- Total hardness of water(standard sample)(in terms of calcium carbonate),27.8mg/L, matrix: H2O, 20ml
- Total hardness of water(standard sample)(in terms of calcium carbonate),60.4mg/L, matrix: H2O, 20ml
- Total hardness of water(standard sample)(in terms of calcium carbonate),98.4mg/L, matrix: H2O, 20ml