E.i. Dupont De Nemours and Company

James L Seago

John R Reader, Jr

Charles F Collier

James A Williamson, Jr

William G DiMaio

A probe is introduced through the elastomeric cap of a closed sample container and moved sideways to stretch the cap and thereby provide an air passage to atmosphere while the sample is aspirated.

Method for pipetting liquid from a sealed container

A method is described for the amperometric determination of the concentration in a biological sample of a constituent which is a substrate for an oxidase enzyme by (1) catalyzing the substrate with the enzyme, thereby consuming O.sub.2 and producing H.sub.2 O.sub.2 and (2) measuring the O.sub.2 consumption or H.sub.2 O.sub.2 production by means of an inert metal indicator electrode intimately coated with a thin film of a perfluorosulfonic acid polymer. A reaction chamber is described which provides means for contacting the sample with the enzyme and means for making amperometric measurements utilizing inert metal indicator electrodes coated with a thin film of a perfluorosulfonic acid polymer.

Perfluorosulfonic acid polymer-coated indicator electrodes

Biological detection process using polymer-coated electrodes

Apparatus and method for NO.sub.x analysis in which a sample gas is introduced into a sample cell and mixed with oxygen to induce conversion of NO to NO.sub.2. After a given time, prior to complete conversion of NO to NO.sub.2, the absorbance and the time rate of change of absorbance is measured. The time rate of change of absorbance is indicative of the initial NO concentration in the sample gas; and the sum of the absorbance and the time rate of change of absorbance is indicative of the initial NO.sub.x concentration in the gas. A better indication of the initial NO.sub.x concentration can be obtained from the sum of the absorbance and the square root of the time rate of change of absorbance.

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Wilmington, DE, United States of America

James L Seago