Preprint Article Version 1 This version is not peer-reviewed Version 1 : Received: 2 September 2024 / Approved: 2 September 2024 / Online: 3 September 2024 (07:30:00 CEST) Wei, Q.; Su, F. Determination of Nine Fentanyl and Six Amphetamine Drugs in Hair Samples by GC-MS/MS and LC-MS/MS. Preprints 2024, 2024090194. https://doi.org/10.20944/preprints202409.0194.v1 Wei, Q.; Su, F. Determination of Nine Fentanyl and Six Amphetamine Drugs in Hair Samples by GC-MS/MS and LC-MS/MS.