Voltammetric determination of amoxicillin using a poly (N-vinyl imidazole) modified carbon paste electrode

Determination of amoxicillin trihydrate impurities 4-HPG and 6-APA by means of ultraviolet spectroscopy

Amoxicillin is one of the broad-spectrum β-lactam antibiotics widely used in the treatment of many diseases. It is inevitable that 4-hydroxyphenylglycine (4-HPG) and 6-Aminopenicylanic acid (6-APA), which are used during the production of this antibiotic, are incorporated into the molecular lattice of the product as impurities. Today, many expensive methods and chemical devices are used for the purification of Amoxicillin by determining 6-APA and 4-HPG, which are defined as impurities. In this study, it was aimed to develop a fast, simple, and specific UV-spectrophotometric method for the determination of 4-HPG and 6-APA. Another aim of this article is to cause as little harm as possible to the environment and human health by using as few chemicals as possible throughout the study. In this study, all attempts to determine 6-APA and 4-HPG, which are impurities in the production of amoxicillin, were carried out with the help of a UV/VIS spectrophotometer. Also, Four different concentrations of NaOH were used as a solvent for each impurity. UV spectra of 4-HPG and 6-APA concentrations between 210 and 400 nm were measured. In the literature, the UV spectrum of 4-HPG has been revealed for the first time in this study and examined in detail. The UV spectrum of 4-HPG was characterized in 3 regions. Again, the response of 6-APA to different NaOH concentrations was demonstrated for the first time in this study. It was determined that the peaks of 6-APA dissolved in NaOH shifted from 222 nm to 227 nm depending on the concentration amount. In addition, it is an ideal green procedure that makes a difference in the literature, as the study is carried out for the control and determination of impurities without the use of any organic solvents or chemicals harmful to the environment.

Development and validation of voltammetric method for determination of amoxicillin in river water

Amoxicillin is an antibiotic that can accumulate in aquatic environments and lead to the development of resistant bacteria; thus, its determination is of great importance. In this study, a glassy carbon electrode modified with reduced graphene oxide and Nafion was used as a sensor in a square-wave voltammetry method for determination of amoxicillin in river water samples from Guarapuava city, Brazil. The method was validated, using parameters and statistical tools recommended by the validation guidelines, in the range of 1.8-5.4 μmol L^-1 (r = 0.922 and R² = 85.1%). The analytical curve was constructed using external standard calibration in pure electrolyte, since the matrix effect was not significant. Results of linear regression analysis, lack of fit test and analysis of the residual plots pointed that the linear regression was significant, without lack of fit of linear model and that the variances had homoscedastic distribution. Both coefficients of regression curve were significant and, thus, they were included in the regression equation: Response = 7.0 + 3.5C_AMX. The limits of detection and quantification were 0.36 and 1.2 μmol L^-1, respectively. The method was selective towards interferents such as humic acids and benzylpenicillin. The relative standard deviations for repeatability and intermediate precision were adequate according to the limits established in literature. The mean recoveries were statistically equal to those obtained through a comparative chromatography method, so, the accuracy of the method was also adequate. Therefore, the method can be applied to the voltammetric determination of amoxicillin in river water, affording reliable and consistent measurements.

Recent advances in electrochemical sensors for amoxicillin detection in biological and environmental samples

Amoxicillin (AMX) is among the most successful antibiotics used for human therapy. It is used extensively to prevent or treat bacterial infections in humans and animals. However, the widespread distribution and excess utilization of AMX can be an environmental and health risk due to the hazardous potential associated to its pharmaceutical industries effluents. Besides, their extensive use in food animal production may result in some undesirable residues in food, e.g. meat, eggs and milk. Consequently, at high enough concentrations in biological fluids, AMX may be responsible of various diseases such as nausea, vomiting, rashes, and antibiotic-associated colitis. For this reason, the detection and quantification of amoxicillin in pharmaceuticals, biological fluids, environmental samples and foodstuffs require new electroanalytical techniques with sensitive and rapid measurement abilities. This review discusses recent advances in the development of electrochemical sensors and bio-sensors for AMX analysis in complex matrices such as pharmaceuticals, biological fluids, environmental water and foodstuffs. The main electrochemical sensors used are based on chemically modified electrodes involving carbon materials and nanomaterials, nanoparticles, polymers and biological recognition molecules.

Different spectrophotometric methods applied for the analysis of binary mixture of flucloxacillin and amoxicillin: A comparative study

Three different spectrophotometric methods were applied for the quantitative analysis of flucloxacillin and amoxicillin in their binary mixture, namely, ratio subtraction, absorbance subtraction and amplitude modulation. A comparative study was done listing the advantages and the disadvantages of each method. All the methods were validated according to the ICH guidelines and the obtained accuracy, precision and repeatability were found to be within the acceptable limits. The selectivity of the proposed methods was tested using laboratory prepared mixtures and assessed by applying the standard addition technique. So, they can be used for the routine analysis of flucloxacillin and amoxicillin in their binary mixtures.

Effect of genetic algorithm as a variable selection method on different chemometric models applied for the analysis of binary mixture of amoxicillin and flucloxacillin: A comparative study

Different chemometric models were applied for the quantitative analysis of amoxicillin (AMX), and flucloxacillin (FLX) in their binary mixtures, namely, partial least squares (PLS), spectral residual augmented classical least squares (SRACLS), concentration residual augmented classical least squares (CRACLS) and artificial neural networks (ANNs). All methods were applied with and without variable selection procedure (genetic algorithm GA). The methods were used for the quantitative analysis of the drugs in laboratory prepared mixtures and real market sample via handling the UV spectral data. Robust and simpler models were obtained by applying GA. The proposed methods were found to be rapid, simple and required no preliminary separation steps.

Construction of an Electrochemical Sensor Based on Carbon Nanotubes/Gold Nanoparticles for Trace Determination of Amoxicillin in Bovine Milk

In this work, a novel electrochemical sensor was fabricated for determination of amoxicillin in bovine milk samples by decoration of carboxylated multi-walled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs) using ethylenediamine (en) as a cross linker (AuNPs/en-MWCNTs). The constructed nanocomposite was homogenized in dimethylformamide and drop casted on screen printed electrode. Field emission scanning electron microscopy (FESEM), energy dispersive X-Ray (EDX), X-Ray diffraction (XRD) and cyclic voltammetry were used to characterize the synthesized nanocomposites. The results show that the synthesized nanocomposites induced a remarkable synergetic effect for the oxidation of amoxicillin. Effect of some parameters, including pH, buffer, scan rate, accumulation potential, accumulation time and amount of casted nanocomposites, on the sensitivity of fabricated sensor were optimized. Under the optimum conditions, there was two linear calibration ranges from 0.2-10 µM and 10-30 µM with equations of Ipa (µA) = 2.88C (µM) + 1.2017; r = 0.9939 and Ipa (µA) = 0.88C (µM) + 22.97; r = 0.9973, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 0.015 µM and 0.149 µM, respectively. The fabricated electrochemical sensor was successfully applied for determination of Amoxicillin in bovine milk samples and all results compared with high performance liquid chromatography (HPLC) standard method.

Utilization of ion exchanger and spectrophotometry for assaying amoxycillin and flucloxacillin in dosage form

A simple, rapid, accurate sensitive spectrophotometry procedure for the determination of amoxycillin (Amox) and flucloxacillin (Fluclox) in bulk samples and in dosage forms are developed. The procedure involves the use of sudan III as chromogenic reagent to produce a violet colored ion-pair with an absorption maximum at 566nm. The ion-pair complexes obey Beer's law and are suitable for the quantitative determination of 0.2-22 and 0.4-25microg/ml of Amox, and Fluclox, respectively. The optimization of different experimental conditions is described in which Amox react after 3min at 25+/-1 degrees C, whereas Fluclox take 10min at 60+/-1 degrees C. Tin(IV) antimonite ion exchanger was utilized to separate a mixture of Amox and Fluclox trihydrate. A column chromatographic technique was applied to separation the antibiotics mixture. Column of 0.3mm diameter and bed height of 3cm of the exchanger was used and the frontal elution technique was utilized. The separation factor for Fluclox and Amox was found to be 2.76. Tin(IV) antimonite ion exchanger exhibit promising feature that can be utilized as stationary phase in either HPLC or HPTLC techniques. The procedure described was applied successfully to determine Amox and Fluclox. The obtained results were compared the official methods. The proposed procedure was successfully applied to determine Amox and Fluclox in their pharmaceutical formulations.

Flow injection-chemiluminescence determination of amoxycillin using potassium permanganate and formaldehyde system

It was found that amoxycillin can react with potassium permanganate in an acidic medium to produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction were studied in detail using a flow-injection system. The experimental results indicate that, under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of amoxycillin in the range 5.48 x 10(-8)-2.74 x 10(-6) mol/L, with a detection limit (3sigma) of 4.1 x 10(-8) mol/L. The relative standard deviation was 1.0% at 1.1 x 10(-6) mol/L amoxycillin (n = 11 measurements). This method has the advantages of high sensitivity, fast response and ease of operation. The method was successfully applied to the determination of amoxycillin in raw medicines and capsules.

Voltammetric analysis of drugs

A review on the voltammetric analysis of drugs is presented. The review includes a summary of the rules that must be considered for drug analysis and a survey of the use of voltammetry for drug analysis in the period from 1998 till 2002.

Advances in the voltammetric analysis of small biologically relevant compounds

The problems associated with attempting to apply voltammetric techniques to the analysis of biologically relevant organics within complex media are identified and, through reviewing the very recent literature (1999-mid-2001), possible solutions are described. The boundaries of the search were limited to research targeted at the resolution of specific problems, associated with quantitative determinations. Various strategies have emerged to counter problems of poor sensitivity and selectivity and these have been summarized and critically appraised. Where possible, the characteristics of each approach have been distilled into a table format to ease comparison. Emphasis has been placed on the collation of information that will improve the intrinsic electrode response and as such should be of value to those interested in pursuing electroanalytical methodologies regardless of context.

Pyrocatechol violet in pharmaceutical analysis. Part I. A spectrophotometric method for the determination of some beta-lactam antibiotics in pure and in pharmaceutical dosage forms

A fairly sensitive, simple and rapid spectrophotometric method for the determination of some beta-lactam antibiotics, namely ampicillin (Amp), amoxycillin (Amox), 6-aminopenicillanic acid (6APA), cloxacillin (Clox), dicloxacillin (Diclox) and flucloxacillin sodium (Fluclox) in bulk samples and in pharmaceutical dosage forms is described. The proposed method involves the use of pyrocatechol violet as a chromogenic reagent. These drugs produce a reddish brown coloured ion pair with absorption maximum at 604, 641, 645, 604, 649 and 641 nm for Amp, Amox, 6APA, Clox, Diclox and Flucolx, respectively. The colours produced obey Beer's law and are suitable for the quantitative determination of the named compounds. The optimization of different experimental conditions is described. The molar ratio of the ion pairs was established and a proposal for the reaction pathway is given. The procedure described was applied successfully to determine the examined drugs in dosage forms and the results obtained were comparable to those obtained with the official methods.

Kinetic spectrophotometric determination of ampicillin and amoxicillin in dosage forms

A kinetic spectrophotometric method has been developed for the determination of ampicillin (I) and amoxicillin (II). The method involves hydrolysis of the antibiotics with 1.0 M HCl, neutralization with 1.0 M NaOH followed by addition of palladium(II) chloride in the presence of 2 M KCl. The produced yellow colour is measured at 335 nm. The proposed method is valid over the concentration range 8-40 microg/ml and 10-40 microg/ml for I and II respectively with minimum detectability of 0.73 microg/ml and 0.76 microg/ml for I and II respectively. The determination of the studied compounds adopting the fixed concentration method is feasible with the calibration equations obtained, but the fixed time method has been found to be more applicable. The proposed method was applied to commercial dosage forms and the results obtained were in good agreement with those given by USP method.