Indirect atomic absorption spectrometric determination of pindolol, propranolol and levamisole hydrochlorides based on formation of ion-associates with ammonium reineckate and sodium cobaltinitrite

A new simple, accurate, precise and sensitive indirect method for the determination of pindolol HCl (1), propranolol HCl (2) and levamisole HCl (3) using atomic absorption spectrometry has been developed. The method is based on precipitation of the ion-associates formed from the reaction of (1), (2) or (3) with ammonium reineckate and/or sodium cobaltinitrite. The solubility of the solid complexes at the optimum conditions of pH and ionic strength values have been studied. Saturated solutions of each ion-associate were prepared under the optimum conditions and the metal ion content in the supernatant was determined. The method has been used for the determination of 1.14-17.07, 1.18-17.75 and 1.08-16.24 microg/ml of (1), (2) and (3), respectively, using ammonium reineckate, and 1.71-25.60, 1.77-26.62 and 1.62-24.36 microg/ml of (1), (2) and (3), respectively, using sodium cobaltinitrite. The method developed was applied for analysis of bulk drugs and some of their pharmaceutical preparations.     

Colourimetric and AAS determination of cephalosporins using Reineck's salt

Two simple, accurate, sensitive and selective procedures for the determination of eight cephalosporins are described. These procedures are based on the formation of ion-pair complexes between the drugs and ammonium reineckate, the formed precipitates are quantitatively determined either colourimetrically or by atomic absorption spectrometrically. The methods consist of reacting drugs with Reinecke's salt in an acidic medium at 25+/-2 degrees. The first colourimetric procedure (procedure I) is based on dissolving the formed precipitate with acetone, the volume was completed quantitatively and the absorbance of the solution was measured at 525 nm against pure solvent blank. Also, the formed precipitates on the atomic absorption spectrometric procedure (procedure II) are quantitatively determined directly or indirectly through the chromium precipitate formed or the residual unreacted chromium in the filtrate at 358.6 nm. The optimum conditions for precipitation have been carefully studied. Beer's law is obeyed for the studied drugs in the range 5-35 microg ml(-1) with correlation coefficients not less-than 0.9989. Both procedures I and II hold well accuracy and precision when applied to the analysis of the cited cephalosporins in different dosage forms with good recovery percent ranged from 98.7+/-0.90 to 100.1+/-0.74 without interference from additives.     

Utilization of colorimetric and atomic absorption spectrometric determination of aztreonam through ion pair complex formation

Three rapid and sensitive, colorimetric and atomic absorption spectrometric methods were developed for the determination of aztreonam. The proposed methods depend upon the reaction of cobaltthiocyanate (I) or reineckate (II) ions with the drug to form stable ion-pair complexes which extractable with chloroform. The greenish blue and pink color complexes are determined either colorimetrically at lambda(max) 625 and 525 nm for I and II reagents, respectively, or by atomic absorption spectrometry, directly using the organic extracted complex, or indirectly, using the supernatant. The three procedures are applied for the determination of aztreonam in pure and in pharmaceutical dosage forms applying the standard additions technique and the results obtained agreed well with those obtained by the official method.     

Indirect atomic absorption spectrometric determination of pindolol, propranolol and levamisole hydrochlorides based on formation of ion associates with manganese thiocyanate and potassium ferricyanide

A new simple, accurate, precise and sensitive indirect method for the determination of pindolol HCl (1), propranolol HCl (2) and levamisole HCl (3) using atomic absorption spectrometry has been developed. The method is based on precipitation of the ion associates formed from the reaction of (1), (2) or (3) with manganese thiocyanate and/or potassium ferricyanide. The solubility of the solid complexes at the optimum conditions of pH and ionic strength values have been studied. Saturated solutions of each ion-associate were prepared under the optimum conditions and the metal ion content in the supernatant was determined. The method has been used for the determination of 1.14-17.07, 1.18-17.75 and 1.08-16.24 microg/ml of (1), (2) and (3), respectively using manganese thiocyanate and 1.71-25.60, 1.77-26.62 and 1.62-24.36 microg/ml of (1), (2) and (3), respectively using potassium ferricyanide. The method developed applied for analysis of bulk drugs and some of their pharmaceutical preparations.     

Determination of lignocaine and amprolium in pharmaceutical formulations using AAS.

The ion-associate complexes of lignocaine hydrochloride (Lig.Cl) with ammonium reineckate (Rk) or sodium cobaltithiocyanate, and that of amprolium hydrochloride (Amp.Cl) with ammonium reineckate, have been prepared. The precipitated ion-associates were subjected to elemental analyses, infrared and nuclear magnetic resonance spectroscopy and determination of the metal content for elucidation of their structures. The solubilities of the solid ion-associate complexes have been studied and their solubility products were determined at different temperatures at the optimum pH for their quantitative precipitation. The thermodynamic parameters DeltaH, DeltaG and DeltaS for the dissolution of the ion-associate complexes were calculated. These ion-associate complexes have been used for the quantitative determination of the above mentioned drugs by precipitating them with an excess of the inorganic metal complex ions and determining the excess metal complex ions using atomic absorption spectrometry. The method was applied for the determination of the above drugs in pure solution and pharmaceutical preparations. 0.135-135.4 and 0.158-157.6 mg of lignocaine and amprolium, respectively, can be determined with mean relative standard deviations (R.S.D.) 0.92-1.20% and recovery values of 99.18+/-0.48 to 100.12+/-0.34% indicating high precision and accuracy.     

Triiodide ion and alizarin red S as two new reagents for the determination of clotrimazole and ketoconazole

The reactions of a triiodide ion and alizarin red S with two important antifungal drugs containing an imidazole ring (ketoconazole (KC) and clotrimazole (CT)) have been studied for the development of two simple, rapid, sensitive and accurate indirect titrimetric and extractive-spectrophotometric methods for determining the concentration of these drugs. Spectroscopic studies and chemical analysis showed that the protonated forms of KC and CT react with triiodide ion forming highly stable and insoluble ion-pair products such as (KCH(2))(I(3))(2) and (CTH)I(3). Formation of ion-association complexes have been applied to the development of an indirect visual titrimetric method for the determination of KC and CT over the range 10(-5)-10(-2) M. The extractive-spectrophotometric method is based on the formation of (1:1) ion-association complexes between drugs and alizarin red S as chromogenic reagent in acidic citrate buffer that are extractable into chloroform with an absorption maximum at 425 nm. The system obeyed Beer's law in the concentration range 2.5-50 and 2.7-80 microgram ml(-1) for CT and KC, respectively. The proposed methods were applied for the analysis of the studied drugs in pure forms and their commercial preparations. Results are in good agreement with those obtained by official methods.     

Determination of some antihistaminic drugs by atomic absorption spectrometry and colorimetric methods

Atomic absorption spectrometry (AAS) and colourimetric methods have been developed for the determination of pizotifen (I), ketotifen (II) and loratadine (III). The first method depends on the reaction of the three drugs (I); (II) and (III) with cobalt thiocyanate reagent at pH 2 to give ternary complexes. These complexes are readily extracted with organic solvent and estimated by indirect atomic absorption method via the determination of the cobalt content in the formed complex after extraction in 0.1 M hydrochloric acid. It was found that the three drugs can be determined in the concentration ranges from 10 to 74, 12 to 95 and 10 to 93 microg ml(-1) with mean percentage recovery of 99.71+/-0.87, 99.70+/-0.79 and 99.62+/-0.75%, respectively. The second method is based on the formation of orange red ion pairs as a result of the reaction between (I); (II) and (III) and molybdenum thiocyanate with maximum absorption at 469.5 nm in dichloromethane. Appropriate conditions were established for the colour reaction. Under the proposed conditions linearity was obeyed in the concentration ranges 3.5-25, 5-37.5 and 2.5-22.5 microg ml(-1) with mean percentage recovery of 99.60+/-0.41, 100.11+/-0.43 and 99.31+/-0.47% for (I): (II) and (III), respectively. The third method depends on the formation of radical ion using 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). The colour formed was measured at 588 nm for the three drugs (I); (II) and (III), respectively. The method is valid in concentration range 10-80 microg ml(-1) with mean percentage recovery 99.75+/-0.44, 99.94+/-0.72 and 99.17+/-0.36% for (I); (II) and (III), respectively. The proposed methods were applied to the analysis of pharmaceutical preparations. The results obtained were statistically analysed and compared with those obtained by applying the official and reference methods.     

Spectrophotometric and atomic absorption spectrometric determination of certain cephalosporins

Two sensitive spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of certain cephalosporins (cefotaxime sodium and cefuroxime sodium). The spectrophotometric methods are based on the charge-transfer complex formation between these drugs as n-donors and 7,7,8,8-tetracyano-quinodimethane (TCNQ) or p-chloranilic acid (p-CA) as π-acceptors to give highly coloured complex species. The coloured products are measured spectrophotometrically at 838 and 529 nm for TCNQ and p-CA, respectively. Beer’s law is obeyed in a concentration range of 7.6–15.2 and 7.1–20.0 μg ml⁻¹ with TCNQ, 95.0-427.5 and 89.0-400.5 μg ml⁻¹ with p-CA for cefotaxime sodium and cefuroxime sodium, respectively. The atomic absorption spectrometric methods are based on the reaction of the above cited drugs after their alkali-hydrolysis with silver nitrate or lead acetate in neutral aqueous medium. The formed precipitates are quantitatively determined directly or indirectly through the silver or lead content of the precipitate formed or the residual unreacted metal in the filtrate by atomic absorption spectroscopy. The optimum conditions for hydrolysis and precipitation have been carefully studied. Beer’s law is obeyed in a concentration range of 1.9–11.4 and 1.78–8.90 μg ml⁻¹ with Ag(I), 14.2–57.0 and 13.3–53.4 μg ml⁻¹ with Pb(II) for cefotaxime sodium and cefuroxime sodium, respectively (for both direct and indirect procedures). The spectrophotometric and the atomic absorption spectrometric procedures hold well their accuracy and precision when applied to the analysis of cefotaxime sodium and cefuroxime sodium dosage forms.     

Spectrophotometric and AAS determination of ramipril and enalapril through ternary complex formation

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of two antihypertensive agents (enalapril maleate and ramipril). The spectrophotometric procedures for the two cited drugs are based on ternary complex formation. The first ternary complex (copper(II), eosin, and enalapril) was estimated by two methods; the first depends on its extraction with chloroform measuring at 533.4 nm. Beer's law was obeyed in concentration range from 56 to 112 microg ml(-1). The second method for the same complex depends on its direct measurement after addition of methylcellulose as surfactant at the pH value 5 at 558.8 nm. The concentration range is from 19 to 32 microg ml(-1). The second ternary complex (iron(III), thiocyanate, and ramipril) was extracted with methylene chloride, measuring at 436.6 nm, with a concentration range 60-132 microg ml(-1). The direct atomic absorption spectrometric method through the quantitative determination of copper or iron content of the complex was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and enalapril dosage forms.     

Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II)

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophotometrically under the optimum condition, the ternary complexes showed an absorption maximum at 535 nm, with apparent molar absorptivities of 6.55 and 4.00×10³ mol⁻¹cm⁻¹ and Sandell’s sensitivities of 5.80×10⁻² and 1.04×10⁻¹μg cm⁻² for perindopril and ramipril, respectively. The solution of ternary complex obeyed Beer’s law in concentration ranges 10–60 and 20–100 μg ml⁻¹ for perindopril and ramipril, respectively. The proposed method was applied to the determination of the two cited drugs in pharmaceutical tablets. The atomic absorption spectrometric method, directly through the quantitative determination of copper content of the organic extract of the complex, was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and perindopril dosage forms.     

Stability-indicating electrochemical methods for the determination of meclophenoxate hydrochloride and pyritinol dihydrochloride using ion-selective membrane electrodes

The construction and electrochemical response characteristics of polyvinyl chloride (PVC) membrane sensors for the determination of meclophenoxate hydrochloride (I) and pyritinol dihydrochloride (II) in presence of their degradation products are described. The sensors are based on the use of the ion-association complexes of (I) and (II) cation with sodium tetraphenyl borate and ammonium reineckate counteranions as ion-exchange sites in the PVC matrix. In addition beta-cyclodextrin (beta-CD) membranes were used in the determination of I and II. These ion pairs and beta-CD were then incorporated as electroactive species with ortho nitrophenyl octyl ether (oNPOE) as a plasticizer. Three PVC sensors were fabricated for each drug, i.e. meclophenoxate tetraphenyl borate (meclo-TPB), meclophenoxate reineckate (meclo-RNC) and meclophenoxate beta-cyclodextrin (meclo-beta-CD), and the same was done for pyritinol (pyrit-TPB), (pyrit-RNC) and (pyrit-beta-CD). They showed near Nernestian responses for meclophenoxate over the concentration range 10(-5)-10(-2) with slopes of 52.73, 51.64 and 54.05 per concentration decade with average recoveries of 99.92+/-1.077, 99.96+/-0.502 and 100.03+/-0.763 for meclo-TPB, meclo-RNC and meclo-beta-CD respectively. Pyritinol also showed near Nernestian responses over the concentration range of 3.162 x 10(-6) - 3.162 x 10(-4) for pyrit-TPB and pyrit-RNC, and 10(-6) - 3.162 x 10(-4) for pyrit-beta-CD with slopes of 30.60, 31.10 and 32.89 per concentration decade and average recoveries of 99.99+/-0.827, 100.00+/-0.775 and 99.99+/-0.680 for pyrit-TPB, pyrit-RNC and pyrit-beta-CD respectively. The sensors were used successfully for the determination of I and II in laboratory prepared mixtures with their degradation products, in pharmaceutical dosage forms and in plasma.     

碳酸锂(缓释)片含量测定方法探讨

目的 探讨四种方法对碳酸锂(缓释)片中碳酸锂含量的测定的影响。方法 采用酸碱滴定法、电位滴定法、原子吸收分光光度法和离子色谱法分别测定碳酸锂的含量,并将结果进行比较分析。结果 通过测定锂离子所得碳酸锂的含量与通过测定碳酸根离子所得的结果具有显著性差异。结论 原子吸收分光光度法是较理想的碳酸锂含量测定方法。     

Studies of complex formation between the bromophenol blue and some important aminoquinoline antimalarials

A simple and rapid colorimetric method for the assay of amodiaquine hydrochloride, chloroquine phosphate and primaquine phosphate is described. The method is based on the interaction of the drug base with bromophenol blue to give a stable ion-pair complex. The spectra of the complex shows a maxima at 415-420 nm with high apparent molar absorptivities. Beer's law was obeyed in the concentration range 1-8, 2-10 and 2-12 micrograms.ml-1 for amodiaquine hydrochloride, primaquine phosphate and chloroquine phosphate respectively. The proposed method was applied to the determination of these drugs in certain formulations and the results were favourably comparable to the official methods.     

Application of new membrane selective electrodes for the determination of drotaverine hydrochloride in tablets and plasma

The construction and electrochemical response characteristics of poly vinyl chloride (PVC) membrane sensors for the determination of drotaverine hydrochloride were described. The sensors are based on the use of the ion association complexes of drotaverine cation with sodium phosphotungestate (Dro-PTA) or ammonium reineckate (Dro-R) counter anions as ion exchange sites in the PVC matrix. The performance characteristics of these sensors, which were evaluated according to IUPAC recommendations, reveal a fast, stable and linear response for drotaverine over the concentration range 10(-5) to 10(-2) M with cationic slopes of 49.55 and 51.36 mV per concentration decade. The direct potentiometric determination of drotaverine hydrochloride using the proposed sensors gave average recoveries of 99.95+/-0.71 and 100.04+/-0.60 for Dro-PTA and Dro-R, respectively. The sensors are used for determination of drotaverine hydrochloride in tablets, in its mixture with caffeine and paracetamol and in plasma. Validation of the method shows suitability of the proposed sensors for use in the quality control assessment of drotaverine hydrochloride. The developed method was found to be simple, accurate and precise when compared with a reported HPLC method.     

AAS and spectrophotometric determination of propranolol HCl and metoprolol tartrate

Two simple and accurate spectrophotometric methods are described for the determination of propranolol hydrochloride (I) and metoprolol tartrate (II). The methods are based on the reaction of each drug as a secondary amine: (a) with carbon disulphide, the formed complex extracted into iso-butyl methyl ketone (IBMK) after chelation with Cu(II) ions at pH 7.5, followed by measuring the absorbance at 435.4 nm or indirectly for the drug by flame atomic absorption spectrophotometry (AAS). The calibration graph is linear up to 40 and 60 microg ml(-1) with apparent molar absorptivities of 6.89 x 10(3) and 1.08 x 104 l mol(-1) cm(-1) and correlation coefficients of 0.9994 and 0.9995 for propranolol and metoprolol, respectively; (b) with pi-acceptors, tetracyanoethylene (TCNE), or chloranilic acid (CLA) to give highly coloured complex species. The coloured products are quantitated spectrophotometrically at 415 or 510 nm for the two drugs with TCNE and CLA, respectively, and obey Beer's Law with RSD less than 2.0. The methods were applied to the determination of these drugs in pharmaceutical preparation without interferences.     

火焰原子吸收分光光度法测定雷奈酸锶干混悬剂中的锶含量

目的：建立测定雷奈酸锶干混悬剂中锶含量的火焰原子吸收分光光度法。方法：使用含有0．1g·L-1铯离子和5．0g·L-1镧离子的0．1％硝酸溶液对样品进行溶解和稀释,采用空气一乙炔火焰原子吸收光谱法在460．7nm波长处进行测定。结果：当锶的质量浓度在6．30～25．20mg·L-1范围内时,其吸光度和质量浓度线性关系良好,相关系数为0．9997;平均加样回收率为101．4％,RSD为1．8％;测得3批雷奈酸锶干混悬剂中锶含量分别为制剂中锶标示含量的98．7％、99．3％和99．8％。结论：该方法便捷、准确、灵敏度高,适用于雷奈酸锶干混悬剂中锶含量的测定。     

Atomic emission spectrometric determination of ephedrine, cinchonine, chlorpheniramine, atropine and diphenhydramine based on formation of ion associates with ammonium reineckate

Ion-associate complexes of ephedrine HCl (I), cinchonine HCl (II), chlorpheniramine maleate (III), atropine sulphate (IV) and diphenhydramine HCl (V) with ammonium reineckate were precipitated and their solubilities were studied as a function of pH, ionic strength and temperature. Saturated solutions of each ion-associate under the optimum precipitation conditions were prepared and the Cr ion content in the supernatant was determined. The solubility products were thus elucidated at different temperatures. A new accurate and precise method using direct current plasma-atomic emission spectrometry for the determination of the investigated drugs in pure solutions and in pharmaceutical preparations is described. The drugs can determined by the present method in the ranges 1.6-52,2.64-85.8,3.12-101.4,5.52-180.4 and 2.72-75.85 microg/ml solutions of I, II, III, IV and V, respectively.     

火焰原子吸收法测定阿戈美拉汀原料中镍残留量

目的：建立阿戈美拉汀原料中镍残留量的检测方法。方法：采用火焰原子吸收分光光度法,以吡咯烷二硫代氨基甲酸铵-甲基异丁基酮体系萃取富集制备样品,在232.0 nm波长处测定吸光度,按外标法计算镍含量。结果：镍在0.05～4.00μg·ml-1浓度范围内有良好的线性关系（r=0.999 0）,平均回收率为93.3%。结论：该法简便快捷,重复性好,能准确测定阿戈美拉汀原料中镍残留量。     

离子选择电极测定注射用头孢他啶中碳酸钠的含量

用离子选择电极法测定注射用头孢他啶中碳酸钠的含量。方法：采用Mettler Toledo MA235/pH离子计及Nernst钠离子选择电极,根据Nernst方程,钠离子的电位与其浓度（活度）的对数成线性的关系,通过简单的电位测量,由钠离子标准工作曲线直接测得注射用头孢他啶中钠离子的浓度。结果：该方法的最大误差约6％,精密度（RSD）为1．07％,线性工作范围为10^-1-10^-3mol/L。本方法与原子吸收分光光度法的测定结果一致。结论：离子选择电极法简便、经济、快速、准确,易于推广,可代替原子吸收分光光度法用于注射用头孢他啶中碳酸钠含量的测定。     

胺(铵)离子梯度法载药理论及条件选择的研究进展

目的对胺(铵)离子梯度法载药的理论及条件选择进行综述。方法参阅近年来国内外文献共52篇,对胺(铵)离子梯度法的载药机制、理论模型、经验模型、药物性质、胺(铵)离子和反离子的选择等进行归纳、总结和分析。结果胺(铵)离子梯度法载药的动力主要来自于间接pH梯度、铵离子扩散电势以及内水相药物沉淀的生成;理论模型能够帮助研究者深刻理解载药机制,经验模型可直接指导载药参数的选择;药物性质、胺(铵)离子和反离子的种类均能影响药物的装载及释放。结论本文为胺(铵)离子梯度法载药的条件选择及相关制剂的开发提供了参考。