FIELD: food industry and medicine. SUBSTANCE: invention, in particular, relates to analyzing crystalline succinic acid preparation prepared from medicine- and food-grade furfural. Successively prepared are first pair of aqueous buffer solutions containing 0.200 ± 0.001 mol/l succinic acid and (2.00 ± 0.01)x 10-3 mol/l sodium tetraborate; second pair of solutions with 0.200 ± 0.001 mol/l succinic acid and (2.00 ± 0.01)x 10-3 mol/l urotropin in 80 vol. % 2-propanol; and third pair of solutions with 0.200 ± 0.001 mol/l succinic acid and (5.00 ± 0.01)x 10-4 mol/l sodium tetraborate in 80 vol.% 2-propanol. Taking into account pH values of solutions, weight percentage of oxalic, maleic, and fumaric acids in sample is determined. When summary weight percentage of maleic and oxalic acids is less than 0.13%, prepared are fourth pair of aqueous solutions containing 0.200 ± 0.001 mol/l succinic acid and (6.00 ± 0.01)x 10-3 mol/l sodium tetraborate and fifth pair of solutions containing 0.200 ± 0.001 mol/l succinic acid and (2.00 ± 0.01)x 10-4 mol/l sodium tetraborate in 96 vol.% ethanol, whereupon weight percentage of fumaric, maleic, and oxalic acids is determined. If concentrations of maleic and oxalic acids in sample are below 0.02 and 0.03%, respectively, sixth pair of solutions with 0.200 ± 0.001 mol/l succinic acid in 97 wt % 2-propanol is prepared and concentrations of the three acids in crystalline succinic acid preparation are determined. EFFECT: increased sensitivity of method. 3 cl, 3 dwg, 4 tbl
