The authors provided information about the developed matrix feed reference materials, certified for quality, nutritional value and toxicological contamination indicators for metrological support of analytical work in the article to confirm the compliance of products with requirements of national standards. Information on the stages of development of feed reference materials (selection and preparation of reference material, studies of heterogeneity and stability of feed reference material) is presented. There are demonstrated the results of reference materials certification according to certified indicators, their correctness confirmed by the results of thirty accredited laboratories.

The developed reference material of sunflower meal is registered in the State Register of approved types of reference materials under the number GSO 11612-2020. Reference materials of the composition of toasted soybean feed meal and complete feed for poultry (broilers) are approved as Industry-Specific by the Ministry of Agriculture of the Russian Federation (Department of Plant Production, Mechanization, Chemicalization and Plant Protection).

Feed reference materials are intended for metrological support of agro-industrial complex laboratories.

The paper considers the contribution of experts from the Laboratory of Metrology of Moisture Measurement and Reference Materials to the improvement of the food industry metrological assurance system. The information on the results of the development of forty types of reference materials (RM) for the composition of various nutrition, food staples and nutritional supplement in the period 2008-2020 is generalized. The development of each new RM type included preparation of the material, research for its stability and homogeneity, and determination of certified value with the appliance of State primary (GET 173) and secondary (GVET 176-1) standards, as well as primary reference measurement procedures and conducting the interlaboratory experiment for checking the applicability of the RM. The creation in 2008 of GET 173 was accompanied by the development of RMs for the composition of grains and dry milk product. The approval in 2010 of GVET 176-1 allowed to add in the RM the certified value for the mass fraction of nitrogen (protein). As a result of successful participation in comparisons, UNIIM got 6 items of calibration and measurement capabilities on measurements of mass fraction of nitrogen in glycine, milk powder, grain, egg powder, cereal and feed-stuff in the BIPM database. 35 types of RM for the composition of dairy and meat products, egg powder, infant food, oil and starch products together with the development of primary reference measurement procedures for measurement of fat, crude fat, ash and carbohydrates mass fraction were created between 2016 and 2019. Moreover, the RM for the composition of nutritional supplement (glycine, melamine, cystine) and dairy products for metrological assurance of IR-analysers as well as RM for the composition of reconstituted milk were developed for the control of measurement results by the enzyme-linked immunosorbent assay (ELISA). Developed RM were systemized on fields of the appliance of Technical regulations of Customs Union and the sectors of the international food triangle model. These RMs allow providing the measurement uniformity of the identification indicators and the nutritional value of food products and food staples.

The article presents the application of the lyophilization system for preparation of reference materials (RM) for composition of nutritive products samples. The purpose of the research was the development of lyophilization procedure of RM for composition of poultry meat samples preparation with certified values of mass fraction of moisture, nitrogen (protein) and fat.

The poultry meat of two types was used as the primary material for RM for poultry meat composition preparation -1) white meat (chicken breast); 2) red meat (chicken thigh). The procedure included pounding, boiling, freezing and lyophilisation (syn. freeze drying). The researches for homogeneity were implemented with hot air dryer standard system from the State primary standard GET 173-2017. Measurement of nitrogen (protein) mass fraction was performed on State secondary standard GVET176-1-2010. Measurements of fat mass fraction were performed with accordance to State Primary Reference Measurement Procedure.

The total time of lyophilization process for samples № 1 and № 2 was 19 and 28 hours, respectively. The total mass loss for sample № 1 was about 63 %, for sample № 2 was about 65 %. The difference in material moisture mass fraction values of materials dried on different trays of freeze dryer was statistically significant, i. e., material was non-homogeneous. To obtain a homogeneous material, an additional homogenization procedure was performed: grinding in a laboratory mill, sieving through a sieve, thorough mixing and conditioning. The certified values of moisture, nitrogen, protein, fat mass fraction for the sample № 1 were accordingly 4,5 %, 14,74 %, 92,1 %, 7,9 %. The same values in the same sequence were 6,3 %, 12,21 %, 76,3 %, 23,8 %.

The procedure of lyophilisation was developed for production of reference materials for composition of boiled and freeze-dried poultry meat. The usage of this lyophilisation system allowed to ensure a RM expiration date of six months at ambient temperature of (7±3) °C and relative humidity no more than 60 %. The Reference Materials for composition of boiled and freeze-dried poultry meat was added into Register of certified RMs under № GSO 11276-2019 by the results.

The article presents the results of the study of the metrological characteristics of NMR analyzers AMV-1006M obtained during their calibration to determine the mass fraction of oleic acid in sunflower seed oil using sunflower seeds and specially developed reference materials (RM) - imitators of the mass fraction of oleic acid in seed oil. When calibrating an NMR analyzer under repeatability conditions, it was found that the relative standard deviations of the measurement results and the limits of the confidence random error of the measurement results using RM simulators are almost 3 times lower than the results of the measurement with use of natural sunflower seeds. When checking the reproducibility of the calibration results using four NMR analyzers, it was found that the reproducibility of the calibration of NMR analyzers using RM simulators of the mass fraction of oleic acid is more than 3 times better than when using sunflower seeds. The data obtained is explained by the fact that RM-simulators have a fairly homogeneous structure, which is formed during their manufacture. Sunflower seeds are a complex heterogeneous system with a heterogeneous structure in the volume of the analyzed sample. The study of the effect of temperature on the calibration results showed that the standard deviation of the measurement results for RM-simulators does not exceed 0.8 % abs., while the using of natural seeds, values of 2.5 % abs. were obtained. Thus, the use of RM simulators can significantly reduce the calibration error of NMR analyzers associated with the effect of temperature. The obtained data confirmed the expediency of using for calibration of the AMV-1006M NMR analyzers precisely CO-simulators of the mass fraction of oleic acid.

The research provides enterprise reference material (ERM) development approach for nanosensor system on the basis of dynamic light scattering and fluorescence for qualitative and quantitative determination of nutrition pollutant - chloramphenicol antibiotic (laevomycetin), as well as marker of ischaemic stroke and a number of other diseases - reduced glutathione.

ERM candidate materials were chosen chloramphenicol and reduced glutathione. The attestation procedure based on calculating-experimental approach by preparation procedure was used to determine the certified value of ERM. During the tests there were determined metrological characteristics of reference material. The certified value of ERM for reduced glutathione mass fraction is 98,5 %, the expanded uncertainty of certified value with coverage factor k=2 is ± 0,3 %. The certified value of ERM for chloramphenicol mass concentration is 10,0 g/dm³, the expanded uncertainty of certified value with coverage factor k = 2 is ± 4,0 %.

The implementation of the developed ERMs showed their appropriateness for optic nanosensor systems calibration on the base of dynamic light scattering and fluorescence.

We suppose that the developed enterprise reference materials further may be certified as CRM (certified reference material) and used for verification, calibration and graduation of compact detection devices of the «point of care diagnostics» type under development, which are intended for express analysis on the sampling site directly.