Cocaine is one of the most worldwide used illicit drugs. We report a magnetic particles-based enzymelinked
immunoassay (mpEIA) method for the rapid and sensitive determination of cocaine (COC) in
saliva, urine and serum samples. Under optimized conditions, the limits of detections were 0.09 ng mL−1
(urine), 0.15 ng mL−1 (saliva), and 0.06 ng mL−1 COC (human serum). Sensitivities were in the range
EC50 = 0.6–2.5 ng mL−1 COC. The cross-reactivity with the principal metabolite benzoylecgonine (BZE)
was only 1.6%. Recovering percentages of doped samples (0, 10, 50, and 100 ng mL−1 of COC) ranged from
about 86–111%. Some advantages of the developed mpEIA over conventional ELISA kits are faster incubations,
improved reproducibility, and consumption of lower amounts of antibody and enzyme conjugates
due to the use of magnetic beads. The reported method was validated following the guidelines on bioanalytical
methods of the European Medicines Agency (2011). Unmetabolized COC detection has a great
interest in pharmacological, pharmacokinetics, and toxicokinetics studies, and can be used to detect a
very recent COC use (1–6 h).