Color-Fading Spectrophotometric Determination of Cerium with DBC-Arsenazo

In the medium of 0.18～1.08 mol·L^(-1) sulfuric acid, cerium(Ⅳ) has the color-fading effect on DBC-arsenazo. The apparent molar absorptivity of the color-fading reaction is ε _(530 nm)=1.03×10~4 L·mol^(-1)·cm^(-1). Beer′s law is obeyed over the range of 1.20～12.0 μg·ml^(-1) of Ce (Ⅳ) which shows a linear relationship with the decrease in the absorbance of the colored solution. The effect of thirty-six coexisting ions was studied. The method was applied to the determination of the trace amount of cerium in water samples and has the advantage of high accuracy and good selectivity.

Spectrophotometric Determination of Water-Soluble Hexavalent Chromium and Determination of Total Hexavalent Chromium Content of Portland Cement in the Presence of Iron (III) and Titanium (IV) Using Derivative Ratio Spectrophotometry

A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg.Kg-1 of water-soluble Cr (VI). The absorbance at 565 nm due to Cr (VI)-QINZ complex is recommended for the determination of water-soluble Cr (VI) in Portland cement. The quantification of Cr (VI) released from cement when mixed with water is performed according to TRGS 613 (Technical Rules of Hazardous Substances). The validity of the method is thoroughly examined and the proposed method gives satisfactory results. A derivative spectrophotometric method has been developed for the determination of total Cr (VI) in Portland cement in the presence of Fe (III) and Ti (IV). The hexavalent chromium complex formed at pH 1.5 allows precise and accurate determination of chromium (VI) over the concentration range 0.05 to 3.0 mg.L-1of chromium (VI). The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The MDL (at 95% confidence level) was found to be 25 ng/mL for chromium (VI) in National Institute of Standards and Technology (NIST) cement samples using the proposed method.

Method Verification and Validation of Hydralazine Hydrochloride: Spectrophotometric Analysis in Pure and Pharmaceutical Formulations

The new method proposed is based on the formation of hydralazine-Bromophenol blue ion pair simply and without further extraction or heating. The ion pair was prepared in the presence of pH 3 citrate buffer forming a yellow-colored chromogen. A new maximum UV-visible band formed at 416 nm. The color was stable for more than 10 hours and obeyed Beer’s Law over the concentration range of 10 - 50 µg/mL. The calculated molar absorptivity and Sandell’s sensitivity were 1.01 × 104 L∙mol−1∙cm−1 and 0.0514 µg/mL, respectively. The elements of method validation stipulated by The International Conference on Harmonization [Q2 (R1)] were applied for hydralazine hydrochloride assay in pure and pharmaceutical tablet formulation. The average recoveries of the pure solution and the pharmaceutical formulation were 98.94% and 99.50%, respectively. The results were statistically compared by F-test, which indicates that the method can be precise and repeatable for both pure and pharmaceutical solutions. The method was found to be accurate, reproducible, and cost-effective, and validated for the assay of hydralazine in terms of the routine quality control.

Spectrophotometric Determination of Lodine in Soils by Chloramine T-Tetrabase System

Optimized the experimental conditions of determination of trace iodine in soil in chloramine T-Tetrabase system, and analysis the national standards material, the results showed that the measured values was to be identical with recommended values with a detection limit of 0.16 μg/g, and the relative standard deviation was less than 8%, the whole process was short in time and simple, so it was applicable to the determination of trace iodine in batches.

Spectrophotometric Determination of Chlordiazepoxide Using Its Charge-transfer Complex with 2,4-Dinitrophenol

A new simple, rapid and sensitive spectrophotometric method for the determination of chlordiazepoxide is described, based on the reaction with 2,4-dinitrophenol in water medium, apparently by a charge-transfer mechanism, to yield 1:1 complex with maximum absorption at 444 nm. Optimum experimental conditions for the determination have been studied. The linear calibration range, apparent molar absorptivity and relative standard deviation are 2.8~96.0 mgmL-1, 1.48103 and 0.32%, respectively. The method is accurate and has been successfully applied to the determination of chlordiazpoxide in tablets. The results are in good agreement with those obtained with the official method.

Determination of Total Flavones Content in Ceratocarpus arenarius L. by Spectrophotometry

[Objective] The aim was to establish the method for determining total flavoens content in Ceratocarpus arenarius L.[Method ] Flavonoids were extracted from C. arenarius by heating refluxing, and determined with rutin as the standard.[Result] In the range of 0.019-0.102 mg/ml, linear relationship was good （r=0.999 1）. This method had higher precision and accuracy with RSD of 0.226% and recoveries of 99.36%. The total flavones content from C. arenarius was 10.12 mg/g. [Conclusion] The method is simple and reliable, which could be used to control the quality of C. arenariu.

鸡肉碎蛋白酶解中水解度测定方法比较

为建立鸡肉碎蛋白酶解过程中水解度检测方法,本文以三种蛋白酶酶解鸡肉碎蛋白,运用pH-stat法、紫外可见分光光度法、福林酚法、茚三酮法测定酶解0~8 h过程中酶解液上清氨基酸含量,并与甲醛滴定法所得水解度结果进行拟合。结果表明:基于耗碱量计算水解度的pH-stat法不适用于监测鸡肉碎蛋白的酶解进程。紫外可见分光光度法对木瓜蛋白酶、中性蛋白酶酶解过程拟合度高,R2分别为0.9436、0.9721,可代替甲醛滴定法实现对酶解过程的实时监测。在风味蛋白酶酶解过程中,紫外可见分光光度法仅在0~1 h内具有较大拟合度,R2为0.9091,在酶解1~8 h中则需使用拟合度更优的茚三酮法(R2为0.9406)。三种方法的加标回收率和变异系数较好,组间平均回收率为99.827%~108.637%,变异系数为1.777%~2.705%。该研究可为工业应用肉类蛋白酶解过程的实时监测和快速检测提供研究基础和数据支持。

石化行业循环水质氨氮浓度自动检测系统

换热器中胺类物料泄漏是导致换热器内漏的重要原因之一,除采取前置措施外,检测换热器出、入口处的氨氮量尤为重要。针对胺类物料的泄漏问题,基于改进的水杨酸分光光度法开发氨氮自动检测系统,并进行试验验证,结果表明:系统的检测量程0~10 mg/L,线性度0.9990,显色时间5 min,重复性实验分析相对标准偏差1.97384%,检测精度控制在±2%。

全自动碘分析仪测定水碘与尿碘的试验研究

为了建立测定水碘和尿碘的全自动碘分析仪的仪器检测方法,并验证该方法可替代手工法进行水碘和尿碘的检测,采用砷铈催化分光光度法(简称手工法)和全自动碘分析仪测定法(简称仪器法)测定水碘和尿碘的标准液梯度曲线、冻干人尿中碘成分分析标准物质以及实际样品的碘含量,从标准曲线线性相关系数r、冻干人尿中碘成分分析标准物质、实际样品检测结果,实验条件等多个方面进行比对分析。结果表明:手工法和仪器法所测水碘和尿碘的线性相关系数r均大于0.9990,所测冻干人尿中碘成分分析标准物质中碘离子的质量浓度与标准值一致,所测实际样品中碘的质量浓度结果经过t检验,p值大于0.05,不存在显著性差异,全自动碘分析仪所测数据更准确可靠。

Spectrophotometric Study on the Interaction between Arsenazo M and Proteins

Arsenazo M could bind with bovine serum albumin to form a complex in Clark-Lube buffer at pH 2.3 and room temperature, which gives a maximum absorption peak at 625 nm with a red shift of 75 nm compared with that of Arsenazo M itself. The apparent molar absorptivity of the BSA-Arsenazo M complex is 3.21105 Lmol-1cm-1. The linear ranges for protein determination are wide (at least 0-100 mg/mL).

甲酚红催化褪色光度法测定微量甲醛的研究

基于甲醛对甲酚红-硫酸-氯酸钾反应体系有显著的促进作用,建立了催化褪色光度法测定微量甲醛的方法。在最优的实验条件下,当甲醛浓度在0~2.0μg·mL^(-1)时,甲酚红在518 nm处的吸光度差值与甲醛浓度具有良好的线性关系,线性方程为ΔA=0.2577c-0.0003,R^(2)=0.9987,检出限为0.08μg·mL^(-1)。该方法应用于实验室废水中甲醛的测定,测定结果与乙酰丙酮法接近,相对标准偏差为2.1%(n=5),加标回收率在91.50%~103.1%之间。方法的准确度可靠,灵敏度高,是实验室废水中甲醛监测的一种有效方法。

Synthesis and Spectrophotometric Studies of 2-(2-Imidazolylazo)-5-Dicthylamino Phenol

In this paper, 2-(2-imidazolylazo)-5-diethylami phenol (IZAPN) was prepared, theprotonation behaviour and the condition of spectrophotometric determination of cobalt with thisreagent are reported. The results show that the new colour reagent reacts with cobalt to from astable purple red complex (l:3). However, the complex formed could be changed into anotherspecies with stable absorptivity by addition of mineral acid (1+1). The, method is highly selectiveand sensitive and has been applied to the direct determination of cobalt in some alloys withsatisfactory results.

Kinetic spectrophotometric method for the determination of cerium(IV) with naphthol green B

A simple and sensitive spectrophotometric method was described for the determination of cerium（IV） based on its catalytic effect on the oxidation of naphthol green B by potassium periodate in the medium of sulfuric acid. The influences of acidity, concentration of reactants, reaction time, reaction temperature, and foreign ions were discussed, and the optimum reaction conditions were established. The reaction was monitored spectrophotometrieally by measuring the decrease in absorbance of naphthol green B at 710 nm after a fixed time （8 min）. The proposed method allowed the determination of cerium（IV） in the range of 0.08-2.4 μg·mL^-1 with good precision and accuracy, and the detection limit was 0.012 μg·mL^-1. The method was applied successfully for the determination of trace cerium in hair samples without previous separation. Recovery experiments were also performed, and the recovery was between 95.7%-111.0%.

Quantitative Determination of Benoxinate Hydrochloride by Three Wavelength Spectrophotometry

hree wavelength spectrophotometry was used to determine the content ofbenoxinate hydrochloride.Using this method could effectively eliminate the devia-tion of background absorption caused by the change of concentration and the errorof quantitative anaiysis caused by asymmetric peaks, and at the same time the lean-ing degree of base line was corrected.This method was simple, the recovery was98. 62% 101. 86% and the coefficient of variation was 0. 551%.

Application of potassium ferricyanide in the spectrophotometric determination of captopril

A novel method for the determination of captopril by spectrophotometer is described in this paper. The experiment is based on the fact that Fe（Ⅲ） is reduced to Fe（Ⅱ） by captopril, then the in sire formed Fe（Ⅱ） reacts with potassium ferricyanide to give the soluble prussian blue at pH 4.00, and its maximal adsorption wavelength （λmax） is 735 nm. Good linear relationship is obtained between the absorbance and the concentration of captopril in the wide range of 0.05-20 μg/mL. The linear regression equation is A = -0.04314 ＋ 0.11423C （μg/mL） with a correlation coefficient R = 0.9998. The detection limit （3σ/k） is 0.04 μg/mL, the molar absorption coefficient is 2.5×10^4 L/mol cm. By mensurating the absorbance of soluble prussian blue, the indirect determination of captopril can be obtained. This method has been successfully applied to determination of captopril in pharmaceutical samples. Analytical results obtained are satisfactory.

Kinetic spectrophotometric determination of vanadium in steels based on the catalytic oxidation of thionine by potassium bromate

A sensitive and selective kinetic spectrophotometric method for the determination of V（V） was developed based on the catalytic oxidation of thionine by KBIO3 in 0.6 mol·L^-1 HaPO4 medium. The linear calibration range and detection limit at 25℃ were 0-0.5 μg·mL^-1 and 0.01 μg·mL^-1, respectively. In the presence of NaF and urea, most of the common ions did not interfere with the determination of V（V）. The proposed method was applied for the determination of vanadium in steels and satisfactory results were obtained.

Rapid measurement of indocyanine green retention by pulse spectrophotometry: a validation study in 70 patients with Child-Pugh A cirrhosis before hepatectomy for hepatocellular carcinoma

BACKGROUND: The indocyanine green (ICG) retention test is the most popular liver function test for selecting patients for major hepatectomy. Traditionally, it is done using spectrophotometry with serial blood sampling. The newly- developed pulse spectrophotometry is a faster alternative, but its accuracy on Child-Pugh A cirrhotic patients undergoing hepatectomy for hepatocellular carcinoma has not been well documented. This study aimed to assess the accuracy of the LiMON , one of the pulse spectrophotometry systems, in measuring preoperative ICG retention in these patients and to devise an easy formula for conversion of the results so that they can be compared with classical literature records where ICG retention was measured by the traditional method. METHODS: We measured the liver function of 70 Child-Pugh A cirrhotic patients before hepatectomy for hepatocellular carcinoma from September 2008 to January 2009. ICG retention at 15 minutes measured by traditional spectrophotometry (ICGR15) was compared with ICG retention at 15 minutes measured by the LiMON (ICGR15(L)). RESULTS: The median ICGR15 was 14.7% (5.6%-32%) and the median ICGR15(L) was 10.4% (1.2%-28%). The mean difference between them was -4.3606. There was a strong correlation between ICGR15 and ICGR15(L) (correlation coefficient, 0.844; 95% confidence interval, 0.762-0.899). The following formula was devised: ICGR15=1.16×ICGR15(L)+2.73.CONCLUSIONS: The LiMON provides a fast and repeatable way to measure ICG retention at 15 minutes, but with constant underestimation of the real value. Therefore, when comparing results obtained by traditional spectrophotometry and the LiMON, adjustment of results from the latter is necessary, and this can be done with a simple mathematical calculation using the above formula.

A Dual Wavelength Differential First Derivative Spectrophotometric Method for Identification and Determination of Carbon Monoxide Generated During the Microsomal Metabolism of Xenobiotics in vitro

A dual wavelength differential first derivative spectrophotometric method has been developed to standardize the concentration of a saturated aqueous solution of carbon monoxide (CO) as the standard and to identify and to determine CO formed during the microsomal metabolism of xenobiotics in vitro. The method can significantly eliminate the background interference in the assay media and increase the quantitative accuracy and the sensitivity. There is a good linear relationship between CO concentration in the range of 2～10 μmol·L 1 CO and the distance D between the first derivative peak at 415 nm amd valley at 426 nm with r=0.9999(n=5),the regression equation being C (mmol·L 1 )=17.6D 0.4, the detection limit lower than 0.1 μmol·L 1 CO. The average recoveries of CO from the assay system and the sample were 102.1%, RSD=2.9% (n=7) and 79.7%, RSD=6.8% (n=12),respectively. The RSD of within day was 4.4%(n=18),and the RSD of day to day was 6.1%(n=16). By this method, four trihaloanilines and one trihalobenzene were tested, the results showed that only 2,4,5 trifluoroaniline could be converted to CO by the incubation with rat hepatic microsomes, NADPH and oxygen, the ability of phenobarbital or dexamethasone to induce rat hepatic microsomes to catalyze CO formation was 3 or 8 times higher than that of the control.

Serum paraquat concentration detected by spectrophotometry in patients with paraquat poisoning

BACKGROUND：Paraquat （PQ） is a world-wide used herbicide and also a type of common poison for suicide and accidental poisoning. Numerous studies have proved that the concentration of serum PQ plays an important role in prognosis. Spectrophotometry, including common spectrophotometry and second-derivative spectrophotometry, is commonly used for PQ detection in primary hospitals. So far, lack of systematic research on the reliability of the method and the correlation between clinical features of patients with PQ poisoning and the test results has restricted the clinical use of spectrophotometry. This study aimed to evaluate the reliability and value of spectrophotometry in detecting the concentration of serum PQ. METHODS：The wavelengths for detecting the concentration of serum PQ by common and second-derivative spectrophotometry were determined. Second-derivative spectrophotometry was applied to detect the concentration of serum PQ. The linear range and precision for detection of PQ concentration by this method were confirmed. The concentration of serum PQ shown by second- derivative spectrophotometry and HPLC were compared in 8 patients with PQ poisoning. Altogether 21 patients with acute poisoning 4 hours after PQ ingestion treated in the period of October 2008 to September 2010 were retrospectively reviewed. The patients were divided into higher and lower than 1.8 μg/mL groups based on their concentrations of serum PQ measured by second-derivative spectrophotometry on admission. The severity of clinical manifestations between the two groups were analyzed with Student＇s t test or Fisher＇s exact test. RESULTS：The absorption peak of 257 nm could not be found when common spectrophotometry was used to detect the PQ concentration in serum. The calibration curve in the 0.4-8.0 μg/mL range for PQ concentration shown by second-derivative spectrophotometry obeyed Beer＇s law with r=0.996. The average recovery rates of PQ were within a range of 95.0% to 99.5%, relative standard deviation （RSD） was within 1.35% to 5.41% （n=6）, and the lower detection limit was 0.05 μg/mL. The PQ concentrations in serum of 8 patients with PQ poisoning shown by second-derivative spectrophotometry were consistent with the quantitative determinations by HPLC （r=0.995, P〈0.0001）. The survival rate was 22.2% in patients whose PQ concentration in serum was more than 1.8 μg/mL, and the incidences of acidosis, oliguria and pneumomediastinum in these patients were 55.6%, 55.6% and 77.8%, respectively. These clinical manifestations were different significantly from those of the patients whose PQ concentration in serum was less than 1.8 pg/mL （P〈0.05）. CONCLUSIONS： For common spectrophotometry, the wavelength at 257 nm was not suitable for detecting serum PQ as no absorbance was shown. Second-derivative spectrophotometry was reliable for detecting serum paraquat concentration. Serum PQ concentration detected by second- derivative spectrophotometry could be used to predict the severity of clinical manifestations of patients with PQ poisoning, and PQ content higher than 1.8 tJg/mL 4 hours after ingestion could be an important predictive factor for poor prognosis.

Spectrophotometric Determination of Trimethylamine-nitrogen in Cadaver Tissues for the Estimation of Late Postmortem Interval:A Pilot Study

To study the relationship between the late postmortem interval （PMI） and trimethyl-amine-nitrogen （TMA-N） in postmortem tissues of cadaver, TMA-N in muscles, livers and kidneys of rats was measured at different postmortem intervals （PMI） by using a modified spectrophotometric method. The results indicated that the detection sensitivity of TMA-N was 1 mg/L, and there was a good linear correlation between the value of absorbance （A value） and TMA-N at the concentration of 1-10 mg/L （R2=0.9991）. Although TMA variation in muscles was different from that in inner organs during the time since death, TMA-N changes in cadaver tissues was positively correlated with PMI. During 2 to 7d since death, the best correlation between PMI and TMA-N concentration was found in muscles. With PMI as an independent variable, the cubic polynomial regression equation was y=-0.457x3 ＋6.519x2-24.574x＋27.207 （R2=0.969）. During 3 to 8 days since death, PMI was best correlated with TMA-N concentration in inner organs. With PMI as the independent variable, the cubic polynomial regression equation was y=0.509x3-9.153x2＋55.727x-95.819 （R2=0.953）. It was concluded that TMA-N in tissues could be used as a new estimator for late PMI. The method used in this study offered advantages such as accuracy, sensitivity, little samples required and wide PMI estimation.