Merck 114414 Copper Test Method: colorimetric with color card and comparator block with long test tubes 0.05 - 0.08 - 0.12 - 0.16 - 0.20 - 0.25 - 0.3 - 0.4 - 0.5 mg/l Cu MQuant®
Merck 109884 Buffer concentrate (citrate/hydrochloric acid), traceable to SRM of NIST and PTB for 500 ml buffer solution, pH 4.00 ± 0.02 (20°C) Titrisol®