Final answer:
The maximum concentration of NADH that can be measured without diluting is 2.38 x 10^-5 M.
Step-by-step explanation:
The maximum concentration of NADH that can be measured without diluting can be calculated using the Beer-Lambert law. According to the information provided, the spectrophotometer can measure an absorbance up to 1.5. We can use the equation A = εcl, where A is the absorbance, ε is the molar absorptivity, c is the concentration, and l is the path length. Rearranging the equation, we have c = A / (εl). Substituting the given values, we have c = 1.5 / (6290 L*mol-1*cm-1*1 cm). Solving this equation gives us a maximum concentration of NADH that can be measured without diluting as 2.38 x 10-5 M.