Simultaneous Determination of Procaine Penicillin G and Benzathine Penicillin G by Second Derivative Spectrophotometry

Abstract

A new method for determining the binary mixtures of procaine penicillin G and benzathine penicillin G using “zero-crossing” second derivative spectrophotometry is described. Calibration graphs were linear up to 8.80 10^?5 M for procaine penicillin G and 4.40 10^?5 M for benzathine penicillin G. The method was realized in ethanol/water medium (30 % v/v). A complete and exhaustive statistical analysis of the experimental data was realized to demonstrate the validity of method. The method was applied for determining procaine penicillin G and benzathine penicillin G synthetic mixtures with good results. The procedure does not require any separation step.     

New Rapid Assay for Nafcillin by Spectrofluorimetry in Pharmaceutical Dosage

Abstract

A method for the spectrofluorimetric determination of nafcillin is proposed (λ_ex = 226 nm, λ_em = 366 nm), for concentrations between 0.10 and 1.0 μg mL^?1. The method was performed in ethanol/water medium (30% V/V), at apparent pH 6.0 provided by adding of phosphate buffer solution with pH = 6.20.

The obtained values of detection and determination limits are 0.016 and 0.054 μg mL^?1, respectively.

The method was successfully applied to assay a commercial injection containing nafcillin sodium monohydrate.     

铁氰化钾高灵敏共振瑞利散射法测定青霉素类抗生素

在稀HCl介质中,K3[Fe(CN)6]与阿莫西林(AMO)、氨苄西林(AMP)、氯唑西林钠(CLO)、羧苄西林钠(CAR)和青霉素钠(BEN)等抗生素药物在加热条件下反应生成结合产物,会导致溶液的共振瑞利散射(RRS)强度急剧增强,并产生新的RRS光谱,5种反应产物的最大散射峰均位于330 nm附近。在一定的浓度范围内,不同的反应体系散射强度(∆I)与药物浓度成正比,反应具有很高的灵敏度,K3[Fe(CN)6]对5种药物的检出限分别在4.61至5.62 ng·mL-1之间。本文研究了RRS的光谱特征和适当的反应条件,并讨论了反应机理和散射增强的原因,还考察了共存物质的影响,表明方法具有较好的选择性,可用于胶囊、片剂和人血清及尿液中青霉素类药物的测定。     

Simultaneous Determination of Atrazine and Chlorpyrifos in Pesticide Formulations,in Soils and Waters by Derivative Spectrophotometry and Ratio Spectra Derivative

Abstract

A new method is described to analyse a binary mixture of atrazine and chlorpyrifos, using first-derivative spectrophotometry for atrazine and first derivative of the ratio spectra for chlorpyrifos. The procedure does not require any separation step. Calibration graphs were linear up to 15 μg.mL^?1 of atrazine and to 10 μg.mL^?1 of chlorpyrifos. The method has been applied to determine both compounds in pesticide formulations, in soils and waters.     

免疫纳米金催化氯金酸与羟胺反应-共振散射光谱检测痕量青霉素G

小粒径的金和免疫金纳米粒子对氯金酸-盐酸羟胺这一反应具有较强的催化作用,其产物在580 nm处有一共振散射峰。以半抗原青霉素G为模型,用粒径为9 nm的金纳米微粒标记羊抗兔青霉素噻唑蛋白抗体制备了青霉素G的免疫纳米金共振散射光谱探针。在pH5.4的柠檬酸-磷酸氢二钠缓冲溶液中,青霉素G与金标兔抗青霉素发生特异性结合生成胶体金免疫复合物,离心分离。取适量金标羊抗兔青霉素的上层清液做催化剂,在pH3.36盐酸-柠檬酸钠缓冲溶液－40μg/mL氯金酸－21.6μg/mL的盐酸羟胺条件下,进行催化反应后金纳米粒径增大,在580nm共振散射强度处增强。随着青霉素G浓度c增大,上层清液中免疫金纳米微粒数量降低,I580nm值降低。其降低值△I580nm与c在0.15-225 ng/mL范围内成线性关系,其回归方程为△I580nm=0.28c+5.16,检出限为0. 05 ng/mL。该法用于牛奶中青霉素G的检测,结果较好。     

Direct Spectrophotometric Determination of Calcium in Human Serum and Cerebrospinal Fluids with Amino G Acid Chlorophosphonazo

ABSTRACT

A novel spectrophotometric method based on amino G acid chlorophosphonazo (AGCPA) has been developed for measuring calcium in human serum and cerebrospinal fluids. The effects of experimental factors including pH, reagent concentrations, and interfering species on calcium determinations were investigated. In a neutral reaction media of pH 7.0, AGCPA reacts rapidly with calcium to form a stable and greenish blue complex, whose absorption maximum is at 670 nm. The molar absorptivity (?) of the complex is 7.2x10⁴ 1 mol^?1cm^?1, and the molar ratio of calcium to AGCPA in the complex is found to be 1:2. Beer's law is obeyed over the range 0.02-0.8 μg ml^?1 of calcium. No interferences were observed from the commonly coexisting species present in serum and cerebrospinal fluids. Compared to the reported and currently often used methods based on o-cresolphthalein complexone, arsenazo III and methylthymol blue, the proposed method in this work provides better analytical characteristics such as high sensitivity, good selectivity and neutral reaction media. In addition, the present method is simple and can be applied to the direct determination of calcium in human serum and cerebrospinal fluid samples with satisfactory results.     

A Fluorimetric Method for the Determination of Cyanide with Fluorescein and Iodine∗

Abstract

A rapid, simple and sensitive fluorimetric method has been developed for the determination of cyanide with fluorescein as fluorogenic reagent (λ_ex = 494 nm, λ_em = 514 nm) at pH 6.0–7.0. A linear calibration curve was obtained in the range 0.004–2.0 μg CN^?/25 ml. The detection limit is 0.004 μg CN^-/25 ml. The method was successfully applied to the determination of cyanide in waste water.

     

The Use of Zirconyl Xylenol Orange for the Post-Column Spectroscopic Detection of Fluoride in Ion Chromatrography

Abstract

A simple post column reaction detection system for fluoride is presented using the decolorization of the zirconyl xylenol orange complex. A 3[sgrave] detection limit of 0.05 μg F^? mL^?1 was achieved with a linear calibration function up to 10 μg F^? mL^?1. The methodology is suitable for the determination of F^? in potable water and some interferences studies were conducted with common cations namely Ca, Mg, Al and Fe(III).     

Application of acidic extract of Platanus orientalis tree leaves as a green reagent for selective spectrophotometric determination of zirconium

Abstract

A novel spectrophotometric method for the determination of zirconium by using a new reagent, acidic extract of Platanus orientalis tree leaves is developed. In 6 M hydrochloric acid, zirconium reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 422 nm with a molar absorptivity value of 0.59×10^? l mol^?1 cm^?1 and the method was linear in the 0.4–8 µg mL^?1 concentration range. The detection limit value was found to be 0.086 µg mL^?1. The proposed method was simple, clean, low cost, selective, and sensitive. It was applied to the determination of zirconium in tap water, wastewater and well water samples with relative standard error of less than 2.5%.     

Development and validation of a generic RP‐HPLC PDA method for the simultaneous separation and quantification of active ingredients in cold and cough medicines

A novel generic reverse phase high performance liquid chromatography (RP‐HPLC) method is developed and validated for simultaneous determination of seven pharmaceutically active ingredients, namely, acetaminophen, dextromethorphan, doxylamine, phenylephrine, guaifenesin, caffeine and aspirin. All seven ingredients were quantified in soft gel, syrup and tablet formulations of the over‐the‐counter US‐marketed products, as per the guidelines of the International Conference on Harmonization. The separation was achieved in a 16 min run time on an Agilent Zorbax Phenyl column using a gradient method with two mobile phases. Mobile phase A was 0.15% trifluoro acetic acid in purified water and while mobile phase B was a mixture of acetonitrile and methanol (750:250 v/v) with 0.02% trifluoro acetic acid. The flow rate was 1.0 mL min^?1 and injection volume was 10 μL. Detection was performed at 280 nm using a photodiode array detector. As part of the method validation, specificity, linearity, precision and recovery parameters were verified. The concentration and area relationships were linear (R² > 0.999), over the concentration ranges 20–120 μg mL^?1 for acetaminophen, 75–450 μg mL^?1 for dextromethorphan, 31.25–187.5 μg mL^?1 for doxylamine, 25–150 μg mL^?1 for phenylephrine, 25–150 μg mL^?1 for aspirin, 6.5–39 μg mL^?1 for caffeine and 12–72 μg mL^?1 for guaifenesin. The relative standard deviations for precision and intermediate precision were <1.5%. The proposed RP‐HPLC generic method is applicable for routine analysis of cold and cough over‐the‐counter products.     

Flow Injection Chemiluminescence Determination Of Tetracyclines

Abstract

A fast and simple flow injection chemiluminescence method for the determination of trace amounts of tetracyclines is proposed based on the chemiluminescence of the KMnO₄ - TCs redox reaction in acidic medium in the presence of a sensitizer, OP. The response to the concentration of tetracyclines is linear in the range of 1.00 to 1000 μg mL^?1 with a relative standard deviation < 2.3 % for determination of 50.0 μg mL^?1 of each antibiotic (n = 11). The detection limits for tetracycline, oxytetracycline and chlortetracycline are 0.40, 0.52 and 0.60 μg mL^?1, respectively. The recommended method is suitable for automatic and continuous analysis and has been successfully tested for determination of tetracyclines in commercial formulations. The chemiluminescence intensity was found to be remarkably enhanced when in the presence of OP micellar system; possible reasons for this observed micellar induced enhanced chemiluminescence is given.     

Solid phase extraction with electrospun nanofibers for determination of retinol and α-tocopherol in plasma

A novel packed-fiber solid phase extraction procedure based on electrospun nanofibers for simultaneous determination of vitamins A (retinol) and E (α-tocopherol) in human plasma has been developed. Parameters affecting extraction efficiency were investigated in detail. The limit of detection is 0.01 μg mL^?1 for retinol, and 0.3 μg mL^?1 for α-tocopherol. The linear range is from 0.05 to 2.0 μg mL^?1 for retinol, and from 0.5 to 30 μg mL^?1 for α-tocopherol. The precision (RSD) is <6%, and the relative recovery >90%. The method was applied to analysis of retinol and α-tocopherol in human plasma with satisfactory results.     

Spectrofluorimetric Determination of Nitrite with Pyridoxal-5-Phosphate-2-Pyridylhydrazone

Abstract

The nitrite ion oxidizes pyridoxal-5-phosphate-2-pyridyl-hydrazone in acid medium giving a fluorescent product (λ_ex 325 nm, λ_em 420 nm). This redox reaction is used to developed a spectrofluorimetric method for the determination of nitrite. The calibration graph is liner in the 0.1 ? 1.0 μg mL^?1 range. The interference levels, stoichiometry and nature of the reaction have been studied. The method is applied to determine nitrite in water and soil samples     

Flow injection spectrophotometric determination of ascorbic acid in soft drinks and beer

Two spectrophotometric methods, a photochemical and a non-photochemical, for the determination of ascorbic acid in soft drinks and beer using a flow-injection system are proposed. The non-photochemical method is based on the redox reaction that takes place between ascorbic acid and Fe(III), yielding dehydroascorbic acid and Fe(II). Fe(II) reacts with 1,10-phenantroline, originating the reddish orange Fe(phen)₃ ²⁺ complex (ferroin). This complex is spectrophotometrically monitored at 512 nm, and the signal is directly related to the concentration of ascorbic acid in the sample. The photochemical method has the same basis, nevertheless, uses the irradiation with visible light to enhance the redox reaction and so achieve higher sensitivities in the analysis. The non-photochemical method shows a linear range between 5 and 80 μg mL^?1, with a relative standard deviation of 1.6% (n = 11), a detection limit of 2.7 μg mL^?1 and a sample throughput of ¶60 samples h^?1. The photochemical method shows a linear range between 1 and 80 μg mL^?1, with a relative standard deviation of 1.0% (n = 11), a detection limit of 0.5 μg mL^?1 and a sample throughput of 40 samples h^?1.     

Determination of Vanadium by Solid-Phase Spectrophotometry in a Continuous Flow System

Abstract

A flow analysis method based on direct absorptiometric measurement in solid phase of the violet complex formed between V(V) and 5-Bromosalicylhydroxamic acid has been developed. The measurement is continuously performed at 555 nm, while the coloured species is being concentrated on-line on the beads of an anion exchanger packed into a flow-through cell. The sensing solid phase is regenerated after each measurement achieving a sampling frequency ranged between 10 to 15 h^?1 depending on the working conditions. The sensitivity of the method depended on the sample volume injected, being the detection limit 0.024 and 0.014 μg mL^?1 for 2 and 5 mL, respectively. The method shows a good selectivity and has been applied to determination of V(V) in many different sample matrices namely mussel, oyster and toadstool tissues, petroleum crudes and water samples.     

Square‐Wave Adsorptive‐Stripping Voltammetric Detection in the Quality Control of Fluoxetine

ABSTRACT

A simple and sensitive extraction-spectrophotometric method for the determination of barium and potassium is reported. The 18C6-Barium-Orange II (18C6-Ba-(OR II)₂) and 18C6-Potassium-Orange II (18C6-K-OR II) ternary complexes are quantitatively extracted into dichloromethane and their absorbances are measured at 483 nm. Linear calibration graphs were obtained over the barium concentration range of 0.1-5 μg ml^?1 and potassium concentration range of 1-8 μg ml^?1. The relative standard deviation for 2.0 μg ml^?1 barium and pottasium are, respectively, 4.16% and 3.60%. The interfering effect of a large number of diverse ions on the determination of barium and potassium was studied. The method was applied to a synthetic sample with natural matrix effects of tap water and the results showed high potential of the recommended method for the determination of Ba and K in water samples.     

Pervaporation as a Separation Technique for Direct Determination of Volatile Selenium Species by Atomic Fluorescence Spectrometry

Abstract

This paper reports for the first time a suitable way to determine methylated selenium compounds using the new approach of pervaporation coupled to atomic fluorescence spectrcmetry (PV-AFS).

The method developed allows direct extraction, separation, preconcentration and determination of dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) from slurry samples. Under the optimum conditions, the detection limits (LODs) were found to be 0.66 ng and 0.39 ng for DMSe and DMDSe, respectively, the precision being about 6–9 % for 10 ng mL as selenium concentration. The linearity ranges were from the LOD to 0.7 μg mL^?1 for DMSe and from the LOD to 0.4 μg mL^?1 for DMDSe (as Se). The pervaporation efficiencies were 55 ± 1 % and 85 ± 5 % for DMSe and DMDSe, respectively. The proposed method was successfully applied to determine methylated selenium species in sewage sludge, garlic and oyster samples. The concentrations found were from 0.07 to 1.42 μg g^?1.

As no certified reference materials are available for these analytes, validation was carried out by recovery studies in these matrices, and the results showed that the proposed method performed satisfactorily.     

Simultaneous Determination of Valsartan and Hydrochlorothiazide in Tablets by High-Performance Liquid Chromatography

ABSTRACT

A method for the simultaneous determination of valsartan and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 5.0-10.0 μg ml^?1 for valsartan and 0.5-2.0 μg ml^?1 for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 1.0 μg ml^?1 for valsartan and 0.05 μg ml^?1 for hydrochlorothiazide.     

Rapid assay for procaine penicillin G in pharmaceutical dosages by spectrofluorimetry

A method for the spectrofluorimetric determination of procaine penicillin G is proposed (lambda(ex) = 294 nm, lambda(em) = 348 nm) for concentrations between 0.10 and 1.0 ppm. The method was performed in ethanol/water medium (60% V/V), at apparent pH 9.9 provided by adding ammonium/ammonia buffer solution with pH = 10.0. The effect of other penicillins on the determination of procaine penicillin G was examined over a wide range of concentrations, interferences were not observed in the range of studied concentrations. The method was successfully applied to assay all Spanish commercialized injections containing procaine penicillin G, penicillin G and/or benzathine penicillin G.