Method for determining Brilliant Black

Abstract

The subject of the application is a method for determining Brilliant Black in bath salts using direct voltammetric measurement. The method involves applying a drop of potassium chloride solution as the base electrolyte to the surface of a screen-printed carbon electrode to cover all electrodes in the system. After recording the first voltammogram for the base electrolyte solution (blank), a second measurement is performed for the analyzed solution, created by mixing a bath salt sample with the base electrolyte. Then, in three subsequent stages (stages 3, 4, and 5), mixtures containing: the actual sample solution, the base electrolyte, and the appropriate volume of a Brilliant Black standard solution are applied to the electrode. The amount of the standard solution in the subsequent stages is 1.5–2.5 times, 2.5–3.5 times, and 3.5–45 times greater than the amount of Brilliant Black in the analyzed sample. The measurement is performed in the potential range of 0.00—1.05 V, using square-wave voltammetry with the following parameters: amplitude 0.050 V, potential step 0.005 V, frequency 8 Hz. The relative increase in the oxidation current of brilliant black relative to the blank is the basis for determining its content using the standard addition method. The result is converted to the mass content of the dye in the actual sample.