Chromium (Cr), 1µg/ml in 2%-HNO3 / Water, 100ml

Mo, 1000 µg/mL in 5% HNO3, tr. HF, 100ml

Copper, 1000ug/ml, 100ml

6,6'-Dihydroxy-5,5'-dimethoxybiphenyl-3,3'-dicarbo