Spectrophotometric determination of microamounts of quercetin based on its complexation with copper(II)

2007 ◽  
Vol 61 (2) ◽  
Author(s):  
D. Kostić ◽  
G. Miletić ◽  
S. Mitić ◽  
I. Rašić ◽  
V. Živanović
Keyword(s):  
Pharmaceutical Preparations ◽  
Relative Standard Error ◽  
Optimal Conditions ◽  
Complex Composition ◽  
Complex Stability Constant ◽  
Relative Standard ◽  
Lower Detection ◽  
Maximum Absorption Wavelength ◽  
Complexation Process

AbstractThe complexation process of the transition metal Cu(II) with quercetin was studied. The investigation was conducted spectrophotometrically in ethanol at the maximum absorption wavelength of 458.5 nm. Cu(II)—quercetin complex composition (1: 1) was determined using the Job, Harvey—Manning, and mole ratio methods. Complex stability constant was calculated by the Job and mole ratio methods and the respective logarithm values were 7.53 ± 0.25 and 7.44 ± 0.03. A new method for quantitative determination of the quercetin content in solution was developed in this work. At the optimal conditions quercetin was determined in concentrations ranging from 0.202 to 1.006 µg cm−3 with relative standard error of 2.5 % to 5.5 %. The lower detection limit was 0.067 µg cm−3. The method was found very accurate, reproducible, and sensitive, capable to determine microamounts of quercetin in pharmaceutical preparations.

scholarly journals Application of Liquid Chromatography to the Simultaneous Determination of Acetylsalicylic Acid, Caffeine, Codeine, Paracetamol, Pyridoxine, and Thiamine in Pharmaceutical Preparations

2001 ◽  
Vol 84 (3) ◽  
pp. 676-683 ◽  
Author(s):  
Natividad Ramos-Martos ◽  
Francisco Aguirre-Gómez ◽  
Antonio Molina-Díaz ◽  
Luis F Capitán-Vallvey
Keyword(s):  
Salicylic Acid ◽  
Acetylsalicylic Acid ◽  
Simultaneous Determination ◽  
Pharmaceutical Preparations ◽  
Reversed Phase ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract This paper describes a rapid reversed-phase liquid chromatographic method, with UV detection, for the simultaneous determination of acetylsalicylic acid, caffeine, codeine, paracetamol, pyridoxine, and thiamine in pharmaceutical preparations. A reversed-phase C18 Nucleosil column is used. The mobile phase consists of 2 successive eluants: water (5 min) and acetonitrile–water (75 + 25, v/v; 9 min), both adjusted to pH 2.1 with phosphoric acid. Before determination acetylsalicylic acid is completely converted to salicylic acid by alkaline hydrolysis. Salicylic acid, caffeine, paracetamol, pyridoxine, and thiamine are all detected at 285 nm, whereas codeine is detected at 240 nm. Calibration curves were linear for salicylic acid, caffeine, paracetamol, and pyridoxine in the range of 50–500 mg/L, and for codeine and thiamine in the range of 50–1000 mg/L. The method was applied to the analysis of 13 fortified commercial pharmaceutical preparations. Recoveries ranged from 92.6 to 105.5%, with relative standard deviations of 1.1–5.8%.

scholarly journals Stability indicating HPLC-Fluorescence detection method for the simultaneous determination of linagliptin and empagliflozin in their combined pharmaceutical preparation

2021 ◽  
Vol 12 (2) ◽  
pp. 168-178
Author(s):  
Mohamed Rizk ◽  
Ali Kamal Attia ◽  
Heba Yosry Mohamed ◽  
Mona Elshahed
Keyword(s):  
Fluorescence Detection ◽  
Mobile Phase ◽  
Pharmaceutical Preparation ◽  
Pharmaceutical Preparations ◽  
Forced Degradation ◽  
Stability Indicating ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
Significant Difference

A sensitive, accurate, and precise liquid chromatographic method has been developed and validated for the determination of Linagliptin (LNG) and Empagliflozin (EMP) in their combined tablets. Chromatographic separation was carried out on ODS-3 Inertsil® C18 column (150×4.6 mm, 5 µm). The mobile phase A (consisting of 0.30% Triethyl amine buffer (TEA) at pH = 4.5, adjusted using ortho-phosphoric acid); the mobile phase B (consisting of acetonitrile) was pumped through the column whose temperature was maintained at 40 °C, with a flow rate 1.7 mL/min, using gradient elution from 0-3 min A:B (75:25, v:v), then from 3-6 min the ratio changed to be A:B (60:40, v:v). Fluorescence detection (FLD) was performed at 410 nm after excitation at 239 nm. Acceptable linearity, accuracy and precision values of the proposed method were found over the concentration ranges of 0.5-15 µg/mL for LNG and 1.0-30 µg/mL for EMP with correlation coefficients of 0.9997 and 0.9998 in the case of LNG and EMP, respectively. The recoveries and relative standard deviations percentages were found in the following ranges: 98.56-101.85 and 0.53-1.52% for LNG and 98.00-101.95 and 0.31-1.05% for EMP. The detection and quantification limits were 0.15 and 0.45 µg/mL for LNG and 0.22 and 0.67 µg/mL for EMP. The optimized method was validated and proved to be specific, robust, accurate and reliable for the determination of the drugs in pure form or in their combined pharmaceutical preparations. No significant difference was found regarding accuracy and precision upon statistical comparison between the obtained results of the proposed method and those of the reported method. Furthermore, the proposed method is proved to be a stability-indicating assay after exposure of the studied drugs to variable forced degradation parameters, such as acidic, alkaline and oxidative conditions, according to the recommendations of the International Conference on Harmonization guidelines. The simplicity and selectivity of the proposed method allows its use in quality control laboratories.

scholarly journals Spectrophotometric determination of Phenylephrine hydrochloride and Salbutamol sulphate drugs in pharmaceutical preparations using diazotized Metoclopramide hydrochloride

2015 ◽  
Vol 12 (1) ◽  
pp. 167-177 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Correlation Coefficients ◽  
Limit Of Quantification ◽  
Pharmaceutical Dosage Forms ◽  
Salbutamol Sulphate ◽  
Phenylephrine Hydrochloride ◽  
Relative Standard ◽  
Metoclopramide Hydrochloride

A spectrophotometric method has been proposed for the determination of two drugs containing phenol group [phenylephrine hydrochloride (PHP) and salbutamol sulphate (SLB)] in pharmaceutical dosage forms. The method is based on the diazotization reaction of metoclopramide hydrochloride (MCP) and coupling of the diazotized reagent with drugs in alkaline medium to give intense orange colored product (?max at 470 nm for each of PHP and SLB). Variable parameters such as temperature, reaction time and concentration of the reactants have been analyzed and optimized. Under the proposed optimum condition, Beer’s law was obeyed in the concentration range of 1-32 and 1-14 ?g mL-1 for PHP and SLB, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for each of PHP and SLB were 0.60, 0.52 ?g mL-1 and 2.02, 1.72 ?g mL-1, respectively. No interference was observed from common excipients present in pharmaceutical preparations. The good correlation coefficients and low relative standard deviation assert the applicability of this method. The suggested method was further applied for the determinations of drugs in commercial pharmaceutical preparations, which was compared statistically with reference methods by means of t- test and F- test and were found not to differ significantly at 95% confidence level. The procedure was characterized by its simplicity with accuracy and precision.

scholarly journals A sensitive spectrophotometric determination of tadalafil in pharmaceutical preparations and industrial wastewater samples

2013 ◽  
Vol 10 (3) ◽  
pp. 1005-1013 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Standard Deviation ◽  
Industrial Wastewater ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Average Recovery ◽  
Relative Standard ◽  
Wastewater Samples ◽  
Sensitive Spectrophotometric Method

A simple, accurate, precise, rapid, economical and a high sensitive spectrophotometric method has been developed for the determination of tadalafil in pharmaceutical preparations and industrial wastewater samples, which shows a maximum absorbance at 204 nm in 1:1 ethanol-water. Beer's law was obeyed in the range of 1-7?g/ mL ,with molar absorptivity and Sandell ? s sensitivity of 0.783x105l/mol.cm and 4.97 ng/cm2respectively, relative standard deviation of the method was less than 1.7%, and accuracy (average recovery %) was 100 ± 0. 13. The limits of detection and quantitation are 0.18 and 0.54 µg .ml-1, respectively. The method was successfully applied to the determination of tadalafil in some pharmaceutical formulations (tablets) and industrial wastewater samples. The proposed method was validated by sensitivity and precision which proves suitability for the routine analysis of tadalafil in true samples.

scholarly journals Simultaneous Determination of Sitagliptin and Metformin in Pharmaceutical Preparations by Capillary Zone Electrophoresis and its Application to Human Plasma Analysis

2012 ◽  
Vol 7 ◽  
pp. ACI.S9940 ◽  
Author(s):  
Mohamed Salim ◽  
Nahed El-Enany ◽  
Fathallah Belal ◽  
Mohamed Walash ◽  
Gabor Patonay
Keyword(s):  
Simultaneous Determination ◽  
Human Plasma ◽  
Capillary Zone Electrophoresis ◽  
Pharmaceutical Preparations ◽  
Effective Length ◽  
Relative Standard ◽  
Significant Difference ◽  
Zone Electrophoresis ◽  
Capillary Zone

A novel, quick, reliable and simple capillary zone electrophoresis CZE method was developed and validated for the simultaneous determination of sitagliptin (SG) and metformin (MF) in pharmaceutical preparations. Separation was carried out in fused silica capillary (50.0 cm total length and 43.0 cm effective length, 49 μm i.d.) by applying a potential of 15 KV (positive polarity) and a running buffer containing 60 mM phosphate buffer at pH 4.0 with UV detection at 203 nm. The samples were injected hydrodynamically for 3 s at 0.5 psi and the temperature of the capillary cartridge was kept at 25 °C. Phenformin was used as internal standard (IS). The method was suitably validated with respect to specificity, linearity, limit of detection and quantitation, accuracy, precision, and robustness. The method showed good linearity in the ranges of 10-100 μg/mL and 50-500 μg/mL with limits of detection of 0.49, 2.11 μm/mL and limits of quantification of 1.48, 6.39 μg/mL for SG and MF, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixtures and co-formulated tablets without interfering peaks due to the excipients present in the pharmaceutical tablets. The method was further extended to the in-vitro determination of the two drugs in spiked human plasma. The estimated amounts of SG/MF were almost identical with the certified values, and their percentage relative standard deviation values (% R.S.D.) were found to be ≤1.50% (n = 3). The results were compared to a reference method reported in the literature and no significant difference was found statistically.

scholarly journals Development and Validation of a Chiral HPLC Method for Quantitative Analysis of Enantiomeric Escitalopram

2018 ◽  
Vol 16 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Asma Rahman ◽  
Mohammad Rashedul Haque ◽  
M Muhibur Rahman ◽  
Mohammad A Rashid
Keyword(s):  
Pharmaceutical Preparations ◽  
Enantiomeric Separation ◽  
Hplc Method ◽  
Enantiomeric Purity ◽  
Chiral Hplc ◽  
Average Percentage ◽  
Quantitation Limit ◽  
Relative Standard ◽  
Development And Validation

In the present study a rapid, accurate and precise chiral HPLC method was developed and validated for enantiomeric separation of racemate citalopram and escitalopram according to the guidelines of United States of Pharmacopeia (USP) and International Conference on Harmonization (ICH). The chiral chromatographic separation was achieved with ammonium acetate/ ethanol/ 2-propanol/ methylene dichloride (100 : 150 : 70 : 30, v/v) at a flow rate of 0.5 ml/min using a chiral CD-PH column. The HPLC analyses were monitored at 254 nm. The method showed a good linearity with regression coefficient (r2) of 0.998 in the range of 20.0-70.0 μg/ml for escitalopram. The detection limit (LOD), quantitation limit (LOQ) and average percentage of recovery for escitalopram were found to be 2.54, 7.68 μg/ml and 100.28% to 102.86%, respectively. The percentage of relative standard deviation (%RSD) for intra- and inter- day precision were found as 0.16% and 0.09%, respectively. The established method proved as reproducible with a %RSD value of less than 2 and having the robustness within specified limit. The present study also showed the enantiomeric purity or excess (%ee) of seven pharmaceutical preparations of escitalopram. Thus the proposed chiral method can be applied for the enantiomeric purity determination of escitalopram formulations.Dhaka Univ. J. Pharm. Sci. 16(2): 165-172, 2017 (December)

scholarly journals Spectrophotometric and Conductometric Determination of Clomiphene Citrate and Nefazodone HCl

2008 ◽  
Vol 5 (s2) ◽  
pp. 1069-1080 ◽  
Author(s):  
Wafaa S. Hassan ◽  
Mervat M. Hosny
Keyword(s):  
Spectrophotometric Method ◽  
Clomiphene Citrate ◽  
Pharmaceutical Preparations ◽  
Conductometric Titration ◽  
Ion Pair ◽  
Experimental Conditions ◽  
Relative Standard ◽  
Colored Complexes ◽  
Standard Deviations

Two accurate, rapid and simple spectrophotometric and conductometric methods were developed for the determination of clomiphene citrate (CMP) and nefazodone HCl (NFZ), the proposed methods depends upon the reaction of ammonium reineckate with the two studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in suitable solvent. The pink colored complexes were determined colorimetrically at 509, 523.6 nm, respectively. Using the conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 60.02-540.18 and 63.3-443.1 μg mL-1for clomiphene citrate and nefazodone HCl, respectively. While for spectrophotometric method the ranges were 0.2-1.8 and 0.2-1.6 mg mL-1for clomiphene citrate and nefazodone HCl respectively. Various experimental conditions were studied. The results obtained showed good recoveries with relative standard deviations of 0.759 and 0.552%. The proposed procedures were applied successfully to the analysis of these drugs in their pharmaceutical preparations and the results were favourably comparable with the official and reference methods. The molar combining ratio reveal that (1:1) (drug : reagent) ion associates were formed.

scholarly journals Voltammetric determination of dopamine in the presence of ascorbic and uric acids using partial least squares regression: determination of dopamine in human urine and plasma

2009 ◽  
Vol 7 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Morteza Bahram ◽  
Khalil Farhadi ◽  
Farzin Arjmand
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Relative Standard Error ◽  
Carbon Electrode ◽  
Least Squares Regression ◽  
Relative Standard

AbstractA new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has been successfully applied to the measurement of dopamine in human plasma and urine.

scholarly journals Validation and Uncertainty Estimation of an Ecofriendly and Stability-Indicating HPLC Method for Determination of Diltiazem in Pharmaceutical Preparations

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Fahimeh Sadeghi ◽  
Latifeh Navidpour ◽  
Sima Bayat ◽  
Minoo Afshar
Keyword(s):  
Degradation Products ◽  
Pharmaceutical Preparations ◽  
Hplc Method ◽  
Forced Degradation ◽  
Solution Ph ◽  
Validation Data ◽  
Column Temperature ◽  
Stability Indicating ◽  
Relative Standard

A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5–50 μg/mL (r2=0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%–101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations.

scholarly journals Kinetic Spectrophotometric Determination of Gemifloxacin Mesylate and Moxifloxacin Hydrochloride in Pharmaceutical Preparations Using 4-Chloro-7-nitrobenzo-2-oxa-1,3-diazole

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Mohammed G. Abdel Wahed ◽  
Ragaa El Sheikh ◽  
Ayman A. Gouda ◽  
Sayed Abou Taleb
Keyword(s):  
Limit Of Detection ◽  
Kinetic Method ◽  
Pharmaceutical Preparations ◽  
Fixed Time ◽  
Spectrophotometric Methods ◽  
Relative Standard ◽  
Significant Difference ◽  
Kinetic Spectrophotometric ◽  
Comparison Of The Results

Simple, sensitive, and accurate kinetic spectrophotometric method was proposed for the determination of gemifloxacin mesylate (GMF) and moxifloxacin hydrochloride (MOX) in pure forms and pharmaceutical preparations (tablets). The method is based on coupling the studied drugs with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in the presence of alkaline borate buffer. Spectrophotometric measurement was achieved by recording the absorbance at 466 and 464 nm for GMF and MOX, respectively, after a fixed time of 20 and 15 min on a water bath adjusted at 70 ± 5°C for both drugs. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The absorbance-concentration plots were linear over the ranges 0.5–8.0 and 2.0–12 μg mL−1for GMF and MOX, respectively. The limit of detection of the kinetic method was about 0.12 (2.47 × 10−7 M) and 0.36 (8.22 × 10−7 M) μg mL−1for GMF and MOX, respectively. The proposed methods have been applied and validated successfully with percentage relative standard deviation (RSD% ≤ 0.52) as precision and percentage relative error (RE% ≤ 1.33) as accuracy. The robustness of the proposed method was examined with recovery values that were 97.5–100.5 ± 1.3–1.9%. Statistical comparison of the results with the reference spectrophotometric methods shows excellent agreement and indicates no significant difference in accuracy or precision.

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