Voltammetric behavior of cefixime and cefpodoxime proxetil and determination in pharmaceutical formulations and urine.

Electrochemical reduction behavior of cephalosporins, Cefixime (CF) and Cefpodoxime Proxetil (CP) have been studied by using different voltammetric techniques in Britton-Robinson buffer system. Two well defined cathodic waves are observed for both the compounds in the entire pH range. Number of electrons transferred in the reduction process was calculated and the reduction mechanism is proposed. The results indicate that the process of both the compounds is irreversible and diffusion-controlled. The peak currents for CF and CP are found to be linear over the range of concentration 6.0 x 10(-8) to 1.2 x 10(-5) mol l(-1) and 8.8 x 10(-8) to 1.1 x 10(-5) mol l(-1), respectively. The lower detection limits are found to be 4.6 x 10(-8) and 8.52 x 10(-8) mol l(-1) for the two compounds. A differential pulse voltammetric method has been developed for the determination of these drugs in pharmaceutical formulations and urine samples.

A study on major inorganic ion composition of atmospheric aerosols at Tirupati.

Atmospheric aerosol samples were collected from an urbanized area (Tirupati, South India) during the period April to September 2001 and were analyzed for major inorganic ions-F, Cl, NO(3,) SO(4), Na, K, Mg, Ca and NH(4) by employing the ion chromatograph. The average mass of the aerosol was found to be 55.64 microgram(-3) with a total water-soluble load (total anion+total cation) of 5.74 microgram(-3). Seasonal distribution of the aerosol mass and temporal variations of the ion concentrations present a clear trend of lowering atmospheric levels during the rainy season due to washout effect. Composition of the aerosols showed higher concentration of SO(4) followed by NO(3) and NH(4) and found to be influenced by local terrestrial sources. The presence of SO(4) and NO(3) may be due to re-suspension of soil particles (formation by heterogeneous oxidation). Ca, Mg and Cl are mainly soil derived ones. The presence of NH(4) may be attributed to the reaction of NH(3) vapors with acidic gases such as H(2)SO(4), HNO(3) and HCl or ammonia vapor may react or condense on an acidic particle surface of anthropogenic origin. Equivalent ratios of NH(4)/(NO(3)+SO(4)) varied between 0.62 and 0.74. It shows the aerosol to be slightly acidic due to the neutralization of basicity by SO(2) and NO(x).