Frontline immunochromatographic device for on-site urine testing of amphetamines: laboratory validation using...

We evaluated a new test device for amphetamines and methamphetamines (Frontline, cut-off limit 300 ng/mL) using authentic clinical and forensic specimens. The device is based on immunochromatography and is dipped into urine and read visually by comparison with a colour scale after a few minutes. A total of 658 specimens were tested by comparing results of the screening procedure with established immunoassays. Discordant results were further investigated by gas chromatography mass spectrometry or gas chromatography (with flame ionization detector). The Frontline device had a sensitivity of 93% and a specificity of 98%. When specimens were classified by urine amphetamine concentration, close agreement was obtained at concentrations below 150 ng/mL and above 1000 ng/mL. A small number of specimens with amphetamine concentrations between 300 and 1000 ng/mL tested negative in the Frontline test. This finding could to some extent be explained by the enantioselectivity of the antibodies in the Frontline test to d-amphetamine. We conclude that the performance of the Frontline test device for amphetamines is adequate for presumptive clinical and forensic screening.