CORS-1: Corn Starch Reference Material for Trace Metals and other Constituents

CORS-1 is a Reference Material prepared from food grade corn starch. Reference and information quantity values are provided in the following tables for trace metals and other constituents. Reference values are equally weighted means of results from at least two analytical methods and/or laboratories. Uncertainties are expressed as a 95% confidence interval. All values are expressed on a dry-mass basis.

Table 1: Reference values for CORS‑1

Element Mass fraction, mg/kg
Calcium 56 ± 15
Copper 0.06 ± 0.04
Magnesium 31 ± 5
Manganese 0.10 ± 0.05
Phosphorus 178 ± 23
Potassium 45 ± 17
Sodium 119 ± 7
Zinc 0.22 ± 0.05

Table 2: Information values for CORS‑1

Element Mass fraction, mg/kg
Aluminium 1.9
Cadmium 0.0003
Chromium 0.02
Chlorine 45
Cobalt 0.0012
Fluorine 0.02
Iron 5
Lead 0.007
Molybdenum 0.02
Nickel 0.02
Nitrogen 680
Selenium 0.0009
Strontium 0.18
Sulfur 200
Tungsten 0.001

Table 2 (continued): Information values for CORS‑1

Quantity Value Unit
Ash 0.13 g/(100 g), %
Protein 0.45 g/(100 g), %
Carbohydrate 98.8 g/(100 g), %
Total dietary fibre 0.6 g/(100 g), %
Energy content 403 kcal/(100 g)
Energy content 1686 kJ/(100 g)

The protein concentration was calculated from the nitrogen values using a conversion factor of 6.25; subsequent calculations of carbohydrates and calories were also based on these protein concentrations. The value for energy content is the mean of the individual caloric calculations. The mean proximate values were used for calculation, with caloric equivalents of 9, 4, and 4 for fat, protein, and carbohydrate, respectively.

Intended use

This Reference Material (RM) is intended for use in evaluating analytical methods and instruments used for the determination of major, minor, and trace constituent elements in flour and other similar food, agricultural, and biological materials. A minimum sample mass of 500 mg is recommended.

This material is intended for laboratory use, not for human consumption.


Original uncertainty estimates for RM 8432 were verified at NRC and were retained in this report. As stated in the RM 8432 report [1], uncertainties are imprecision estimates expressed as a 95% confidence interval, based on a sample mass of at least 500 mg. These uncertainties, based on between-method and between-laboratory, between-unit and within-unit estimates of variances, include measures of analytical method and laboratory imprecisions and biases and material inhomogeneity.

Date of Issue: September 2015
Date of Expiry: September 2025
Revised: March 2016 (editorial update)

Date modified: