed. Determination ranges are 0.05-22 mg l⁻¹ for silicate and 0.1-24 mg l⁻¹ for phosphate. Relative standard deviations for metasilicate and orthophosphate were ≤1.2 and 1.3%, respectively. Recovery ranges of silicate and phosphate in the samples are 98-103%.     

顺序注射分光光度法测定硫氰酸盐

根据硫氰酸盐、K2S2O8和3,5-二溴-吡啶偶氮-二乙基氨基苯酚反应形成紫红色产物的现象,建立了顺序注射分光光度测定硫氰酸盐的新方法,其线性范围为0．70～24．39μg/mL、检出限为0．25μg／mL。已用于工业废水和饮用水中硫氰酸盐的测定,回收率为96．0％-100．8％。     

Selective determination of arsenite by flow injection spectrophotometry

This paper describes the application of the well-known Molybdenum Blue method for selective determination of arsenite in a flow injection system. Selectivity is achieved by on-line separation of the main interferents phosphate, arsenate and silicate using a strong anion-exchange microcolumn located in the aspiration line of injection valve. Arsenite passing through the microcolumn unretained is determined using Molybdenum Blue method following in-line oxidation to arsenate by permanganate. A thorough investigation of optimal experimental conditions for both, the separation of interferents and sensitive detection of arsenite is presented. The method developed permits arsenite to be determined in the concentration range 5-500 microg/l with high precision and reliability. A sample throughput of 20 hr(-1) is achieved. Phosphate, arsenate and silicate do not interfere at concentration levels significantly higher than that of arsenite. The application to real water samples reveals excellent recovery of spiked samples and the absence of matrix interferences.     

DMSO-accelerated rapid gelation of crude oils at room temperature

Dimethyl sulfoxide (DMSO), carrying a highly polarized S = O bond as the H-bond acceptor, possesses an extraordinarily high capacity to compete for H-bond formation. This strongly H-bonding character renders DMSO with a strong ability to interfere with or even disrupt self-assembled structures mediated predominantly by intermolecular H-bonds. While this might be quite disturbing in many applications, in this study, we show that oil gelation actually could benefit significantly from DMSO’s such a strong H-bond-breaking ability. More specifically, we found that use of a minute but optimized amount of DMSO, assisted further by polar acetonitrile of a suitable amount, weakens the H-bonds in the gelling network formed by organogelators to a just right extent so as to allow for a faster disassembly-reassembly of fibers in the wetted powder gelator in oil and subsequent occurrence of rapid room-temperature gelation of both light and heavy crude oils of widely ranging viscosities within 6–25 mins at gelator loadings of ≤12% w/v.     

鲁米诺-高锰酸钾体系化学发光法测定5-磺基水杨酸

基于碱性介质中5-磺基水杨酸对鲁米诺-KMnO4体系化学发光的增强作用,建立了流动注射化学发光法测定5-磺基水杨酸的新方法。最佳实验条件下,测定5-磺基水杨酸的线性范围为5.0×10-6~8.0×10-4mol/L,线性相关系数为0.9994(n=8),检出限为3.8×10-6mol/L(n=11),对5.0×10-5mol/L的5-磺基水杨酸进行测定,其相对标准偏差为1.4%(n=11)。方法应用于强力霉素废水中5-磺基水杨酸的测定。     

反向流动注射阻抑动力学光度法测定微量锑(Ⅲ)

锑是一种广泛分布的有毒元素,许多研究证明锑对人体及生物具有毒性及致癌性,由于锑矿的开采和加工以及自然过程的影响,环境水样中锑污染日趋严重,而人体及生物对锑的摄取,一般来自饮用水、空气等,因此有效、快速、灵敏的测定环境水样中的锑具有实际的意义.     

Determination of trace amounts of manganese in nickel by fourth-derivative spectrophotometry

Fourth-derivative absorption spectra were used to determine trace amounts of manganese in nickel salts. Optimum conditions for the oxidation of microgram amounts of Mn(II) to MnO(-)(4) in the presence of large amounts of nickel were established. Fourth-derivative spectra provided good sensitivity and selectivity for this determination. Attention has been paid to the effect of instrumental parameters on the results obtained. Limitations of the peak-to-trough and zero-crossing measurement techniques have been examined. Manganese (1 x 10(-3)-2 x 10(-5)%) in nickel salts (nitrate, sulphate and chloride) and in nickel powder was determined with good precision and accuracy.     

Alloy formation at the deposition of palladium on gold at room temperature

Palladium is shown to be deposited underpotentially on gold electrodes in 1 M H₂OSO₄. The deposit forms an alloy according to a t^1/2 law. The rate of alloy formation is strongly dependent on the potential. The diffusion coefficient is about 10^?16 cm² s^?1. This value is discussed in comparison with earlier measurements on gold-palladium alloys at higher temperatures.