Iron phosphide anchored nanoporous carbon as an efficient electrode for supercapacitors and the oxygen reduction reaction.

Inspired by their distinctive properties, transition metal phosphides have gained immense attention as promising electrode materials for energy storage and conversion applications. The introduction of a safe and large-scale method of synthesizing a composite of these materials with carbon is of great significance in the fields of electrochemical and materials sciences. In the current effort, we successfully synthesize an iron phosphide/carbon (FeP/C) with a high specific surface area by the pyrolysis of the gel resulting from the hydrothermal treatment of an iron nitrate-phytic acid mixed solution. In comparison with the blank (P/C), the as-synthesized FeP/C appears to be an efficient electrode material for supercapacitor as well as oxygen reduction reaction (ORR) applications in an alkaline medium in a three-electrode system. In the study of supercapacitors, FeP/C shows areal capacitance of 313 mF cm-2 at 1.2 mA cm-2 while retaining 95% of its initial capacitance value after 10 000 cycles, while in the ORR, the synthesized material exhibits high electrocatalytic activity with an onset potential of ca. 0.86 V vs. RHE through the preferred four-electron pathway and less than 6% H2O2 production calculated in the potential range of 0.0-0.7 V vs. RHE. The stability is found to be better than those of the benchmark Pt/C (20 wt%) catalyst.

Square wave anodic stripping voltammetric determination of metoclopramide in tablet and urine at carbon paste electrode.

A simple, reliable and selective square wave anodic stripping (SWAS) voltammetric method at carbon paste electrode (CPE) of metoclopramide hydrochloride (MCP) in pharmaceutical dosage forms (tablet) and in biological fluids (spiked and real urine samples) has been developed and evaluated. Different parameters such as medium, supporting electrolyte, pH, accumulation potential, scan rate, accumulation time and ionic strength, were tested to optimize the conditions for the determination of MCP. The adsorbed form is oxidized irreversibly under optimal conditions, viz., 0.4M HCl-sodium acetate buffer (pH approximately 6.2), 0.2M KCl, a linear concentration ranges from 0.067 to 0.336, 0.067 to 0.269 and 0.067 to 0.269 ng/mL of MCP, at accumulation times 60, 120 and 180 s, respectively, can be determined successfully. The interferences of some common excipients and some metal ions were studied. The standard addition method was used to determine the MCP in pure solutions, tablets and in biological fluids with satisfactory results. The data obtained are compared with the standard official method.

Simultaneous determination of aluminium and iron in glasses,phosphate rocks and cement using first- and second-derivative spectrophotometry.

First- and second-derivative spectrophoto-metric methods for the simultaneous determination of aluminium and iron in their mixtures are described. The methods are based on the colored complexes formed by aluminium and iron with hematoxylin in the presence of cetyltrimethylammonium bromide as a surfactant. The zero-crossing method has been utilized to measure the first- and second-derivative value of the derivative spectrum. Aluminium (0.05-1 microg ml(-1)) could be determined in the presence of iron (0.09-1.6 microg ml(-1)) and vice versa. The detection limits of aluminium and iron are 0.01 and 0.09 microg ml(-1), respectively in the first-derivative mode and 0.014 and 0.1 microg ml(-1) in the second-derivative mode. The proposed method has been applied to the simultaneous determination of aluminium and iron in glasses, phosphate rocks, cement and magnesite alloy.

Extraction-spectrophotometric determination of iron(II) by ternary complex formation with pyrocatechol violet and cetyltrimethylammonium bromide.

A method for iron(II) determination based on reaction with Pyrocatechol Violet to form a 1:2 binary complex at pH 5-7 is described and has been extended to an extraction-spectrophotometric procedure for the determination of iron(II) by formation of the 1:2:2 iron(II)-Pyrocatechol Violet-cetyltrimethylammonium bromide ternary complex. The molar absorptivities of the binary and ternary complexes at 595 and 605 nm are 6.55 x 10(4) and 1.35 x 10(5)1.mole(-1).cm(-1), respectively. The method has been successfully applied to the determination of iron in felspar, Portland cement and sodium hydroxide.