ABSTRACT
This article reports on the development and validation of a disposable microfluidic paper-based analytical device (µPAD) for on-hand, in-situ, and cheap Fe(III) determination in natural waters complying with World Health Organization guidelines. The developed µPAD used 3-hydroxy-4-pyridinone (3,4-HPO) as a colour reagent due to its considerably lower toxicity than traditionally used iron analytical reagents. It was selected among a group of hydrophilic 3,4-HPO chelators containing ether-derived chains in their structure which were prepared using green methods. The relatively high water solubility of these chelators improved the detection limit and applicability as µPAD reagents. Under optimal conditions, the µPAD is characterised by a quantification range between 0.25 and 2.0 mg/L, a detection limit of 55 µg/L and 15 min of analysis time. The signal stability extends up to 4 h and the device is stable for at least one month. The reagent consumption is below 0.2 mg per analysis and the µPAD method was validated by analysis certified reference materials and by comparison with atomic absorption results (RD < 10%). The newly developed µPAD was successfully applied to the determination of iron in river, well and tap waters with no need of any prior sample pre-treatment.
