Mixture Of Buffer pH Research Articles

Analytical Method Development and Validation for Simultaneous Estimation of Memantine and Donepezil in Pharmaceutical Dosage form by RP-HPLC

A simple, precise and accurate method was developed for the simultaneous estimation of memantine and donepezil. The chromatogram was performed with a Thermo scientific C18 (150 x 4.6mm, 5µm). At a flow rate of 1ml/min, mobile phase used is 70:30% v/v mixture of buffer pH 4.5 and ACN. The best detection wave length for memantine and donepezil was at 265nm. The retention time was 2.325 and 3.088minutes. Assay results of 100.87 percent and 99.31 percent, %RSD values are below 2 and linearity R2 values are 0.999 for both the drugs. The strategy appears to have been compact and worth, and it is proper for everyday Quality Control Estimates in Industry sections since Maintenance Times are Diminishing and that Gathered Code was reducing. Thus, the developed method was validated according to 1CH guidelines for routine analysis of the sample.

DEVELOPMENT OF REVERSE PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR SIMULTANEOUS ESTIMATION OF SILDENAFIL CITRATE AND DEPOXETINE HYDROCHLORIDE IN PHARMACEUTICAL FORMULATION

Simple, accurate and precise reversed-phase high-performance liquid chromatographic (RP-HPLC) methods for simultaneous estimation of sildenafil citrate (SIL) and depoxetine hydrochloride (DAP) in combined tablet dosage form have been developed and validated. The RP-HPLC method uses a Shimadzu – 1800, Software Version – UV Prob 2.33 with BDS hypersil C18 column and mixture of Buffer pH 4.0 and ACN in the ratio of 40:60 as the mobile phase. The detection was carried out using a UV–Visible Detector: Shimadzu SPD–20AT diode array detector set at 229 nm. Linearity of chromatographic method was found in the concentration range of 50 - 150 ppm for Sildenafil and 30 - 90 ppm for Dapoxetine respectively. % recovery for SIL was found to be 99.3 – 100.5 %, while for DAP it was found to be in range of 99.1 – 100.4 % in HPLC methods respectively. Both methods may be used for routine analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically. KEYWORDS: Linearity, Validation, HPLC, Sildenafil, Depoxetine.

Solid phase fractionation techniques for segregation of red cabbage anthocyanins with different colorimetric and stability properties

Red cabbage anthocyanin extract contains cyanidin derivatives as various non-, mono-, and di-acylated forms capable of expressing various colors from red to blue. The objective of this study was to develop a simple solid phase extraction (SPE) method to fractionate and segregate di-acylated anthocyanins which have greater stability and more desirable blue colorimetric properties. Two different sorbents with different separation chemistries: SCX (Strong Cation Exchange) and C18 sorbents were evaluated. Red cabbage anthocyanins were fractionated and eluted from the SCX cartridge using combinations of different buffers (pH 6–8) and MeOH (20–70%) or eluted from the C18 cartridge using different percentages of acidified (0.01% HCl) MeOH (30–100%) or EtOH (10–100%). With SCX SPE, washing the loaded pigments with a mixture of buffer pH 6 + 20% MeOH followed by elution with buffer pH 8 + 70% MeOH proved most effective in segregating the di-acylated pigments; however, some anthocyanins were permanently retained by the sorbent. When using the C18 cartridge, washing bound pigments with 32% MeOH or 18.5% EtOH and eluting with 100% alcohol respectively resulted in high (> 93%) recovery of di-acylated pigments. The C18 cartridge with MeOH eluent was the most effective for isolating the target di-acylated red cabbage anthocyanins that produced desirable blue colors with increased stability.

Glutathione conjugation of chlorobenzylidene malononitriles in vitro and the biotransformation to mercapturic acids in rats.

The glutathione conjugation of 2-chloro-, 3-chloro-, 4-chloro- and 2,6-dichlorobenzylidene malononitrile (chloroBMNs) was investigated in vitro. In incubation mixtures containing rat liver cytosol (9000 g), the decrease in the initial amount of glutathione due to the various chloroBMNs ranged from 40 to 60% and occurred both enzymatically and spontaneously at physiological conditions (37 degrees C, pH 7.4). 2,6-DichloroBMN, however, depleted glutathione largely spontaneously (38 +/- 3%). The steric hindrance of the two chlorosubstituents probably plays an important role during the glutathione-S-transferase catalyzed reaction. The hydrolysis of the chloroBMNs to the corresponding chlorobenzaldehydes and malononitrile was studied in a mixture of buffer pH 7.4 and ethanol. The rate of hydrolysis of 2,6-dichloroBMN was slower than those of the related chloroBMNs. This means that 2,6-dichloroBMN will be the most stable compound in the presence of water. Only IP administration of 2-chloroBMN (CS) to adult male Wistar rats gave enhancement of urinary thioether excretion. A thioether could be isolated and was identified as the N-acetyl-S-[2-chlorobenzyl]-L-cysteine. The quantity of this benzylmercapturic acid in the urine of rats amounted to 4.4% dose (0.07 mmol/kg, n = 12). After IP administration of 2-chloro- and 3-chlorobenzaldehyde to rats benzylmercapturic acid excretion in the urine was found to be 7.6 and 1.1% of the dose, respectively. Administration of the related 4-chloro- and 2,6-dichlorobenzaldehyde, however, resulted in no urinary mercapturic acid excretion.(ABSTRACT TRUNCATED AT 250 WORDS)