NMI continually develops new reference methods for chemical measurements and characterises reference materials to act as calibration standards. NMI is a leader in research into analytical methods for high accuracy measurements. The principle technique used is isotope dilution analysis which provides intrinsic correction for analytical difficulties such as matrix effects and instrument instability. For cases where isotope dilution is not possible a specialised application of the method of standard additions has been developed and successfully applied.
High accuracy reference measurements are required:
Research is ongoing to expand the range of sample types and analytes that can be measured by high accuracy methods.
NMI's isotope dilution methodology was recently applied to measurement of mercury in natural water at the European regulatory limit of 70 ng/L (parts per trillion). Analysis at such low levels creates unique analytical challenges such as ultra-clean sample handling, measurement of low instrument response and assessment of analytical blanks. Overall measurement uncertainty for the analysis was 2.3% and NMI results were in excellent agreement with other national metrology institutes from around the world.
NMI is conducting research relevant to the growing pharmaceutical industry. Particularly challenging metals have been identified for development of high accuracy measurement methods and production of a certified reference material.
Food Standards Australia and New Zealand (FSANZ) recently introduced Standard 2.1.1 Cereals and Cereal Products requiring that all wheat flour for making bread (except organic bread) be fortified with folic acid at between 2 and 3 milligrams per kilogram of flour. NMI runs proficiency testing programs to support Australian laboratories in their analysis of flour for folic acid. A high-accuracy method was developed to demonstrate homogeneity and provide reference values for these proficiency testing samples.