铁氰化钾分光光度法测定头孢他啶

建立了K3[Fe(CN)6]光度法测定头孢他啶的方法。研究表明:控制溶液pH 4.0左右,头孢他啶可以将Fe(III)还原为Fe(II),还原生成的Fe(II)与K3[Fe(CN)6]反应生成可溶性的普鲁士蓝,其最大吸收波长为735 nm。头孢他啶在0.05～7.2μg/mL范围内与吸光度呈良好的线性关系,线性回归方程A=0.03414+0.07334c(μg/mL),线性相关系数R=0.9992,表观摩尔吸光系数ε=4.0×104 L/(mol.cm),检出限为0.026μg/mL。本法能直接用于注射用头孢他啶的含量的测定,结果满意。     

Determination of phenylephrine hydrochloride by flow injection analysis with chemiluminescence detection

A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80 degrees C. The calibration graph is linear over the range 0.03-8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.     

Sequential injection spectrophotometric determination of ritodrine hydrochloride using 4-aminoantipyrine

A sequential injection spectrophotometric determination of ritodrine hydrochloride is described. The method is based on the condensation of aminoantipyrine with phenols in the presence of an alkaline oxidizing agent to yield a pink coloured product the absorbance of which is monitored at 503 nm. Different sequential injection analysis (SIA) parameters including reagent concentrations have been optimised and used to obtain the analytical figures of merit. A linear concentration range of 3.1-123.5 μmol L⁻¹ and a detection limit (as 3σ-value) of 1.0 μmol L⁻¹ were obtained. The precision was 2.4 and 2.3% relative standard deviation (R.S.D.) at 6.2 and 15.4 μmol L⁻¹, respectively. This method is superior over previously reported ones in terms of linear range, short analysis time, high sample throughput, excellent reagent economy and minimum waste generation.     

Spectrophotometric determination of ascorbic acid in pharmaceuticals by background correction and flow injection

Background correction has been shown to be an effective and indispensable modification in the spectrophotometric determination of ascorbic acid. The decomposition of ascorbic acid in pharmaceutical samples was carried out by incubation with sodium hydroxide to give products that were insensitive to ultraviolet light. The rapid oxidation in air of ascorbic acid, especially in dilute solutions, was avoided by the use of the flow injection principle for spectrophotometric determination and by employing a carrier stream of an anti-oxidizing nature consisting of 6 micrograms ml(-1) of 2-mercaptoethanol in 0.25% sulphuric acid. The optimized method with a single channel manifold made use of a carrier stream flow rate of 1.1 ml min(-1), an injection volume of 50 microl, a delay coil of 50 cm (0.5 mm i.d.) and detection at 245 nm. The throughput was at least 180 injections h(-1). The proposed flow injection method yielded results for the analysis of 0-20 micrograms ml(-1) of ascorbic acid that were 99-102% (relative standard deviation 0.6% or better) in agreement with those produced by comparable methods involving titration with iodine, chloranil or 2,6-dichlorophenolindophenol [4-(2,6-dichloro-4-hydroxyphenylimino)cyclohexa-2,5-dieno ne], and high-performance liquid chromatography. When the agreement was not good (as low as 14% with respect to the method being compared), this was traced to the presence of substances which are known to interfere in one or other of the methods of comparison.     

铁氰化钾氧化分光光度法测定左旋多巴含量

研究了铁氰化钾与左旋多巴之间的氧化反应所引起的吸收光谱的变化.实验发现,碱性溶液中铁氰化钾氧化左旋多巴生成红色化合物,其最大吸收波长为475nm,铁氰化钾与左旋多巴的物质的量之比为2∶1.体系的吸光度与左旋多巴的浓度在3.2~54.4mg/L范围内呈良好的线性关系,线性回归方程A=-0.038 88+0.020 8c(mg/L),相关系数r=0.999 2,表观摩尔吸光系数ε=5.1×103 L·mol-1cm-1.该方法的检出限为2.32mg/L,对浓度为16.0mg/L的左旋多巴进行平行11次测定,其相对标准偏差为0.3%.据此建立了测定左旋多巴的新方法,能够直接用于市售的左旋多巴片中左旋多巴含量的测定,回收率为96.7%~104.4%.     

Spectrophotometric determination of acid volatile sulfide in river sediments by sequential injection analysis exploiting the methylene blue reaction

This paper demonstrates the application of sequential injection analysis to perform sulfide determination using the methylene blue chemistry, based on two reagents: 3.63 mmol l(-1)N,N dimethyl-p-phenylene diamine hydrochloride in 1.1 mol l(-1) HCl solution and 19 mmol l(-1) FeCl(3), also in 1.1 mol l(-1) HCl. These solutions are aspirated inside the holding coil of the sequential injection system as two reagent zones sandwiching the sample zone. Under optimized conditions, the detection limit was calculated at 40 mug l(-1) S(2-), with a linear dynamic range from 0.05 to 2 mg l(-1) S(2-). This linear range can be extended up to 32 mg l(-1) using in-line dilution for sulfide concentrations greater than 2 mg l(-1). The robust characteristic of the SI system with syringe pump leads to very stable analytical curves (precision of 4%), minimizing the laborious preparation of sulfide standards. The method was applied in the determination of acid volatile sulfide in river sediments.     

Rapid determination of corticosteroids in pharmaceuticals by flow injection analysis

The proposed method is based on the reduction of blue tetrazolium by the steroid in an alkaline medium to form a highly colored formazan. The effects of reagent concentration, temperature, flow rate, and manifold design on the reaction are discussed for a typical steroid, methylprednisolone acetate. Analytical readout is obtained within 30 s after sample introduction and up to 100 samples/h can be processed with baseline resolution between peaks. Typical relative standard deviations of 0.5% are obtained with 10-μ1 injection volumes. Results obtained by flow injection analysis are similar to those obtained with the AutoAnalyzer technique.     

Spectrophotometric determination of papaverine hydrochloride by reaction with phloxin

The optimum conditions for the formation of a complex of papaverine hydrochloride with phloxin have been determined: pH 2.5–3.2. A procedure has been developed for the spectrophotometric determination of papaverine hydrochloride. The sensitivity of the determination is 0.4 µg/ml.Vitebsk Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 836–838, November–December, 1988.     

Spectrophotometric determination of papaverine hydrochloride by reaction with phloxin

A new withasteroid — vamonolide — has been isolated from the epigeal part ofPhysalis angulata L. (Solanaceae). On the basis of spectral characteristics, its structure has been established as 5,14-dihydroxyl-l-oxo-6,7-epoxy-20R,22R-with-2-enolide.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 856–858, November–December, 1987.     

Spectrophotometric determination of nitrite in foodstuffs by flow injection analysis

A simple method for the determination of nitrite in foodstuffs by flow injection analysis is described. Nitrite samples are prepared in a microwave oven, treated with a 1 mol/lNH₄Cl solution at a pH of 9 (all under nitrogen atmosphere) and are immediately analysed. Nitrite is diazotised in the FIA system with N-(1-naphthyl) ethylenediammonium dichloride to form the highly coloured azo dye, which is measured at 540 nm. The detection limit is 0.036 mg/kg for sample injections of 400 l. The sampling rate is about 50 samples per hour and the relative standard deviation is 0.67%.     

Spectrophotometric determination of dopamine and methyldopa with metaperiodate by flow injection analysis

A flow-injection spectrophotometric method for determining dopamine and methyldopa is described. It is based on the oxidation reaction with metaperiodate. Calibration graphs were linear up to 2 × 10^–4 mol/l catecholamines. The method allows the measurement of 130 samples per hour and was successfully applied to the analyis of pharmaceuticals.     

Spectrophotometric determination of dopamine and methyldopa with metaperiodate by flow injection analysis

A flow-injection spectrophotometric method for determining dopamine and methyldopa is described. It is based on the oxidation reaction with metaperiodate. Calibration graphs were linear up to 2 x 10(-4) mol/l catecholamines. The method allows the measurement of 130 samples per hour and was successfully applied to the analyis of pharmaceuticals.     

Chemiluminescence determination of bufrenorphine hydrochloride by flow injection analysis

A direct, simple and rapid flow-injection method is described for determining buprenorphine hydrochloride (10^?8–10^?4 M) based on its chemiluminescent oxidation with potassium permanganate in polyphosphoric acid. The limit of detection is 1 × 10^?8 M (0.5 pmol per injection) and the log-log calibration is linear up to 1 × 10^?4 M; the r.s.d. is 0.7% for a 10 μg ml^?1 solution (n = 10). The method is directly applicable to aqueous solutions of tablets containing the drug (0.2 mg/tablet).     

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.     

Spectrophotometric determination of palladium with sulfochlorophenolazorhodanine by flow injection

Sulfochlorophenolazorhodanine (as its sodium salt) has been used in the automated development of a sensitive flow-injection procedure for the spectrophotometric determination of palladium. The resulting method has high sample throughput, good precision, and low consumption of both sample and reagents. The optimum pH for the reaction is 5.0 and the response is constant at pH between 4.7 and 5.3. The sensitivity (calibration slope) of the procedure is 4.4 x 10(3) l./mole. The linear dynamic range is 0.045-30.0 mug/ml. The sample throughput is at least 120/hr. An automated procedure for optimization of analytical variables is described and a two-variable response surface for the system is given. Interference studies on 19 metal ions show that the method has good selectivity.     

Spectrophotometric determination of pH by flow injection

Flow injection is used for the determination of pH over a wide range. Using an appropriate combination of pH-indicating dyes, plots of absorbance vs. pH are linear in the range pH < 1–8 for static measurements and pH 3.6–6.8 in the flow-injection experiment. In the current configuration, the flow-injection method has the capability of measuring approximately 100 samples h^?1 with a precision and accuracy of ±0.2 pH. The reasons for the linear calibration graphs, effects of ionic strength and day to day reproducibility are presented together with results for lake-water samples.     

Determination of formaldehyde by flow injection analysis with spectrophotometric detection exploiting brilliant green-sulphite reaction

A method for the determination of formaldehyde by flow injection analysis with spectrophotometric detection is proposed, based on retarding the reaction between brilliant green and sulphite by the addition of formaldehyde; this was investigated for formaldehyde quantification in extracts from wood-based panels. For the first time, a heating step was explored, providing a sample throughput of 50 analyses per hour, with a limit of detection of 0.02 mg L^?1 and linearity of 0.20–3.0 mg L^?1, which was adequate for the expected range of formaldehyde concentration in the extracts. The mean recovery observed for actual samples was in the range of 92–106 %, with a maximum relative standard deviation of 6.0 %. The paired t-test revealed no significant difference between this method and the official Nash method, demonstrating an appropriate accuracy and precision; the method is proposed as a simple, fast and inexpensive alternative for the routine determination of formaldehyde in an aqueous medium.