Crimp Cap HS Vial: PN#21162 and Crimp Cap: PN#21761. Sample preparation included adding propane, butane, and isobutane standards in N,N-Dimethylacetamide (DMA) along with α,α,α-Trifluorotoluene as the ISTD to a 20 mL HS vial. To model the vial cap’s ability to keep these volatile compounds from escaping the vial, we designed a time study.