Bureau of Analytical Standards. CRMs or SRMs are produced in various forms
and for different purposes and they may contain one or more certified compo-
nents, such as● pure substances or solutions for calibration or identification;
● materials of known matrix composition to facilitate comparisons of analytical
data;
● materials with approximately known matrix composition and specified
components.They have a number of principal uses, including● validation of new methods of analysis;
● standardization/calibration of other reference materials;
● confirmation of the validity of standardized methods;
● support of quality control and quality assurance schemes.A5 – Calibration and standards 17
Table 1. Some primary standards used in titrimetric analysis
Type of titration Primary standard
Acid-base Sodium carbonate, Na 2 CO 3
Sodium tetraborate, Na 2 B 4 O 7 .10H 2 O
Potassium hydrogen phthalate, KH(C 8 H 4 O 4 )
Benzoic acid, C 6 H 5 COOH
Redox Potassium dichromate, K 2 Cr 2 O 7
Potassium iodate, KIO 3
Sodium oxalate, Na 2 C 2 O 4
Precipitation (silver halide) Silver nitrate, AgNO 3
Sodium chloride, NaCl
Complexometric (EDTA) Zinc, Zn
Magnesium, Mg
EDTA (disodium salt), C 10 H 14 N 2 O 8 Na 2