IMPROVING JOAP FTIR CONDITION MONITORING ANALYTICAL THROUGHPUT BY SAMPLE DILUTION F.R. van de Voort and J. Sedman McGill IR Group, McGill University, 21,111 Lakeshore Road, Ste. Anne de Bellevue, PQ, Canada H9X 3V9. E-mail: vandevoort@macdonald.mcgill.ca and D. Pinchuk Thermal-Lube Inc., 255 Labrosse, Pointe Claire, PQ, Canada H9R 1A3. E-mail: dave@thermal-lube.com ABSTRACT Although the JOAP FTIR protocol provides a relatively simple and standardized means of assessing oil condition, sample throughput is restricted by oil viscosity and the need for solvent rinsing to avoid sample carryover. A new approach to overcoming this bottleneck is presented in this paper along with supporting experimental validation data. In this new approach, the oil sample is diluted in ~1:1 ratio with kerosene containing an IR quantifiable marker. The amount of kerosene present is determined by measuring the ‘residual’ marker in the sample, with the kerosene spectral contribution subsequently subtracted out of the sample spectrum on the basis of this measurement. The resulting residual oil spectrum is then “re-concentrated” mathematically to compensate for the initial dilution of the sample, and the standard JOAP FTIR spectral analysis is performed to provide the values for the oil condition parameters. In validation studies with 23 diesel oils, the analytical results obtained by this approach were very similar to those obtained for the undiluted oils. The benefit of this approach is that sample handling is facilitated because of the substantially reduced viscosity of the diluted samples while still yielding valid JOAP FTIR data. The Thermal-Lube COAT system, which is configured for the quantitative analysis of acid number, base number and moisture, is now also able to run the standard JOAP FTIR protocol at speeds of >120 samples/h without rinsing between samples.