Search

A simple and sensitized spectrophotometric method for the determination of trace amounts of beryllium has been described. The method is based on the formation of a ternary complex by the reaction of beryllium with haematoxylin in the presence of micellar medium (cationic surfactant, cetyltrimethylammonium bromide). The ternary complex of beryllium has a maximum absorbance at 592 nm and showed an excellent sensitivity (molar absorption coefficient of 7.07 x 10(4)L mol(-1)cm(-1) and the Sandell's sensitivity being 1.27 x 10(-4) microg cm(-2)) and reproducibility (within-day precision: R.S.D.

A new, simple, sensitive, and reliable method is presented for the rapid spectrophotometric determination of trace amounts of iron(III) using leuco Xylene cyanol FF. The method is based on the oxidation of leuco Xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by iron(III) in sulfuric acid medium (pH 2.0-3.0), the absorbance of the formed dye is measured in an acetate buffer medium (pH()2.8-4.4) at 615 nm. The method obeys Beer's law over a concentration range of 0.15-0.9 microg mL(-1) iron, having a molar absorptivity of 5.6 x 10(4) L mol(-1) cm(-1) and a Sandell's sensitivity of 0.0001 microg cm(-2). The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of iron in water, soil, industrial effluent, plant material, pharmaceutical preparations, synthetic mixtures, and aluminum alloys.

A simple, rapid, and sensitive spectrophotometric method has been developed for the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic cosmetic and in pharmaceutical preparations. The method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine. The liberated iodine bleaches the violet color of thionin, and which is measured at 600 nm. This decrease in absorbance is directly proportional to selenium concentration and obeys Beer's law in the range 1-5 micro g selenium in a final volume of 10 mL (0.1-0.5 microg mL(-1)). The molar absorptivity and Sandell's sensitivity of the method were found to be 7.33 x 10(4) L mol(-1) cm(-1) and 0.0011 microg cm(-2), respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described.

Two simple and sensitive spectrophotometric methods are described for the determination of ritodrine hydrochloride (RTH) in both pure and dosage forms. The methods are based on the interaction of diazotised p-nitroaniline (DPNA) and sulphanilic acid (DSNA) with RTH in an alkaline medium. The resulting azo dyes are measured at 480 nm (for the DPNA method) and at 440 nm (for the DSNA method) and are stable for more than 1 h. The optimum reaction conditions and other analytical parameters are evaluated. A study of the effect of commonly associated excipients and additives do not interfere with the determinations. Statistical analysis of results indicates that the methods are precise and accurate.

A sensitive spectrophotometric method for the determination of amitriptyline hydrochloride, nortriptyline hydrochloride and doxepin hydrochloride in pure and dosage forms, is described. The method is based on the oxidative coupling of the drugs with 3-methylbenzothiazolin-2-one hydrazone in the presence of iron(III) chloride in 1 M hydrochloric acid. The commonly encountered excipients and additives do not interfere with the determinations. Results of the present method are comparable with those of official methods. The new method offers the advantage of simplicity and rapidity.

Two simple, selective, and rapid spectrophotometric methods are described for the determination of mycophenolate mofetil (MPM) in pure form and in tablets. Both methods are based on charge-transfer complexation reaction of MPM with p-chloranilic acid (p-CA) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in dioxane-acetonitrile medium resulting in coloured product measurable at 520 nm (p-CA) or 580nm (DDQ). Beer's law is obeyed over the concentration ranges of 40-400 and 12-120 µgmL-1 MPM for p-CA and DDQ, respectively, with correlation coefficients (r) of 0.9995 and 0.9947. The apparent molar absorptivity values are calculated to be 1.06 × 10³ and 3.87 × 10³ Lmol-1 cm-1, respectively, and the corresponding Sandell's sensitivities are 0.4106 and 0.1119 µg cm-1. The limits of detection (LOD) and quantification (LOQ) are also reported for both methods. The described methods were successfully applied to the determination of MPM in tablets. Statistical comparison of the results with those of the reference method showed excellent agreement. No interference was observed from the common excipients present in tablets. Both methods were validated statistically for accuracy and precision. The accuracy and reliability of the methods were further ascertained by recovery studies via standard addition procedure. [ABSTRACT FROM AUTHOR]

A simple, accurate and sensitive visible spectrophotometric method for the determination of nimodipine (NMD) and nitrazepam (NTZ) is described. The method is based on the diazotization of reduced drugs with nitrous acid followed by coupling with resorcinol to form colored azo-dye in an alkaline medium. The resulting colored azo-dye exhibits maximum absorption peak at 480 nm for both NTZ and NMD. Beer's law was obeyed over the concentration ranges 0.5-10 and 1.0-40.0 μg/mL for NTZ and NMD, respectively. The calculated molar absorptivities are 1.84 × 104 and 0.67 × 10-4 L mol-1cm-1 for NTZ and NMD, respectively. All the variables such as effect of acid, alkali and reaction time were studied in order to optimize the reaction conditions. No interference from the excipients added to tablets was found. Statistical analysis of the results using Student's t-test for accuracy and F-test for precision revealed no significant difference between the proposed method and the literature method. The accuracy and validity of the methods were further established by recovery studies through the standard addition technique. [ABSTRACT FROM AUTHOR]

Three simple, sensitive, accurate and indirect visible spectrophotometric methods have been developed for the estimation of lamotrigine (LMT) in both pure and in pharmaceutical preparations. They are based on the oxidation of lamotrigine with a known excess of cerium(IV) in acid medium. The unreacted cerium(IV) oxidize leuco crystal violet to crystal violet colored dye (Method A), leuco malachite green to bluish-green malachite green dye (Method B), leuco xylene cyanol FF to xylene cyanol FF bluish dye (Method C) and exhibiting absorption maxima (λmax) at 580, 610 and 610 nm, respectively. In these methods, the amount of cerium(IV) reacted corresponds to the amount of LMT. The results of the three methods have been validated statistically and by recovery studies. The results obtained in the proposed methods were in good agreement with the label claim. [ABSTRACT FROM AUTHOR]

One titrimetric and two spectrophotometric methods which are simple, selective, sensitive, accurate, precise and economical for the determination of etamsylate (ETM) in bulk drug and in tablets employing permanganate as the oxidimetric reagent are described. In titrimetry, ETM is titrated directly with permanganate in sulphuric acid medium. A direct spectrophotometry (method A) involves treating the aqueous solution of the drug with permanganate in alkaline medium and measuring the bluish green product at 610 nm. In indirect spectrophotometry (method B), the drug solution was treated with a fixed concentration of permanganate in H2SO4 medium, and after a specified time, the unreacted permanganate was measured at 545 nm. The molar combining ratio in titrimetry and the optimum assay conditions were studied. Titrimetry is applicable over 1-10 mg range and the calculations are based on a 1:4 (ETM:KMnO4) molar ratio. In spectrophotometry, Beer's law is obeyed over 0.5- 5.0 and 1.5- -15 μg ml-1 for method A and B, respectively. The molar absorptivity values are calculated to be 2.79x104 and 4.17x104 l mol-1 cm-1 for method A and B, respectively and the corresponding sandell sensitivity values are 0.0094 and 0.0063 μg cm-2. The limits of detection (LOD) and quantification (LOQ) are also reported for spectrophotometric methods. The applicability of the developed methods was demonstrated by the determination of etamsylate in pure drug as well as in commercial dosage forms. [ABSTRACT FROM AUTHOR]

A new, simple, sensitive, and reliable method is presented for the rapid spectrophotometric determination of trace amounts of iron(III) using leuco Xylene cyanol FF. The method is based on the oxidation of leuco Xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by iron(III) in sulfuric acid medium (pH 2.0–3.0), the absorbance of the formed dye is measured in an acetate buffer medium (pH2.8–4.4) at 615 nm. The method obeys Beer's law over a concentration range of 0.15–0.9 μg mL-1 iron, having a molar absorptivity of 5.6×104 L mol-1 cm-1 and a Sandell's sensitivity of 0.0001 μg cm-2. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of iron in water, soil, industrial effluent, plant material, pharmaceutical preparations, synthetic mixtures, and aluminum alloys. [ABSTRACT FROM AUTHOR]

A new, simple, highly sensitive and rapid spectrophotometric method has been described for the determination of platinum(IV). The method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by platinum(IV) in sulfuric acid medium (pH 1.0–2.5), the formed dye shows an absorption maximum at 620 nm in acetate buffer medium (pH 3.0–4.5). The method obeys Beer's law over a concentration range of 0.3 to 2.6 µg mL–1 platinum, having molar absorptivity and Sandell's sensitivity of 5.1×104 L mol–1 cm–1 and 0.0038 µg cm–2, respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of platinum in pharmaceutical preparations, soil, natural water, plant material, platinum-containing catalyst, and synthetic alloy samples. [ABSTRACT FROM AUTHOR]

Acetyl acetone is introduced as a new coupling agent for the spectrophotometric determination of some chemotherapeutic agents, such as metoclopramide, dapsone, p-aminobenzoic acid, and cisapride in both pure and dosage forms. The method is based on the diazo-coupling reaction of these chemotherapeutic agents with a new coupling agent, acetyl acetone, in an alkaline medium. The optimum reaction conditions and other analytical parameters are evaluated. The influence of the substrates commonly employed as excipients with these chemotherapeutic agents has been studied. The method is simple, rapid, and sensitive. The results obtained compare favorably with those obtained with other reference methods. [ABSTRACT FROM AUTHOR]