STATE PRIMARY REFERENCE PROCEDURE FOR THE MEASUREMENT OF ASH MASS FRACTION IN FOOD, FOODSTUFF AND ALIMENTARY RAW MATERIALS

The lack of traceability of the results of ash content measurements to the state standards of measurement units is considered. The problems of ash mass fraction measurement in food industry are revealed: dependence of the measurement results on conditions of the analysis, incomplete information on the modes of measurements and metrological characteristics in standardized methods, the absence of reference materials. We present information about the measurement method and equipment for implementation of the State primary reference procedure (SPRP) for measuring the ash mass fraction in food and foodstuff (grain, grain products, starch, sugar, dairy products, low-lactose products, lactose-free products, compound feeds and feed components) and describe the procedure of determining the methodological parameters (temperature, duration of combustion, weight of sample) in the course of the SPRP development using a stereoscopic pancratic microscope and thermogravimetric analyzer with mass spectrometric detector (implementing TGA-MS methods) included in the State primary measurement standard of mass fraction and mass (molar) concentration of water in liquid and firm substances and materials GET 173 – 2017. The described algorithm for estimating the uncertainty of the ash mass fraction measurements using multifactor experiment, regression analysis and single-factor ANOVA provide information about the sources of the uncertainty and their contributions to the total uncertainty of measurement results. The metrological characteristics, scope and purpose of SPRP are presented. The results of interlaboratory comparisons confirming the equivalence of the developed SPRP to similar measurement procedures (methods) of foreign countries are presented. The applicability of the developed SPRP for determination of the certified values of the mass fraction of crude ash to testing reference standards of compound feed composition is demonstrated.

1. Customs Union Technical Regulation N 67 of October 09, 2013 TR CU 033/2013. On safety of milk and dairy products [in Russian].

2. TR CU 027/2012. N 34 of June 15, 2012. On Safety of Certain Types of Specialized Food Products Including Therapeutic and Preventive Dietary Food [in Russian].

3. Bock R. A handbook of decomposition methods in analytical chemistry. — New York: John Wiley & Sons Inc, 1979. — 444 p.

4. Nielsen S. S. Food Analysis. 5th ed. — New York: Springer, 2017. — 649 p.

5. Knauer G. A. The determination of magnesium, manganese, iron, copper and zinc in marine shrimp / Analyst. 1970. N 95(130). P 476 - 480.

6. Sakac M. B., Jovanov P. T., Marie A. Z., et al. Physicochemical properties and mineral content of honey samples from Vojvodina (Republic of Serbia) / Food Chem. 2019. Vol. 276. P. 15 - 21.

7. Poitevin E. Official methods for the determination of minerals and trace elements in infant formula and milk products: a review / J. AOAC Int. 2016. Vol. 99. N 1. P. 42 - 52.

8. Byun Y.-K., Hwang S.-H., Lee J.-H. Characterization of physicochemical properties of casein mixture preparation extracted from organic milk for use as an emulsifier in organic processed foods / J. Sci. Food Agric. 2018. Vol. 99. N 5. P. 2375 - 2383.

9. State Standard GOST R RF 8.735.0-2011. State system for ensuring the uniformity of measurements. State verification schedule for instruments measuring the content of components in liquid and solid media. Basic principles. — Moscow: Standartinform, 2012. — 6 p. [in Russian].

10. Interstate Standard GOST 10847-74. Grain. Methods of determination of ash content. — Moscow: Standartinform, 2009. — 5 p. [in Russian].

11. Federal Law of June 6, 2007. N 102-FZ On Ensuring the Uniformity of Measurenents [in Russian].

12. Strategy to Enhance Food Quality in the Russian Federation until 2030, approved by Executive Order of the Russian Federation Government N 1364-r of June 29, 2016 [in Russian].

13. Medvedevskikh M. Y., Krasheninina M. P., Sergeeva A. S., Shokhina O. S. A reference installation based on thermo-gravimetric analysis with mass-spectrometric detection as a part of the state primary standard GET 173 / Zavod. Lab. Diagn. Mater. 2018. Vol. 84. N 6. P. 63 - 70 [in Russian].

14. Lidin R. A., Molochko V A., Andreeva L. L. Chemical Properties of Inorganic Substances. — Moscow: Khimiya, 2000. — 480 p. [in Russian].

15. EURACHEM/CITAC Guide. Quantifying uncertainty in analytical measurement. 2nd Ed. — London: Laboratory of the Government Chemist, 2000 — 121 p.

16. Derffel K. Statistics in analytical chemistry. — Moscow: Mir, 1994. — 268 p. [Russian translation].

17. Recommendations for Interstate Standardization RMG 612010 State system for ensuring the uniformity of measurements. Accuracy, trueness and precision measures of the procedures for quantitative chemical analysis. Methods of evaluation. — Moscow: Standartinform, 2013. — 58 p. [in Russian].

18. ISO Guide 35:2006. Reference materials. General and statistical principles for certification. https://www.iso.org/standard/ 39269. html (accessed April 28, 2009).

19. Lavrova G. P., Mashkina Ye. I. Zootechnical analysis of feed — Barnaul: Izd. AGAU, 2006. — 30 p. [in Russian].