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Linear Response Range (linear + response_range)
Selected AbstractsVoltammetric Sensor for Sodium Nitroprusside Determination in Biological Fluids Using Films of Poly- L -LysineELECTROANALYSIS, Issue 9 2007Claudece Pereira, Francisco Abstract Sodium nitroprusside (NP), a commercial vasodilator, can be pre-concentrated on vitreous carbon electrode modified by films of 97.5%: 2.5% poly- L -lysine (PLL): glutaraldehyde (GA). This coating gives acceptable anion exchange properties whilst giving the required improvement of adhesion to the glassy carbon electrode surface. Linear response range and detection limit on nitroprusside in B-R buffer pH,4.0, were 1×10,6 to 2×10,5 mol L,1 and 1×10,7 mol L,1, respectively. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was measured as 4.1% for 10 experiments. The voltammetric sensor was directly applied to determination of nitroprusside in human plasma and urine samples and the average recovery for these samples was around 95,97% without any pre treatment. [source] A sweeping-micellar electrokinetic chromatography method for direct detection of some aromatic amines in water samplesELECTROPHORESIS, Issue 4 2008Jianhua Zhang Abstract A simple and rapid sweeping method for the online improvement of detection limit of some aromatic amines has been developed in this work. The optimum sweeping and separation conditions for 4-methylaniline, 3,4-dichloroaniline, 4-chloroaniline, and 4-aminophenyl were investigated in detail. Under the optimum conditions, the detection limits of these four aromatic amines ranged from 5.4×10,10 to 4.6×10,8,mol/L (S/N,=,3), which was about 80,1090-folds lower than those of conventional sample injections. Linear response range were in the range of 2.5×10,8,2.0×10,6,mol/L with the correlation coefficient between 0.9965 and 0.9994. Baseline separation was achieved within 10,min. After validation, the developed method was applied to determine 4-methylaniline, 3,4-dichloroaniline, 4-chloroaniline, and 4-aminophenyl in river water sample with average recoveries of 79.6,88.7%. [source] The NADH Electrochemical Detection Performed at Carbon Nanofibers Modified Glassy Carbon ElectrodeELECTROANALYSIS, Issue 14 2007Adina Arvinte Abstract In this work, the capability of carbon nanofibers to be used for the design of catalytic electrochemical biosensors is demonstrated. The direct electrochemistry of NADH was studied at a glassy carbon electrode modified using carbon nanofibers. A decrease of the oxidation potential of NADH by more than 300,mV is observed in the case of the assembled carbon nanofiber-glassy carbon electrode comparing with a bare glassy carbon electrode. The carbon nanofiber-modified electrode exhibited a wide linear response range of 3×10,5 to 2.1×10,3,mol L,1 with a correlation coefficient of 0.997 for the detection of NADH, a high specific sensitivity of 3637.65 (,A/M cm2), a low detection of limit (LOD=3,) of 11,,M, and a fast response time (3,s). These results have confirmed the fact that the carbon nanofibers represent a promising material to assemble electrochemical sensors and biosensors. [source] Ionic-Liquid-Doped Polyaniline Inverse Opals: Preparation, Characterization, and Application for the Electrochemical Impedance Immunoassay of Hepatitis B Surface AntigenADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Xing-Hua Li Abstract A 3D ordered macroporous (3DOM) ionic-liquid-doped polyaniline (IL-PANI) inverse opaline film is fabricated with an electropolymerization method and gold nanoparticles (AuNPs) are assembled on the film by electrostatic adsorption, which offers a promising basis for biomolecular immobilization due to its satisfactory chemical stability, good electronic conductivity, and excellent biocompatibility. The AuNP/IL-PANI inverse opaline film could be used to fabricate an electrochemical impedance spectroscopy (EIS) immunosensor for the determination of Hepatitis B surface antigen (HBsAg). The concentration of HBsAg is measured using the EIS technique by monitoring the corresponding specific binding between HBsAg and HBsAb (surface antibody). The increased electron transfer resistance (Ret) values are proportional to the logarithmic value of the concentration of HBsAg. This novel immunoassay displays a linear response range between 0.032,pg mL,1 and 31.6,pg mL,1 with a detection limit of 0.001,pg mL,1. The detection of HBsAg levels in several sera showed satisfactory agreement with those using a commercial turbidimetric method. [source] Rapid screening of clenbuterol in urine samples by desorption electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Ziqing Lin Rapid screening of clenbuterol in urine was performed by combining desorption electrospray ionization (DESI) and tandem mass spectrometry (MS/MS). Optimization experiments were carried out including the selection of substrates, spray solutions, nebulizing gas pressures, high-voltage power supplies and flow rates of spray solution. The limit of detection (LOD), defined as the lowest quantity that can be detected, was 5.0 pg for the pure compound. Using DESI coupled with solid-phase extraction (SPE), the linear response range was from 10 to 400,ng/mL (R2,=,0.993) and the concentration LOD for urine sample was 2.0,ng/mL. The analysis for one spiked urine sample was achieved within 4,min. In addition to the fast analysis speed, MS/MS provided structural information for the confirmation of clenbuterol. Urine samples from different people were investigated and the recoveries were within 100,±,20%. The developed method can potentially be used for screening of clenbuterol in doping control. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||