1,2,3-Propanetricarboxylic acid, 2-hydroxy-, tributyl ester;
Tributyl 2-hydroxypropane-1,2,3-tricarboxylate;
1,2,3-Propanetricarboxylic acid, 2-hydroxy-, 1,2,3-tributyl ester [77-94-1]
BRIEFING
Tributyl Citrate. This proposal is based on the version of the monograph official as of May 1, 2020. On the basis of comments and data received, it is proposed to make the following changes:
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Update the Chemical Information section to include three chemical names for tributyl citrate and a CAS number, as well as update the molecular weight.
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In the Definition and Assay, revise the acceptance criteria from NLT 99.0% to NLT 98.0% and NMT 102.0% to account for the performance of the proposed gas chromatographic (GC) procedure used in the Assay that utilizes an internal standard method for quantitation instead of the current normalization, and for variability of the Assay values obtained for Tributyl Citrate samples tested per the proposed GC procedure.
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Rename Identification B to Chromatographic Identity and update the test to reflect the use of the Standard solution from the Assay.
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In the Assay, replace the current GC procedure based on normalization for quantitation with a GC procedure that uses an internal standard method for quantitation. The newly proposed GC procedure in the Assay is based on analyses performed with the Agilent DB-225MS brand of column with G7 phase (as a primary column) or the Restek Rtx-225 brand of column with G7 phase (as an alternative column). The typical retention times for butyl stearate (internal standard) and tributyl citrate are about 14.7 and 21.4 min, respectively.
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Add an Organic Impurities test based on the GC method in the Assay. The typical retention times for butyl-p-toluenesulfonate and tributyl citrate are about 13.5 and 21.4 min, respectively.
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In Specific Tests, delete the tests for Specific Gravity and Refractive Index. Move the information for specific gravity and refractive index listed as acceptance criteria in the corresponding tests to the Description and Relative Solubility table appearing elsewhere in this issue of PF.
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In Specific Tests, revise the Acidity test to add the preparation of Neutralized isopropyl alcohol and to align the preparation of the Sample solution and description of the Analysis with those in the Acetyltributyl Citrate monograph.
Additionally, minor editorial changes have been made to update the monograph to current USP style.
(SE: S. Saladi)
Correspondence Number—C153704