Conduct and Detect: A One-Step Conductometric Screen for Fraudulent Urine Specimens
SOFT-TIAFT 2026 Joint Meeting, Michigan, Amerika Birleşik Devletleri, 19 - 24 Eylül 2026, ss.518, (Özet Bildiri)
- Yayın Türü: Bildiri / Özet Bildiri
- Basıldığı Şehir: Michigan
- Basıldığı Ülke: Amerika Birleşik Devletleri
- Sayfa Sayıları: ss.518
- Dokuz Eylül Üniversitesi Adresli: Evet
Özet
Introduction: Urine sample tampering remains a significant challenge in forensic toxicology, especially in drug testing programs where individuals may attempt to evade detection. Manipulation strategies include dilution and the use of synthetic urine products designed to mimic physiological characteristics. Conventional validity testing relies primarily on creatinine and specific gravity; however, these parameters are often insufficient to differentiate between dilution mechanisms or to reliably identify synthetic matrices. Conductometry, represents a rapid, cost‑effective analytical approach that may provide additional discriminatory power. This study evaluates the effectiveness of conductivity measurements in identifying various forms of urine sample adulteration. Objectives: The primary objective of this study was to assess the utility of electrical conductivity as a screening tool for detecting fraudulent urine specimens. Specifically, we aimed to (i) determine whether conductivity can distinguish between authentic, diluted, and synthetic urine samples, (ii) evaluate its relationship with conventional validity parameters, and (iii) explore its ability to provide additional insight into the mechanisms of sample manipulation. Methods: A total of 153 urine specimens were categorised into six groups: healthy volunteers (n=61), authentic drug‑negative specimens(n=30), laboratory‑prepared synthetic urine (n=5), commercial synthetic urine products(n=11), dilute specimens (n=30; defined by concurrent creatinine <20 mg/dL and specific gravity ≤1.002), and specimens flagged as fraudulent during routine forensic casework (n=16). For each sample, conductivity was measured at room temperature using a conductivity meter. Creatinine, pH, specific gravity and nitrite were measured using standard methods with CEDIA/DRI immunological test kits (Thermo Scientific). All test results were analysed using SPSS 25. Results: The conductivity reference interval for healthy volunteers was 5.12–30.70 µS/cm (median 18.4 µS/cm). Strong positive correlations were observed between conductivity and both creatinine (ρ=0.675, p<0.0001) and specific gravity (ρ=0.708, p<0.0001). Authentic drug‑negative specimens (median 21.4 µS/cm) were comparable to volunteer samples (p=0.09). All dilute specimens fell outside the reference interval, exhibiting a bimodal conductivity distribution: 8 specimens showed very low values (2.05–3.16 µS/cm), 22 showed markedly elevated values (997–1939 µS/cm). Critically, both subgroups were indistinguishable by conventional validity markers, median creatinine 13 mg/dL and specific gravity 1.002 in each, demonstrating that conductometry provides discriminatory information beyond standard testing parameters. Laboratory‑prepared synthetic urine demonstrated consistently low conductivity values, significantly different from authentic samples. Commercial synthetic urine products showed heterogeneous profiles, with most falling within the reference range but some exhibiting abnormally high conductivity and nitrite positivity. Among forensic case samples, a subset displayed elevated conductivity despite unremarkable traditional parameters. Overall differences between groups were statistically significant (p=0.0003).