Square-wave, polarographic determination of lead as a pollutant in river water

Abstract

smoke the ratio of indole (13.9 yug/cig.) to 1-methylindole (0.42 pg) is 100:3 and that of 3-methylindole (14.0 pg) to 1,3dimethylindole (0.28 pg) is 100:2. In the pyrolyzate, the ratios are 100:2.25 and 100:1.6. Despite the use of different analytical methods the indole value for the tryptophan pyrolysis (880 °C) is comparable to the 3% yield reported by Patterson et al. from the pyrolysis of tryptophan at 850 °C ( 14). This suggests that free and/or protein bound tryptophan in (14) J.

Electrochemistry of phenazine at a platinum electrode in aprotic solvents

“…The ratio of the anodic peak current to the cathodic peak current in cyclic voltammetry should be unity for a well behaved diffusion-controlled process involving no chemical processes in addition to the electron transfer. This is limited to cases which have switching potentials not less than 35jn mV beyond the cathodic peak (10). An empirical formula for determining this ratio of peak currents is given by TEAP; scan rate, 0.10 V/sec where all currents are absolute values, iap/iCp is the ratio of anodic to cathodic peak currents, (iCp)o the measured cathodic peak current, (iap)o the measured anodic peak current from the zero current line, and (isn)0 the measured cathodic current at the switching potential (see Table I).…”

“…Values of ««" may be calculated from cyclic voltammetric data relating the difference between peak potentials for a given reduction to the logarithms of the scan rates (10) where (Ep)i and (Ep}> are the peak potentials for scan rates of xi and x2, and na the number of electrons in the rate-determining step. The data have been treated as points for a line rather than using the equation to make a two-point determination.…”

“…H,Ph + 02 -3» Ph + H202 (9) The kinetic experiments for dihydrophenazine with varying amounts of hydrogen peroxide indicate a first-order dependence for dihydrophenazine, and probably a half-order dependence for hydrogen peroxide. A possible reaction mechanism for such a dependence is H202 ^2 (10) OH + H2Ph H20 + HPh The HPh is not a stable species in DMSO and a disproportionation reaction is probable.…”

“…Polarographic techniques for trace analysis (7,8) have infiltrated almost every field in which analytical chemistry is used. The scope of these applications is illustrated by the following examples: pollution, with particular reference to water analysis (9,10); pharmaceuticals (77); rocks and minerals, (72-74); pesticides (15); and petroleum products (16).…”

Determination of lead using charged particle activation analysis

“…sorption, spectrophotometry, and neutron and photon activation methods have been reported with detection limits for lead ranging from 10-100 ppb (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Still more sensitive techniques (~2 ppb) have been described recently, based on polarography (11). Isotope ratio measurements are usually carried out via mass spectrometry (12); a few methods based on nuclear reactions have also been proposed (13-15).…”