J. Cosmet. Sci., 61, 225–234 (May/June 2010) 225 Simplifi ed assay of diethylene glycol and ethylene glycol in various raw materials by capillary gas chromatography K. MOLEVER, Research and Development Department, The Dial Corporation, a Henkel company, 19001 N. Scottsdale Road, Scottsdale, AZ 85255. Accepted for publication November 16, 2009. Synopsis The FDA has recently taken steps to reduce risks due to raw materials affected by economically motivated adulteration (EMA). One area of great interest is diethylene glycol (DEG) or ethylene glycol (EG) adultera- tion of glycerin, propylene glycol, and solutions of sorbitol, for which the USP monographs have recently been revised (1). Such adulterations have occurred many times and in many countries, including a tragic episode between November 2008 and January 2009 in which 84 children in Nigeria died after ingesting teething syrup contaminated with DEG (9,10). To eliminate this problem, the FDA has required manufac- turers of fi nished products to assay and confi rm that incoming glycerin, propylene glycol, and sorbitol solu- tions meet the USP limits, and the FDA/USP has incorporated such testing into the identity requirements of its updated monographs. Unfortunately, even though USP test procedures detail a simultaneous DEG and EG assay for these materials, different standard solutions are specifi ed depending upon whether the incoming sample is glycerin, propyl- ene glycol, or a sorbitol solution in addition, a certain gas chromatography (GC) capillary phase is detailed for sorbitol solutions, while the assays for glycerin and propylene glycol use a different capillary phase, requir- ing column changeovers, separate GC systems, or front/rear column confi guration. In addition, NF mono- graphs for polyethylene glycols (PEG) and polyethylene glycol monomethyl ethers (MPEG) used in pharmaceutical products also require DEG and EG testing (detailing their own specifi c tests) three separate test procedures for these types of raw materials (the larger PEG-type polymers are assayed differently than their smaller counterparts), making assay at QC unwieldy. This paper describes a single, simple test procedure that is applicable to the simultaneous assay of DEG and EG in all types of the described raw materials, using one standard solution. The assay procedure involves straightforward isolation, trimethylsilylation, and simultaneous capillary gas chromatographic quantitation using capillary GC with fl ame ionization detection. Although the USP-NF limits are 0.10% DEG and 0.10% EG (and 0.25% total DEG plus EG for the PEG and MPEG products), in reality any EMA would be at levels signifi cantly higher than that, as low-level illegal EMA would not be economically advantageous. The scope of this project was not to fully validate this technique for inclusion in USP-NF, but just to dem- onstrate its applicability for those wishing to utilize it or take it further. INTRODUCTION The FDA has become more concerned about raw materials affected by economically mo- tivated adulteration (EMA)—willfully adulterating more expensive desired material by adding less expensive material. Many times, this adulteration is done using signifi cant scientifi c understanding, to produce adulterated material that passes most quality checks.