Electrochemical preparation of a molecularly imprinted polypyrrole modified pencil graphite electrode for the determination of phenothiazine in model and real biological samples.

Pharmaceuticals can be classified into inorganic, organic compounds as well as excipients. The need to have a readily adaptable method for the quality control of these compounds has led to the development of a wide range of reactions and procedures. Majority of these pharmaceuticals lack adequate chromophores which can permit analysis at wavelength regions beyond the non‐ specific UV‐region of the electromagnetic spectrum. Thus derivatization reactions are carried out to convert these pharmaceuticals to readily determinable compounds whose properties and concentrations can be related to the original compound. An avalanche of reaction has been reported in the literature for the assay of pharmaceuticals. This paper presents an overview of these reactions. The need to have simple methods for the analysis of pharmaceuticals, in spite of the improvement in modern‐day technology, will continue to make these derivatization methodologies relevant in the quality control of these compounds especially in poor‐resource economies.

/pdf/chemical-derivatization-methodologies-for-uv-visible-1lq59w8wjx.pdf

Chemical derivatization methodologies for uv-visible spectrophotometric determination of pharmaceuticals

https://cyberleninka.org/article/n/21382.pdf

Spectrophotometric determination of carbamazepine and mosapride citrate in pure and pharmaceutical preparations

A new spectrophotometric sequential injection analysis (SIA) method for the assay of olanzapine in pharmaceutical formulations was optimized by the factorial design and the response surface approaches. The method was based on the oxidation of olanzapine by an excess amount of permanganate in sulfuric acid media. The reduction of permanganate was spectrophotometrically detected at 570 nm. The 23 full factorial design was adopted for the optimization of permanganate concentration, sulfuric acid concentration and flow rate. The method was validated based on the IUPAC guidelines. Real pharmaceutical samples were subjected to the proposed SIA method and the results were in satisfactory agreement with those obtained by a previous spectrophotometric method. The full-automation of SIA empowered the proposed method with high repeatability (RSD 1.74%, n = 7) and intermediate-precision (RSD 2.53%, n = 5). Additionally, both automation and miniaturization offered high sampling frequency (26 samples/h). Furthermore, the employment of chemometric optimization enhanced sensitivity of the method with limits of detection and quantification of 1.07 and 3.57 mg/L, respectively. Comparing with previous olanzapine assay methods, which employing conventional analytical techniques, the new SIA method is inexpensive in terms of instrumentation, consumption of reagents and samples as well as effort and manpower. The SIA method is also safer for handling solutions and for the environment.

Factorial design and response surface optimization of spectrophotometric sequential injection analysis of olanzapine formulations

Objective: Develop a simple, rapid, sensitive, selective, and accurate method for the spectrophotometric determination of metoclopramide hydrochloride (MCP-HCl) in bulk and dosage forms. Methods: The method is based on diazotization of primary amine group of (MCP-HCl) with sodium nitrite and hydrochloric acid followed by coupling with 2,5-dimethoxyaniline (DMA) in aqueous mildly acidic medium to form a stable orange azo dye, showed a maximum absorption at 486 nm. Results: Beer's law was obeyed over the concentration range of 0.1-12 ppm with a molar absorptivity 4.55×104 L.mol-1.cm-1. Sandell’s sensitivity, limit of detection (LOD), and limit of quantification (LOQ) are 0.008 μg.cm-2, 0.016 ppm, and 0.054 ppm respectively, the recoveries range 99.15100.80%. Conclusions: The method has been successfully applied to the determination of (MCP-HCl) in its pharmaceutical preparations tablet, syrup, injection and drop with very good recoveries.

Spectrophotometric determination of metoclopramide hydrochloride in bulk and pharmaceutical preparations by diazotization-coupling reaction

A simple, accurate, and sensitive spectrophotometric method for the determination of promethazine hydrochloride (PMH), prochlorperazine maleate (PCPM), trifluoperazine hydrochloride (TFPH), trimeperazine tartrate (TMT), fluphenazine dihydrochloride (FH), and trifluopromazine hydrochloride (TPH) is described. The method is based on the oxidation of the studied drugs by a known excess of chloramine-T in a hydrochloric acid medium and subsequent determination of the unreacted oxidant by interacting it with iodide in the same acid medium. Liberated iodine subsequently reacts with starch to form a stable starch-iodine complex. The reacted oxidant corresponds to the drug content. The colored complex exhibits a maximum absorption at 590 nm. The apparent molar absorptivity and Sandell sensitivity values are in the range 4.07 × 104 − 1.18 × 105 L/mol cm and 45.00−95.00 ng/cm2, respectively. The proposed method has been applied to the assay of phenothiazine drugs in pure and dosage forms. The reliability of the analysis was established using parallel determination by the reference method.

Spectrophotometric determination of some phenothiazine drugs using chloramine-T-iodine-starch

Two simple and sensitive spectrophotometric methods (A and B) have been described for the determination of ascorbic acid. Method A is based on the oxidation of ascorbic acid (AA) by known excess of Se(IV) in hydrochloric acid medium and subsequent determination of unreacted Se(IV) by reacting it with iodide in the same acid medium to liberate iodine, which react with starch to form a stable blue coloured iodine-starch complex, which shows maximum absorbance at 590 nm. Method B is based on the oxidation of ascorbic acid (AA) by known excess of Cr(VI) in sulphuric acid medium and the determination of unreacted Cr(VI) with diphenyl carbazide (DPC) under the same acidic medium to produce a stable red-violet coloured species, which shows a maximum absorbance at 550 nm. The reacted oxidants (in methods A and B) correspond to the AA content. The apparent molar absorptivity values are found to be 1.627×104 and 1.641×104 L mol-1 cm-1 for methods A and B, respectively. The proposed methods are simple, sensitive and suitable for the routine analysis of AA in pharmaceutical formulations and in real samples.

/pdf/sensitive-spectrophotometric-methods-for-the-determination-50qq52q8no.pdf

Sensitive Spectrophotometric Methods for the Determination of Ascorbic Acid

A simple, sensitive and selective spectrophotometric method for the detn. of metoclopramide hydrochloride (MCP) and dapsone (DAP) in both pure and dosage forms is described. The method is based on the diazo - coupling reaction of the studied drugs with a new coupling agent, imipramine hydrochloride, in an acid medium. The resulting violet - colored azo dyes exhibit max. absorption at 570 nm for both MCP and DAP. All variables were studied in order to optimize the reaction conditions. The method is suitable for the detn. of MCP and DAP in the presence of other ingredients that are usually present in dosage forms and the recoveries were obtained in the range of 99.5-100.5%. The results are reproducible with an accuracy of Â± 1 %, and the validity of the method was tested against ref. method. [on SciFinder(R)]

Sensitive spectrophotometric determination of metoclopramide hydrochloride and dapsone in bulk sample and dosage forms.

Two simple and sensitive spectrophotometric methods (M1 and M2) for the determination of mosapride in pure and in pharmaceutical preparations are described. These methods are based on the interaction of diazotized mosapride (MSP) couples with chromotropic acid (CTA) [M1] in alkaline medium and diphenylamine (DPA) [M2] in acidic medium. The resulting azo-dyes exhibit maximum absorption at 560 nm and at 540 nm for methods M1 and M2, respectively. All variables were studied in order to optimize the reaction conditions. No interferences were observed from excipients, and the validity of the each method was tested against reference method.

/pdf/spectrophotometric-determination-of-mosapride-in-pure-and-3vnl38xaua.pdf

Spectrophotometric determination of mosapride in pure and pharmaceutical preparations

Highly sensitive and selective spectrophotometric methods (A and B) were developed for the determination of micro amounts of olanzapine (OLZ). Method A (direct method) is based on the oxidation of olanzapine with a known excess of iodine monochloride (ICl) in an acidic medium. Under the same condition, thymol blue was iodinated by unreacted ICl, and the absorbance of uniodinated thymol blue was measured at 536 nm. The decrease in ICl concentration is a measure of drug concentration. In method B (indirect method), oxidation of OLZ by a known excess of Ce(IV) in sulfuric acid medium followed by the reaction of unreacted Ce(IV) with leuco crystal violet (LCV) to crystal violet (CV), which is measured in an acetate buffer medium ( pH 4.9) at 580 nm. These methods obey the Beer's law in the concentration range of 0.2-1.6 µg mL-1 (method A) and 0.1-1.4 µg mL-1 (method B). The developed procedures have been successfully applied to the determination of OLZ in pure and in dosage forms. The results exhibit no interference from the presence of excipients. The reliability of the methods was established by parallel determination of OLZ against the reference method.

/pdf/highly-sensitive-spectrophotometric-methods-for-the-341l5nz60v.pdf

Highly sensitive spectrophotometric methods for the determination of olanzapine

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