SIMULTANEOUS GC ASSAY OF DEG AND EG 231 Figure 6. Typical chromatograms for standard mix (top), sorbitol solution sample (middle), and sorbitol solution sample spiked at USP limits of 0.10% EG and 0.10% DEG to demonstrate how sample at compli- ance threshold would appear (bottom). Figure 5. Typical chromatograms for standard mix (top), propylene glycol sample (middle), and propylene glycol sample spiked at USP limits of 0.10% EG and 0.10% DEG to demonstrate how sample at compliance threshold would appear (bottom). and 0.1584% EG were 93.8% and 93.2%, respectively. Recoveries of the sample spiked with 0.0831% and 0.1662% DEG were 102.9% and 103.4%, respectively. DISCUSSION This test procedure is offered as a single simplifi ed alternative to six separate DEG and EG test procedures specifi ed in the USP-NF. This test procedure enables a single mixed standard and one set of GC conditions to be used that would replace fi ve separate USP GC

JOURNAL OF COSMETIC SCIENCE 232 Figure 7. Typical chromatograms for standard mix (top) and PEG-12 sample (bottom). Table I Experimental Results Identifi cation Sample type Suppler code % DEG % EG Glycerin B BDL BDL Proplene glycol E BDL BDL 70% Sorbitol solution F BDL BDL 39157-1 PEG-8 A 0.0268 0.0118 0.0291 0.0124 39157-2 PEG-8 C 0.0482 0.034 0.0495 0.0349 39158-1 PEG-12 A 0.0477 0.0216 0.0493 0.0223 39158-2 PEG-12 D 0.1138 0.0417 0.1174 0.0428 39191-1 PEG-6 ME A 0.0087 0.0087 0.0083 0.0086 39191-2 PEG-6 ME C BDL BDL 39191-3 PEG-6 ME D 0.0218 0.0096 PEG-6 ME = PEG-6 methyl ether. BDL = Below detection levels. tests with four different sets of standards and four different column types (two capillaries and two packed columns). This test also replaces the vacuum distillation-colorimetric test used for larger PEG and MPEG homologs. Utilizing this technology could greatly simplify and improve effi ciencies in the quality control laboratories of facilities receiving these USP-NF materials. CONCLUSION This test procedure has not been validated, but has been detailed here to be amenable for the assay to determine DEG and EG compliance in various polyol raw materials. With