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677.044.22 T. I. Samsonova, and O. A. Roshchina Studies were conducted to evaluate the indexes of the accuracy of methods of determining the mass fraction of oil on chemical fibres and data were obtained on the accuracy of the methods. The values of the standard deviations of the repeatability and the standard deviation of the reproducibility for each method are presented in the form of the wt. percent content in absolute form. Based on the results of the studies conducted in the SRISF Testing Center together with Studies to establish indexes of the accuracy of methods of determining the mass fraction of oil on chemical fibres for a new intergovernmental standard to replace GOST 29332-92 are reported [1]. Two methods of removing the oil from the fibre are proposed in the new standard: a shaker is used in the first and a Soxhlet apparatus is used in the second. The accuracy of the methods is established in the entire range of measurements of the oil content. The studies were conducted in accordance with the requirements of GOST R ISO 5725-2002 [2].An interlaboratory experiment involving laboratories that constantly measure the mass fraction of oil on a fibre was conducted to establish the accuracy of the methods. The testing laboratories at SRISF, Grodnokhimvolokno, Khimvolokno Amtel Kuzbass, Saratovorgsintez, Mogilevkhimvolokno, and Svetlogorsk Khimvolokno IA participated in the experiment using the shaker, and the laboratories at SRISF and Mogilevkhimvolokno participated in the experiment using the Soxhlet apparatus.Samples of the fibres with different levels of oil content (test level), one close to the lower boundary of the range of measurements, the other close to the upper boundary, while the remainder were positioned between them, were prepared for conducting the interlaboratory experiment. The experiment using the shaker was conducted on eight test levels, and the experiment with the Soxhlet apparatus was conducted on five levels ( Table 1).The analytical samples were prepared in accordance with . The coded samples were sent to the laboratories involved in the experiment. The tests in each laboratory were performed by the same person, on the same equipment in accordance with the methods in draft GOST 29332. The oil was extracted from the fibre samples with n-hexane* (samples No.