A sensitive arsenic (III) (As(III)) detection method based on the fluorescence quenching system using bovine serum albumin (BSA) capped carbon-gold composite (C-Au-BSA) was developed. BSA could attach to the surface of C-Au composite and increase the photoluminescence (PL) efficiency, As(III) could combine with BSA and remove it from C-Au composite to decrease the PL efficiency. A linear relationship was observed between (As(III)) concentration and PL quenching at low concentrations (5–50 ppb - for drinking and bore water detection) and high concentrations (100–800 ppb - sedimentary arsenic) of the metal. The limit of detection was more superior (low conc; R2 = 0.96 with sensitivity 0.004 ppb, high conc; R2 = 0.98 with sensitivity 0.0002) when compared to other techniques. Thus, this method can be applied to determine low levels as well as sedimentary levels of As(III). © 2018 Elsevier B.V.