Spectrophotometric determination of vitamin B1 in dosage forms using drugs compounds as reagents by normal and reverse flow injection methods

Background: Thiamine hydrochloride (THY), also known as vitamin B1, is a water soluble vitamin usually found in food, and considered as a dietary supplement and treatment in case of vitamin deficiency for example in malabsorption and chronic diarrhea. Objective: Rapid, green and sensitive methods for the assay of vitamin B1 (thiamine hydrochloride, THY) in pharmaceutical forms, using normal and reverse flow injection manifolds and sulfonamide drugs as green and safe reagents were reported. Sulfamethoxazole and sulfadimidine drugs were used rather than toxic and expensive reagents. Methods: nFIA and rFIA manifolds were used for automated the reaction of THY with diazotized sulfamethoxazole (DSMZ) and diazotized sulfadimidine (DSDM) in alkaline medium respectively. The absorbance of the resultant red-orange azo dyes was monitored spectrophotometrically at λmax 494 and 496 nm for both methods respectively. Results: The linearity of the suggested methods was in the ranges 2–80 µg/mL (LOD 0.69 µg/mL, % RSD 0.32, n=6) for nFIA method and 0.5-70 µg/mL (LOD 0.29 µg/mL, %RSD 0.85, n=6) for rFIA. Sampling frequency was 84 and 51 injections per hour for nFIA and rFIA methods respectively. Chemical and physical variables for both methods were studied carefully. Conclusion: Both flow injection modes were effectively applied in assay of THY in its pharmaceutical forms. The results were compared with those of standard pharmacopeia method and the statistical analysis indicated insignificant differences in accuracy and precision between the methods.

Charge Transfer Spectrophotometric Determination of Metronidazole in Pharmaceutical Formulations by Normal and Reverse Flow Injection Analysis Coupled with Solid-Phase Reactor Containing Immobilized FePO4

Two rapid, simpleand sensitive flow injection methods were developed for the estimation of metronidazole (MRZ) in pharmaceutical formulations. The proposed methods were based on charge transfer reaction between metol (N-methyl-p-aminophenol sulfate) as a π-acceptorand reduced MRZ as an n-donor to produce a blue colored chargetransfer complex. Method A depends on the reaction of reduced MRZ with metol (MT) in the presence of NaIO4 using two lines manifold to form blue colored product exhibiting absorption maxima at 700 nm.While method B depends on charge transfer reaction of reduced MRZ with MT in presence of a solid phase reactorcontainingfixedFePO4 on cellulose acetateusing reverse flow injection manifold to form a blue colored productwhich was measured spectrophotometrically at690 nm.Various experimental parameters for both methods were studied. Beer's law was obeyed in the ranges of2.5-200 and 2.5-150 μg mL-1,with r2 of 0.9995 and 0.9972;whilethe detection limit values were2.53 and 2.12μg mL-1 for methods A and B, respectively. Both of the suggested methods were successfully applied for the estimation of MRZ in commercial formulations. The results of the developed methods were compared with those obtained by the British pharmacopeia method, showinghigh accuracy and precision.

Spectrophotometric and Reverse Flow Injection Method Determination of Nitrazepam in Pharmaceuticals Using O-Coumaric Acid as a New Chromogenic Reagent

A spectrophotometric- reverse flow injection analysis (rFIA) method has been proposed for the determination of Nitrazepam (NIT) in pure and pharmaceutical preparations. The method is based upon the coupling reaction of NIT with a new reagent O-Coumaric acid (OCA) in the presence of sodium periodate in an aqueous solution. The blue color product was measured at 632 nm. The variation (chemical and physical parameters) related with reverse flow system were estimated. The linearity was over the range 15 - 450 µg/mL of NIT with detection limits and limit of quantification of 3.425 and 11.417 µg mL-1 NIT,respectively. The sample throughput of 28 samples per hour was achieved. Suggested method was successfully applied for the determination of NIT in its dosage forms.

Determination of Bendiocarb Insecticide by Reverse Flow Injection Analysis Using a Solid-Phase Reactor Containing Micro PbO2, Nano PbO2 and Grafted SiO2 - PbO2 Immobilized

Bendiocarb (BEN) is an acutely toxic carbamate insecticide which used in public places and agriculture, it is also effective against a wide range of nuisance and disease vector insects. A new rapid and sensitive reverse flow injection spectrophotometric procedure coupled with on-line solid-phase reactor is designed in this article for the determination of BEN in its insecticidal formulations and water samples, by using three different solid-phase reactors containing bulk PbO2 (B-SPR), PbO2 nanoparticles (N-SPR) and grafted nanoparticles of SiO2-PbO2 (G-SPR) immobilized on cellulose acetate matrix (CA). This method of oxidative coupling is based on alkaline hydrolysis of the BEN pesticide, and then coupled with N,N dimethyl-p-phenylenediamine sulphate (DMPD) to give a blue color product which measured at λmax 675 nm. It worth to mentioned that under optimal conditions, Beer’s law is obeyed in the range of 1-175 μg mL-1 for B-SPR and 0.25-70 μg mL-1 of BEN for both N-SPR and G-SPR respectively within limit of detection (LOD) of 0.931, 0.234 and 0.210 μg mL-1 for B-SPR N-SPR and G-SPR respectively. The surface methodology of the solid phase was also investigated by using atomic force microscopy.

DETERMINATION OF NITRAZEPAM IN PHARMACEUTICAL PREPARATIONS USING SOLID-PHASE REACTOR - REVERSE FLOW INJECTION ANALYSIS

Objective: A simple and fast reverse flow injection system including a solid-phase reactor containing PbO2 with spectrophotometric detection was suggested for the determination of nitrazepam (NIT) in pharmaceutical tablets.Methods: The method was based on oxidation of the reagent (phloroglucinol) with PbO2 immobilized in a polymeric matrix which was then coupled with reduced NIT in aqueous medium. The pink-colored product was measured at 530 nm.Results: The calibration graph was linear over the range of 50–400 μg/mL with a relative standard deviation of <2% (n=29) and a sample throughput of 48 samples per hour. The variables of the solid-phase reactor such as composition, particle size, and length of the reactor were studied. The chemical and physical parameters, which affect the reverse flow method, were also studied.Conclusion: The oxidation reactor engaged with a flow system was successfully applied for the determination of NIT with good sensitivity and precision.