Secondary standard
Under a secondary standard is meant a substance which, although not themselves volumetric standard ( primary standard ), but a very high degree of purity and having, set against a primary standard is suitable for setting of standard solutions. The secondary standard does not have to meet the strict requirements that are placed on primary titre substances. Due to the lower resistance, a new setting of the secondary standard is always required.
Examples of secondary standards:
- Hydrochloric acid standard solution adjusted against sodium carbonate
- Sodium thiosulphate adjusted against potassium bromate
- Standard silver nitrate solution adjusted against sodium chloride
- Perchloric acid standard solution adjusted against potassium hydrogen phthalate
- Disodium ethylenediaminetetraacetic acid measuring solution adjusted against zinc (Na 2 -EDTA)