Hoppe-Seyler’s successor Gustav Hüfner determined, amongst others, the maximum oxygen binding to the hemoglobin – this figure is still known today under the name “Hüfner number”.
Hüfner’s assistant William Küster also researched the red blood pigment. After his departure from Tübingen in 1903 he even managed to create a formula for the complicated hemin molecule. The formula was later largely confirmed by Hans Fischer through the synthesis of the substance. Fischer received the Nobel Prize for this in 1930 – if Küster had still been alive then, he would have probably received the Nobel Prize with Fischer. He had been nominated for the Nobel Prize in 1913 already.
In order to determine the hemoglobin content in the blood, so called colorimetric methods were applied, the determination of the substance concentration through color comparison. In the color bar hemometer, a hydrochloric acid solution of the blood sample is diluted in the tube located in the middle until the color precisely matches the reference tubes. Hoppe-Seyler also created a hemoglobinometer which, however, was more cumbersome to operate than other devices, so that it did not assert itself.