{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T19:06:46Z","timestamp":1777489606971,"version":"3.51.4"},"reference-count":38,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,2,19]],"date-time":"2023-02-19T00:00:00Z","timestamp":1676764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Sciences and Engineering Research Council"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A mechanically robust in-tube stainless steel microneedle solid phase microextraction (SPME) platform for dual electrochemical and chromatographic detection has been demonstrated. The SPME microneedle was fabricated by layer-by-layer (LbL) in-tube coating, consisting of carbon nanotube (CNT)\/cellulose nanocrystal (CNC) film layered with an electrically conductive polyaniline (PANI) hydrogel layer (PANI@CNT\/CNC SPME microneedle (MN)). The PANI@CNT\/CNC SPME MN showed effective analysis of caffeine by GC-MS with an LOD of 26 mg\/L and excellent precision across the dynamic range. Additionally, the PANI@CNT\/CNC SPME MN demonstrated a 67% increase in sensitivity compared to a commercial SPME fiber, while being highly robust for repeated use without loss in performance. For electrochemical detection, the PANI@CNT\/CNC SPME MN showed excellent performance for the detection of 3-caffeoylquinic acid (3-CQA). The dynamic range and limits of detection (LOD) for 3-CQA analysis were 75\u2013448 mg\/L and 11 mg\/L, respectively. The PANI@CNT\/CNC SPME MN was demonstrated to accurately determine the caffeine content and 3-CQA in tea samples and dark roast coffee, respectively. The PANI@CNT\/CNC SPME MN was used for semiquantitative antioxidant determination and composition analysis in kiwi fruit using electrochemistry and SPME-coupled GC-MS, respectively.<\/jats:p>","DOI":"10.3390\/s23042317","type":"journal-article","created":{"date-parts":[[2023,2,20]],"date-time":"2023-02-20T02:29:08Z","timestamp":1676860148000},"page":"2317","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["A Hybrid Stainless-Steel SPME Microneedle Electrode Sensor for Dual Electrochemical and GC-MS Analysis"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0015-1947","authenticated-orcid":false,"given":"Samuel M.","family":"Mugo","sequence":"first","affiliation":[{"name":"Department of Physical Sciences, MacEwan University, Edmonton, AB T5J 4S2, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Scott V.","family":"Robertson","sequence":"additional","affiliation":[{"name":"Department of Physical Sciences, MacEwan University, Edmonton, AB T5J 4S2, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marika","family":"Wood","sequence":"additional","affiliation":[{"name":"Department of Physical Sciences, MacEwan University, Edmonton, AB T5J 4S2, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,19]]},"reference":[{"key":"ref_1","unstructured":"Mugo, S.M., and Zhang, Q. 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