The effect of pH on analyte charge state varies based on each compound\u2019s pKa, so pH effects must be evaluated carefully during method development. With HILIC methods, the high concentration of organic solvent in the mobile phase raises the pH, and the actual eluent pH can be 1\u20131.5 units higher than in the aqueous portion alone. The charge state of the column itself can also be affected. For example, in a Raptor HILIC-Si column, the bare silica has a pKa between 3.8 and 4.5, so the mobile phase pH changes the charge of the silica surface, making it neutral in very acidic conditions and ionized (negatively charged) as the pH begins to approach 3.8 and above. For this reason, if your analyte has one or more protonated amine or quaternary amine groups, it\u2019s a good candidate for analysis on a Raptor HILIC-Si column.<\/p>\n","protected":false},"excerpt":{"rendered":"
The effect of pH on analyte charge state varies based on each compound\u2019s pKa, so pH effects must be evaluated carefully during method development. With HILIC methods, the high concentration of organic solvent in the mobile phase raises the pH, and the actual eluent pH can be 1\u20131.5 units higher than in the aqueous portion…<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"footnotes":""},"categories":[802],"tags":[2702,2682],"industries-application":[],"post-badge":[],"resource-type":[],"product-library":[],"resource-technique":[],"ppma_author":[414],"class_list":["post-4064","post","type-post","status-publish","format-standard","hentry","category-faq-de","tag-faq-hilic-methods","tag-faq-hplc-and-uhplc"],"acf":[],"taxonomy_info":{"category":[{"value":802,"label":"FAQ"}],"post_tag":[{"value":2702,"label":"FAQ: HILIC Methods"},{"value":2682,"label":"FAQ: HPLC and UHPLC"}]},"featured_image_src_large":false,"author_info":{"display_name":"Restek Corporation","author_link":"https:\/\/discover.restek.com\/ja\/author\/restek-corporation\/"},"comment_info":0,"category_info":[{"term_id":802,"name":"FAQ","slug":"faq-de","term_group":0,"term_taxonomy_id":802,"taxonomy":"category","description":"","parent":0,"count":271,"filter":"raw","cat_ID":802,"category_count":271,"category_description":"","cat_name":"FAQ","category_nicename":"faq-de","category_parent":0}],"tag_info":[{"term_id":2702,"name":"FAQ: HILIC Methods","slug":"faq-hilic-methods","term_group":0,"term_taxonomy_id":2702,"taxonomy":"post_tag","description":"Browse frequently asked questions for HILIC methods.","parent":0,"count":6,"filter":"raw"},{"term_id":2682,"name":"FAQ: HPLC and UHPLC","slug":"faq-hplc-and-uhplc","term_group":0,"term_taxonomy_id":2682,"taxonomy":"post_tag","description":"Browse frequently asked questions for HPLC and UHPLC products.","parent":0,"count":61,"filter":"raw"}],"authors":[{"term_id":414,"user_id":11,"is_guest":0,"slug":"restek-corporation","display_name":"Restek Corporation","avatar_url":{"url":"https:\/\/discover.restek.com\/wp-content\/uploads\/Restek_Favicon_300x300.jpg","url2x":"https:\/\/discover.restek.com\/wp-content\/uploads\/Restek_Favicon_300x300.jpg"},"0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/4064","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/comments?post=4064"}],"version-history":[{"count":2,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/4064\/revisions"}],"predecessor-version":[{"id":71288,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/4064\/revisions\/71288"}],"wp:attachment":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/media?parent=4064"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/categories?post=4064"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/tags?post=4064"},{"taxonomy":"industries-application","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/industries-application?post=4064"},{"taxonomy":"post-badge","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/post-badge?post=4064"},{"taxonomy":"resource-type","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/resource-type?post=4064"},{"taxonomy":"product-library","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/product-library?post=4064"},{"taxonomy":"resource-technique","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/resource-technique?post=4064"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/ppma_author?post=4064"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}