Cheap glass sample vials supplier,manufacturer and factory . Sigma cod digestion vials with pp cap-COD Vials Supplier Pipet 2 ml (0.2 ml for the 0-500 mg/l range) of sample into the vial. 5. Replace the vial cap tightly. Rinse the outside of the COD vial with deionized water and wipe the vial clean with towel paper. 6.