Background
Metformin hydrochloride (MFH) is a biguanide class anti-diabetic drug used to treat type-2 diabetes mellitus. Its reaction with two charge-transfer complexing agents,
p
-chloranilic acid ...(PCA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in acetonitrile medium to yield coloured products measurable at wavelengths of maxima 530.0 and 460.0 nm, respectively, was conveniently used to develop two spectrophotometric methods for analyses of bulk sample and tablets.
Results
The effect of solvent, reagent concentration and reaction time to form charge-transfer (CT) complexes was meticulously studied and optimized. Under optimised conditions, the absorbance at the respective wavelength of maximum versus concentration of MFH was in linear correlation for the range from 8.0 to 320.0 and from 1.6 to 64.0 μg mL
-1
in PCA and DDQ methods, respectively, and correspondingly, the values of molar absorptivity of 0.733 × 10
3
and 0.257 × 10
4
L mol
-1
cm
-1
and Sandell sensitivity of 0.3620 and 0.0644 μg cm
-2
. The quantification (QL) and detection (DL) limits were 2.67 and 0.88 μg mL
-1
for PCA method, and 0.33 and 0.11 μg mL
-1
for DDQ method.
Conclusion
The new methods were emerged as repeatable and reproducible, with replicate measurements for intra- and inter-day variations as showed by obtained RSD values of < 2%. Within a day and between day relative errors were ≤ 2.18%. Methods were also validated for robustness, ruggedness and selectivity and agreeing results were produced. The methods were used to analyse MFH-containing tablets very accurately and precisely as reflected by the mean recovery value close to 100% and lower RSD values, respectively. Analysis of spiked human urine yielded excellent mean recoveries, indicating the absence of interference from endogenous substances.
Background
Lisinopril (LNP) is an angiotensin-converting enzyme inhibitor used as anti-hypertensive, cardiovascular, in anti-prophylactic and anti-diabetic nephropathy drug. Development of two new, ...simple, low cost, and selective membrane-based ion-selective electrodes has been proposed for the determination of LNP in pharmaceuticals.
Methods
The electrodes are based on poly(vinyl)chloride membrane doped with LNP-phosphotungstic acid (LNP-PTA) and LNP-phosphomolybdic acid (LNP-PMA) ion-pairs as molecular recognition materials.
Results
The developed LNP-PTA and LNP-PMA electrodes are applicable for the determination of LNP over the linear range of 5 × 10
−5
–2.4 × 10
−3
mol l
−1
. The working pH ranges to measure potentials were 2.5 to 6.4 and 2.3 to 6.0 for LNP-PTA and LNP-PMA ISEs, respectively. The electrodes displayed the rapid Nernstian responses as revealed by the values of slopes 55.06 and 52.39 mV/decade, with limit of detection (LOD) values of 1.2 × 10
−5
and 1.18 × 10
−5
mol l
−1
for LNP-PTA and LNP-PMA electrodes, respectively. The limits of quantitation (LOQ) values have also been calculated for both the electrodes. The developed electrodes have potential stability for up to 1 month and emerged as highly selective for the determination of LNP over other spiked ions and compounds.
Conclusions
The proposed electrodes have been validated and found that they are suitable for the determination of LNP in pharmaceuticals in pure form and in dosage forms. The results obtained in the analysis of LNP using proposed electrodes have been compared statistically with reference method’s results to assess the accuracy and precision. Robustness and ruggedness of the developed electrodes have also been checked and found satisfactory. The recovery studies have been performed by standard addition procedure to assess the role of excipients in tablets containing LNP and the results obtained are satisfactory.
Pioglitazone hydrochloride (PGH) is an oral anti-hyperglycemic agent used in the treatment of type-2 diabetes mellitus. Potassium permanganate was found to oxidize PGH both in acidic and basic ...conditions, based on which two simple and sensitive methods were developed for its determination in bulk sample and tablets, and validated. In the first method (indirect method), PGH was reacted with a measured excess of standard permanganate in H2SO4 medium, and the residual oxidant was determined by measuring its absorbance at 550 nm. The second method (Direct method) entails treating PGH with permanganate in NaOH medium, followed by the measurement of the resulting bluish-green manganite at 610 nm. Experimental variables affecting the reactions were studied and optimized. Under optimum conditions, linear relationships with good correlation coefficients were found between absorbance and concentration in the ranges, 1.25 – 25 µg mL-1 (Indirect method) and 1-12 µg mL-1 (Direct method) with respective molar absorptivity values of 1.10 × 104 and 2.77 × 104 l mol-1 cm-1. The limits of detection (LOD) and quantification (LOQ) were 0.36 and 1.08 (Indirect method) and 0.23 and 0.69 µg mL-1 (Direct method). Intra-day and inter-day precisions were satisfactory, with %RSD values of ≤2.11, and the respective accuracies were excellent with %RE values of ≤2. The methods were also validated for robustness, ruggedness and selectivity. The methods were applied to the determination of PGH in its tablets with good accuracy and precision, and no interference from the tablet additives was encountered. The results were also compared with those obtained by a reference method.
Piroxicam (POC) and oxfendazole (OFA) are two widely used veterinary non-steroidal anti-inflammatory and anthelmintic medicines, respectively. Simple, precise and accurate and cost-effective methods ...for the determination of POC and OFZ in bulk drug and in its dosage forms have been developed and validated. The methods are based on the potentiometric titration of compound with acetous perchloric acid in glacial acetic acid medium using modified glass-saturated calomel electrode system. The methods are applicable over the ranges 1.5 - 15 mg and 7.5-15 mg, for POC and OFA, respectively. The proposed methods were successfully applied to the determination of active substances in their pharmaceutical dosage forms. A statistical comparison was made on the results of proposed methods with those obtained for reference method. The intra-day and inter-day precision and accuracy values obtained were satisfactory with RSD and RE values less than 3%. Excipients in tablets did not interfere to the assay as shown by the recovery study via standard addition technique with mean percentage recoveries in the range 97.8 – 100.6%.
Two new spectrophotometric methods using permanganate as the oxidimetric reagent for the determination of olanzapine (OLP) were developed and validated as per the current ICH guidelines. The methods ...involved the addition of known excess of permanganate to OLP in either acid or alkaline medium followed by the determination of unreacted permanganate at 550 nm (method A) or bluish-green color of manganate at 610 nm (method B). The decrease in absorbance in method A or increase in absorbance in method B as a function of concentration of OLP was measured and related to OLP concentration. Under optimized conditions, Beer's law was obeyed over the ranges 2.0 to 20 and 1.0 to 10 μg mL-1 in method A and method B, respectively. The calculated molar absorptivity values were 1.34 x 10(4) and 2.54 x 10(4) l mol-1cm-1 for method A and method B respectively, and the respective Sandell sensitivities were 0.0233 and 0.0123 μg cm-2. The LOD and LOQ for method A were calculated to be 0.37 and 1.13 μg mL-1and the corresponding values for method B were 0.16 and 0.48 μg mL-1. Intermediate precision, expressed as RSD was in the range 0.51 to 2.66 %, and accuracy, expressed as relative error ranged from 0.79 to 2.24 %. The proposed methods were successfully applied to the assay of OLP in commercial tablets with mean percentage recoveries of 102 ±1.59 % (method A) and 101 ±1.53 % (method B). The accuracy and reliability of the methods were further confirmed by performing recovery tests via standard addition procedure.
Dois métodos espectrofotométricos novos, usando o permanganato como o reagente oxidimétrico para a determinação da olanzapina (OLP) foram utilizados e validados de acordo com as diretrizes atuais do ICH. Os métodos envolveram a adição de excesso conhecido de permanganato à OLP em meio ácido ou alcalino, determinando-se o permanganato que não reagiu em 550 nm (método A), ou pela cor verde-azulada do manganato a 610 nm (método B). A diminuição da absorbância no método A ou o aumento da absorbância no método B, em função da concentração de OLP, foi medida e relacionada à concentração de OLP. Sob condições otimizadas, a lei de Beer foi obedecida, nas faixas de concentração de 2,0 a 20 e 1,0 a 10 ao μg mL-1, no método A e no método B, respectivamente. Os valores de absortividade molar foram de 1,34 x 104 e 2,54 x 104 l mol-1cm-1 para o método A e para o método B, respectivamente, e as sensibilidades respectivas de Sandell foram de 0,0233 e 0,0123 μg cm-2. Os LOD e os LOQ para o método A calculados foram 0,37 e 1,13 μg mL-1e os valores correspondentes para o método B foram 0,16 e 0,48 μg mL-1. A precisão intermediária, expressa como RSD, encontrou-se na faixa de 0,51 a 2,66%, e a exatidão, expressa como o erro relativo, variou de 0,79 a 2,24%. Os métodos propostos foram aplicados com sucesso ao ensaio de OLP em comprimidos comerciais, com porcentagens médias de recuperação de 102± 1,59% (método A) e de 101± 1,53% (método B). A exatidão e a confiabilidade dos métodos foram confirmadas executando testes de recuperação através de procedimento padrão de adição.
Background
Fabrication of two membrane sensors using two acidic indicators among sulphonthalein dyes, namely bromophenol blue (BPB) and bromocresol green (BCG), and their use as indicative electrodes ...for the quantification of frusemide (FUR) is presented. The ion pair complexes of FUR with BPB or BCG are used to prepare the membranes in THF solvent, PVC matrix and dibutyl phthalate (DBP) as plasticizer and subsequently to fabricate FUR-BPB (Sensor I) and FUR-BCG (Sensor II) sensors.
Results
Sensors I and II are employable to determine 2.4 × 10
-5
–2.4 × 10
-3
mol/L FUR at operative pH of 3.71. The calibration curve between the potentials against the concentration of FUR yielded the slopes of 58.73 ± 1 and 57.66 ± 1 mV/decade, respectively, using Sensors I and II, and this confirmed the Nernstian behaviour. Satisfactory correlation was obtained between the measured potentials and FUR concentration with the proposed sensors, and this was revealed by regression coefficient values of 0.9987 and 0.9980 for Sensors I and II, respectively. The LOD (limit of detection) values were calculated and reported for both the sensors. The experimental parameters were optimised to yield acceptable characteristics of both the sensors in the context of performance. The role of excipients of tablets and interferences were assessed by standard addition protocol. The obtained results confirmed the ineffective role of excipients of tablets and foreign species used as interferents.
Conclusion
The designed sensors were validated to confirm the accurate, precise, robust and rugged functioning in determining FUR. The mean of recovered FUR, close to 100%, revealed the acceptable and effective functioning of the proposed sensors. Excellent results were obtained by FUR tablets’ analysis using both the sensors.
Two simple, rapid, cost-effective and sensitive spectrophotometric procedures are proposed for the determination of hydroxyzine dihydrochloride (HDH) in Pharmaceuticals and in spiked human urine. The ...methods are based on the charge transfer complexation reaction of the drug with either iodine (I sub(2)) as a sigma -acceptor (method A) in dichloromethane or picric acid (PA) as a capital pi --acceptor (method B) in chloroform. The coloured products exhibit absorption maxima at 380 and 400 ran for I sub(2) and PA, respectively. The Beer Law was obeyed over the concentration ranges of 1.25-15 and 3.75-45 mu g mL super(-1) for method A and B, respectively. The molar absorptivity values, Sandell sensitivities, limits of detection (LOD) and quantification (LOQ) are reported. The accuracy and precision of the methods were evaluated on intra-day and inter-day basis. The proposed methods were successfully applied for the determination of HDH in tablets and spiked human urine.
Quetiapine fumarate (QTF) is an antipsychotic drug belonging to the
benzisoxazole derivatives indicated for the treatment of schizophrenia. A
sensitive and selective method based on ...dichloromethane-extractable ion-pair
of QTF with calmagite (CGT), which exhibited an absorption maximum at 490 nm,
is described. At this wavelength, Beer?s law is obeyed over the concentration
range of 3.0 - 30.0 ?g ml-1. The apparent molar absorptivity, limit of
detection (LOD) and quantitation (LOQ) values are 1.32 ? 104 l mol-1 cm-1,
0.27 and 0.81 ?g ml-1 respectively. The reaction is extremely rapid at room
temperature and the absorbance values remain unchanged upto 19 h. The
precision results, expressed as intra-day and inter-day relative standard
deviation values, are satisfactory (RSD ? 2.2%). The accuracy is satisfactory
as well (RE ? 2.44%). The method was successfully applied to the
determination of QTF in pharmaceuticals and spiked human urine with
satisfactory results. No interference was observed from common pharmaceutical
adjuvants in tablets. Statistical comparison of the results with official
method showed an excellent agreement and indicated no significant difference
in precision.
nema
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