System suitability solution— Add 0.2g of methyl heptadecanoate to 0.3g of Dibutyl Sebacate,and mix to dissolve.

Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 2-mm ×1.8-m column packed with 10%liquid phase G41on 100-to 120-mesh support S1A.The carrier gas is helium,flowing at a rate of about 30mLper minute.The chromatograph is programmed as follows.Initially,the column temperature is maintained at 150for 2minutes,then increased at a rate of 4per minute to 280,and maintained at 280for 30minutes.Make adjustments if necessary.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the resolution,R,between dibutyl sebacate and methyl heptadecanoate,at relative retention times of about 1.0and 0.8,respectively,is not less than 1.8;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject about 1.0µLof Dibutyl Sebacate into the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of C18H34O4in the portion of Dibutyl Sebacate taken by the formula: in which Ais the peak response for dibutyl sebacate;and Bis the sum of the responses of all the peaks.