A method for evaluating the acidity of oil samples in small amounts, applicable at any stage of the petroleum industry, includes labelling by an isotope of a chemical element present in at least one acid function present in petroleum samples. A typical embodiment of the invention may include a method performed according to the following steps: Glass substrates including deposited Indium Tin-Oxide are prepared. A second layer adjacent to the first layer is also included that has a plurality of signal wires. A VLAN group information sharing unit shares the VLAN group information among the first relay server, the second relay server, the client terminal connected to the first relay server, and the client terminal connected to the second relay server.