Spectrophotometric Study of Basicity of Some Substituted α-(Benzamtoomethyl)phenylhydrazines

The protonation behavior at 25°C in water and in aqueous sulfuric acid solutions of some substituted α-(p-R-benzamidomethyl)phenyl hydrazines (R=H, CH₃, Cl, Br) was investigated by UV spectrophotometry. The absorption spectra in sulfuric acid solutions were analyzed by the method of multivariate analysis. The premonition constants of hydrazine (pK₁) and amide (pK₂) moieties were determined; pK₂ values were calculated from the reconstituted absorption spectra by Cox - Yates method. Dependence of pK₂ on Hammett's a constants was discussed.     

Multipumping Nitrite Determination in Exhaled Breath Condensate

Abstract

A flow system based on multicommutation is proposed for the rapid, clean, and inexpensive determination of nitrites in small volumes of breath condensates. The procedure exploits the colorimetric detection of nitrite with the Griess reagent [0.03% naphthylethylene diamine dihydrochloride (NED), 0.5% sulpfhanilamide, and 3.0% phosphoric acid] in acidic medium at 540 nm correcting the variations of the baseline with measurements at 424 nm. The flow system was designed with a set of solenoid micropumps to minimize sample and reagent consumption and waste generation. The detection limit was estimated as 3.8 ng mL^?1 (99.7% confidence level) with a linear response ranging up to 500 ng mL^?1. The coefficient of variation was estimated as 0.7% for a solution containing 300 ng mL^?1 nitrite (n=9). Approximately 144 determinations can be carried out per hour, consuming only 678.4 µg Griess reagent and generating 1.184 mL of effluent per determination, thus providing an environmentally friendly alternative and a nonexpensive method. The procedure was successfully applied to determine nitrite in breath condensates.     

Derivative Spectrophotometric and Colorbmetric Methods for the Determination of Guanoxan Sulphate in Tablets,Urine, and Serum.

Three simple and rapid methods for the determination of guanoxan sulphate in tablets, urine and serum are presented. The first method is based on the direct measurement of the first (¹D) and second (²D) (peak-trough) derivative values at 274–250 nm and 276–260 urn respectively. The other two methods depend on the formation of a charge- transfer chromogen with either tetracyanoethylene (TCNE) and 7,7,8,8- tetracyanoquinodimethane (TCNQ). The absorbance of the color developed at 416 and 840 nm respectively. The first and second derivative (¹D & ²D) values for the charge- transfer products were also measured. The methods were proved to be accurate and reproducible as indicated by relative standard deviation of less than 2%. The proposed methods have been applied to the determination of guanoxan sulphate in tablets, and spiked human urine and serum.     

Solid-Phase Spectrophotometric Determination of Beryllium at ng mL−1

Abstract

A microdetermination method at ng mL^?1 level for beryllium by solid-phase spectrophotometry was been developed. Chrome Azurol S was used as chromogenic reagent to form a blue complex which was easily and strongly sorbed and concentrated on a dextran-type anion-exchange resin. The resin-phase absorbances at 594- and 800 nm were measured directly. Beryllium could be determined over the 1.5 - 15.0 ng mL^?1 range with a RSD of 2.7 % by using 100 mL of sample solution. The detection limit was 0.21 ng mL^?1. By using only 10 mL of sample solution, the calibration graph was linear over the concentration range 10–85 ng mL^?1, the RSD being 1.2 %. The method was applied to the determination of beryllium in underground and mining waste water samples and in beryl mineral.     

The Application of 7-Chloro-4-nitrobenzoxadiazole (NBD-Cl) for the Analysis of Pharmaceutical-Bearing Amine Group Using Spectrophotometry and Spectrofluorimetry Techniques

Abstract

Many papers have been presented in recent years regarding the field of application of 7-chloro-4-nitrobenzoxadiazole (NBD-Cl) as a fluorogenic and chromogenic reagent for the determination of pharmaceutical amines using spectrophotometry and spectrofluorimetry techniques. In this review article, various spectrophotometric and spectrofluorimetric methods using NBD-Cl as a labeling reagent for determination of pharmaceutical amines are covered. The application of these methods for the determination of drugs in pharmaceutical and real samples is also discussed.     

茚三酮为显色剂分光光度法测定氨苄西林钠

采用分光光度法研究了氨苄西林钠与茚三酮间的显色反应。 确定了反应条件,建立了一种快速、简便测定氨苄西林钠的分光光度法。 实验表明,氨苄西林钠与茚三酮在pH=5.4的水溶液中,沸水浴1 h可以反应完全,产物在λmax=564 nm下,表观摩尔吸光系数为3.72×103 L/(mol·cm)。 氨苄西林钠质量浓度在10~90 mg/L范围内服从比耳定律, 相关系数为0.9981,当氨苄西林钠浓度为40 mg/L时,测定结果的相对标准偏差为1.5%(n=6),回收率在99.0%以上。     

灵芝、枸杞等样品中微量锗的胶束增溶分光光度法测定

研究用离子缔合物胶束增溶分光光度法测定灵芝、枸杞、蘑菇、茶叶和大蒜中锗的含量,采用标准加入法考查了不同的消解方法对样品中锗的溶解情况,用高压罐密闭消解处理样品,锗的测定结果的相对标准偏差(n=4)小于4.3%,回收率为90%～105%.     

水溶苯胺蓝褪色光度法测定庆大霉素及妥布霉素的研究

在酸性条件下,水溶苯胺蓝(ABWS)与硫酸庆大霉素(GEN)或硫酸妥布霉素(TOB)反应,生成离子缔合物,使水溶苯胺蓝溶液褪色,其最大褪色波长分别位于606nm(GEN)和608nm(TOB);在0～1.2×10-5mol·L-1(GEN)和0～1.5×10-5mol·L-1(TOB)的浓度范围内遵从比耳定律;表观摩尔吸光系数(ε)分别为2.21×104L·mol-1·cm-1(GEN)和3.10×104(TOB)L·mol-1·cm-1。本法已用于市售药物及人体尿液中庆大霉素及妥布霉素含量的测定,结果满意。     

催化动力学光度法测定人发中的痕量铜

在NH3.H2O介质中,微量Cu(Ⅱ)能显著催化过硫酸铵氧化溴百里酚蓝的褪色反应。研究了该褪色反应的最佳反应条件,建立了催化动力学测定铜的新分析方法。本法测定铜的线性范围在0.00~0.08μg.mL-1。回收率在97.5%~99.0%之间,RSD为0.6%~1.6%,检出限为4.8×10-8g.L-1。用于人发中痕量Cu(Ⅱ)的测定,结果满意。     

对磺酸基苯亚甲基硫代若丹宁固相萃取光度法测定烟草添加剂中的汞

合成了新试剂对磺酸基苯亚甲基硫代若丹宁(SBDTR),并用红外光谱、核磁共振氢谱和元素分析鉴定其结构。研究了SBDTR与汞的显色反应。在pH3.5的HAc NaAc缓冲介质中,吐温 80存在下,SBDTR与汞反应生成2∶1稳定络合物。该络合物可用WatersSep ParkC18固相萃取柱萃取,用乙醇洗脱后,在乙醇介质中用分光光度法测定,体系摩尔吸光系数为8.36×104L·mol-1·cm-1。汞含量在0～4μg/mL内符合比耳定律。本方法可用于烟草添加剂中汞含量的测定,结果满意。