A description is given of a new method for determining free fatty acids in blood plasma. The free fatty acids are extracted from the plasma, transferred to heptane and washed with H2SO4 (O.OlN). The earlier two-phase tritration procedure is now performed in a one-phase medium by means of an autoburette using tetrabutylammoniumhydrcxide. A curve, simultaneously recorded by means of a compensatio...

Intracellular pH was recorded in immature starfish oocytes using pH-sensitive microelectrodes, and inwardly rectifying potassium currents were measured under voltage clamp. When the intracellular pH was lowered using acetate-buffered artificial sea water from the normal value of 7.09 to 5.9, inward rectification was completely blocked. The relationship between inward rectification and internal ...

Active site titration by a reversible tight-binding inhibitor normally depends on prior knowledge of the inhibition constant. Conversely, the determination of tight-binding inhibition constants normally requires prior knowledge of the active enzyme concentration. Often, neither of these quantities is known with sufficient accuracy. This paper describes experimental conditions under which both t...

Rapid acid-base titrations can be performed at the surface of a noble-metal electrode with coulometrically generated ions. An ISFET is used as an indicator electrode to detect the equivalence point in the resulting titration curve. The time needed to reach the equivalence point is typically 0.5 to 10 s for acid/base concentrations ranging from 0.5 x lop3 to 20 x lop3 mol 1 -I. A model is presen...

A modified Gran and a non-Iinear curve-fitting method of evaluation are applied to the photometrie titration of seawater with hydrochloric acid. The procedures are tested on theoretical and experimental data using bromocresol purple as an indicator. Oceanol. Acta, 1983, 6, 4, 357-364. RÉSUMÉ Détermination de l'alcalinité et du carbone inorganique total dans l'eâu de mer par dosage photométrique...

In number of research projects various adaptive control methods have been applied to the control of pH with varying success. Recently, intelligent control methods based on fuzzy systems and neural networks have been studied intensively (for example, see Ylén and Jutila, 1996). In some of these studies (see Loh et al, 1995 and Aoyama et al, 1995) nonlinear models are created explicitly for model...

pH SENSOR The final control element can be a pump or an ON/OFF valve. Sizing of the final control element is complicated and depends on many factors. This is one situation where a titration curve can be invaluable. In many cases, it may be necessary to use two final control elements, each delivering different amounts of chemical and having different setpoints. For example, one valve may deliver...

Escherichia coli isocitrate lyase was inactivated by iodacetate in a pseudo-first-order process. Complete inactivation was associated with the incorporation of only one carboxymethyl group per enzyme subunit. The substrate and products of the enzyme protected against inactivation, suggesting that the reactive group may be located at the active site. Isolation and sequencing of a carboxymethylat...