Section 5- Nucleic Acids
5. Nucleic Acids
Nucleic acid samples can be readily checked for concentration and quality using the NanoDrop
®
ND-1000
Spectrophotometer. To measure nucleic acid samples select the ‘Nucleic Acid’ application module.
Sample Volume Requirements
Field experience has indicated that 1ul samples are sufficient to ensure accurate and reproducible results when
measuring aqueous nucleic acid samples. However, if you are unsure about your sample or your pipettor accuracy, a 1.5-
2ul sample is recommended to ensure that the liquid sample column is formed and the light path is completely covered by
sample.
Measurement Concentration Range
The NanoDrop
®
ND-1000 Spectrophotometer will accurately measure dsDNA samples up to 3700 ng/ul without dilution.
To do this, the instrument automatically detects the high concentration and utilizes the 0.2mm pathlength to calculate the
absorbance.
Detection
Limit
(ng/ul)
Approx.
Upper Limit
(ng/ul)
Typical Reproducibility
(minimum 5 replicates)
(SD= ng/ul; CV= %)
2
3700 ng/ul (dsDNA)
3000 (RNA)
2400 (ssDNA)
sample range 2-100 ng/ul:
±
2 ng/ul
sample range >100 ng/ul:
±
2%
Unique Screen Features
Sample Type:
used to select the (color-keyed) type of nucleic acid being measured. The user can select ‘DNA-50’ for
dsDNA, ‘RNA-40’ for RNA
,
‘ssDNA-33’ for single-stranded DNA, or ‘Other’ for other nucleic acids. The default is DNA-50.
If ‘Other’ is selected, the user can select an analysis constant between15-150. When navigating amongst the three
general sample types within the Nucleic Acids module, the last constant value entered within the ‘Constant’ sample type
will be retained. See the “Concentration Calculation (Beer’s Law)” Appendix for more details on this calculation.
λ
and
Abs:
the user selected wavelength and corresponding absorbance. The wavelength can be selected by moving the
cursor or using the up/down arrows to the right of the wavelength box. Note: The user-selected wavelength and
absorbance are not utilized in any calculations.
A260 10 mm path:
absorbance of the sample at 260 nm represented as if measured with a conventional 10 mm path.
Note: This is 10X the absorbance actually measured using the 1 mm path length and 50X the absorbance actually
measured using the 0.2 mm path length.
A280 10 mm path:
sample absorbance at 280 nm represented as if measured with a conventional 10 mm path. Note:
This is 10X the absorbance actually measured using the 1 mm path length and 50X the absorbance actually measured
using the 0.2 mm path length.
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