Section 17- Appendices
For nucleic acid quantification, the Beer-Lambert equation is modified to use an extinction coefficient with units of ng-cm/ml. Using this
extinction coefficient gives a manipulated equation:
c = (A * e)/b
Where
c
is the nucleic acid concentration in ng/microliter,
A
is the absorbance in AU,
e
is the wavelength-dependent extinction
coefficient in
ng-cm/microliter
and
b
is the path length in cm.
The generally accepted extinction coefficients for nucleic acids are:
•
Double-stranded DNA: 50 ng-cm/ul
•
Single-stranded DNA: 33 ng-cm/ul
•
RNA: 40 ng-cm/ul
For the NanoDrop
®
ND-1000 Spectrophotometer, path lengths of 1.0 mm and 0.2 mm are used compared to a standard
spectrophotometer using a 10.0 mm path. Thus, the NanoDrop
®
ND-1000 Spectrophotometer is capable of measuring samples that
are 50 times more concentrated than can be measured in a standard spectrophotometer.
Note
: Absorbance data shown in archive files are represented as displayed on the software screen. For Nucleic Acid, Protein A280 and
Proteins and Labels modules, data are normalized to a 1.0 cm (10.0 mm) path. For MicroArray, UV-Vis, Protein BCA, Protein Bradford,
Protein Lowry and Cell Culture modules the data are normalized to a 0.1 cm (1.0 mm) path. For high absorbance UV-Vis samples, data
are normalized to a 0.1mm path.
Solvent Compatibility
The NanoDrop
®
ND-1000 Spectrophotometer is compatible with most solvents typically used in life science laboratories. These include:
methanol, ethanol, n-propanol, isopropanol, butanol, acetone, ether, chloroform, carbon tetrachloride, DMSO, DMF, Acetonitrile, THF,
toluene, hexane, benzene, sodium hydroxide, sodium hypochlorite (bleach), dilute HCl, dilute HNO3, dilute acetic acid.
All forms of Hydrofluoric Acid (HF) are incompatible, as the fluoride ion will
dissolve the quartz fiber optic cable.
Decontamination of Measurement & Optical Surfaces
If decontamination is necessary, a sanitizing solution, such as a 5.25% solution of sodium hypochlorite (bleach – freshly prepared), can
be used to ensure that no biologically active material is present on the measurement pedestals. The metal fiber optic fittings are made
from 303 stainless steel and are resistant to most common laboratory solvents (see “Solvent Compatibility” appendix).
Setting Up a Dymo 400 Label Writer Printer
To set DYMO default label to print with ND-1000:
1. Open Control Panel, then Printers and Faxes
2. Right click on Dymo printer then select Properties
3. Under General tab, choose ‘Printing Preferences’ then ‘Advanced’. Then set the following:
•
Paper Size:
30256
•
Halftoning:
Super Cell
•
Print Quality:
Barcodes and Graphics
4. Click ‘OK’ to close this window then click ‘Apply’
5. Next, click on the ‘Advanced’ tab. Ensure that ‘Enable advanced printing features’ box is checked. Then click on ‘Printing
Defaults’ then ‘Advanced’. Then set the following:
•
Paper Size:
30256
•
Halftoning:
Super Cell
•
Print Quality:
Barcodes and Graphics
6. Click ‘OK’ to close this window then click ‘Apply’
7. Last, click on the ‘Device Settings’ tab and ensure 30256 Shipping Label is selected as the ‘Default’ label.
17-2
