To compare this method, the creatinine content in the samples was quantified using a commercial kit (Creatinine liquicolor, HUMAN) and was measured using a spectrophotometer (Evolution 600, Thermo Scientific). Briefly, a urine sample was diluted 50-fold with distilled water and then, it reacted with 1000 mL of the alkaline picrate working solution. After 30 s, the absorbance A1 was read, and after 2 min, the absorbance A2 was read at 500 nm.