Abstract. The analysis of two phosphate ester additives found in the formulation of metalworking fluids is reported. These are isopropylated triarylphosphates which are used as extreme pressure additives and polyethoxylated phosphates with emulgating properties. The additives are first analyzed as raw materials; then within a typical lubricant where they are identified and quantified. The methodology makes use of chromatography (TLC, HPLC, SPE) and NMR spectroscopy ( 1 H, 13 C, 31 P). The valuable contribution of 31 P NMR to the deformulation of such products is particularly emphasized.