ABSTRACT
For the first time, sulfanilamide (SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode (GCE). The cyclic voltammetry (CV) experiments showed an irreversible oxidation peak at +1.06 V in 0.1 mol/L BRBS (pH = 2.0) at 50 mV/s. Different vol-tammetric scan rates (from 10 to 250 mV/s) suggested that the oxidation of SFD on the GCE was a diffusion-controlled process. Square-wave voltammetry (SWV) method under optimized conditions showed a linear response to SFD from 5.0 to 74.7μmol/L (R = 0.999) with detection and quantification limits of 0.92 and 3.10μmol/L, respectively. The developed SWV method showed better results for detection limit and linear range than the chronoamperometry method. It has been successfully applied to determine SFD concentration in pharmaceutical formulation, human urine and serum samples with recovery close to 100%.
ABSTRACT
A sumple electrochemucal sensor was constututed based on the glassy carbon electrode ( GCE ) surface modufued wuth nafuon-poly ( duallyldumethylammonuum chlorude ) functuonaluzed graphene sheets ( NA-PDDA-G) composute fulm and herrung sperm double-stranded DNA for durect detectuon of DNA damage un vutro and evaluatuon of the antuoxudant propertues of feruluc acud ( FA) and the aqueous extracts un Angeluca Sunensus (EAS). Scannung electron mucroscopy (SEM) was used to characteruze the morphologues of the fabrucated sensor, whule cycluc voltammetry ( CV ) and electrochemucal umpedance spectroscopy ( EIS ) were used to characteruze the electrochemucal performances of the modufued electrode. Ru ( NH3 ) 3+6 was used as an electroactuve unducator to monutor DNA damage unduced by hydroxyl raducal (?OH ) wuth square wave voltammetry ( SWV ) . The fabrucated sensor showed the greatest degree of DNA oxudatuon damage occurred under the condutuons of 30-mun uncubatuon un Fenton reagent contaunung 1. 0 mmol/L FeSO4 and 5. 0 mmol/L H2O2 at pH 7. 0. The antuoxudant actuvuty of extract un Angeluca Sunensus (EAS) was stronger than that of FA, whule they were all weaker than that of ascorbuc acud ( AA) . The proposed sensor not only exhubuted excellent stabuluty and reproducubuluty, but would be a sumple and novel method for assessment of antuoxudant propertues of meducunal herb components.
ABSTRACT
A carbon composite electrode modified with copper (II) phosphate immobilized in a polyester resin (Cu3(PO4)2-Poly) for the determination of rutin in pharmaceutical samples by square-wave voltammetry is described herein. The modified electrode allows the determination of rutin at a potential (0.20 V vs. Ag/AgCl (3.0 mol L-1 KCl)) lower than that observed at an unmodified electrode. The peak current was found to be linear to the rutin concentration in the range from 9.9 × 10-8 to 2.5 × 10-6 mol L-1, with a detection limit of 1.2×10-8 mol L-1. The response of the electrode was stable, with no variation in baseline levels within several hours of continuous operation. The surface morphology of the modified electrode was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) system. The results obtained are precise and accurate. In addition, these results are in agreement with those obtained by the chromatographic method at a 95% confidence level.
Descreve-se um eletrodo de carbono modificado com fosfato de cobre (II) imobilizado em uma resina de poliéster (Cu3(PO4)2-Poly) para a determinação de rutina em amostras farmacêuticas por voltametria de onda quadrada. O eletrodo modificado permite a determinação de rutina em potencial (0.20 V vs Ag / AgCl (3,0 mol L-1 KCl)) menor que o observado em um eletrodo não modificado. Verificou-se que a corrente de pico foi linear com a concentração de rutina na faixa de 9,9 × 10-8 a 2,5 × 10-6 mol L-1, com um limite de detecção de 1,2 × 10-8 mol L¹. A resposta do eletrodo foi estável, sem variação significativa dentro de várias horas de operação contínua. A morfologia da superfície do eletrodo modificado foi caracterizada por microscopia eletrônica de varredura (MEV) e pelo sistema de energia dispersiva de raios-X (EDX). Os resultados obtidos foram precisos e exatos. Ademais, estes resultados estão de acordo com aqueles obtidos pelo método cromatográfico a um nível de confiança de 95%.
Subject(s)
Rutin/analysis , Chemistry, Pharmaceutical/classification , Electrodes/classification , Microscopy, Electron, ScanningABSTRACT
Erythromycin A (EA) is now one of antibiotics limited in seafood products in general and in giant freshwater prawns (Macrobrachium rosenbergii) and tilapia (Oreochromis niloticus) in particular while exporting to the US, EU, Japan, Canada. There are many methods used for analyzing this antibiotic in these aqua species such as ELISA, HPLC, LC-MS/MS, GC-MS, etc. A new sensitive analytical approach for determination of erythromycin A using stripping square wave voltammetry at the slowly dropping mercury electrode was primarily developed and validated to quantify this antibiotic with simple and short time analysis, not too pure analytical solutions, not high price equipments. Electrochemical signals were measured at potential wave -1430 mV. The optimal experimental parameters for the method were: supporting electrolyte ammonium acetate 0.1 M, pH 8.0, the solvents for dissolving erythromycin standard: acetonitril, Vstart = -400 mV, Vstop = -1700 mV, Vstep = 6 mV, Vpulse = 40 mV, Tdrop = 5000 ms , Velctrolise = -1100 mV, Telectrolyse = 5 s. The method showed high recovery (85.07 ÷ 96.50 %), high sensitivity (lower limit of detection, LoD = 0.57 μg kg-1 in giant prawn and LoD = 0.52 μg kg-1 in tilapia) and high precision (RSD 0.91 ÷ 2.1 %) as well as excellent linearity (r2 adjusted ≥ 0.99999).