DERIVITISATION OF PREGABALIN FOR SIMULTANEOUS ESTIMATION WITH METHYLCOBALAMINE USING ULTRAVIOLET SPECTROSCOPY

Accurate, sensitive, and economical procedures for simultaneous estimation of pregabalin and methylcobalamine in tablet dosage form have been developed. The method employed is simultaneous equation method. This method employs the formation and solving of simultaneous equation using 528 nm and 568 nm as the two wavelengths for forming equation. Drugs obey Beer’s law in the concentration range 10-50 µg mL-1 for pregabalin and 10-50 µg mL-1 for methylcobalamine. The proposed spectrophotometric method was validated and successfully applied for the assay of both drug combinations in several laboratory prepared mixtures and commercial tablets

Effect of Boiling on Carotenoids content of Pumpkin available in Damascus, Syria

The carotenoids contents of pumpkin were determined in this study by spectrophotometric method. This method was applied on beta-carotene as standard solution as well as samples. The absorption were determined at λmax 454 nm, the analytical method was validated by evaluating linearity, precision, accuracy, LODs, and LOQs of the analyts. Beer’s law is obeyed over the concentration of (0.3-9) µg/ml with a linear regression correlation coefficient of 0.9986, and recovery in range from 98.5-102.2%. After the validation was performed using standard solution, the method then was applied on samples of pumpkin available in local market in Syria after extraction the carotenoids by using Acetone/ Dichloromethane 70/30 .The results ranged between 216.46 - 80.56 µg/g. During boiling for pumpkin, the level of carotenoid reduced between 0.45-13.26 %, 0.18 – 23.07%, 17.3-40.54%, 22.65-51.73%, 14.91_55.82% and 26.16 – 72.56%, for 5, 10, 15, 30, 45 and 60 min respectively. According to the obtained result results, it is concluded that the boiling reduced carotenoid at different rates.

Non-extractive spectrophotometric determination of valsartan in pure form and in pharmaceutical products by ion-pair complex formation with bromophenol blue and methyl red

Two simple, rapid, green non extractive spectrophotometric methods are described for the estimation of valsartan in tablet dosage form. The determination is based on the ion-pair formation using the dyes, bromophenol blue (BPB) and methyl red (MR). Valsartan forms ion-pair complex selectively with the dyes, as indicated by the formation of a coloured complex with BPB at pH 5.5 with λmax at 424 nm and MR at pH 4.3 with λmax at 494 nm. For both methods, optimal spectrophotometric conditions were established. The linear relationship was found between absorbance at λmax and concentration of drug in the range 8–24 µg/mL for BPB and 4–20 µg/mL for MR. Regression analysis of Beer’s law plot at 424 nm yielded the regression equation, y = 0.0102x + 01636 (BPB) and at 494 nm y = 0.0222x – 0.0063 (MR). High values of correlations coefficient (R2 = 0.9988 (BPB) and R2 = 0.9991 (MR)) and small values of intercept validated the linearity of calibration curve and obedience to Beer’s law. The LOD and LOQ values were calculated to be 1.03 µg/mL and 3.43 µg/mL respectively (BPB) and 0.68 µg/mL and 2.26 µg/mL respectively (MR). Intra-day and inter-day accuracy and precision, robustness were in acceptable limits. The proposed methods were applied for the quantification of valsartan in tablets pertaining to three commercial formulations. Analytical eco-scale for greenness assessment of the proposed spectrophotometric methods showed that both methods corresponds to excellent green analysis with a score of 89.

Spectrophotometric assay of Nicotinamide in Pharmaceutical Dosages

The reaction of nicotinamide and alizarin reagent using charge transfer reaction at a pH of 5.54 lead to produce a red colored compound measured at 527 nm., while the blue colored complex was formed using the oxidation reduction reaction between nicotinamide and chromate at pH 3.49 in the presence of an indigo cochineal dye. Theses tow colored products were measured at 527 and 610 nm respectively using two simple, fast and an accurate spectrophotometric methods. The linearity of the charge transfer method was followed Beer’s law 0.4 - 32 μg while the oxidation reduction method was obeyed Beer’s law from 1.6 - 40 μg in depending on the concentration range. Molar absorptivity was 1.95×104 and 2.16×104 mol−1 cm−1 for the red and blue colored complex respectively. Finally, the values of Sandal’s sensitivity were 0.00626 and 0.00565 μg−2 cm−1 for the first and second methods respectively. These two methods have been applied to quantify the amount of nicotinamide in pharmaceuticals with good recovery.

Spectrophotometric methods for the determination of lisinopril in medicines

Two simple, rapid and green spectrophotometric methods are described for the determination of lisinopril medicines. The determination is based on the reaction of the primary amino group of the lisinopril with ninhydrin in aqueous medium (Method I) and reaction on the carboxylic group of the lisinopril with copper (II) sulfate (Method II). For both methods, optimal spectrophotometric conditions were established. The linear relationship was found between absorbance at λmax and concentration of drug in the range 40–60 µg/mL (Method I) and 0.592–2.072 mg/mL (Method II). Regression analysis of Beer’s law plot at 400 nm yielded the regression equation, y = 7.4929x – 0.0545 (Method I) and at 730 nm y = 0.0443x – 0.0832 (Method II). High values of correlations coefficient (R2 = 0.9917 (Method I) and R2 = 0.999 (Method II)) and small values of intercept validated the linearity of calibration curve and obedience to Beer’s law. The LOD and LOQ values were calculated to be 6.91 µg/mL and 23.01 µg/mL respectively (Method I) and 0.11 mg/mL and 0.36 mg/mL respectively (Method II). Intra-day and inter-day accuracy and precision were in acceptable limits. The proposed methods were applied for the quantification of lisinopril in tablets pertaining to three commercial formulations. Analytical eco-scale for greenness assessment of the proposed spectrophotometric methods showed that both methods correspond to excellent green analysis.

METHOD DEVELOPMENT AND VALIDATION OF OLMESARTAN AND HYDROCHLOROTHIAZIDE BY UV SPECTROSCOPY

In the present work a simple, inexpensive, rapid, easy, sensible and reproducible UV Spectrophotometric method has been developed and validated for determination of Olmesartan (OLM) and Hydrochlorothiazide (HCT) in bulk drug and pharmaceutical dosage form. A simple double beam UV spectrophotometric method has been developed using area under curve method and validated with different parameters such as linearity, precision, Accuracy, limit of detection (LOD), Limit of Quantification (LOQ), accuracy as per ICH guidelines. UV-visible spectrophotometric method, measurement of absorption at maximum wavelength in 10 ml methanol and volume make with water solvent system as reference OLM and HCT were found to be at 256 nm and 276 nm respectively. The drug obeyed the Beer’s law and showed good correlation. Beer’s law was obeyed in concentration range 2-32 µg/ml for Olmesartan and Hydrochlorothiazide respectively with correlation coefficient was 0.999. LOD values for OLM and HCT were found to be 0.056 µg/mL and 0.1050 µg/mL respectively and LOQ values for OLM and HCT were found 0.1698 µg/mL and 0.3183 µg/mL respectively. The proposed method is precise, accurate and reproducible and can be used for routine analysis of OLM and HCT in bulk and pharmaceutical dosage form.

4, 4’-Diantipyrylmethane (DAM): A tool for spectrophotometric microdetermination of cerium (IV)

A simple and hasty method has been employed for the direct spectrophotometric determination of trace amount of Ce(IV) using a complexing agent 4,4’-diantipyryl methane (DAM) with absorption maximum at 445-455nm in acidic medium at 1.3 -1.5 pH. Molar absorptivity and Sandell’s sensitivity were calculated to be 9.1 × 103 l mol-1 cm-1 and 0.015 μg Ce cm-2. Beer’s law was found to be defensible over the cerium concentration range of 0-5.5 μg ml-1. Effect of large number of cations, anions and complexing agents was also studied and several analytically important ions do not cause interference in the procedure except thiourea and EDTA. The method has good reproducibility and has been satisfactorily applied in the determination of cerium in samples.

Quantitative Vibrational Spectroscopy on Liquid Mixtures: Concentration Units Matter

Quantitative vibrational absorption spectroscopies rely on Beer’s law relating spectroscopic intensities in a linear fashion to chemical concentrations. To address and clarify contrasting results in the literature about the difference...