The acid-base homeostasis in a human body is maintained by the kidneys, which eliminate the acid (H + ) in the form of NH4 + through excretion. Low ammonium excretion is associated with the impaired ability of the kidneys to remove the acids which is classified as chronic kidney disease (CKD and further linked to an elevated risk of end-stage renal disease (ESRD), acidosis and kidney failure. Hence, monitoring the ammonium excretion level in patients at early stages is effective to circumventing the occurrence of such unlikely clinical events. Previous studies reported the utilization of graphene for ultra-low detection of ammonia (NH3), where graphene sheets were functionalized to fabricate a nanocomposite film as sensor. However, in the present study, the bio-prepared few-layer graphene exhibited the presence of residual functional groups as shown in the FTIR study, which can effectively provide sites for NH4 + absorption or binding, without requiring further post-synthesis modification. Therefore, as-prepared few-layer graphene were explored for their use in low-level sensing of NH4 + ions (sensing mechanism shown in Fig. ). The binding of ammonium ions to graphene sheets was examined using UV-Vis spectroscopic analyses. The change in UV-Vis spectra of graphene was recorded for different concentrations of NH4Cl solution as shown in Fig. .