Potentiality of PARAFAC approaches for simultaneous determination of N-acetylcysteine and acetaminophen based on the second-order data obtained from differential pulse voltammetry.

N-acetylcysteine (N-AC) has widespread application such as pharmaceutical drug and nutritional supplement. Its adverse effects are rash, urticaria, and itchiness and large doses of N-AC could potentially cause damage to the heart and lungs. Therefore, in this work, a sensitive voltammetric sensor based on a carbon paste electrode modified with silica nano particles (i.e. Mobil Composition of Matter (No. 41) modified with Boron Trifluoride or BF3@MCM-41) with a combination of 4,4'-dihydroxybiphenyl (DHB) (BF3@MCM-41/DHB/CPE) was designed for determination of N-AC. The electrochemical oxidation of N-AC was examined using various techniques such as cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV). Under the optimum conditions, some parameters such as electron transfer coefficient (α) and heterogeneous rate constant (ks) were estimated for N-AC. Due to the use of N-AC for the treatment of acetaminophen (AC) overdose, the application of modified electrode was investigated for the simultaneous determination of N-AC and AC in blood serum and tablet samples. Since, the signals of these species overlap and due to the presence of interfering species in blood samples, the simultaneous determination of mentioned species is difficult or impossible. To overcome this challenge, parallel factor analysis (PARAFAC) was used for the analysis of the complex matrices to obtain the spectral profile of each component and interference. To achieve this goal, electrochemical second-order data were generated using a simple change in pulse height of differential pulse voltammetry. The results of the presently proposed strategy for the real samples analysis are similar to those obtained with HPLC. Thus, the proposed method has acceptable performance for simultaneous determination of the two species in real samples.

Application of nanosized MCM-41 to fabrication of a nanostructured electrochemical sensor for the simultaneous determination of levodopa and carbidopa.

A novel carbon paste electrode modified with nanosized mesoporous MCM-41 was prepared, and used as an electrochemical sensor to study the electro oxidation of levodopa (LD), carbidopa (CD) and their mixtures. Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of LD and CD has been explored at the modified electrode. The electrochemical sensor displayed a good resolving function for the overlapping voltammetric responses of LD and CD into two separate peaks with a potential difference of 370 mV. DPV peak currents of LD increased linearly with concentration over the 0.13 µM to 1250.00 µM range and exhibited a detection limit of 0.072 µM. Also, the proposed electrochemical sensor was used for the determination of LD and CD in some real samples, using the standard addition method.

Simultaneous and selective voltammetric determination of , and at a nanoparticles modified paste electrode.

A new carbon paste electrode modified with ZrO2 nanoparticles (ZONMCPE) was prepared, and used to study the electrooxidation of epinephrine (EP), acetaminophen (AC), folic acid (FA) and their mixtures by electrochemical methods. The modified electrode displayed strong resolving function for the overlapping voltammetric responses of EP, AC and FA into three well-defined peaks. The potential differences between EP - AC, AC - FA and EP - FA were 210, 290 and 500 mV respectively. Differential pulse voltammetry (DPV) peak currents of EP, AC and FA increased linearly with their concentration at the ranges of 2.0 × 10-7-2.2 × 10-3 M, 1.0 × 10-6-2.5 × 10-3 M and 2.0 × 10-5-2.5 × 10-3 M, respectively. The detection limits for EP, AC and FA were found to be 9.5 × 10-8, 9.1 × 10-7and 9.8 × 10-6 M, respectively.

Alumina supported potassium permanganate: an efficient reagent for chemoselective dehydrogenation of 2-imidazolines under mild conditions.

Potassium permanganate supported on alumina was found to be an efficient reagent system for dehydrogenation of 2-imidazolines to imidazoles under mild conditions at room temperature. Selective oxidation of 2-alkylimidazolines in the presence of 2-arylimidazolines was achieved using this reagent system. 2-Imidazolines were also selectively converted to their corresponding imidazoles in the presence of other oxidizable functional groups such as sulfide, ether, aldehyde, acetal and THP ether. The oxidation procedure described here is easy to carry out and does not require strict reaction conditions.