{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T23:23:15Z","timestamp":1774308195628,"version":"3.50.1"},"reference-count":55,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,1,19]],"date-time":"2022-01-19T00:00:00Z","timestamp":1642550400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/00709\/2020"],"award-info":[{"award-number":["UIDB\/00709\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDP\/00709\/2020"],"award-info":[{"award-number":["UIDP\/00709\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/04378\/2020"],"award-info":[{"award-number":["UIDB\/04378\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDP\/04378\/2020"],"award-info":[{"award-number":["UIDP\/04378\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["LA\/P\/0140\/2020"],"award-info":[{"award-number":["LA\/P\/0140\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["SFRH BD\/148753\/2019"],"award-info":[{"award-number":["SFRH BD\/148753\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BD\/149360\/2019"],"award-info":[{"award-number":["SFRH\/BD\/149360\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"European Regional Development Fund (FEDER)","award":["UBIMEDICAL - CENTER- 01-0145-FEDER-000019- C4 - Centre for Competences in Cloud Computing"],"award-info":[{"award-number":["UBIMEDICAL - CENTER- 01-0145-FEDER-000019- C4 - Centre for Competences in Cloud Computing"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Drug abuse still represents a global problem, and it is associated with an increased risk of diseases, injuries, and deaths. Cocaine (COC) and opiates are the most abused drugs and account for a significant number of fatalities. Therefore, it is important to develop methods capable of effectively identifying and quantifying these substances. The present study aims to evaluate the long-term stability of COC, ecgonine methylester (EME), benzoylecgonine (BEG), cocaethylene (COET), norcocaine (NCOC), morphine (MOR), codeine (COD) and 6-monoacetylmorphine (6-MAM) in oral fluid samples. The analytes of interest were isolated from the matrix (50 \u00b5L) using the dried saliva spots (DSS) sampling approach and were subsequently analyzed by gas chromatography coupled with tandem mass spectrometry (GC\u2013MS\/MS). The parameters that could influence the stability of the target compounds were studied, and these were storage temperature, light, use of preservatives (and respective concentrations), and time. The effects of each parameter were evaluated using the design of experiments (DOE) approach. The stability of the target analytes was improved when the DSS were stored at room temperature, in the presence of light and using 1% sodium fluoride. The best conditions were then adopted for the DSS storage and long-term stability was assessed. COD was only stable for 1 day, EME was stable for 3 days, COC, COET, NCOC and 6-MAM were stable for 7 days, MOR for 14 days and BEG remained stable throughout the study (136 days). This is the first study that evaluates the stability of these compounds in oral fluid samples after application in DSS cards, and optimizes the conditions in order to improve their stability.<\/jats:p>","DOI":"10.3390\/molecules27030641","type":"journal-article","created":{"date-parts":[[2022,1,19]],"date-time":"2022-01-19T21:01:51Z","timestamp":1642626111000},"page":"641","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Stability of Cocaine, Opiates, and Metabolites in Dried Saliva Spots"],"prefix":"10.3390","volume":"27","author":[{"given":"Ema","family":"Almeida","sequence":"first","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. Infante D. Henrique, 6201-556 Covilh\u00e3, Portugal"}]},{"given":"Sofia","family":"Soares","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. Infante D. Henrique, 6201-556 Covilh\u00e3, Portugal"},{"name":"Laborat\u00f3rio de F\u00e1rmaco-Toxicologia, Ubimedical, Universidade da Beira Interior, Estrada Municipal 506, 6200-284 Covilh\u00e3, Portugal"}]},{"given":"Joana","family":"Gon\u00e7alves","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. Infante D. Henrique, 6201-556 Covilh\u00e3, Portugal"},{"name":"Laborat\u00f3rio de F\u00e1rmaco-Toxicologia, Ubimedical, Universidade da Beira Interior, Estrada Municipal 506, 6200-284 Covilh\u00e3, Portugal"}]},{"given":"Tiago","family":"Rosado","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. Infante D. Henrique, 6201-556 Covilh\u00e3, Portugal"},{"name":"Laborat\u00f3rio de F\u00e1rmaco-Toxicologia, Ubimedical, Universidade da Beira Interior, Estrada Municipal 506, 6200-284 Covilh\u00e3, Portugal"},{"name":"C4-Cloud Computing Competence Centre, Universidade da Beira Interior, 6200-000 Covilh\u00e3, Portugal"}]},{"given":"Nicol\u00e1s","family":"Fern\u00e1ndez","sequence":"additional","affiliation":[{"name":"Laboratorio de Asesoramiento Toxicol\u00f3gico Anal\u00edtico (CENATOXA), C\u00e1tedra de Toxicolog\u00eda y Qu\u00edmica Legal, Facultad de Farmacia y Bioqu\u00edmica, Universidad de Buenos Aires, Jun\u00edn 956, 7mo piso, Ciudad Aut\u00f3noma de Buenos Aires (CABA), Buenos Aires C1113AAD, Argentina"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6114-3572","authenticated-orcid":false,"given":"Jesus M.","family":"Rodilla","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica, Universidade da Beira Interior, FibEnTech-Materiais Fibrosos e Tecnologias Ambientais, Rua Marqu\u00eas d\u2019\u00c1vila e Bolama, 6200-001 Covilh\u00e3, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6910-7576","authenticated-orcid":false,"given":"Lu\u00eds A.","family":"Passarinha","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. Infante D. Henrique, 6201-556 Covilh\u00e3, Portugal"},{"name":"Laborat\u00f3rio de F\u00e1rmaco-Toxicologia, Ubimedical, Universidade da Beira Interior, Estrada Municipal 506, 6200-284 Covilh\u00e3, Portugal"},{"name":"UCIBIO-Applied Molecular Biosciences Unit, Departamento de Qu\u00edmica, Faculdade de Ci\u00eancias e Tecnologia, Universidade NOVA de Lisboa, 1099-085 Caparica, Portugal"},{"name":"Associate Laboratory i4HB-Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA, 2819-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8848-2734","authenticated-orcid":false,"given":"M\u00e1rio","family":"Barroso","sequence":"additional","affiliation":[{"name":"Servi\u00e7o de Qu\u00edmica e Toxicologia Forenses, Instituto de Medicina Legal e Ci\u00eancias Forenses-Delega\u00e7\u00e3o do Sul, 1169-201 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1802-8998","authenticated-orcid":false,"given":"Eugenia","family":"Gallardo","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Ci\u00eancias da Sa\u00fade, Universidade da Beira Interior (CICS-UBI), Av. 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