User manual

Section 3- Applications
Unique Screen Features
The right pane displays features specific to the Nucleic Acid application. Task bars in the left pane not described
below are described in “
Software Overview.”
The spectral display shows data for the current sample normalized to a 10 mm path for all measurements including
measurements made with any cuvette pathlength.
The following features are to the right of the spectral display:
• Sample ID - field into which a sample ID is entered. The appropriate sample ID should be entered prior to
each measurement.
• Type - a drop down list from which the user may select the (color-keyed) type of nucleic acid being
measured. Options include DNA-50 for dsDNA, RNA-40 for RNA, and ssDNA-33 for single-stranded DNA.
Additional options include Oligo DNA and Oligo RNA which utilize the appropriate extinction coefficient
based upon user-defined base sequences. The Custom option allows the user to enter an extinction
coefficient between 15 and 150.
• Conc - concentration based on absorbance at 260 nm and the default or user defined extinction coefficient.
Concentration units may be selected from the adjacent drop-down box. Refer to “
Nucleic Acid Calculations”
for more details.
• A260 - displays absorbance at 260 nm normalized to a 10 mm pathlength.
• A280 - displays absorbance at 280 nm normalized to a 10 mm pathlength.
• 260/280 - ratio of absorbance at 260 nm and 280 nm. The ratio of absorbance at 260 and 280 nm is used to
assess the purity of DNA and RNA. A ratio of ~1.8 is generally accepted as “pure” for DNA; a ratio of ~2.0 is
generally accepted as “pure” for RNA. If the ratio is appreciably lower in either case, it may indicate the
presence of protein, phenol or other contaminants that absorb strongly at or near 280 nm. See “260/280
Ratio” in “
Diagnostics and Troubleshooting” for more details on factors that can affect this ratio.
3-4