5.1 Sampling equipment, for discrete sampling. 5.1.1 Vial—25 mL capacity or larger, equipped with a screw cap with a hole in the center (Pierce #13075 or equivalent). Detergent wash, rinse with tap and distilled water, and dry at 105°C before use. 5.1.2 Septum—Teflon-faced silicone (Pierce #12722 or equivalent). Detergent wash,