Abstract: With the release of Implementation Plan for the Household Waste Classification System, the pilot work of waste classification in China has begun to move toward standardization and legalization, and the compost products from the resource treatment of kitchen waste have also shown broad application prospects. Organic matter content is an important index of compost quality evaluation. According to NY/T 525—2021 Organic Fertilizer, the content of organic matter in kitchen waste compost products was determined by using potassium dichromate volumetric method, the source of uncertainty was analyzed and the component of uncertainty was calculated. The research results showed that organic matter content of 12 samples ranged from 33.37% to 70.17% and the extended uncertainty ranged from 0.362% to 0.779%, which indicated all the above 12 samples were qualified samples. Under the same experimental conditions and procedures, the components of uncertainty of ferrous sulfate standard solution calibration, sample weighing, sample extraction and sample solution separation were basically stable and not affected by difference among samples. The main source of the sample moisture content test was repetitive test deviation, and the smaller deviation showed the smaller uncertainty. The component of titration sample was mainly determined by the content of organic matter, the higher content of organic matter had bigger uncertainty. The component of titration sample was also significantly affected by sample weight, and the smaller weight showed the smaller uncertainty. The component of repetitive tests were mainly determined by experimental deviation, it decreased with the increase of water content and organic matter content in the sample.

Key words: potassium dichromate volumetric method, kitchen waste； compost； organic matter content； uncertainty