Where solvent destruction systems are used to comply with EPA new source performance standards in the surface coatings industries, capture and control device efficiencies may have to be determined separately to demonstrate the combined overall reduction efficiency. The capture efficiency is determined as the percent of total VOC emissions that are captured and delivered to the control device. Presently, the EPA requires determination of capture efficiency through use of an exhausted enclosure around the operation and a gasphase material balance. The feasibilities of less costly and cumbersome alternate methods are examined. The alternate methods include material balances other than enclosure type gas-balances, use of tracers, computer modeling, and assumption/approximation techniques. The liquid/gas-phase measurement methodology using a total capture (100%) evaporation chamber. The pure solvent evaporation tests demonstrated that a combination of EPA Methods 2 and 25A for gas streams and a mass loss determination of liquid provided acceptable closure results (e.g., mean closure = 99.9% and coefficient of variation = 5.9%). The methodology was recommended for field evaluation.