Group reagents for precipitating ions:
| Group | Cations | Group reagent | |
| Zero | NH4+ | None | |
| I | Pb2+ | Dilute HCl | |
| II | Pb2+,Cu2+,As3+ | H2S gas in presence of dil. HCl | |
| III | Al3+,Fe3+ | NH4OH in presence of NH4Cl | |
| IV | Co2+,Ni2+,Mn2+,Zn2+ | H2S in presence of NH4OH | |
| V | Ba2+,Sr2+,Ca2+ | (NH4)2CO3 in presence of NH4OH | |
| VI | Mg2+ | None |