As a simple test, Opol was used to determine the specific optical rotation θs of D-sucrose, using a nine-membered linear concentration series spanning the range 0 to 0.2 g/ml, where the zeroconcentration measurement served as the blank. The solutions were analysed in a randomised order, rinsing thoroughly with ultra-pure water between each test. For each concentration the rotation angle was determined by averaging 500 outputs of the microcontroller over a 5-s time period. Figure shows the dependence of the measured rotation angle on the sucrose concentration [S]. The rotation angle θrot is related to [S] by the linear equation θrot = lθs [S], where l = 5 cm is the path-length of the optical cell. Least-squares fitting yielded a θs value of 53.3 ± 0.4 deg•mL•g -1 •dm -1 at 654.8 nm, with a high linear correlation coefficient of 99.97%. This is consistent with a value of 53° ± 2° calculated using the Drude model 𝜃 5 = 𝐴/(𝜆 9 -𝜆 - 9 ) with A = 2.16 × 10 7 nm 2 dm -1 g -1 mL and λ = 146 nm as previously reported by Compton et al. for D-sucrose in water (20 °C, 650 nm).