Interactions of polyadenylic acid with the mercury electrode were followed by means of direct current (d.c.), alternating current (a.c.), and pulse polarography. It was ascertained that the electrode reaction of polyadenylic acid did not differ significantly from the reaction of its monomeric components. In contrary to the latter reaction, the polarographic reduction of poly­ adenylic acid take...

Double-stranded (ds) complexes of poly(C) with poly(G) and poly(G,I) were studied using differential pulse polarography (DPP) and differential pulse voltammetry at a pyrolytic graphite electrode (DPV). The complex formed by copolymer was found to be DPP inactive. On the other hand, poly(G).poly(C) yielded a small DPP peak corresponding to single-stranded (ss) poly(C). It was suggested that ss p...

The regulation of metallothionein (MT) biosynthesis in rainbow-trout liver was studied after a single intraperitoneal injection of oestradiol-17 beta. Sampling was performed after 2, 7, 14, 21, 28 and 35 days. Following induction of vitellogenin synthesis in the liver, liver somatic index (LSI) rose from 1.25 to 2.00 in 14 days. Associated with the increase in LSI was an elevation of hepatic vi...

Ahatcaet Factors involved in construction and utilization of an inexpensive, rapid-response potentiostat with 50 mA current capabilities are discussed. The potentiostat can be used with ancillary units, eg function generators, for a variety of rapid perturbation approaches, eg cyclic voltammetry at scan rates to 4000 V/s or greater, potential-step chronoamperometry with data acquisition after 4...

The electrochemical activity of poly(8-hydroxyquinoline) (PHQ) in acid and alkaline media has been investigated by use of differential pulse polarography (DPP). The reduction peak height (I(p)) of PHQ in universal buffer solutions is not useful as an analytical signal, because it is highly affected by hydrogen evolution in acid media and appears as a small peak located at more negative potentia...

A differential pulse polarographic method is proposed for the trace determination of bismuth and copper from large volumes of aqueous samples after adsorption of their 1-(2-thiazolylazo)-2-naphthol complexes onto microcrystalline naphthalene in the pH ranges of 7.2-9.0 and 4.0-7.8, respectively. Bismuth and copper are desorbed from microcrystalline naphthalene with 9 mL 1M HCl. Well-defined pea...

In this study we investigated the effects of competing trace metals and Ca2+ on Cd(II), Pb(II), and Cu(II) complexation by humic acid extracted from groundwater in Orange County, California. Two types of titration experiments were conducted, those using a single metal and those in which the humic acid had been preequilibrated with a competing metal (either a trace metal or Ca2+). The labile met...

Determination of selenium in biological and environmental samples is usually difficult due to its trace or ultra-trace quantities, pre-concentration stages, destruction of organic matrices by acid digestion and oxygen plasma combustion followed by separation from interfering metal ions such as ion exchange separation, solvent extraction or hydride generation. Selective separation of selenium is...