Basavaraj Hiremath and Bennikallu Mruthyunjayaswamy
Development and validation of spectrophotometric methods for determination of ceftazidime in pharmaceutical dosage forms
Two spectrophotometric methods for the determination of ceftazidime (CFZM) in either pure form or in its pharmaceutical formulations are described. The first method is based on the reaction of 3-methylbenzothiazolin-2-one hydrazone (MBTH) with ceftazidime in the presence of ferric chloride in acidic medium. The resulting blue complex absorbs at λmax 628 nm. The second method describes the reaction between the diazotized drug and N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to yield a purple colored product with λmax at 567 nm. The reaction conditions were optimized to obtain maximum color intensity. The absorbance was found to increase linearly with increasing the concentration of CFZM; the systems obeyed the Beer's law in the range 2-10 and 10-50 μg mL-1 for MBTH and NEDA methods, resp. LOD, LOQ and correlation coefficient values were 0.15, 0.79 and 0.50, 2.61. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, sensitive, accurate and suitable for quality control applications.
Maria Balcerzak, Anna Tyburska and Elżbieta Święcicka-Füchsel
Selective determination of Fe(III) in Fe(II) samples by UV-spectrophotometry with the aid of quercetin and morin
Selective UV-spectrophotometric methods for determination of iron(III) in iron(II) samples have been developed. The methods are based on the interaction of Fe(III) with quercetin and morin, compounds of the flavonoid group. Redox reactions occurring between Fe(III) ions and the reagents used make the basis for the detection. Iron(II) does not react with quercetin and morin under the conditions applied [aqueous-methanolic (3:2) soluions, 0.3 mol L-1 HCl, 1.2 x 10-4 mol L-1 quercetin (morin)] and does not interfere with the determination of Fe(III). Iron(III) can be determined up to 15 μg mL-1 using both the examined systems. The detection limits are 0.06 and 0.38 μg mL-1 when using quercetin or morin, respectively. The method with quercetin was applied to the determination of Fe(III) (ca. 0.2%) in a Fe(II) pharmaceutical product.
A new approach to the spectrophotometric determination of metronidazole and tinidazole using p-dimethylaminobenzaldehyde
A new approach to the spectrophotometric determination of metronidazole (MZ) and tinidazole (TZ) has been developed. The procedure involves coupling of diazotized nitroimidazoles with p-dimethylaminobenzaldehyde (DMAB) to form a greenish-yellow solution. Optimal temperature and time were 0 °C (iced) and 3 minutes for diazotization and 30 °C and 2 minutes for coupling for both MZ and TZ. Coloured adducts of MZ and TZ showed shoulders at 406 nm and 404 nm, respectively, which were selected as analytical wavelengths. The reaction with p-DMAB occurred in a 1:1 mole ratio. Beer's law was obeyed within the 4.8-76.8 μg mL-1 concentration range with low limits of detection. The azo adducts were stable for over a week. Molar absorptivities were 1.10 × 103 (MZ) and 1.30 × 103 L mol-1 cm-1 (TZ). Overall recoveries of MZ and TZ from quality control samples were 103.2 ± 1.3 and 101.9 ± 1.3% over three days. There was no interference from commonly utilized tablet excipients. No significant difference was obtained between the results of the new method and the BP titrimetric procedures. The azo approach using the p-dimethylaminobenzaldehyde procedure described in this paper is simple, fast, accurate and precise. It is the first application of DMAB as a coupling component in the diazo coupling reaction.
Ibrahim Darwish, Samiha Hussein, Ashraf Mahmoud and Ahmed Hassan
A sensitive spectrophotometric method for the determination of H2-receptor antagonists by means of N-bromosuccinimide and p-aminophenol
A simple, accurate and sensitive spectrophotometric method for determination of H2-receptor antagonists: cimetidine (CIM), famotidine (FAM), nizatidine (NIZ), and ranitidine hydrochloride (RAN) has been fully developed and validated. The method was based on the reaction of these drugs with NBS and subsequent measurement of the excess N-bromosuccinimide by its reaction with p-aminophenol to give a violet colored product (λmax at 552 nm). Decrease in the absorption intensity (ΔA) of the colored product, due to the presence of the drug, was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under optimal conditions, linear relationships with good correlation coefficients (0.9988--0.9998) were found between ΔA values and the corresponding concentrations of the drugs in a concentration range of 8--30, 6--22, 6--25, and 4--20 μg mL-1 for CIM, FAM, NIZ, and RAN, respectively. Limits of detection were 1.22, 1.01, 1.08, and 0.74 μg mL-1 for CIM, FAM, NIZ, and RAN, respectively. The method was validated in terms of accuracy, precision, ruggedness, and robustness; the results were satisfactory. The proposed method was successfully applied to the analysis of the above mentioned drugs in bulk substance and in pharmaceutical dosage forms; percent recoveries ranged from 98.5 ± 0.9 to 102.4 ± 0.8% without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods.
Use of Folin-Ciocalteu phenol reagent and 3-methyl-2-benzothiazolinone hydrazine hydrochloride in the determination of oxcarbazepine in pharmaceuticals
Two spectrophotometric methods are proposed for the assay of oxcarbazepine (OXC) in bulk and dosage forms using Folin-Ciocalteu phenol reagent (FCP) and 3-methyl-2-benzothiazolinone hydrazine hydrochloride (MBTH) as reagents. The first method involves addition of FCP reagent to OXC in alkaline medium followed by measurement of absorbance at 760 nm (method A), and the other involves addition of a fixed volume of MBTH after treatment of OXC with ferric chloride and measurement of absorbance at 456 nm (method B). In both methods, the amount of chromogen formed corresponds to the amount of OXC and the measured absorbance was found to increase linearly with the concentration of OXC, which is corroborated by the correlation coefficients of 0.9985 and 0.9984 for method A and B, respectively.
The systems obey Beer's law for 5--30 μg mL-1 and 10--50 μg mL-1 for methods A and B, respectively. The apparent molar absorptivity was calculated to be 8.06 x 103 L mol-1 cm-1 and 3.126 x 103 L mol-1 cm-1 for methods A and B, respectively. The limits of detection (LOD) and limit of quantification (LOQ) were calculated to be 1.6 and 5 μg mL-1 for method A and 3 and 10 μg mL-1 for method B. The inter-day and intra-day imprecision of the methods were found to be in the range of 1.1--1.7 and 0.9--1.1% for method A, and 1.1--1.9 and 0.6--0.9% for method B. The accuracy ranged between 98.9--99.7% and 99.3--100.1 for method A and B, respectively. No interference was observed from common pharmaceutical excipients. The methods were successfully applied to the assay of OXC in tablet preparations.
D. Nagavalli, V. Vaidhyalingam, A. Santha, A. Sankar and O. Divya
Simultaneous spectrophotometric determination of losartan potassium, amlodipine besilate and hydrochlorothiazide in pharmaceuticals by chemometric methods
In the present work, four different spectrophotometric methods for simultaneous estimation of losartan potassium, amlodipine besilate and hydrochlorothiazide in raw materials and in formulations are described. Overlapped data was quantitatively resolved by using chemometric methods, classical least squares (CLS), multiple linear regression (MLR), principal component regression (PCR) and partial least squares (PLS). Calibrations were constructed using the absorption data matrix corresponding to the concentration data matrix, with measurements in the range of 230.5-350.4 nm (Δλ = 0.1 nm) in their zero order spectra. The linearity range was found to be 8-40, 1-5 and 3-15 μg mL-1 for losartan potassium, amlodipine besilate and hydrochlorothiazide, respectively. The validity of the proposed methods was successfully assessed for analyses of drugs in the various prepared physical mixtures and in tablet formulations.
Pavagada Ramesh, Kanakapura Basavaiah and Nagaraju Rajendraprasad
Sensitive and selective spectrophotometric assay of doxycycline hyclate in pharmaceuticals using Folin-Ciocalteu reagent
A spectrophotometric method for the determination of doxycycline (DOX) is described. The method is based on the formation of blue colored chromogen due to reduction of tungstate and/or molybdate in Folin-Ciocalteu (F-C) reagent by DOX in alkaline medium. The colored species has an absorption maximum at 770 nm and the system obeys Beer's law over the concentration range 0.75-12.0 μg mL-1 DOX. The apparent molar absorptivity is 2.78 × 104 L mol-1 cm-1. The limit of quantification and detection values are reported to be 0.20 and 0.08 μg mL-1, respectively. Over the linear range applicable, the accuracy and precision of the method were evaluated on intra-day and inter-day basis. The reported mean accuracy value was 101.0 ± 1.7 %, the relative error was ≤ 2.7 % and the relative standard deviation was ≤ 2.5 %. Application of the proposed method to bulk powder and commercial pharmaceutical tablets is also presented. No significant difference was obtained between the results of the proposed method and the official BP method. The procedure described in this paper is simple, rapid, accurate and precise.
Ibrahim Darwish, Ashraf Mahmoud and Abdul-Rahman Al-Majed
A novel analytical approach for reducing the consumption of organic solvents in the charge transfer-based spectrophotometric analysis: Application in the analysis of certain antihypertensive drugs
The present study describes the development of a novel analytical approach that can reduce by 50-fold the consumption of organic solvents in the charge transfer (CT)-based spectrophotometric analysis. The proposed approach employed 96-microwell assay plates for carrying out the reaction. The CT reaction between the electron-donating analyte and electron-accepting reagent was performed in microwells (200-μL of organic solvent) and the color signals were measured with a microwell-plate reader. Optimum conditions for the proposed approach were established for two antihypertensive drugs, namely ramipril (RML) and lisinopril (LSL) as model compounds for the electron-donating analytes, and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as a π-electron acceptor. Under the optimum conditions, Beer's law was obeyed in the concentration range of 6-100 and 6-60 μg mL-1 for RML and LSL, respectively. The limits of detection were 0.97 and 1.10 μg mL-1 for RML and LSL, respectively. The precision of the methods was satisfactory; the values of relative standard deviations did not exceed 1.1 %. The proposed approach was successfully applied to the analysis of pharmaceutical dosage forms with good accuracy and precision. The results were comparable with those of the reported methods. The approach described herein is of great practical value in pharmaceutical analysis because it reduces the exposure of analysts to the toxic effects of organic solvents, lowers the analysis cost by 50-fold, and it has a high throughput property. Although the approach was validated for RML and LSL, the same methodology could be used for any electron-donating analyte for which a CT-reaction can be performed.
Kanakapura Basavaiah, Hullikal Prameela and Bankavadi Somashekar
Spectrophotometric determination of pefloxacin mesylate in pharmaceuticals
A spectrophotometric method is described for assay of pefloxacin mesylate (PFM) in bulk drug and in tablets. The method is based on back extraction of the bromophenol blue dye at pH 5.2 from the dye-drug ion pair followed by measurement of the dye absorbance at 590 nm. The working conditions of the method were investigated and optimized. Beer's law plot showed a good correlation in the concentration range of 0.15-1.25 μg mL-1. Sensitivity indices such as molar absorptivity, limits of detection and quantification are reported. Intra-day and inter-day precision, and accuracy of the methods were established according to the ICH guidelines, and the er values were in the range of -1.7 to 1.8% with RSD values ranging from 1.0 to 1.1%. The method was successfully applied to the assay of PFM in tablet preparations with recoveries varying from 97.5 to 101.9%, with standard deviation in the range of 0.6 to 1.9. The results were statistically compared with those of the reference method by applying Student's t-test and F-test. Accuracy evaluated by means of the spike recovery method, range from 97.0 to 106.0%, with precision better than 3%.
Padmarajaiah Nagaraja, Shailendra Naik, Ashwinee Shrestha and Anantharaman Shivakumar
A sensitive spectrophotometric method for the determination of sulfonamides in pharmaceutical preparations
A new, simple and sensitive spectrophotometric method for the determination of some sulfonamide drugs has been developed. The method is based on the diazotization of sulfacetamide, sulfadiazine, sulfaguanidine, sulfamerazine, sulfamethazine, sulfamethoxazole, and their coupling with 8-hydroxyquinoline in alkaline media to yield red coloured products with absorption maxima at 500 nm. Beer's law is obeyed from 0.1--7.0 μg mL-1. The limits of quantification and limits of detection were 0.11--0.18 and 0.03--0.05 μg mL-1, respectively. Intraday precision (RSD 0.1--0.5%) and accuracy (recovery 97.3--100.8%) of the developed method were evaluated. No interference was observed from common adjuvants. The method has been successfully applied to the assay of sulpha drug in pharmaceutical formulations.