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ATR-FTIR spectroscopy was employed to detect and differentiate metabolites of heroin (6-AM), ecstasy (MDA), and cocaine (BE) in urine samples across a range of concentrations. Advanced chemometric approaches, encompassing principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA), were applied to construct robust discriminative models. Spectral data from both the fingerprint region and the full spectral range were analyzed to maximize analytical precision. The proposed ATR-FTIR method demonstrated remarkable sensitivity, achieving detection of drug metabolites in urine at concentrations as low as 0.02\u00a0mg\/mL without necessitating sample separation or extraction steps. The OPLS-DA model exhibited superior discriminative performance, effectively distinguishing all three metabolites in both calibration and validation sets. These findings underscore the potential of integrating ATR-FTIR with chemometrics for the development of a rapid and reliable drug screening tool. This pilot investigation demonstrates that the integration of ATR-FTIR spectroscopy with chemometric analysis represents a highly promising strategy for the detection of urinary drug metabolites, circumventing the need for complex sample pretreatment procedures. This approach offers a novel, efficient, and non-invasive solution for the rapid identification of drug abuse, with substantial implications for forensic medicine and public health surveillance.<\/jats:p>","DOI":"10.1007\/s12024-025-01017-4","type":"journal-article","created":{"date-parts":[[2025,5,30]],"date-time":"2025-05-30T15:56:13Z","timestamp":1748620573000},"page":"1617-1625","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Detection of common drug metabolites in urine using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR)"],"prefix":"10.1007","volume":"21","author":[{"given":"Yawen","family":"Yu","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tangdong","family":"Chen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lijuan","family":"Yuan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mao","family":"Sun","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5276-4382","authenticated-orcid":false,"given":"Yuanming","family":"Wu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2025,5,30]]},"reference":[{"issue":"4","key":"1017_CR1","doi-asserted-by":"publisher","first-page":"251","DOI":"10.1097\/YCO.0000000000000073","volume":"27","author":"H Sun","year":"2014","unstructured":"Sun H, Bao Y, Zhou S, et al. 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