Figure 5.7 High-pressure liquid chromatography (HPLC). Gel filtration by HPLC clearly defines the individual proteins because of its greater resolving power. Proteins are detected by their absorbance of 220-nm light waves: (1) thyroglobulin (669 kDa), (2) catalase (232 kDa), (3) bovine serum albumin (67 kDa), (4) ovalbumin (43 kDa), and (5) ribonuclease (13.4 kDa).