{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T21:49:46Z","timestamp":1790200186512,"version":"4.1.0"},"reference-count":23,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T00:00:00Z","timestamp":1753747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"I+D+i projects","award":["PID2023-149799OB-C21"],"award-info":[{"award-number":["PID2023-149799OB-C21"]}]},{"name":"I+D+i projects","award":["PID2023-149799OBC22"],"award-info":[{"award-number":["PID2023-149799OBC22"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Birch (Betula sp.) bark is a well-known natural source of betulin (Bet) and betulinic acid (BAc), both of which have several bioactive properties. The evaluation of the extraction performance, relative to these lupane-type triterpenoids, provided by different biosolvents requires the development of a high-resolution and high-sensitivity liquid chromatography-mass spectrometry (LC-MS) approach that is also compatible with challenging extractants such as natural deep eutectic solvents (NADESs). In this work, an LC-MS method was developed and analytically characterized prior to its application for the quantitation of Bet and BAc in birch bark extracts obtained using conventional solvents (methanol and acetone) and biosolvents (limonene and NADESs). High precision (RSD &lt; 3.3%), sensitivity (LOD: 23 ng mL\u22121 and 29 ng mL\u22121 for Bet and BAc, respectively), and accuracy (95\u2013102% recovery) were found for this optimized method, using an acidulated water\u2013methanol mixture as the mobile phase and sodium acetate as an additive. Extraction experiments conducted at 55 \u00b0C revealed that the NADESs, particularly thymol:1-octanol (1:1 molar ratio), outperformed the other solvents and were highly effective for the recovery of both triterpenoids (17.50 mg g\u22121 and 0.92 mg g\u22121 of Bet and BAc, respectively). This method can also be applied to similar extracts obtained from other biomasses.<\/jats:p>","DOI":"10.3390\/molecules30153181","type":"journal-article","created":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T16:16:10Z","timestamp":1753805770000},"page":"3181","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Development of an LC-MS Method for the Analysis of Birch (Betula sp.) Bark Bioactives Extracted with Biosolvents"],"prefix":"10.3390","volume":"30","author":[{"given":"Inmaculada","family":"Luque-Jurado","sequence":"first","affiliation":[{"name":"Instituto de Qu\u00edmica Org\u00e1nica General (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1863-7408","authenticated-orcid":false,"given":"Jes\u00fas E.","family":"Quintanilla-L\u00f3pez","sequence":"additional","affiliation":[{"name":"Instituto de Qu\u00edmica-F\u00edsica \u2018Blas Cabrera\u2019 (CSIC), Serrano 119, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6103-6814","authenticated-orcid":false,"given":"Rosa","family":"Lebr\u00f3n-Aguilar","sequence":"additional","affiliation":[{"name":"Instituto de Qu\u00edmica-F\u00edsica \u2018Blas Cabrera\u2019 (CSIC), Serrano 119, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ana Cristina","family":"Soria","sequence":"additional","affiliation":[{"name":"Instituto de Qu\u00edmica Org\u00e1nica General (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8156-4734","authenticated-orcid":false,"given":"Mar\u00eda Luz","family":"Sanz","sequence":"additional","affiliation":[{"name":"Instituto de Qu\u00edmica Org\u00e1nica General (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"929","DOI":"10.1007\/s11101-019-09623-1","article-title":"Betulin and Betulinic Acid: Triterpenoids Derivatives with a Powerful Biological Potential","volume":"18","author":"Hordyjewska","year":"2019","journal-title":"Phytochem. 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