Of the seven method variations examined, acidity of the
extraction fluid had the greatest impact on the results.
Four of 13 metals from an API separator sludge/
electroplating waste (API/EW) mixture and two of three
metals from an ammonia lime still bottom waste were
extracted at higher levels by the more acidic buffer.
Because of the sensitivity to pH changes, the method
requires that the extraction fluids be prepared so that
the final pH is within + 0.05 units as specified.