A microfluidic paper-based analytical device for salivary aldehydes is reported.
Aldehydes react with 3-methyl-2-benzothiazolinone hydrazone and iron(III).
The colour intensity of the blue coloured formazan dye is measured.
The working range, LOD and RSD (n = 5) are 20–114 μM, 6.1 μM and less than 12.7%.
The device is stable for more than 41 days when stored in a freezer (≤-20 °C).