DEFINITION
This analytical method describes the separation and quantification of monobasic, dibasic, and polybasic acids in “dimer acids” manufactured by the catalytic polymerization of fatty acids. The method utilizes HPLC and laser mass detection. The components of the dimer acids are separated according to their polarity by normal-phase HPLC. Historically, area percent results from this meth-od are within ±0.6% w/w of dimer acid standards whose compositions were determined by semi-preparative HPLC (gravimetrically). Within the linear ranges of the components as described in this method, the response factors of the mono-, di-, and polybasic acids are assumed to be equal and, therefore, uncorrected area percent results are reported (see Precision, 1).

SCOPE
This analytical method is applicable to finished dimer acids derived from tall oil, oleic acid, and mixed vegetable oils, and dimer acids that have been bleached, distilled, or hydrogenated.