Patent ID: 8268624

Claim:
A method of characterizing acid content of a lubricant sample, comprising: a) providing an ethanolic solution of ethanol and sodium hydrogen cyanamide; b) preparing a mixture by adding a first portion of the ethanolic solution to the lubricant sample, wherein sodium hydrogen cyanamide of the ethanolic solution reacts with acidic components of the lubricant sample to form a reaction product that is part of the mixture; c) performing infrared spectroscopic testing of the mixture of b) to generate mixture absorption data representing at least one absorption characteristic of the mixture of b), wherein the mixture absorption data includes a first infrared light absorption value of the mixture of b) at a wavelength between 2105 cm −1 and 2115 cm −1 as well as a second infrared light absorption value of the mixture of b) at a wavelength between 1565 cm −1 and 1575 cm −1 ; and d) generating acidity data characterizing acid content of the lubricant sample based on the mixture absorption data of c), wherein the acidity data is based upon at least one calibration equation relating the mixture absorption data to acidity of the lubricant sample.