We demonstrate a novel and versatile sensing platform, based on electrolyte-gated graphene field-effect transistors, for easy, low-cost and scalable production of chemical sensor test strips. The Lab-on-PCB platform is enabled by low-boiling, low-surface-tension sprayable graphene ink deposited on a substrate manufactured using a commercial printed circuit board process. We demonstrate the versatility of the platform by sensing pH and Na+ concentrations in an aqueous solution, achieving a sensitivity of 143 ± 4 μA per pH and 131 ± 5 μA per log10Na+, respectively, in line with state-of-the-art graphene chemical sensing performance.