Template synthesis of maghemite nanoparticle in carboxymethyl cellulose and its application for electrochemical cabergoline sensing.

Maghemite (γ-Fe2O3) nanoparticles were produced via coprecipitation onto carboxymethyl cellulose matrix based templates followed by calcination. The resulting maghemite nanoparticles were characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The magnetization measurement of as-synthesized γ-Fe2O3 displayed superparamagnetic characteristics at room temperature. Then, a novel maghemite nanoparticles carbon paste modified electrode was developed for determination of cabergoline. The modified electrode has an outstanding catalytic effect on the oxidation current of cabergoline and the mechanism was studied using cyclic voltammetry. The oxidation peak current was proportional to the concentration of cabergoline from 1×10-7 to 3.5×10-5molL-1 with a detection limit of 3×10-8molL-1 at signal to noise ratio of 3. The proposed method was examined as a selective, simple and precise method for voltammetric determination of cabergoline in plasma and pharmaceutical samples.

Simultaneous determination of ascorbic acid, acetaminophen and codeine based on multi-walled carbon nanotubes modified with magnetic nanoparticles paste electrode.

Based on incorporating ZnCrFeO4 into multi-walled carbon nanotubes paste matrix (MWCNTs/ZnCrFeO4/CPE), a chemically modified electrode was prepared for the simultaneous determination of ascorbic acid (AA), acetaminophen (AC) and codeine (CO). The prepared electrode, MWCNTs/ZnCrFeO4/CPE, was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The MWCNTs/ZnCrFeO4/CPE showed an efficient electrocatalytic activity for the oxidation of AA, AC, and CO. The separations of the oxidation peak potentials for AA-AC and AC-CO were about 250mV and 630mV, respectively. The calibration curves obtained for AA, AC, and CO were in the ranges of 0.4-730.0µmolL(-1), 0.1-368.0µmolL(-1), and 0.3-250.0µmolL(-1), respectively. The detection limits (S/N=3) were 0.03µmolL(-1), 0.009µmolL(-1), and 0.01µmolL(-1) for AA, AC, and CO, respectively. The method was also successfully employed as a selective, simple, and precise method to determinate AA, AC, and CO in pharmaceutical and biological samples.

Simultaneous determination of cysteine, uric acid and tyrosine using Au-nanoparticles/poly(E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol film modified glassy carbon electrode.

A novel Au nanoparticles/poly(E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol (AuNPs/PTAT) film modified glassy carbon electrode (AuNPs/PTAT/GCE) was fabricated for the simultaneous determination of three antioxidants named, cysteine (Cys), uric acid (UA) and tyrosine (Tyr). The bare glassy carbon electrode (GCE) fails to separate the oxidation peak potentials of these molecules, while PTAT film modified electrode can resolve them. Electrochemical impedance spectroscopy (EIS) study indicates that the charge transfer resistance of bare electrode increased as (E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol was electropolymerized at the bare electrode. Furthermore, EIS exhibits enhancement of electron transfer kinetics between analytes and electrode after electrodeposition of Au nanoparticles. Differential pulse voltammetry results show that the electrocatalytic current increases linearly in the ranges of 2-540µmolL(-1) for Cys, 5-820µmolL(-1) for UA and 10-560µmolL(-1) for Tyr with detection limits (S/N=3) of 0.04µmolL(-1), 0.1µmolL(-1) and 2µmolL(-1) for Cys, UA and Tyr, respectively. The proposed method was successfully applied for simultaneous determination of Cys, UA and Tyr in human urine samples.

Simultaneous chemiluminescence determination of amoxicillin and clavulanic acid using least squares support vector regression.

In this work, both the batch and flow injection chemiluminescence (CL) methods have been proposed for the simultaneous determination of two structurally similar beta-lactams including amoxicillin and clavulanic acid (CLAV). Chemiluminescence spectral overlap of these two structurally similar beta-lactams is the main limitation for the simultaneous analysis of the two compounds. Least squares support vector regression (LS-SVR) was applied to relate concentration of both the compounds to their CL profiles. The parameters of the model, consisting of kernel parameter, sigma(2), and the regularization parameter, gamma, were optimized by constructing different LS-SVR models and the model with the minimum root mean squared error of cross-validation (RMSECV) for the calibration set was selected as the best model and its parameters were chosen as the optimized values. The performance of LS-SVR model was compared with Partial Least Squares (PLS) and the results revealed the superiority of the LS-SVR over PLS model. Under the optimized experimental conditions for both the compounds, when LS-SVR was applied, the detection limits obtained were 0.2 and 0.60 micromol L(-1) in the batch mode and 0.3 and 0.5 micromol L(-1) in the flow injection mode for CLAV and amoxicillin, respectively. The proposed method was utilized for the simultaneous determination of the compounds in pharmaceutical formulations and spiked plasma samples.

Simultaneous voltammetric determination of enrofloxacin and ciprofloxacin in urine and plasma using multiwall carbon nanotubes modified glassy carbon electrode by least-squares support vector machines.

A simple and sensitive method is proposed for the electrochemical determination of enrofloxacin (ENRO) and its primary metabolite ciprofloxacin (CIPRO) at a multiwall carbon nanotubes/glassy carbon electrode (MWCNT/GCE) using a least-squares support vector machine (LS-SVM) and linear sweep voltammetry. Simultaneous determination of ENRO and CIPRO at bare glassy carbon is associated with certain difficulties due to voltammogram overlapping and their low sensitivity. The resolution of the mixture was carried out using LS-SVM as a multivariate calibration method. Under the optimum conditions at pH 7.0, the linear sweep currents increased linearly with ENRO and CIPRO concentrations in ranges of 2.0-780.0 micromol L(-1) (0.7-280.3 microg mL(-1)) and 3.0-1200 micromol L(-1) (1.0-397.7 microg mL(-1)), respectively. The detection limits for ENRO and CIPRO were 0.5 and 0.9 micromol L(-1), respectively. The proposed method was applied to simultaneously determine both compounds in human urine, plasma and in pharmaceutical samples.

Simultaneous chemiluminescence determination of thebaine and noscapine using support vector machine regression.

In this work, a batch chemiluminescence (CL) method has been proposed for the simultaneous determination of two structurally similar alkaloids, noscapine and thebaine. The method is based on the kinetic distinction of the CL reactions of noscapine and thebaine with Ru(bipy)(3)(2+) and Ce(IV) system in a sulfuric acid medium. The least squared support vector machine (LS-SVM) regression was applied for relating the concentrations of both compounds to their CL profiles. The parameters of the model consisting of sigma(2) and gamma were optimized by constructing LS-SVM models with all possible combinations of these two parameters to select the model with the minimum root mean squared error of cross validation (RMSECV) as the best. The parameters of this model were then selected as optimized values. Under the optimized experimental conditions for both compounds, the detection limits obtained using the LS-SVM regression were 0.08 and 0.1 micromo lL(-1) for noscapine and thebaine, respectively. The proposed method was utilized for the simultaneous determination of the compounds in pharmaceutical formulations and plasma samples with satisfactory results.

Simultaneous chemiluminescence determination of promazine and fluphenazine using support vector regression.

In this work, chemiluminescence (CL) behaviors of two selected phenothiazines, namely promazine and fluphenazine hydrochloride, were investigated for their simultaneous determination using oxidation of Ru(bipy)(3)(2+) by Ce(4+) ions in acidic media. This method is based on the kinetic distinction of the CL reactions of fluphenazine and promazine with Ru(bipy)(3)(2+) and Ce(4+) system in a sulfuric acid medium. Least square support vector regression models were constructed for relating concentrations of both compounds to their CL profiles. The parameters of the model consisting of sigma(2) and gamma were optimized using all possible combinations of sigma(2) and gamma to select the model with the minimum root mean square cross validation. Under optimized conditions, the univariate calibration curve was linear over the concentration ranges of 0.4-30.0 microg mL(-1) and 0.07-5.0 microg mL(-1) with detection limits of 0.1 microg mL(-1) and 0.04 microg mL(-1) for promazine and fluphenazine, respectively. The influence of potential interfering substances on the determination of promazine and fluphenazine were studied. The proposed method was used for simultaneous determination of both compounds in synthetic mixtures and in spiked human plasma.

Determination of glutathione in hemolysed erythrocyte by flow injection analysis with chemiluminescence detection.

In this work, a new sensitive method is introduced for analysis of glutathione at trace levels in blood samples. The method is based on the effect of glutathione on the chemiluminescence signal of the oxidation of luminol by sodium periodate in basic solution. The influence of chemical and manifold variables on the sensitivity was studied. At the optimized conditions, the linear range for the determination of glutathione was 1.0x10(-8) to 1.0x10(-5) mol L(-1) with the detection limit (3sigma) of 8x10(-9) mol L(-1). The relative standard deviation for 10 repeated measurements of 1.0x10(-6) mol L(-1) of glutathione was 4%. The results of the method were compared with the Ellman reference method and no significant difference was found. The influence of potential interference substances on the determination of glutathione was studied. The proposed method was applied successfully for the determination of glutathione in real samples such as erythrocyte hemolysed in normal subjects and diabetes.