Thiamine In Pharmaceutical Preparations Research Articles

A new approach for automated liquid-liquid extraction in a sequential injection manifold.

A new approach for the implementation of liquid-liquid extraction in a sequential injection manifold is presented. The manifold consists of two syringe pumps and one multi-position valve. The use of a 30% MeOH/H2O (v/v) solution as the carrier, with isobutanol as the extractant, made it possible to avoid the problems associated with the different affinities of the organic and aqueous phases for Teflon tubing, and the formation of bubbles. The suitability of the proposed method was demonstrated by the determination of thiamine in pharmaceutical preparations and dietary supplements. Detection and quantification limits were estimated as 9 and 30μgL(-1), respectively. The repeatability was lower than 3% and the intermediate precision (3d) was lower than 7%. The sample throughput was 14 samples per h. The results were in agreement with a high-performance liquid chromatography-electrospray/mass spectrometry reference method.

Determination of Thiamine in Pharmaceutical Preparations by Reverse Phase Liquid Chromatography Without Use of Organic Solvent

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time (t0) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][PF6]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at t0. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.

A simple and sensitive analytical method for the determination of thiamine in pharmaceutical preparations

A simple and sensitive method for spectrophotometric determination of thiamine with leucocrystal violet was elaborated. Spectrophotometric quantification based on the following reaction sequence: thiamine was oxidized with potassium iodate(V) to the colourless product and a stoichiometric amount of iodide ions was formed. The latter reacted with the excess of iodate(V) ions in acidic medium, to form free iodine which oxidized leucocrystal violet to the crystal violet dye. The absorbance of the crystal violet dye formed was measured at pH 4.1 ± 0.1 and 589 nm. The measured absorbance obeyed Beer’s law over the thiamine concentration range 0.4-2.4 μg/mL. The linear regression coefficients were a = 0.3339, b = −0.0001, and r = 0.9998 (for the general form of the linear equation y = ax + b). The apparent molar absorptivity of the coloured compound was 1.12 × 105 L/mol cm for thiamine. The limit of detection and limit of thiamine determination were found to be 0.19 and 0.26 μg/mL, respectively. Optimum reaction conditions providing maximum and constant absorbance were optimized. The procedure was successfully used to the determination of vitamine B1 in pharmaceutical formulations. The obtained results were compared with those obtained by the method proposed by Polish Standard.

A Simple and Sensitive Analytical Method for the Determination of Thiamine in Pharmaceutical Preparations

A Simple and Sensitive Analytical Method for the Determination of Thiamine in Pharmaceutical Preparations

Fabrication and Applications of Silver Sulphide Based Ion Sensors

An electrochemical sensor based on the silver sulphide precipitate was fabricated in the laboratory and characterized by x-ray diffraction, SEM equipped with EDAX, and electrochemical techniques. Ion selective electrode (ISE) was found to be sensitive enough to sense the sulphide ion concentration from 10-1 to 10-5 M in alkaline medium. The change in electrode potential per decade change in sulphide ion concentration was found to be 31.5 mV at laboratory temperature indicating adherence of the ion selective electrode to Nernst’s equation. The sensor have been successfully used for the quantitative determination of thiamine in pharmaceutical preparations, hydrogen sulphide in cigarette smoke and determination of solubility products of sparingly soluble silver salts. A trace amount of hydrogen sulphide, a toxic gas, is present in the cigarette smoke. The quantitative estimation of hydrogen sulphide in cigarette smoke is a challenging task to analytical chemist. Hydrogen sulphide in cigarette smoke had been determined by absorbing the cigarette smoke in 0.1 M sodium hydroxide and the resulting solution was analyzed using silver sulphide based ion sensor by standard addition technique using modified Gran plot. The average amounts of hydrogen sulphide produced by a stick of cigarette in 8 different brands of Nepalese cigarette ware found to range from 0.0332 mg to 0.0766 mg. The sensitivity and reliability of these home made ion sensors were excellent and in par with commercial electrodes. For developing countries like Nepal, who can not afford to procure high cost commercial ion selective electrodes, these home made ion sensors are especially appealing since the sensor can be fabricated with ease from the materials that are readily available in the chemistry laboratory and the sensor is quite sensitive and gives reproducible results which are sufficiently accurate for the analysis with ion selective electrodes.

Determination of thiamine in pharmaceutical preparations by sequential injection renewable surface solid-phase spectrofluorometry.

Fluorometric determination of thiamine requires the conversion of the analyte to fluorescent thiochrome by hexacyanoferrate(III) oxidation in alkaline solution and the isolation of the produced thiochrome from the reaction medium by solvent extraction. It was observed that thiochrome could be concentrated and separated from the reaction medium by solid-phase extraction. The thiochrome sorpted on the surface of octadecyl-alklylated poly[styrene/divinylbenzene] (C18-PS/DP) microbeads emitted strong fluorescence upon excitation, the maximum excitation and emission wavelengths being 385 nm and 433 nm, respectively. Based on this observation, a sequential injection renewable surface solid-phase spectrofluorometry was developed for the determination of thiamine. A sequential injection system on-line coupled to a chip-based flow-through cell was employed to handle the chemical reaction, bead injection and discharging, and adsorption of thiochrome. Solid-phase fluorometric detection was realized by coupling the chip-based flow-through cell to a spectrofluorometer with a multistrand bifurcated optical fiber. Under the optimized condition, a detection limit of 0.03 microg ml(-1) was achieved at the sample throughput of 30 h(-1) and consumption of 1 mg C18-PS/DP microbeads for each run. Eleven runs of a 2 microg ml(-1) thiamine standard solution gave a relative standard deviation of 1.0%. The developed approach was successfully applied for the determination of thiamine contents in pharmaceutical preparations.

Electrochemical behavior of thiamine on a self-assembled gold electrode and its square-wave voltammetric determination in pharmaceutical preparations.

The electrochemical behavior of thiamine on a self-assembled electrode of L-cysteine (Cys/SAM/Au) has been investigated and Cys/SAM/Au can be used to detect thiamine using square-wave voltammetry (SWV). At pH 11.40 Britton-Robinson buffer, thiamine exhibits a well-defined anodic peak on Cys/SAM/Au. Under the optimized conditions, the anodic peak current of SWV was linear with the content of thiamine in the range of 1.1 x 10(-8) - 2.2 x 10(-6) mol/L; the detection limit was 5.5 x 10(-9) mol/L. The method was successfully applied to the determination of thiamine in pharmaceutical preparations.

Flow injection chemiluminescence determination of thiamine based on its enhancing effect on the luminol–hydrogen peroxide system

A new flow injection chemiluminescence (CL) method is proposed for the determination of thiamine, based upon its enhancing effect on the CL reaction of luminol with hydrogen peroxide in alkaline solution. The method allows the determination of thiamine within 0.05–8 μg ml −1 range with a detection limit (3 σ) of 0.01 μg ml −1. The relative standard deviation is 1.4% ( n=11, 0.5 μg ml −1 thiamine) and the sample throughput is about 90 samples h −1. The method was successfully applied to the determination of thiamine in pharmaceutical preparations.

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

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%.

Flow-Injection Fluorimetric Determination of Thiamine in Pharmaceutical Preparations

A new fluorimetric procedure for the determination of thiamine using flow injection analysis is proposed. The method is based on the derivatization reaction of the primary amine group with o-phthalaldehyde in the presence of 2-mercaptoethanol using fluorimetric detection. The calibration graph based on peak area was linear in the range 0.2–6 ng mL−1. The detection limit was close to 0.1 ng mL−1. The method was applied to the determination of the vitamin in commercial pharmaceutical preparations.

Highly sensitive electrochemical luminescence determination of thiamine

A highly sensitive electrochemical luminescence (ECL) method has been developed for the determination of thiamine based on electrochemically oxidizing thiamine with rhodamine B as a sensitizer. A weak ECL signal of thiamine was electrochemically generated on a platinum electrode in an alkaline solution and strongly enhanced in the presence of rhodamine B. Under the condition of 0.10 mM rhodamine B, 6 mM CTMAB and 0.36 M sodium hydroxide, the response to the concentration of thiamine is linear range from 0.1 μg ml −1 to 2 μg ml −1 and a detection limit of 0.08 μg ml −1 can be achieved. This method has been successfully applied to the determination of thiamine in pharmaceutical preparations. The energy transfer ECL scheme is also postulated.

Indirect spectrophotometric determination of thiamine in pharmaceutical preparations.

An indirect, sensitive spectrophotometric method for the assay of thiamine is described. The procedure is based on the formation of a mercaptide by thiamine, with a known excess of silver ions in a buffered medium of pH 9.0 +/- 0.1. The unreacted silver ions are determined by the formation of an ion-pair complex with 1,10-phenanthroline and 2,4,5,7-tetrabromofluorescein, which shows an absorption maximum at 550 nm. The absorbance is found to decrease linearly with increasing concentrations of thiamine, which is corroborated by the calculated correlation coefficient value of -0.998. The system obeys Beer's law for 0-25 micrograms of thiamine in an overall aqueous volume of 10 ml. The molar absorptivity and relative standard deviation (RSD) were calculated to be 7.8 x 10(4) l mol-1 cm-1 and 2.5% (n = 10), respectively. The proposed method was applied successfully to the determination of thiamine in pharmaceutical preparations. The reliability of the assay was established by parallel determination by the standard thiochrome method and recovery studies.

Kinetic study of N-bromosuccinimide reactions and kinetic determination of pyridoxine using a bromide-selective electrode

The bromide released by the alkaline hydrolysis of N-bromosuccinimide and its reactions with bromide, pyridoxine and thiamine have been studied potentiometrically using a solid-state bromide-selective electrode to monitor the consumed or produced bromide ion. Potential—time indications are obtained using a microcomputer-controlled potentiometric system. The overall rate constants and the activation energies have been calculated. A kinetic—potentiometric procedure for the determination of pyridoxine in the presence of thiamine in pharmaceutical preparations, based on its reaction with N-bromosuccinimide, is presented.

Determination of thiamine in pharmaceutical preparations by thin-layer chromatography.

Thin-layer chromatography has been applied to the selective determination of thiamine in pharmaceutical preparations as it enables the thiamine to be separated from its decomposition products and other ingredients. Coated plates of silica gel G and the solvent mixture chloroform-ethanol (98 per cent.)-water (50 + 25 + 1) were used. The spots of thiamine were localised by viewing under ultraviolet light, scraped off the plate, extracted with 2 N hydrochloric acid and the solution was measured spectrophotometrically at 246 nm.

Automated Determination of Thiamine (Vitamin B1) in Pharmaceutical Preparations

Abstract The chemical principles used for the determination of thiamine in pharmaceutical preparations by the official USP and AOAC methods were adapted to an automated flowthrough analyzer. The system could analyze 20 samples (including blanks) per hour. Thiamine extracts from 12 different multivitamin preparations were analyzed by one analyst on 5 different days by the automated method and the AOAC method. Both methods yielded comparable values for 10 of the preparations. The thiamine content of 2 preparations containing liver extract was found to be about 9% higher by the automated method than by the AOAC method. Further analysis of other samples of these 2 preparations containing liver extract showed that chromatography on Decalso did not change the results obtained by the automated method, but raised the results obtained by the manual method to a level comparable to the automated method. The AOAC method showed a tendency for a slightly higher reproducibility of assays.

Characterization and Applications of Silver Sulphide Based Membrane Electrodes

The polycrystalline materials obtained by co-precipitation of silver sulphide and appropriate silver halide are used to prepare silver sulphide based membrane electrodes selective to the silver, chloride, bromide, iodide, and sulphide ions. The powder materials are characterized by x-ray diffraction, SEM equipped with EDAX. These membrane electrodes are found to give Nernstian response with the appropriate ions in the concentration range from 1x10-1 to 1x10-5 M. The performance of these home made electrodes is at par with the commercial electrodes. The electrodes have been successfully used for the quantitative determination of chloride, bromide iodide, silver, and sulphide ions and also for the determination of thiamine in pharmaceutical preparations. For developing countries like Nepal, who can not afford to procure high cost commercial ion selective electrodes, these home made ion selective electrodes are especially appealing since the electrode can be fabricated with ease in low cost and the electrode is well behaved and sufficiently accurate for the analysis with ion selective electrodes. Key words: Ion selective electrode; Home made ion selective electrode; Silver sulphide; Thiamine; Vitamin B1. DOI: 10.3126/sw.v7i7.3818 Scientific World Vol.7(7) 2009 pp.19-23

Methods for micro- and semi-micro determination of thiamine in pharmaceutical preparations.

Methods for micro- and semi-micro determination of thiamine in pharmaceutical preparations.

Absorptiometric Determinotion of Thiamine by Thiochrome Reaction (II) : Determination of Thiamine in Pharmaceutical Preparations

Absorptiometric Determinotion of Thiamine by Thiochrome Reaction (II) : Determination of Thiamine in Pharmaceutical Preparations

The Chemical Determination of Thiamine in Pharmaceutical Preparations

The Chemical Determination of Thiamine in Pharmaceutical Preparations