Spectrophotometry

A new technique has been devised to find tiny quantities of manganese (II). For the spectrophotometric detection of manganese, the 4-Amino antipyrine -3, 5-diaminobenzoic acid (AAPDAB) has been proposed as a new analytical reagent. The color responses happen instantly, and for more than five hours, the greatest absorbance was found at 390 nm. The pH range from 3 to 5 is where complex formation is seen. Metal and ligand were obtained in a 1:1 (M: L) composition using the Molar ratio relationship and the Job's approach. The calibration graph had a limit of detection (LOD) of 0.15 g ml-1 and was linear in the range A390 = 0.27577 - 0.00765. In the Mn (II) concentration range of 0.126–2.628 g/ml, the system complies with Beer's law. The AAPDAB method was used to determine the presence of manganese in some plant samples since it is more sensitive.  The AAPDAB was discovered to have a molar absorptivity of 6.35 X 103 L mol-1cm-1 and a Sandell's sensitivity of 0.00157 g/ml g cm-2 of Mn (II). Manganese (II) levels in environmental plant samples have been successfully determined using the approach, with satisfactory results.

A simple, rapid, sensitive, accurate, precise spectrophotometric method has been developed for the estimation of Tamsulosin in the presence of Dutasteride  in pharmaceutical formulations. During the course of study, it is observed that acidic solution of the drug formed colored ion-association complexes with Bromo Thymol Blue (BTB) which is soluble in methanol. This property of the drug was followed for the development of spectrophotometric method for analysis of drug. The complex of Tamsulosin in the presence of Dutasteride with Bromo Thymol Blue showed ?max at 430 nm. The linearity range for Tamsulosin in the presence of Dutasteride was 10 µg/ml to 250 µg/ml. Recovery studies gave satisfactory results indicating that none of common additives and excipients interfere the assay method. The molar absorptivity and the sandell sensitivity of the method are found to be 6.6123×104 lit/mole/cm and 0.0067 µg/ml/cm2 respectively. 

A simple, versatile and a new spectrophotometric method is proposed for the estimation of microgram quantities of the drug Megagliptin.  The drug forms a charge transfer (CT) complex with 2,3-Dichlro-5,6-Dicyano-1,4- Benzoquinone (DDQ), the stoichiometry of which is established as 1:1 by Job’s continuous variation method.   The wavelength of maximum absorbance of the CT complex is found to be 385 nm.  The absorbance values of the CT complex increased linearly with the increase in the amount of the drug Megagliptin upto 300 μg/ml.  This suggests that suitability of the method for the determination of the drug in the range 10 μg/ml to 300 μg/ml.  This also indicates the verification of the Beer-Lambert’s Law in this range.  The method is successfully applied to evaluate the assay of commercial tablets in pharmaceutical formulations for Megagliptin and the results agreed very well.  The molar absorptivity and Sandell Sensitivity of the method are 2.346 x 104  lit. mol-1. cm-1  and 0.01818 μg.ml-1.cm2 respectively.

Levocetirizine Dihydrochloride is an orally active, non-sedative antihistamine drug. To determine the assay content of Levocetirizine Dihydrochloride drug substance, a very simple, accurate, specific and precise UV- spectrophotometric method has been built up as well as evaluated. The suggested method comprises dissolving Levocetirizine Dihydrochloride in 0.1M Hydrochloric acid solution and subjecting the consequential solution to UV Spectroscopic measurement. An Absorption maximum was found to lie at about 231nm and the measurements were carried out at this wavelength. Beer's law was followed in the concentration range of 7.5 to 22.5 μg/mL. The linearity showed on the calibration curve between concentration and absorbance by the line equation of y = 0.0377x - 0.0043 (R² = 0.9992). Reproducibility by repeating methods as %RSD was found to be less than 2%. The results of the accuracy and precision were found very satisfactory and here the suggested method was statically validated as per the ICH guidelines in terms of the specificity, linearity, accuracy, precision and robustness. Validation studies have discovered that the method is simple, specific, rapid, reproducible, precise, accurate and economical which is useful for the routine analysis of Levocetirizine Dihydrochloride

A simple and sensitive spectrophotometric method for the determination of albendazole and levamisole hydrochloride in pharmaceutical dosage forms has been developed. The absorption maxima were found at 295nm for albendazole and 213 nm for levamisole hydrochloride using ammonium dihydrogen phosphate: methanol as solvent. Beer's law was obeyed for both the drugs in the concentration range of 5-25 for albendazole with correlation coefficient 0.998 and 2-10 for levamisole hydrochloride with correlation coefficient 0.997. The limits of detection for albendazole and levamisole hydrochloride were found to be 0.305µg/mL and 0.732µg/mL respectively and the limits of quantitation were 0.924µg/mL and 2.2µg/mL respectively. Accuracy of the method verified by performing recovery using simultaneous equation method and found to be 98 to 99.5%w/w for albendazole and 97.97 to 99.55 %w/w for levamisole hydrochloride. %RSD of repeatability and intermediate precision studies were found to be

Simple, sensitive and specific spectrophotometric method was developed and validated for quantification of nebivolol (NBV) in tablet dosage form. Studies were carried out to investigate the reaction between NBV and 1, 2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 9), a red-colored product exhibiting maximum absorption peak (λmax) at 521 nm was produced. The stoichiometry of the reaction was investigated and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance with NBV concentration was obeyed in the range of 2 - 55μg/ml with good correlation coefficient 0.9996. The molar absorptivity was 0.124 × 104l/mol.cm. The limits of detection and quantification were 0.539 and 1.634μg/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of NBV in its pharmaceutical tablets with good accuracy and precisions. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories.

Embelin is the principal phytoconstituent of Embelia tsjeriam-cottam A. DC., commonly known as Baibidanga, belonging to the family Myrsinaceae. Embelin, obtained from E. tsjeriam-cottam (an alternative source to E. ribes),is having diverse biological activities and used as anti-inflammatory, anti-diabetic, antimicrobial, anticancer and antioxidant. Fruit-samples of E. tsjeriam-cottam were collected from five different geographical locations of Odisha. These fruits were extracted and assessed for embelin content through spectrophotometric and high performance liquid chromatographic (HPLC) methods utilizing different solvent systems. Significant variation in embelin content was observed among the samples. Embelin content in fruits of E. tsjeriam-cottam was ranged from 4.93 to 2.1% (dry wt.), when extracted with chloroform and 4.88 to 1.03% (dry wt.), when extracted with methanol. However, in case of HPLC analysis, embelin content in the selected fruits were varied from 2.72 to 1.32% (dry wt.), when extracted with chloroform and 1.75 to 0.5% (dry wt.), when extracted with methanol. In general, embelin content was found higher in the fruits collected from Chura Reserve Forest (AG3) followed by Sulia Reserve Forest (AG4), Bargarh (AG1), Ghana Reserve Forest (AG5) and Jajpur (AG2). Among the selected solvent systems, chloroform prevailed to be the excellent solvent for extraction of embelin.

In this study, a simple, sensitive and highly accurate ultraviolet spectrophotometric method has been developed and validated for determination of atenolol in bulk and pharmaceutical formulations. The method is based on the measurement of the absorbance of atenolol solution in methanol: phosphate buffer pH 6.8 (10:90) at 224 nm in the wavelength range of 200 - 400 nm. Beer’s law was obeyed in the concentration range of 5-25 µg/mL. The slope, intercept and correlation coefficient were also calculated. Results of percentage recovery shows that the method was not affected by the presence of common excipients in tablets. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification which proves suitability of proposed method for routine estimation of atenolol in bulk and pharmaceutical formulations.

Two simple, rapid and inexpensive methods based on visible spectrophotometry have been developed for the determination of felodipine in pure form and in dosage forms with two acidic dyes [Bromophenol Blue (BPB) and Bromothymol Blue (BTB)] as the reagents. The proposed methods were based on the formation of ion-pair color complexes between the drug and the two acidic dyes in an acidic buffer. The ion-pair complexes formed, which has an absorption maximum at 420 and 424nm, and were quantitatively extracted into chloroform. All experimental variables for both the proposed methods were studied and optimized. Statistical analysis of the experimental results indicated that the proposed methods were precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures. The proposed procedures were successfully applied to the determination of the bulk drug and its pharmaceutical formulations.

  3-methylbenzthiazolinone-2(3H)-hydrazone is a chromogenic reagent used in spectrophotometric determination of pharmaceuticals. This review explains the work done by different researchers so far for estimation of the drugs by spectrometric analysis. Therefore, this review gives compiled data on utilisation of MBTH reagent in spectrometric analysis   Key Words: Spectrophotometry, MBTH, Chromogen.