Determination Of Methimazole Research Articles

SnS2/AuNPs surface-enhanced Raman scattering sensor for rapid and selective quantification of methimazole in serum and meat samples

Rapid and selective quantification is a great challenge for on-site analysis and point-of-care detection. Herein, we developed a SnS2/AuNPs sensor for quick and selective surface-enhanced Raman scattering (SERS) determination of methimazole in clinic serum and meat samples. SnS2/AuNPs hybrid with adjustable size, electromagnetic field enhancement, and surface plasmon resonance was facilely prepared by ultrasonic assistance. The SnS2/AuNPs sensor exhibited good SERS sensing performances for methimazole detection: a high enhancement factor of 4.5 × 107, good intra-batch uniformity with RSD of 6.1 % (n = 27), good batch-to-batch stability with RSD of 6.6 % (n = 15), and good selectivity to thyroid antagonists possibly due to the lowest energy charge transfer. Subsequently, a rapid SERS sensing method was established for quantitative analysis of methimazole ranging from 5 to 1000 µg/L with a detection limit down to 2.7 µg/L. Clinic serum samples from eight patients were accurately found with concentrations of 86.5–345.9 µg/L, recoveries of 89.7–104.7 % and RSDs of 2.1–8.8 %. The whole analysis time of clinic serum samples could be finished in 10 min without any pretreatment. The sensor with good sensitivity, reproducibility, and selectivity possessed great values for rapid food safety analysis and point-of-care detection in clinic diagnosis.

Determination of Methimazole in Pharmaceutical Preparation and Human Serum by Square Wave and Differential Pulse Polarographic Methods

Objectives: In this study, the polarographic behaviour of methimazole was studied using cyclic, square wave and differential pulse polarographic methods. Methods: The influence of several variables (including nature of the buffer, concentration, scan rate, drop size, etc.) was examined in square wave and differential pulse polarographic methods for methimazole. The best square wave and differential pulse polarographic responses were obtained in 0.1 M sulfuric acid. The peak currents were measured with a static mercury drop electrode at 0.10 V versus Ag/AgCl. Results: The linearity was established over the concentration range of 5-80 mg/mLfor both methods in supporting electrolyte and human serum. The methods were validated and applied to the determination of methimazole in a commercial tablet. There was no significant differences between the results obtained by square wave and differential pulse polarographic methods. Square wave and differential pulse polarographic methods are also available and applicable for the determination of mentioned substance in human serum. No electroactive interferences from the endogenous substances were found in the serum samples. Mean recovery was 99.9%. Conclusion: They were concluded that the developed methods were accurate, sensitive, precise, reproducible and useful for the quality control of methimazole in pharmaceuticals and spiked serum.

NOVEL SELECTIVE SPECTROPHOTOMETRIC METHODS FOR THE DETERMINATION OF METHIMAZOLE IN PURE FORM AND IN PHARMACEUTICAL FORMULATION

Objective: To develop and validate new, selective spectrophotometric colorimetric analytical methods for the quantification of methimazole in its pure form and in its pharmaceutical preparations.
 Methods: Method A is based on the oxidation of methimazole with potassium permanganate in alkaline medium, the manganate ion produced was measured at λmax= 610 nm. Method B is a kinetic determination of methimazole using fixed-time method based on the oxidation of methimazole using known excess of cerium (IV) nitrate in acidic medium and assessing the unreacted Ce (IV) by adding a fixed amount of methyl orange and measuring the absorbance of the resultant solution at λmax=507 nm which is equivalent to the unreacted methyl orange. The reaction conditions and analytical parameters are investigated and optimized. Method validation was carried out according to ICH guidelines in terms of linearity, LOD, LOQ, precision, and accuracy.
 Results: Beer’s law is obeyed in the range of 1.50–15.00 μg/ml for method A and 0.25–3.00 μg/ml for method B. The developed methods were subjected to the detailed validation procedure. The proposed spectrophotometric methods were applied for the determination of the methimazole in its pure form and in its pharmaceutical formulation. The percentage recoveries were found to be 100.82 % and 99.85 % in the pharmaceutical formulation for the two proposed methods, respectively.
 Conclusion: Both developed spectrophotometric methods, considered as green analytical chemistry, were found to be novel, highly selective and can be applied for the quality control of methimazole in its pure form and in its pharmaceutical formulation based on the simplicity, applicability of the parameters, accessibility of the reagents employed and reasonably low time of analysis.

Determination of Methimazole in Tablets Using Spectrophotometric Methods

This study describes the spectrophotometric quantification of methimazole in tablets using zero-order absorption spectrophotometry and first derivative spectrophotometry methods. In preliminary experiments, linearity range was found between 2.0-24.0 µg/mL in zero-order spectrophotometry and first-order derivative spectrophotometry. Calibration curves were obtained by measurements of the zero-order absorbances and their first derivative values at 260.0 and 269.0 nm for the zero-order spectrophotometry and first derivative spectrophotometry, respectively. The recovery and relative standard deviations were calculated as 103.3 % and 2.18 % for UV absorption spectrophotometry and 98.0% and 0.64% for first derivative spectrophotometry, respectively. The proposed techniques were used for the analysis of tablets preparations. The methods proposed in this study were verified by analyzing validation test samples containing methimazole. Determination results showed that the applied methods were found to suitable for the quantitation of the related drug.

A method for the determination of total and reduced methimazole in various biological samples

A simple, rapid, reproducible and sensitive method based on HPLC with ultraviolet detection was developed for the determination of methimazole (MMI) in animal tissues and plasma samples. Under the optimum experimental conditions, the calibration curves for MMI were linear in the tested range 0.5–20 mg kg−1 tissue sample (mg l−1 plasma) with correlation coefficients better than 0.99. The performance of the proposed method was tested for the determination of MMI levels in brain, liver, thyroid gland and plasma of MMI-treated hens, as well as in their eggs and embryos. The proposed method reduces time and simplifies the sample preparation procedure.

Determination of Methimazole on a Multiwall Carbon Nanotube Titanium Dioxide Nanoparticle Paste Electrode

A multiwall carbon nanotube titanium dioxide nanoparticle modified carbon paste electrode was used for direct determination of methimazole. The nanoparticles in the carbon paste increased the surface area of the electrode and improved the sensitivity by enhancing the peak current. The electrochemical behavior of methimazole on the modified electrode was investigated. Experimental variables such as pH and electrode composition were optimized. At the optimum pH 7.0 (universal buffer), the modified electrode had a linear dynamic range of 0.5 to 100.0 μmol L− 1 (0.1–11.4 ppm) with a limit of detection of 0.17 μmol L− 1 . The application of the electrode for the determination of methimazole in pharmaceuticals and blood serum was investigated.

Indirect Determination of Methimazole in Pharmaceutical Sample by Discoloration Spectrophotometry Using Fe (III)-Tiron System

A novel method for the indirect determination of methimazole by discoloration spectrophotometry using Fe (Ш)-tiron system has been established.The various effect factors on the determination of methimazole by discoloration spectrophotometry using tiron-Fe (Ш) system were investigated in detail. The results showed that by controlling pH=2.8,Fe (Ш) could be reduced to Fe (II) by hydrosulfuryl (-SH) in methimazole molecule,and then using tiron as chromogenic reagent of Fe (Ш),and the content of methimazole was determinated indirectly through determinating the surplus content of Fe (Ш) in the system.The maximum absorption wavelength of chromogenic system was 663 nm, good linear relationship was obtained between A and the concentration of methimazole in the range of 3.2~12.8μg·mL-1,the equation of the linear regression was A=-0.1849+57.277ρ (mg·mL-1),with a linear correlation coefficient was 0.9998.This proposed method had been successfully applied to determinate of methimazole in real pharmaceutical.

Indirect Spectrophotometric Determination of Methimazole Using Phenanthroline-Fe(II)

A novel method for the indirect determination of methimazole by spectrophotometry using phenanthroline-Fe(Ⅱ) has been established.The results showed that in acid medium, Fe(Ш) could be reduced to Fe(Ⅱ) by hydrosulfuryl(-SH) in methimazole molecule,and then using phenanthroline as chromogenic reagent of Fe(Ⅱ), and the content of methimazole was determinated indirectly through determinating the content of Fe(Ⅱ) by spectrophotometry. The various effect factors on the determination of methimazole by spectrophotometry using phenanthroline-Fe(Ⅱ) were investigated in detail.The maximum absorption wavelength of chromogenic system was 509 nm, good linear relationship was obtained between the absorbance and the concentration of methimazole in the range of 0.0016～0.0064 mg/mL,the equation of the linear regression was A = 0.1942 + 64.598ρ (mg•mL-1),with a linear correlation coefficient was 0.9995.This proposed method had been applied to determinate of methimazole in real pharmaceutical,and the results agreed well with those obtained by pharmacopoeial method.

A novel method for methimazole determination using CdSe quantum dots as fluorescence probes

A novel method has been developed for methimazole analysis based on the quenching of fluorescence emission from CdSe quantum dots by methimazole. Under optimum conditions, the calibration graph was linear over the range of 50 nM to 5 μM (r2 = 0.990). The limit of detection (S/N = 3) was 30 nM. The R.S.D. for ten determinations of 500 nM methimazole was 3.4%. The method was applied to determine methimazole in tablets and rat urine, and the results were satisfactory, i.e. consistent with those of gas chromatography–mass spectrometry. The possible cause of fluorescence quenching is due to the exchange of surface capping organic molecules of quantum dots induced by methimazole.

Determination of methimazole in urine with the iodine-azide detection system following its separation by reversed-phase high-performance liquid chromatography

The iodine-azide detection system to determine methimazole following its separation by RP-HPLC is described in this paper. The reaction between iodine and azide ions induced by methimazole was applied as a post-column reaction detection system. Neither extraction nor preconcentration of the sample was necessary. The methimazole standards added to normal urine show that the response of the detector, set at 350 nm (corresponding to unreacted iodine in the post-column iodine-azide reaction), was linear within the concentration range 2–10 nmol/mL of urine. The relative standard deviation values for precision and recovery within the calibration range were from 0.3 to 3.2% and from 97 to 102%, respectively. Limits of detection (LOD) and quantitation (LOQ) were 1 and 2 nmol/mL of urine, respectively. The method was applied to the separation and determination of patient urine samples and the analytical results were satisfactory.

Determination of Methimazole in Pharmaceutical Preparations using an HPLC Method Coupled with an Iodine-Azide Post-Column Reaction

A simple and reliable high performance liquid chromatographic (HPLC) method with iodine-azide post-column reaction as a detection system has been developed and validated for determination of methimazole in tablets. A chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile, water, and 2.5% sodium azide solution (pH 5.5) with isocratic elution (20:30:50, v/v/v). The detection is based on spectrophotometric measurement of the residual iodine (λ = 350 nm) from the post-column iodine-azide reaction induced by methimazole, after mixing an iodine solution containing iodide ions with the column effluent containing azide ions and methimazole. Obtained chromatograms for methimazole showed negative peaks as a result of the decrease in background absorbance. The method developed for methimazole was linear over the concentration range of 0.2–2 µmol L−1. The method is accurate and precise (relative standard deviation, R.S.D. < 4%). The detection limit (defined as S/N = 3) was 0.18 µmol L−1 (3.6 pmol injected amount) for the described compound. The elaborated method was applied to determine methimazole in tablets.

Determination of methimazole in urine by liquid chromatography

A liquid chromatography methodology is developed and validated for detection and quantification of methimazole in urine. The approach is based on derivatization with 2-chloro-1-methylquinolinium tetrafluoroborate, reversed-phase high-performance liquid chromatography (HPLC) separation of so formed methimazole 2- S-quinolinium derivative from other urine matrix components, followed by detection and quantification with the use of ultraviolet–visible detector. Neither extraction, nor preconcentration of the sample are necessary. The methimazole standards added to normal urine before derivatization step show that the response of the detector, set at 345 nm, is linear within the concentration range studied, that is, from 0.25 to 50 mg/l urine. The relative standard deviation values for precision and recovery within the calibration range were from 1.8 to 5.0% and from 95.7 to 103.3%, respectively. Lower limits of detection and quantitation were 0.15 and 0.25 mg/l urine, respectively.

Study of the British Pharmacopeia method on methimazole (thiamazole) content in carbimazole tablets

The analysis of carbimazole tablets in The British Pharmacopoeia, 1993, includes a quantitative thin layer chromatography (TLC) determination of methimazole. Repeated analysis of the same samples did not give similar results. The repeatability and reproducibility of the method was studied. It was proved that the residence time of the methimazole spot on the TLC plate is time dependent.

Determination of Methimazole and Carbimazole Using Polarography and Voltammetry

Abstract Anodic waves of methimazole (I) (1-methylimidazole-2-thiol) and carbimazole (II) (1-ethoxycarbonyl-3-methyl-2-thio-4-imidazoline) on mercury electrodes correspond to mercury salt formation. Both compounds form in the thiono form a soluble complex at pH < 6, compound (I) at higher pH-values a slightly soluble salt of the thiol form. Electrode processes involving the thiol form are complicated by adsorption. Oxidation at solid electrodes occurs only at potentials more than 0.5 V more positive. For compound (I) spectrophotometry indicated pKa=12.0 ± 0.2. By d.c. polarography in 0.1 M H2SO4 containing 10% ethanol the determination of both compounds is possible between 4 × 10− and 1 × 10−3 M, by differential pulse polarography between 1 × 10− and 1 × 10−4 M, by differential pulse voltammetry at HMDE between 5 × l0−7 and 6 × 10− M.

Determination of methimazole in plasma using gas chromatography--mass spectrometry after extractive alkylation.

A gas chromatography--mass spectrometry method for quantitation of the thyreostatic agent methimazole in plasma is described. The drug was transferred from the plasma sample and derivatized in one step by extractive alkylation. Either of two alkylating agents benzyl-chloride or pentafluorobenzyl bromide were used. Deuterium-labelled methimazole was used as internal standard. The precision of the method at the level of 5 ng methimazole per ml plasma was 6%.

Determination of Methimazole by Infrared Spectrophotometry

Abstract A method is described in which melhimazole is separated from tablet excipients by column chromatography on Celite 545 with chloroform as the eluant and then quantitatively measured and identified by infrared spectrophotometry. This method was studied collaboratively by 10 analysts; average recoveries from two simulated and two tablet mixtures ranged from 96.6% ± 1.0 to 101.1% ± 0.9. This method is recommended for adoption as official, first action.

The Determination of Methimazole by Infrared Spectrophotometry

Abstract A method for the determination of methimazole by column chromatography and infrared spectrophotometry was subjected to collaborative study in four district laboratories. Although the results were favorable, they were not sufficiently precise nor accurate to recommend the method for adoption. Further study of the method is recommended.