What are the pretreatment methods for the determination of hexavalent chromium and water samples?

(2) if it is turbid, filtering;

(3) If there is chroma, if it is serious, it should be diluted appropriately and deducted by turbidity correction; If it is not serious, directly carry out chromaticity correction (mentioned in the standard method);

(4) If the acidity (alkalinity) of the sample is too strong, it is suggested to adjust it to strong alkali (acid). If there is precipitation after adjustment, it should be filtered, then adjusted to neutral, and then colored after adjustment;

(5) If it is known that it contains more other heavy metals, adjust it to strong alkalinity; if precipitation occurs, filter it and transfer it back to neutral color development;