Determination of lithium hydroxy pyruvate concentration

In a well with a total volume of 250 µL, the following components are added: 219 µL of 0.1 M TEA buffer, pH 7.5 1 µL of L-LDH (550 U.mL-1) 10 µL of NADH (10 mg.mL-1) 20 µL of the sample to be assayed

The initial absorbance (Ainitial) was measured at 340 nm, followed by the introduction of the Li-HPA sample solution, whether diluted or not. After stabilization, the final absorbance (Afinal) was measured. The concentration of Li-HPA was determined using the equation:

[Li-HPA]=((A_initiale-A_finale)×V_well)/(V_sample×ε_NADH×l)×10^3 Equation 3. [Li-HPA] expressed in mM, Vwells et Vsample in mL and the molar extinction coefficient εNADH = 6220 M-1.cm-1, volume final of 250 µL, height of wells ℓ = 0,73 cm.