GB/T 24990-2010 "Paper, board and pulps — Determination of chromium content" specifies the use of flame atomic absorption spectrometry or diphenylcarbazide photometry for the determination of chromium content in paper, board, and pulps. It is applicable to samples that can be digested by dry ashing or wet digestion with nitric acid, with detection limits of approximately 10 mg/kg and 50 μg/kg, respectively. The sample is collected according to GB/T 450, and moisture is measured according to GB/T 462. After digestion, the sample is analyzed using the corresponding method. The standard specifies reagents, instruments, and calculations to ensure accurate and comparable results.