This work developed a simple silver nanosensor functionalized with pyrophosphate (AgNPs-PYRO) by the reduction method with sodium citrate and sodium borohydride at low temperaturesThe nanosensor showed satisfactory performance in the detection of barium ions (Ba2+), strontium (Sr+2), magnesium (Mg+2), calcium (Ca+2), and iron (Fe+3), which are commonly found in scales formed in the oil industry.The anal. conducted through UV-Vis spectroscopy allowed identifying the species at concentrations between 0.5 and 10 ppm.In addition, the obtained colors also made it possible to distinguish the divalent species (Ba+2, Sr+2, Mg+2, and Ca+2) from iron III, which is trivalent.The decrease in the plasmon band at 400 nm after the addition of the metallic sample, directly related to the stability of the nanosensor, indicated the destabilization and aggregation of AgNPs.The morphol. was analyzed by FE-SEM, where silver showed a size of approx. 20 nm and uniform distribution.After adding barium, it was possible to observe relatively empty spaces and the aggregation of nanoparticles, which is the detection mechanism of the proposed nanosensor.The zeta potential values obtained for the AgNPs, AgNPs-PYRO, and AgNPs-PYRO-Ba samples, resp., were -25.0, -52.2, and -43.2 mV, confirming that the sensor is based on the aggregation process since the decrease in charge is a sign of reduced stability.The nanosensor proved to be sensitive to metals, where the inserted samples resulted in colors of different intensities, proportional to the concentrationsThe obtained results demonstrate that the nanosensor is efficient for qual. and quant. anal. of these species involved in the fouling process, in an easy and simple anal., and can be used as an alternative method for this purpose.