A: Infrared Absorption 197F.

B: The retention time for the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of a similar preparation of USP Tributyl Citrate RS.

(Official January 1, 2007)

System suitability solution— Prepare a solution in toluene containing about 30 mg each of USP Tributyl Citrate RS and USP Acetyltributyl Citrate RS per mL.

Assay preparation— Transfer about 300 mg of Tributyl Citrate, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with toluene to volume, and mix.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector maintained at about 275, a split injection system with a split ratio of about 30:1, and a 0.32-mm × 30-m column bonded with a 0.5-µm layer of phase G42. The column temperature is programmed to be maintained at about 80 for 0.5 minute, then to increase to about 220 at a rate of 20 per minute, and to hold at about 220 for 10 minutes. The injection port temperature is maintained at about 85. Helium is used as the carrier gas at a flow rate of about 2.3 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.9 for tributyl citrate and 1.0 for acetyltributyl citrate; the resolution, R, between tributyl citrate and acetyltributyl citrate is not less than 1.5; and the relative standard deviation for replicate injections is not more than 2.0% determined from both the tributyl citrate and acetyltributyl citrate peaks, based on area percent calculation.

Procedure— Inject 1 µL of the Assay preparation into the chromatograph, record the chromatogram, and measure all of the peak areas, excluding the solvent peak. Calculate the percentage of C18H32O7 in the portion of Tributyl Citrate taken by the formula: in which A is the tributyl citrate peak area response; and B is the sum of the area responses of all the peaks.