Determination of Pentachlorophenol in Environmental Samples by Spectrophotometry

Pentachlorophenol (PCP) (2,3,4,5,6- pentachlorophenol) is an organochlorine compound used as a pesticide and a disinfectant. PCP is used as a herbicide, insecticide, fungicide and disinfectant. Some applications include agricultural seeds (for nonfood uses), leather, masonry, wood preservation, cooling tower water, rope, and paper mills. Determination of Pentachlorophenol was based on the reaction of PCP with concentrated nitric acid followed by potassium iodide for the liberation of iodine. Liberated iodine reacted with leuco malachite green for the formation of green colour dye which was measured at 610 nm against a reagent blank. Parameters affecting the reaction were studied. The interfering effect of various species was also investigated and the methods were applied on some vegetables and fruit samples.

OPTIMIZED AND VALIDATED SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF AMPICILLIN IN PHARMACEUTICAL FORMULATIONS

Objective: A simple, precise, and accurate spectrophotometric method has been developed to determine Ampicillin in pharmaceutical formulations. Methods: The proposed method, based on the carboxylic acid group reaction, present in Ampicillin with a mixture of KIO3 and KI, form a yellow-colored product in an aqueous medium. The response was allowed to proceed at 25±1 °C, and absorbance measured after 5 min against a reagent blank prepared simultaneously using a UV-Vis spectrophotometer. The parameters verified were specificity, linearity, linearity range, accuracy, precision, detection limit, quantitation limit, robustness, and ruggedness. Results: The yellow-colored product was measured at 352 nm against the reagent blank using UV–Vis spectrophotometer. The linear dynamic range of concentration was 0.25–2.5 µg/ml with a correlation coefficient of 0.9999. The LOD, LOQ values to be 0.086 and 0.261 µg/ml, respectively, for the proposed method. The percentage of recoveries was 98.27–100.89% with an acceptable relative standard deviation (±2%). The robustness and ruggedness values were excellent. Conclusion: The ICH guidelines for pharmaceuticals and human use were followed and applied to validate the proposed method. The method was compared with available literature and found similar results that confirmed the reliability and effective way for Ampicillin's determination.

SPECTROSCOPIC AND VOLUMETRIC TECHNIQUES FOR THE ESTIMATION OF IVABRADINE IMPURITY 3,3'-(PROPANE-1,3-DIYL)BIS(7,8-DIMETHOXY-1,3,4,5-TETRAHYDRO-2H-BENZO[D]AZEPIN-2-ONE)

Objective: Two simple and sensitive techniques - one spectrophotometric and one titrimetric- have been developed for the determination of 3,3'-(propane-1,3-diyl)bis(7,8-dimethoxy-1,3,4,5-tetrahydro-2H-benzo[d]azepin-2-one) commonly known as ivabradine impurity-9 (IVA-9). Methods: The spectrophotometric method is based on the oxidation of drug impurity by excess cerium (IV) sulphate in acidic medium and the subsequent reaction of the remaining Ce(IV) with a known amount of ferrous ammonium sulphate. The resultant ferric ion is then made to react with thiocyanate in acid medium to form a brown coloured complex which is analyzed spectrophotometrically against the reagent blank. In the volumetric method, the un-reacted Ce(IV) is titrated against standard ferrous ammonium sulphate to estimate the quantity of IVA-9. Results: The colored complex showed an absorption maximum at 479 nm when measured spectrophotometrically. The stated methods are validated statistically using the International Council for Harmonization guidelines-ICH Q2(R1) for precision and accuracy. The method showed a linear response from 0.5 to 100µg/ml with a correlation coefficient of 0.9985 Conclusion : No estimation techniques have been reported to date for the determination of this molecule. The proposed techniques may be used for the routine quantification in its pure form and also in presence of its parent drug molecule Ivabradine.

Direct Spectrophotometric Determination of Glimepiride in Pure Form And Pharmaceutical Formulations Using Bromocresol Purple

A simple, direct and accurate spectrophotometric method has been developed for the determination of Glimepiride (GLM) in pure and pharmaceutical formulations by complex formation with bromocresol purple (BCP). The method involves the formation of a yellow ion-pair complex between BCP with glimepiride at pH<3,8; after reacting GLM with Na2CO3 to give C24H33N4H+O5NaS which is extracted by chloroform. The formed complex [GLM]:[ BCP] was measured at lmax 418 nm against the reagent blank prepared in the same manner. Variables were studied in order to optimize the reaction conditions. Molar absorptivity (e) for complex was 20600 L.mol-1.cm-1. Beer’s law was obeyed in the concentration range of 1.226 – 46.608 mg.mL-1 in present of 5.0x10-4 mol/l of BCP with good correlation coefficient (R2= 0.9997). The relative standard deviation did not exceed 3.6%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.15 and 0.46 mg.mL-1, respectively. The proposed method was validated for specificity, linearity, precision and accuracy, repeatability, sensitivity (LOD and LOQ) and robustness. The developed method is applicable for the determination of GLM in pure and different dosage forms with average assay of 98.8 to 102.0% and the results are in good agreement with those obtained by the RP-HPLC reference method.

NEW REAGENTS FOR THE SPECTROPHOTOMETRIC DETERMINATION OF RANITIDINE HYDROCHLORIDE

A new spectrophotometric method is proposed for the assay of ranitidine hydrochloride (RNH) in bulk drug and in its dosage forms using ceric ammonium sulphate (CAS) and two dyes, malachite (MAG) green and crystal violet (CV) as reagents. The method involves the addition of a known excess of ceric ammonium sulphate to ranitidine hydrochloride in acid medium, followed by the determination of unreacted CAS by reacting with a fixed amount of malachite green or crystal violet and measuring the absorbance at 615 or 582 nm respectively against the reagent blank. The Beer’s law is obeyed in the concentration range of 0.4-8.0 μg/ml of ranitidine hydrochloride (RNH) for RNH-MAG system and 0.2-1.6μg/ml of ranitidine hydrochloride for RNH-CV system. The molar Absorptivity, Sandell’s sensitivity for each system were calculated. The method has been successfully applied to the determination of ranitidine hydrochloride in pure and dosage forms.

Development of a Dispersive Liquid–Liquid Microextraction Method Combined with UV-Visible Spectrophotometry for Determination of Trace Aluminum(III) in Water, Wastewater, Food, Biological, and Pharmaceutical Samples

A simple and sensitive method was proposed for the preconcentration of trace levels of Al(III) prior to its determination by spectrophotometry, based on dispersive liquid–liquid microextraction. The complexation of the Al(III) was performed by chelation with Eriochrome Cyanine R (ECR). In this method, cetyltrimethyl ammonium bromide (CTAB) as a dispersant was dissolved in chloroform as an extractant solvent, and then the solution was rapidly injected by a syringe into the samples containing Al(III), which had already been complexed by ECR at optimized pH. Various parameters were studied and optimized for a 10 mL sample volume. Under the optimum conditions, the LOD (3 times the SD of 10 replicate readings of the reagent blank) and the dynamic range of the calibration obtained were 0.2 ng mL−1 (7 nM) and 1.0–80.0 ng mL−1, respectively. The RSDs for eight replicate determinations of10 and 60 ng mL−1 of Al(III) were 3.3 and 1.8%, respectively. This strategy was successfully applied to determine the Al concentration in water, wastewater,yogurt, apple, carrot, celery, bread, potato, urine, and Al–Mg syrup samples.

Spectrophotometric Determination of Carbofuran with Diazotized Benzidine in Environmental Water Samples

A simple, rapid, accurate and sensitive spectrophotometric method has been developed for the determing carbamate pesticides in both pure and water samples. The method is appropriate for the determination of carbofuran in the presence of other ingredients that are usually available in dosage forms. The effect of organic solvents on the spectrophotometric properties of the azo dye and the structure of the resulting product have also been worked out and it is found to be 1:1 benzidine :carbofuran. The method can be successfully applied to determination of carbofuran in water samples. The method is based on diazotization of Benzidine (4, 4 – diamino biphenyl) with sodium nitrite and hydrochloric acid followed by coupling with carbofuran in alkaline medium to form a yellow colored azo dye having the absorption maximum at 429nm against reagent blank solution. Beer’s law is obeyed in the concentration range of (0-14) ?g of 10mL carbofuran. Molar absorptivity of 1×104 L.mol-1.cm-1 which depend on the concentration level of carbofuran.

An ionic liquid-based microextraction method for highly selective and sensitive trace determination of nickel in environmental and biological samples

Nickel was complexed with BTAHQ at pH 4.0. The IL-DLLME procedure was performed by using a few mL of [C6mim][PF6] as the extractant while methanol was the disperser solvent. The Ni-enriched RTIL phase was solubilized in methanol and the absorbance atλmax682 was directly measured against a reagent blank similarly prepared.

NEW SPECTROPHOTOMETRIC METHODS FOR THE QUANTITATIVE ESTIMATION OF ELETRIPTAN IN DRUG FORMULATION

Five simple, accurate, sensitive and economical UV spectrophotometric methods has been developed and subsequently validated for the determination of eletriptan in bulk and pharmaceutical formulations. The methods were based on the formulation of colored complex of eletriptan with different reagents. Absorbance of the formed color complex is measured against the reagent blank at the wavelength of maximum absorbance. In this paper, five spectrophotometric methods were proposed. Method A is based on the formation of oxidative coupling reaction involving the use of iron (III) – MBTH (3-methyl-2-benzo thiazolinone hydrazone hydrochloride). The resulting green colored chromogen complex absorbs at λmax = 520 nm. Reaction of eletriptan with ferric chloride and K3 [Fe (CN)6 ] to form a green colored species having absorption maxima at λmax =790 nm is used in Method B. Method C is based on the reaction eletriptan with FeCl3 and 1,10 phenanthroline to form a blood red colored chromogen, exhibiting absorption at λmax = 620 nm. Formation of oxidative coupling of drug with brucine in the presence of sodium meta periodate to form a purple red colored species is used in Method D which exhibits absorption maxima at λmax = 520 nm. Method E is based on the formation of complex with acidic dye WF BBL having absorption maxima at λmax = 610 nm. All these methods have different linearity ranges. Statistical analysis proves that the proposed methods are reproducible and selective for the estimation of eletriptan in bulk drug and in its tablet dosage form.

Determination of 25 Trace Element Concentrations in Biological Reference Materials by ICP-MS following Different Microwave-Assisted Acid Digestion Methods Based on Scaling Masses of Digested Samples

The use of normalized procedures designed for soil and sediment samples (like US-EPA 3051) to chemically prepare some kind of organic samples is a common practice in some laboratories. However, the performance of this method for other matrices has to be demonstrated. Three microwave-assisted digestion procedures with 0.5 g of sample and simplified reagents (10 mL HNO3 alone and mixtures of HNO3/HCl- and HNO3/H2O2 procedures A, B, and C, resp.) were compared for quantitative determination of 25 elements (Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Pb, Th and U) in three biological reference materials provided by NIST (mussel tissue (MT), tomato leaves (TL), and milk powder (MP)) by ICP-MS. From scaling masses (from 0.1 up to 0.9 g at 0.1 g interval) in procedure A, a linear relationship among instrumental signal and mass of digested sample could be constructed at 99% CL for most of the target analytes. The slope of this linear fit provided the estimation of sample concentration, while the ordinate in origin allowed the identification of matrix interferences which were absent in the reagent blank.