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» Tributyl Citrate contains not less than 99.0 percent of C18H32O7, calculated on the anhydrous basis.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
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.
Specific gravity 841: between 1.037 and 1.045.
Refractive index 831: between 1.443 and 1.445.
Acidity Dissolve 32.0 g in 30 mL of isopropyl alcohol, previously neutralized to bromothymol blue, add bromothymol blue TS, and titrate with 0.10 N sodium hydroxide to a faint blue endpoint: not more than 1.0 mL is required.
Water, Method I 921: not more than 0.2%.
Heavy metals, Method II 231: 0.001%.
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 an on-column, temperature-programmable injector, a flame-ionization detector maintained at about 275, and a 0.32-mm × 30-m column bonded with a 0.5-µm layer of phase G42. The column temperature is programmed as follows. Initially the temperature is maintained at about 80 for 0.5 minute, then increased at a rate of 20 per minute to about 220, and maintained at about 220 for 10 minutes. The injection port temperature is programmed as follows. Initially the temperature is maintained at about 85 for 0.5 minute, then increased at a rate of 20 per minute to about 225, and maintained at about 225 for 10 minutes. The carrier gas is helium, flowing at a 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:
100(A/B)in which A is the tributyl citrate peak area response; and B is the sum of the area responses of all the peaks.
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USP35NF30 Page 2008Pharmacopeial Forum: Volume No. 32(1) Page 179