2.5.1. Glucose Concentration

Glucose concentration was determined according to the glucose oxidase/peroxidase method [22]. One hundred microliters of solids-free, properly diluted samples were mixed with 1 mL of the glucose oxidase/peroxidase reagent (R1 + R2 40:1 *v*/*v*, from Impact Ltd., Moscow, Russia) and incubated for 15 min at 40 ◦C. Absorbance was read at 490 nm in a UV-vis spectrophotometer (Agilent Technologies Inc., Santa Clara, CA, USA).
