“…The spectrophotometer principle is based on the absorption of certain wavelengths by Hb in the blood [ 11 ]. Researchers have developed absorption spectrophotometry methods [ 12 , 13 ], occlusion spectroscopy [ 14 ], and near infrared spectrophotometry [ 15 ] to identify Hb. It has also become more common that measurement tools are portable [ 16 ].…”