Leon N. Klatt

Minimization of a sodium dithionite-derived interference in nitrate reductase-methyl viologen reactions

Abstract The use of sodium dithionite as the reducing agent to produce the radical cation of methyl viologen cofactor for the nitrate reductase-catalyzed reduction of nitrate to nitrite causes a negative interference in the diazonium salt azo dye determination of nitrite. The interference results from bisulfite, a reaction product of dithionite, reacting with the diazonium salt formed from nitrite and sulfanilamide. Addition of formaldehyde before the diazotization reaction masks this interference but at low acidity introduces a nonlinearity in the nitrite calibration curve. This nonlinearity is due to a competing reaction of formaldehyde with sulfanilamide to yield a Schiff base and can be eliminated by increasing the HCL content of the sulfanilamide reagent.

Electroreduction of pyridazine in aqueous media

Summary The reduction of pyridazine, A, in aqueous media is characterized by a single well shaped wave, I, with two smaller ill defined waves, II and III, at more negative potentials. Wave I involves two electrons and two protons yielding 1,2-dihydropyridazine, B, or a tautomeric form, as the product. This reduction is reversible up to pH 4. Controlled potential electrolysis on the plateau of wave I is characterized by a kinetically controlled process with napp=2.1−2.3. Functional group test showed the presence of primary aliphatic amine during the electrolysis, indicating that B decomposes via ring opening at a C−N site to yield H2N-NH-CH=CH-CH2-CHO, C, which polymerizes producing a variety of products. In the presence of phosphate buffers a polymeric salt precipitates. The decomposition of B is first-order and has a maximum rate at pH 4.7 (k=120 s−1). The limiting currents of waves II and III are never more than 10% that of wave I. Both waves show an inverse dependence upon pyridazine concentration and are not observable above 5 mM pyridazine. Cyclic voltammetric data suggests that the reactant for wave II is formed from the reactant for wave III and that C is electroinactive. Spectral data indicate that this mechanism is valid at least to pH 7.

An Inexpensive Digital Integrator for Gas Chromatography

SUMMARY An inexpensive gas chromatographic integrator with digital readout is described. The device is precise to ±1 count and shows linear response to within ±2%. It is directly compatible with flame ionization detectors and is easily adapted to thermal conductivity detectors.

Analysis of The Polarographic Method of Studying Metal Complex Equilibria. ii

Abstract The complexation between Pb(II) and tartrate has been used to experimentally ascertain the effect of precision in the ΔE1/2 measurement and ligand concentration range upon the data analysis of the polarographic method of studying metal complex equilibria. The need to obtain data at the lowest ligand concentration possible and with ΔE1/2 ≤ 0.4–0.6 mV was clearly shown. If this precision is unachievable, data from some other technique, based upon a different property, may be required. These experimental results are in agreement with the simulation study of Klatt and Rouseff (Anal. Chem., 42, 1234 (1970)).

COMPENSATION FOR THERMAL DRIFT IN AN OPTICAL FEEDBACK STABILIZED PHOTOMETER.

A simple circuit based upon an equal arm Wheatstone Bridge which senses temperature changes of the optical chassis permits compensation of thermally induced long term drift in a single beam optical feedback stabilized photometer. A drift rate of 0.004 percent T/hr was achieved.