The study on the structure of pigments in the outer skin of squid

以太平洋褶柔鱼（Todarodes pacificus）为原料，用盐酸/甲醇混合溶液提取其红色素。提取物的反相LC-ESI-MS分析表明，在提取物中存在黄色素及其衍生物，黄色色素，但红色色素未洗脱。用加入离子对试剂的溶剂进行HPLC分析，发现提取物中存在各种色素。色素的最大吸收波长在450 ~ 530 nm之间，表明提取物中含有黄色、红色和红紫色等多种色素。提取物通过正离子交换和随后的反相色谱进行分配，得到亲水性红色素。超高效液相色谱-飞行时间-质谱（UPLC-TOF-MS）分析表明，红色素的分子量在450 ~ 800 Da之间，表明红色素分子中含有硫。

The red pigments were extracted from the outer skin of Japanese flying squid Todarodes pacificus with HCl/methanol mixture solution. The reverse-phase LC-ESI-MS analysis of the extract showed the presence of xanthommatin and derivatives, yellow ommochrome pigments, in the extract, but red pigments were not eluted. The HPLC analysis with solvents added a ion-pair reagent revealed the presence of various pigments in the extracts. The wavelength of maximum absorbances of the observed pigments were in the range of 450 nm to 530 nm, indicating the extracts to be composed with various pigments containing yellow, red and red-purple color. The extract was partitioned by a positive ion-exchange and a subsequent reverse-phase chromatographies, which yielded hydrophilic red pigments. The UPLC-TOF-MS analysis of the red pigments indicated that the molecular weight of the pigments were between 450 and 800 Da and suggested the presence of sulfur in the pigment molecules.