SIMULTANEOUS GC ASSAY OF DEG AND EG 233 appropriate standards, this basic test procedure could also be useful as an assay procedure for incoming glycerin, propylene glycol, and sorbitol. REFERENCES (1) U.S. Pharmacopeia, USP 32-NF 27, May 2009. (2) USP Hot Topics, USP Propylene Glycol and Sorbitol Solution Information, http://www.usp.org/hottopics/ propyleneGlycolSorbitolInformation.html (3) Guidance for Industry, Testing of Glycerin for Diethylene Glycol, U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research CDER), May 2007. Figure 8. Five standard chromatograms overlaid, demonstrating reproducibility. Figure 9. Chromatograms from spiking study.

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