VOA Vials, Volatile Organic Analysis, EPA Certified. Class 2: (Precleaned) Class 2: (Precleaned) Class 2: (Precleaned) vials are processed according to EPA recommended wash procedures. Washed with laboratory grade biodegradable, non-phosphate detergent, rinsed with ASTM Type 1 De-ionized water, oven dried, and assembled in a contaminate-free