ABSTRACT
The present work deals with the development and validation of a stability indicating HPLC-diode arrayfluorescence method (HPLC-DAD-FL) for the determination of meclofenoxate hydrochloride (MFX) and its hydrolytic degradation product p-chlorophenoxyacetic acid (pCPA). The chromatographic separation was achieved using a reversed phase Zorbax Eclipse SB-C18 column (250 x 4.6 mm i.d., 5 μm particle size), a mobile phase composed of 20 mM phosphate buffer, adjusted to pH 3, and acetonitrile (65: 35, v/v); and isocratic flow at a rate of 1 mL min-1.The detection was carried out using a diode array detector (DAD) at 225 nm and a fluorescence detector (FL) at λex/em, 225/310 nm. The linear dynamic ranges were found to be 0.5-100 and 0.25-100 μgmL-1 (DAD); and 0.05-20 and 0.01-8 μg mL-1 (FL) for MFX and pCPA, respectively. Detection limits were 0.05 and 0.04μgmL-1 (DAD); and 0.005 and 0.001 μg mL-1 (FL) for MFX and pCPA, respectively. The investigated method was applied to the assay of MFX in tablets and vials dosage forms and also to the kinetics stability studies of MFX in different media. Further, the dissolution rate of the tablets was examined using the proposed method.
ABSTRACT
An analytical method for simultaneous determination of five quinolones in spicy soup was developed. Spicy soup samples were firstly extracted by EDTA-Mcllvaine buffer at pH 4, then purified and concentrated by a novel Packed fiber solid phase extraction ( PFSPE ) coulumn. The extracted liquid supernatant was loaded onto the column, rinsed with water, and then eluted with 2% ammoniated methanol. The mobile phase was methanol-water-phosphoric acid (25:75:0. 1, V/V, adjusting the pH to 2. 8 with triethylamine) . These analytes were quantified by high performance liquid chromatography-fluorimetric detector( HPLC-FLD) at excitation and emission wavelength of 280 nm and 450 nm respectively. Recoveries of spiked quinolone antibiotics in spicy soup were from 72 . 1% to 110 . 3% with intraday relative standard deviation (RSD) between 1. 6% and 4. 3% and inter-day RSD from 2. 0% to 4. 3%. Limit of detection (LOD) and limit of quantitation(LOQ) were from 1. 2 to 5. 4 μg/L and from 3. 9 to 18 μg/L, respectively. The method could be applied to determine the quinolones in spicy soup.
ABSTRACT
A high performance liquid chromatographic method with fluorimetric detector was developed for the simultaneous determination of three sulfonamides in vegetable samples. Vegetable samples were extracted with methanol for three times, and then the combined extracts were evaporated to dryness under reduced pressure at 45 ℃. The residue was dissolved in 0.1 mol/L HCl and the analytes were derivatized with fluorescamine. The chromatographic separation was performed on an ODS column with a gradient elution program using mobile phases based on mixtures of acetonitrile and 0.5% acetic acid aqueous solution. The derivatized compounds were detected with fluorimetric detector. The limit of detection was 1.02-1.29 μg/L and the limit of quantification was 3.4-4.3 μg/kg(fresh weight, F.W.) for three sulfonamides in vegetable. The average recoveries were higher than 87%, inter and intra RSDs were lower than 10% for all samples spiked with 0.2-1.0 μg/g of sulfonamides. The proposed method has been applied to the analysis of vegetables sold in Hefei markets. The result indicated that 3 SAs were found at different degree in the practical vegetable samples with the total concentrations between 0.0726-0.3709 μg/g(F.W.).
ABSTRACT
An analytical method for the simultaneous determination of four quinolones in soil was developed. Soil samples were extracted by a mixture of 50% magnesium nitrate and 10% ammonia(96∶ 4, V/V)with an ultrasonic-assisted extraction, then purified and concentrated by HLB cartridge, and eluted with acetonitrile and 0.067 mol/L phosphoric acid(5∶ 1, V/V). Using acetonitrile and 0.067 mol/L phosphoric acid(pH=2.5) as the mobile phase, these analytes were quantificated by HPLC(fluorimetric detector) at excitation and emission wavelength of 280 nm and 450 nm respectively. The detective limits for four quinolones in soil were from 0.58 to 0.03 g/kg. The recoveries were 60.4% to 99.3% for soil samples. The method was successfully applied to determine the quinolones in soil samples from vegetable fields. Four quinolone compounds were detected to a different extent with total amounts of quinolones ranged from 27.84 to 129.26 μg/kg.