Isolasi, pemurnian, dan karakterisasi kolagen dari kulit babi serta analisis kandungan glisin, prolin, dan hidroksiprolin secara kromatografi cair kinerja tinggi-fluoresensi = Isolatio, purification, and characterization of porcine skin collagen and analysis component of glycine, proline, and hydroxyproline by high performance liquid chromatography-fluorescence