{"id":5,"date":"2024-04-04T00:39:45","date_gmt":"2024-04-03T21:39:45","guid":{"rendered":"https:\/\/sisu.ut.ee\/lcms_method_validation\/82-examples-unstable-analytes\/"},"modified":"2024-04-04T00:41:47","modified_gmt":"2024-04-03T21:41:47","slug":"82-examples-unstable-analytes","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/lcms_method_validation\/82-examples-unstable-analytes\/","title":{"rendered":"8.2 Examples of unstable analytes"},"content":{"rendered":"<h5 style=\"text-align: center\">\r\n\t\u00a0\r\n<\/h5>\r\n\r\n<h5 class=\"media-title\" style=\"text-align: center\">\r\n\t<div class=\"ratio ratio-16x9 mb-3\"><div class=\"video-placeholder-wrapper video-placeholder-wrapper--16x9\">\n\t\t\t    <div class=\"video-placeholder d-flex justify-content-center align-items-center\">\n\t\t\t        <div class=\"overlay text-white p-2 w-100 text-center d-block justify-content-center align-items-center\">\n\t\t\t            <div>To view third-party content, please accept cookies.<\/div>\n\t\t\t            <button class=\"btn btn-secondary btn-sm mt-1 consent-change\">Change consent<\/button>\n\t\t\t        <\/div>\n\t\t\t    <\/div>\n\t\t\t<\/div>\n<\/div>Examples of unstable analytes\r\n<\/h5>\r\n\r\n<h5 style=\"text-align: center\">\r\n\t\u00a0\r\n<\/h5>\r\n\r\n<h5 style=\"text-align: center\">\r\n\t<span style=\"color: #000000;font-family: roboto, arial, sans-serif\"><a href=\"http:\/\/www.uttv.ee\/naita?id=23671\" target=\"_blank\" rel=\"noopener\">http:\/\/www.uttv.ee\/naita?id=23671<\/a><\/span>\r\n<\/h5>\r\n\r\n<h5 style=\"text-align: center\">\r\n\t<span style=\"color: #000000;font-family: roboto, arial, sans-serif\"><span style=\"color: #000000;font-family: roboto, arial, sans-serif\"><a href=\"https:\/\/www.youtube.com\/watch?v=Gn8Wde6lD-w&amp;feature=youtu.be\" target=\"_blank\" rel=\"noopener\">https:\/\/www.youtube.com\/watch?v=Gn8Wde6lD-w&amp;feature=youtu.be<\/a><\/span><\/span>\r\n<\/h5>\r\n\r\n<h5>\r\n\t<span style=\"color: #000000;font-family: roboto, arial, sans-serif\">\u00a0<\/span>\r\n<\/h5>\r\n\r\n<p>\r\n\t\u00a0\r\n<\/p>\r\n\r\n<p>\r\n\t\u00a0\r\n<\/p>\r\n\r\n<h4 style=\"text-align: center\">\r\n\tTable 1.\u00a0Examples of unstable analytes\r\n<\/h4>\r\n\r\n<div align=\"center\">\r\n\t<table class=\"table table-hover\" style=\"height: 663px\" cellspacing=\"0\" cellpadding=\"0\" border=\"1\" align=\"center\">\r\n\t\t<tbody>\r\n\t\t\t<tr>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\t<strong>Compound<\/strong>\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\t<strong>Typical cause of instability<\/strong>\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tAcyl glucoronide\u00a0metabolites\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tHydrolysis to parent drug, acyl migration [ref 48]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tLactones\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tReversible hydrolysis to hydroxyl acid [ref 49]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tProdrugs\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tConversion into active drug by ester bond cleavage [ref 50]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tAmides\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tHydrolysis to acid [ref 51]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tOxidizable compounds\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tOxidative degradation\u00a0\r\n\t\t\t\t\t<\/p>\r\n\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\t(e.g. alcohol to ketone or aldehyde [ref 40],<br>adrenaline to adrenochrome [ref 41],<br>5-aminosalicylic acid to 5-aminosalicylic quinoneimine [ref 42],<br>cholesterol to 7-beta\u2013hydroperoxy isomer [ref 43],<br>thiols dimerization [ref 44],\r\n\t\t\t\t\t<\/p>\r\n\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tdobutamine [ref 62])\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tCytostatic nucleosides\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tEnzymatic deamination [ref 45]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tEnantiomers\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tRacemization [ref 46]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tCis\/trans isomers\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td>\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tCis-trans interconversion [ref 47]\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t\t<tr>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tBeta-lactams [ref 10, ref 11, ref 63] (all penicillin derivatives)\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t\t<td valign=\"top\">\r\n\t\t\t\t\t<p>\r\n\t\t\t\t\t\tHydrolysis, enzymatic degradation, oxidation, presence of metal ions\r\n\t\t\t\t\t<\/p>\r\n\t\t\t\t<\/td>\r\n\t\t\t<\/tr>\r\n\t\t<\/tbody>\r\n\t<\/table>\r\n\r\n\t<p>\r\n\t\t\u00a0\r\n\t<\/p>\r\n<\/div>\r\n\r\n<p>\r\n\tIn one example, the bench-top\/short term stability of the\u00a0beta-lactam antibiotic \u2013 meropenem \u2013 in processed blood plasma samples at the room temperature (+20 \u00b0C) was investigated during 24 h using overnight injections and\u00a0after 12 h the concentration of meropenem in the samples was only 17% of the original concentration at both concentration levels 1 \u00b5g\/mL and 25 \u00b5g\/mL. After keeping the autosampler at 4 \u00b0C and samples stored at -20 \u00b0C until loading into the autosampler, the stability (<em>ST<\/em>%) (see <a data-url=\"https:\/\/sisu.ut.ee\/lcms_method_validation\/83-evaluation-stability\" href=\"https:\/\/sisu.ut.ee\/lcms_method_validation\/83-evaluation-stability\" target=\"_blank\" title=\"\" rel=\"noopener\">section 8.3<\/a>) remained around 95% after 3 h and 92 % after 12 h storage in an autosampler (+4 \u00b0C) [ref 10]. Thus, storage of samples and solutions at low temperature is a powerful means of increasing stability.\r\n<\/p>\r\n\r\n<p>\r\n\tIn another example [ref 11], the stability of\u00a0Penicillin G was examined over a\u00a016 h time-period and also compared in different pH conditions since\u00a0Penicillin G is well known for its instability in solutions and the\u00a0stability of penicillins is also highly dependent on the pH of the solution. The bench-top\/short term stability of the Penicillin G in\u00a0the processed blood plasma samples in an autosampler thermostated at +4 \u00b0C showed rapid degradation: <em>ST<\/em>% was 20% after 16 h for samples with a pH 6.2. After the pH adjustment to 7.0, processed blood plasma samples showed significant improvement on <em>ST<\/em>%, resulting in 78% after 16 h at the +4 \u00b0C. This example convincingly demonstrates how small changes in conditions can strongly influence an analyte stability.\r\n<\/p>\r\n\r\n<p>\r\n\tMoreover, microbial contamination can lead to the degradation of the analyte as it was observed for two biomarkers thymidine and 2\u2032-deoxyuridine in urine samples. No analytes were detected in urine after storage at ambient temperature for 24 h and at 4 \u00b0C for 14 days [ref 61]. The stability of samples was improved with the usage of perchloric acid.\r\n<\/p>\r\n\r\n<p>\r\n\tOxidation of dobutamine was observed when the stability of plasma samples were\u00a0tested. After the addition of the ascorbic acid as the\u00a0stabilizer to the plasma samples, a significantly increased sample stability has been onserved [ref 62]. Interestingly, the internal standard of dobutamine\u00a0(dobutamine-D4) indicated a decrease of peak area over 115 injection run in samples where ascorbic acid was not added as a stabilizer. A stabilizer helped clearly to maintain the concentration of an\u00a0analyte and an internal standard\u2019s concentration in the processed sample. However, this also means that suitable internal standards could potentially help to overcome analyte stability issues in case degradation of internal standard mimics the degradation of an analyte and additional analyte degradation would not take place before the addition of internal standard.\r\n<\/p>\r\n\r\n<p>\r\n\t<img loading=\"lazy\" decoding=\"async\" width=\"885\" height=\"380\" class=\"alignnone wp-image-66\" src=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/130\/fig_dobutamine.png\" title=\"fig_dobutamine.png\" alt=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S2376999818300400#f0025\" srcset=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/130\/fig_dobutamine.png 885w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/130\/fig_dobutamine-300x129.png 300w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/130\/fig_dobutamine-768x330.png 768w\" sizes=\"auto, (max-width: 885px) 100vw, 885px\">\r\n<\/p>\r\n\r\n<p>\r\n\t\u00a0\r\n<\/p>\r\n\r\n<h4 style=\"text-align:center\">\r\n\t<strong>Figure 3.\u00a0 <\/strong>Dobutamine internal standard\u2019s (dobutamine-D<sub>4<\/sub>) response in stabilised (green) and unstabilised (blue) plasma samples during the analytical batch run [ref 62].\r\n<\/h4>\r\n<br><div class=\"wp-block-group attached-files-group is-layout-constrained wp-block-group-is-layout-constrained\"><div class=\"wp-block-file\"><a href=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/130\/8.2_examples_of_unstable_analytes.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">8.2_examples_of_unstable_analytes.pdf<\/a><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>\u00a0 To view third-party content, please accept cookies. Change consent Examples of unstable analytes \u00a0 http:\/\/www.uttv.ee\/naita?id=23671 https:\/\/www.youtube.com\/watch?v=Gn8Wde6lD-w&amp;feature=youtu.be \u00a0 \u00a0 \u00a0 Table 1.\u00a0Examples of unstable analytes Compound Typical cause of instability Acyl glucoronide\u00a0metabolites Hydrolysis to parent drug, acyl migration [ref 48] &#8230;<\/p>\n","protected":false},"author":60,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"class_list":["post-5","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/pages\/5","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/users\/60"}],"replies":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/comments?post=5"}],"version-history":[{"count":2,"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/pages\/5\/revisions"}],"predecessor-version":[{"id":909,"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/pages\/5\/revisions\/909"}],"wp:attachment":[{"href":"https:\/\/sisu.ut.ee\/lcms_method_validation\/wp-json\/wp\/v2\/media?parent=5"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}