Determination of nitrite ion in unused cutting fluids and cutting oils using a gas-sensing electrode method

Abstract

Modifications of the Orion NO_x gas-sensing electrode method that were made to determine nitrite ion in unused cutting fluids and cutting oils are described. Detection limits for both types of lubricants of the order of 15 µg g^–1 of NO₂^– ion were obtained. Previous analysis of six cutting fluids, collected in the Ottawa region and analysed by spectrophotometry, confirmed the presence of high levels of nitrite ion and showed fair agreement between results. Analysis of six other cutting fluids and 20 cutting oils collected in the same region showed the presence of nitrite ion in only three instances. The operation of the electrode, interferences, the use of standard-addition and -subtraction methods and the possibility of applying this method to used cutting lubricants are discussed.