Use of on-site immunoassay devices to screen urine absorbed in disposable diapers for methamphetamine: a preliminary study with artificial urine

The aim of this preliminary study was to establish a simple, rapid method for recovering urine absorbed in disposable diapers in order to test for methamphetamine (MAP) using the Instant-View™ M-1 and Triage^® DOA on-site immunoassay devices. A 4-ml aliquot of drug-free artificial urine was absorbed into a disposable diaper (Pampers^®) that had been cut into 3 × 3 cm pieces. Further addition of 4 ml of saturated KCl solution to the piece of diaper led to the recovery of substantial amounts (c.a. 2 ml) of fluid sample within 3–5 min. After diluting recovered fluids two-fold with distilled water, both immunoassays showed all samples were negative for all drug classes. After absorption of artificial urine containing 500–5,000 ng/ml of MAP in similar-sized pieces of diaper using the identical processing method, positive results were observed with Instant-View™ M-1 for artificial urine containing 2,000 ng/ml or more of MAP and with Triage^® DOA for urine containing 4,000 ng/ml or more of MAP. Diapers dosed with artificial urine containing 500, 2,500, and 5,000 ng/ml of MAP were further examined by gas chromatography–mass spectrometry, with recoveries of MAP of 98.6 ± 36.7 % (n = 6), 115 ± 22.4 % (n = 6), and 102 ± 15.1 % (n = 6), respectively. Use of this new sample preparation method may be applicable for analyzing infant urine absorbed in disposable diapers. Additionally, the sensitivity of the method along with the availability of Instant-View™ M-1 screening suggests the potential usefulness of this technique in clinical settings.