Conclusion
The combination of a PAD and LOC for sample preparationand analysis provides a new, fast approach for identification ofexplosive mixtures in soil. To the best of our knowledge this is thefirst report where a filter paper device containing the sample hasbeen directly inserted into a microfluidic device for electrokineticextraction. This approach directly inserting the paper chad intothe chip sample wells represents a significantly simplified extrac-tion process. The LOC device does not require any pumps or gasfor its operation; this along with its low weight (approximately10 kg), small size and robust nature gives it excellent potential forportable use in mobile laboratories. The current method was opti-mized for the analysis of eight target explosives that were wellseparated and visualised using fluorescence quenching. The mini-mum detectable amounts for all eight explosives were between 1.4and 5.6 ng with recoveries ranging from 65 to 82% from the paperchad and 12–40% from soil. Sample extraction and preparation maybe performed in approximately 12 min, with up to 12 samples pro-cessed by the LOC per hour. This rapid turnaround, the ability toanalyze explosive mixtures, and relatively low costs per analysis(currently ∼$4/sample) makes this approach a viable alternativemethod of explosive screening [