State system for ensuring the uniformity of measurements. Reference gauge-blocks of the 1st and the 2nd accuracy orders and working gauge-blocks of 00 and 0 accuracy classes up to 1000 mm. Methods and means for verification
Fertilizers. Determination of N-(2-nitrophenyl) phosphoric triamide (2-NPT) in urea and fertilizers containing urea using high-performance liquid chromatography