Abstract: The reference turpentine oil sample from Pinus elliottii Engelm. (slash pine) was prepared, and their homogeneity, stability, and method of its certification were studied. The turpentine oil was prepared through steam distillation from slash pine oleoresin, and measured by a gas chromatographic area normalization. The reference turpentine oil from P. elliottii Engelm. has passed the test of homogeneity, and it has kept tobe stable for at least 36 months. The certification results of the reference sample through multiple lab's co-works showed that the standard content values of 3 index components were: α-pinene 62.41% with standard uncertainty U_A=0.15%, extended uncertainty U_0.95=0.30%; β-pinene 31.66% with standard uncertainty U'_A=0.09%, and extended uncertainty U'_0.95=0.18%; β-phellandrene 3.33% with standard uncertainty U″_A=0.05%, extended uncertainty U″_0.95=0.10%, respectively.

Key words: turpentine oil of Pinus elliottii Engelm., reference materials, certification