d) Use the toggle to switch the Spec-20 from Transmittance (T) to Absorbance (A). The Spec-20 is now set to read the absorbance of your sample. DO NOT change any settings!!! Clean the cuvette containing Solution #1 with a Kimwipe to remove all prints. Remove the cuvette with water, and replace it with the cuvette containing Solution #1. e) Record the absorbance on the display. If it reads a small negative number, record an absorbance of 0 for that reading. 4) Repeat steps a-e for a wavelength of 425 nm. Record the absorbance value for Solution #1 at this new wavelength, then repeat steps a-e to obtain absorbance readings at wavelengths every 25 nm between 400 and 600 nm. 5) Repeat steps a-e in 5-nm increments for three wavelengths above and three wavelengths below the maximum. For example, if you found the highest absorbance at 450 nm, repeat steps a-e for wavelengths of 455, 460, 465, 445, 440, and 435 nm. 6) The wavelength that gives the maximum absorbance for these readings is the λ max to use for Part III below. 7) Have your instructor approve your chosen λ max before you continue to Part III.