Table 2-1R: US-EPA Method NPDES Standard Method
US-EPA Method NPDES (A22, 23)
Closed Vessel Microwave Digestion of Wastewater
Samples for Metals Determination
Type |
Matrix |
Analytes |
Detection |
Control |
Microwave Acid Leach |
Domestic and Industrial Wastewater |
Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, Zn |
FAAS ICP-AES DCP-AES |
Microwave Unit Specific Power Settings |
Condensed Procedure |
50.0 mL sample, 3 mL HNO3, and 2 mL HCl For 1 - 6 samples: For MW units with 364 - 420 W use 75% power for 30 min to a maximum temperature of 164 ± 4°C For MW units with > 364 - 420 W at 75%, adjust power setting to deliver 364 - 420 W for 30 min. For 7 - 12 samples: For MW units with 575 - 635 W use 100% power for 50 min to a maximum temperature of 165 ± 5°C. For MW units with 635 - 700 W use 100% power for 30 min to a maximum temperature of 165 ± 5°C. For MW units with > 700 W adjust power settings to reproduce temperature versus time profiles illustrated in the method. |