No abstract

An HPLC-PDA method was developed and validated for the determination of hydrochlorothiazide in bulk and pharmaceutical formulation. The method was optimized selecting chromatographic conditions of 50 : 50 acetonitrile : water, Inertsil5 column (ODS-3 250 mm × 4.6 mm 5 m), 20 L injection volume, flow rate of 1 mL/min at ambient temperature (30 ∘ C), and 272 nm. Another column of C 18 Zorbax5 (Eclipse Plus, 4.6 × 250 mm, 5 m) was tested showing no big difference in the method results. The method was validated giving good precision (RSD% < 1), acceptable linearity ( 2 ≥ 0.9978), and low LOD and LOQ (0.5 and 1.7 g/mL, resp.) on both columns. Successful application on pharmaceutical dosage tablet form gave high recovery of 99.93%. The method was compared with official BP and other reported methods. The proposed method is economic, simple, and rapid and hence can be employed for routine analysis in quality control laboratories. Materials and Methods2.1. HPLC System. Analytical HPLC system comprised a Flexar autosampler injector-no Peltier, Flexar Binary pump,

1,4-Dimethylnaphthalene (1,4-DMN) is effective sprout suppressant used in potato stores in many countries in the world. High residue levels of this compound on the potatoes and in other environmental samples are considered for human health and environmental risks. Determination of the residue requires specific analytical methods to be developed and validated. In this study, HPLC-UV was selected for validating a separation method based on reversed phase for the analysis of 1,4-DMN using 2-methylnaphthalene (2-MeN) as internal standard testing three HPLC systems. Under the same chromatographic conditions, all three systems achieved good separation on a Jones column (Hypersil ODS 5 μm, 250 mm × 4.6 mm) at ambient temperature isocratically using 70% acetonitrile as mobile phase at a flow rate of 1.5 mL min−1, 20 μL injection volume, a run time of 10 min, and a detection wavelength of 228 nm. All three systems showed high precision, good linearity, and low limit of detection (LOD) and quantification (LOQ); particularly, the SpectraSERIES UV100-autosampler system offered lower values of LOD (0.001–0.004 μg mL−1) and LOQ (0.002–0.013 μg mL−1) for both compounds. This system can be used for the quantitative determination of 1,4-DMN residue in potato and environmental samples.

This study involves a development method for spectrophotometric analysis of sulfamethoxazole (SMZ) with vanillin reagent in acidic medium. The reaction mechanism was proposed by Schiff's base reaction of the amine group in SMZ with the carbonyl group in vanillin. The spectrum of SMZ complex showed high absorbance at 399.09 nm following the Beer–Lambert law in the concentration levels ranging from 5 to 80 µg.mL-1 with good sensitivity. The stability constant of the product was determined. The values of relative standard deviation (≤ 6.63) and recovery (> 98.73%) indicated a reasonably precise and accurate method with a good limit of detection and quantification. The present method was compared with other spectrophotometric methods in the literature. The procedure of the method showed to be simple since no need for temperature control and solvent extraction. The suggested method was used to determine of SMZ in commercial pharmaceutical drops and compared with the certified method.