Terms in this set (67)

A. Turn on the spectrophotometer (left-hand knob on the front of the instrument (A)) and allow it to warm up for at least 15 min.
B. Adjust the wavelength to the appropriate value. The knob on the right top (C)of the instrument controls the wavelength, which is indicated at the left of the digital display.
C. With the sample holder empty and the lid closed, adjust the Zero Adjust Knob (A) until the instrument reads 0% on the transmittance scale. Be sure that the display function is set to transmittance, if not push the "Mode" button until the display is set to transmittance.
D. Carefully insert the appropriate blank tube (cuvette) into the sample holder (E) and close the cover. Be sure you are using a cuvette with white markings. The cuvette's outside surface must be dry and clean, including free of fingerprints!! Use a Kimwipe to clean the cuvette before inserting. The white markings should line up with the notch on the sample holder. It is important to line up the markings. The cuvettes will be scratched otherwise.
E. Adjust the 100% Adjust Knob (B), on the right front of the instrument, until the display reads 100% on the transmittance scale.
F. Remove the blank cuvette and immediately insert the sample cuvette as described in step d above. Do not change any instrument setting! Switch the display to read absorbance by pushing the "Mode"(D) button.
G. Record the value indicated on the absorbance scale.
H. Repeat this procedure for additional cuvettes or wavelengths as required. Always adjust the blank transmittance to 100% before inserting and reading a new set of cuvettes.