After modification with syringaldazine electrodes were tested in buffers of different pH. First tests were performed in buffers from pH 4 to 9.5 (acetate, phosphate and carbonate-bicarbonate buffers) but the most basic solution had sometimes detrimental effect on the modification. To keep similar composition of the test solution phosphate buffer of three different pH values was chosen for subsequent tests of the electrodes. All electrochemical measurements were performed with PalmSens 4 potentiostat in a threeelectrode system consisting of a chosen carbon working electrode, Ag/AgCl (3 M KCl) reference electrode (IJ Cambria Scientific Ltd.), and platinum wire of 1 mm diameter (Mennica Metale Sp. z o.o.) as an auxiliary electrode. If not stated otherwise cyclic voltammetry (CV) measurements were conducted in the potential range from -0.2 V to +0.8 V with 100 mV/s scan rate and 10 mV potential step. Differential pulse voltammetry (DPV) measurements were performed in the potential range from -0.5 V to +0.5 V with 25 mV/s scan rate, 10 mV potential step, 0.2 V potential pulse and 0.02 ms pulse time. Square wave voltammetry (SWV) measurements were performed in the potential range from +0.8 V to -0.4 V with 10 mV potential step, 100 mV amplitude and 20 Hz frequency.