Some selected discrepancies observed in food chemistry proficiency tests

Main Article Content

M. Sykes
M. Knaggs
S. Hunter
E. Leach
C. Eaton
D. Anderson

Keywords

food chemistry, repeatability, reproducibility

Abstract

Hundreds of food chemistry proficiency tests are carried out annually across the world. The protocols for these are well established. Very occasionally, the data associated with a proficiency test are unexpected in relation to the dispersion or distribution. This may reflect differences between the test material characterisation data and the participants’ data in terms of repeatability and reproducibility. The dispersion of participants’ data could also reflect a difficulty with a particular analyte/matrix combination. There might also be some unanticipated chemistry occurring in a test material. In all circumstances, there are means of characterising the differences in order to obtain an appropriate outcome for the test. This paper describes some of these differences, observed from a food chemistry proficiency testing scheme.

Abstract 73 | PDF Downloads 58

References

Eurachem, 2011. Selection, use and interpretation of proficiency testing (PT) schemes (2nd Ed.). Eurachem, Uppsala, Sweden. Available at: http://www.eurachem.org/images/stories/Guides/pdf/Eurachem_PT_Guide_2011.pdf.
European Commission (EC), 2006. Commission Regulation (EC) no. 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. Official Journal of the European Union L364: 5-24.
European Commission (EC), 2010. Commission Regulation (EC) no. 37/2010 of 22 December 2009 on pharmacologically active substances and their classification regarding maximum residue limits in foodstuffs of animal origin. Official Journal of the European Union L15: 1-76.
FAPAS, 2010a. FAPAS® proficiency test report 02155. Avermectins and benzimidazoles in bovine liver. FAPAS, York, UK.
FAPAS, 2010b. FAPAS® proficiency test report 1568. Nitrate and nitrite in meat. FAPAS, York, UK.
FAPAS, 2012a. FAPAS® proficiency test report 03106. Artificial colours in soft drink. FAPAS, York, UK.
FAPAS, 2012b. FAPAS® proficiency test report 04185. Aflatoxins B&G in ginger spice. FAPAS, York, UK.
FAPAS, 2012c. FAPAS® proficiency test report 3036. Melamine & cyanuric acid in animal feed. FAPAS, York, UK.
Fearn, T. and Thompson, M., 2001. A new test for sufficient homogeneity. Analyst 126: 1414-1417.
International Standardisation Organisation (ISO), 2010. Conformity assessment – General requirements for proficiency testing – ISO/IEC 17043. ISO, Geneva, Switzerland.
Lowthian, P.J. and Thompson, M., 2002. Bump-hunting for the proficiency tester-searching for multimodality. Analyst 127: 1359-1364.
Sykes, M., Thompson, M. and Reynolds, S., 2013. Pesticide residues in food-based proficiency test materials, spiking values versus consensus assigned values. Journal of Agricultural and Food Chemistry 61: 4205-4209.
Thompson, M., 2000. Recent trends in inter-laboratory precision at ppb and sub-ppb concentrations in relation to fitness for purpose criteria in proficiency testing. Analyst 125: 385-386.
Thompson, M., Ellison, S.L.R. and Wood, R., 2006. the international harmonised protocol for the proficiency testing of analytical chemistry laboratories. Pure Applied Chemistry 78: 145-196.
Thompson, M. and Fearn, T., 2011. A long-term look at homogeneity testing: prospects for a cheaper ‘quality control’ based test. Analytical Methods 3: 2529-2533.