The Arkray Cyanmeth-HB Standard likely refers to the standardization solution for the cyanmethemoglobin method of hemoglobin (Hb) estimation, which is a stable, colored solution of cyanmethemoglobin used to calibrate spectrophotometers or colorimeters. This method converts hemoglobin to a stable cyanmethemoglobin complex that has a consistent color intensity, allowing for accurate Hb concentration measurement at a specific wavelength (typically 540 nm) by comparing the sample's absorbance to the known concentration of the standard solution.