Thermo Scientific NanoDrop Lite Plus User manual

NanoDrop Micro-UV Spectrophotometer
NanoDrop Lite Plus
User Guide
S120 NanoDrop Lite Plus UG Revision Date March 2022

© 2022 Thermo Fisher Scientific Inc. All rights reserved.
Thermo Fisher Scientific Inc. provides this document to its customers with a product purchase to
use in the product operation. This document is copyright protected and any reproduction of the
whole or any part of this document is strictly prohibited, except with the written authorization of
Thermo Fisher Scientific Inc.
For U.S. Technical Support, please contact:
Thermo Fisher Scientific
3411 Silverside Road
Tatnall Building, Suite 100
Wilmington, DE 19810 U.S.A.
Telephone: [phone]
Toll Free: 1 877 724 7690 (U.S. & Canada only)
E-mail: [e-mail]
For International Support, please contact:
http://www.thermofisher.com/
NanoDropSupport
Contact your local distributor. For contact
information go to:
http://www.thermofisher.com/
NanoDropDistributors
The contents of this document are subject to change without notice. All technical information in this
document is for reference purposes only. System configurations and specifications in this document
supersede all previous information received by the purchaser.
Thermo Fisher Scientific Inc. makes no representations that this document is complete, accurate or
error-free and assumes no responsibility and will not be liable for any errors, omissions, damage or
loss that might result from any use of this document, even if the information in the document is
followed properly.
This document is not part of any sales contract between Thermo Fisher Scientific Inc. and a
purchaser. This document shall in no way govern or modify any Terms and Conditions of Sale,
which Terms and Conditions of Sale shall govern all conflicting information between the two
documents.
For Research Use Only. This instrument or accessory is not a medical device and is not intended to
be used for the prevention, diagnosis, treatment or cure of disease.
WARNING Avoid an explosion or fire hazard. This instrument or accessory is not
designed for use in an explosive atmosphere.

Thermo Scientific NanoDrop Lite Plus User Guide iii
C
Chapter 1 NanoDrop Lite Plus User Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
General Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
NanoDrop Lite Plus Basic Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Menu Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Measurement Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Nucleic Acid Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Making a Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Nucleic Acid Measurement Screen . . . . . . . . . . . . . . . . . . . . . . . . . .11
Nucleic Acid Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Protein Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Making a Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Protein Measurement Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Protein Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Transferring Data From Instrument to Computer . . . . . . . . . . . . . . . . . .16
Helpful Information for Measuring Samples . . . . . . . . . . . . . . . . . . . . . .17
Sample Volume Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Sample Measurement Accuracy and Reproducibility . . . . . . . . . . . . .17
Sample Homogeneity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Sample Carryover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
A260/A280 Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Run a Blanking Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Effect of Evaporation and Solvent Usage . . . . . . . . . . . . . . . . . . . . . .21
Using NanoDrop Lite Plus With Optional Printer. . . . . . . . . . . . . . . . . . .21
Troubleshooting Paper Feed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Printing Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Printer Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Performance Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Reconditioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Solvent Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Decontamination of Upper and Lower Pedestals . . . . . . . . . . . . . . . .31
Contents

Contents
iv NanoDrop Lite Plus User Guide Thermo Scientific
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Frequently Asked Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Thermo Scientific NanoDrop Lite Plus User Guide 5
1
NanoDrop Lite Plus User Guide
The Thermo Scientific™ NanoDrop™ Lite Plus is a small, stand-alone UV
spectrophotometer developed specifically for microvolume measurements of nucleic
acids and purified proteins. The NanoDrop Lite Plus comes with preloaded software
and is designed to be used without a computer. The NanoDrop Lite Plus can also be
connected to an accessory printer for printing measurement information on labels.
The sample retention system of the NanoDrop Lite Plus is identical to that used in all
NanoDrop instruments: surface tension is used to hold 1-2 μL of sample between
two stainless steel pedestals that contain optical fibers. The patented sample
retention system enables the measurement of highly concentrated samples without
the need for dilutions.
The NanoDrop Lite Plus measures the sample absorption at 230, 260, and 280 nm
and corrects for scattering and background effects in the sample with light from a
reference wavelength at 340 nm.

1NanoDrop Lite Plus User Guide
General Safety
6 NanoDrop Lite Plus User Guide Thermo Scientific
General Safety
The power supply can remain plugged into the NanoDrop Lite Plus while the
instrument is not in use. When the instrument is plugged in but not in use, the power
consumption is ~3 W at idle, 18 W at working conditions.
NanoDrop Lite Plus Basic Operation
Installation
CAUTION Operating the instrument with the cover off exposes the operator to
the instrument’s sharp metal edges and delicate fiber optics. Removal of the
cover may also void the warranty.
Note The NanoDrop Lite Plus is supplied with a 12 V power supply. Use only
the power supply provided with the instrument. The unit also comes with a
grounded power cord. Plug this cord into a properly grounded outlet. Use of the
instrument in a manner not specified by the manufacturer may impair the
protection provided by the supplied power cord and power supply.

1 NanoDrop Lite Plus User Guide
NanoDrop Lite Plus Basic Operation
Thermo Scientific NanoDrop Lite Plus User Guide 7
USB for
data transfer
USB*
DC power
On/Off switch
Printer dock connector
* For factory calibration only

1NanoDrop Lite Plus User Guide
NanoDrop Lite Plus Basic Operation
8 NanoDrop Lite Plus User Guide Thermo Scientific
Menu Selection
Table 1.Navigation menu
Menu option Function
Back Return to the previous screen
Home Return to the Home screen
History View and export sample history
Settings View and configure instrument parameters such as display
settings, printers, and instrument info.
Maintenance Perform performance verification, instrument diagnostics
and software updates.
Table 2.Sample category reference settings
Nucleic Acids
dsDNA factor = 50
ssDNA factor = 33
RNA factor = 40
Protein
Protein (1 Abs= 1 mg/mL) Default general reference setting
Protein (IgG) E1%=13.7
Protein (BSA) E1%=6.7
Lysozyme E1%=26.4
Other protein (+ MW) User entered molar extinction coefficient
and molecular weight
Other protein (1%) User entered mass extinction coefficient
Settings
History
Home
Back
Maintenance
Connected hardware Applications
NanoDrop Lite Plus Home screen

1 NanoDrop Lite Plus User Guide
NanoDrop Lite Plus Basic Operation
Thermo Scientific NanoDrop Lite Plus User Guide 9
Settings screen
Maintenance screen
Measurement Basics
The NanoDrop Lite Plus spectrophotometer uses surface tension to hold a small
volume of sample between two pedestals. The patented sample retention system
enables the measurement of highly concentrated samples without the need for
dilutions. A fiber optic cable embedded in the upper pedestal leads to a xenon light
source. A second cable embedded in the lower pedestal leads to a detector. When
the instrument arm is down, the sample forms a liquid column, essentially bridging
the gap between the two fiber optic cables.
Raise the arm and pipette the sample onto the lower pedestal.
1. Lower the arm and initiate a measurement.
The sample column is automatically drawn between the upper and lower
pedestals and the measurement is made.
2. When the measurement is complete, raise the arm and wipe the sample from
both the upper and lower pedestals using a dry, lint-free laboratory wipe.
Tip Simple wiping with a dry laboratory wipe is sufficient to prevent sample
carryover in subsequent measurements.

1NanoDrop Lite Plus User Guide
Nucleic Acid Measurements
10 NanoDrop Lite Plus User Guide Thermo Scientific
Nucleic Acid Measurements
Nucleic acid samples can be easily checked for concentration and purity using the
NanoDrop Lite Plus spectrophotometer. To measure nucleic acid samples (dsDNA,
ssDNA and RNA) from the Home screen, select Nucleic Acids and select the
appropriate Nucleic Acid application.
Making a Measurement
1. From the Home screen, select Nucleic Acids and select the appropriate
sample type.
For DNA measurements, select either the dsDNA or ssDNA assay.
2. Following the on-screen instructions, establish a blank by pipetting 1-2 μL of the
blanking buffer onto the bottom pedestal, lower arm and select Blank.
3. When measurement is complete, raise the arm and wipe the buffer from both the
upper and lower pedestals using a dry laboratory wipe.
4. Measure sample by pipetting 1-2 μL of sample onto the bottom pedestal, lower
arm and select Measure.
5. Wipe the upper and lower pedestals using a dry laboratory wipe and the
instrument is ready to measure the next sample.
Note Use a fresh aliquot of sample for each measurement.

1 NanoDrop Lite Plus User Guide
Nucleic Acid Measurements
Thermo Scientific NanoDrop Lite Plus User Guide 11
Nucleic Acid Measurement Screen
Nucleic Acid Calculations
The NanoDrop Lite Plus should be used to measure the concentration of purified
nucleic acid samples. Direct nucleic acid concentration measurements assume a
purified sample as all absorbance at 260 nm is included in the calculation of the
nucleic acid concentration. Carryover of nucleotides, primers, purifying reagents,
and cell material into the measured nucleic acid sample will overestimate the nucleic
acid concentration.
For nucleic acid quantification, the Beer-Lambert equation is modified to use a
conversion factor with units of ng-cm/μL. The modified equation used for nucleic
acid calculations is the following:
Measure sample
solution
Sample name
Run blank Print
Sample measurement screen
Sample measurement data
Return to Home
Application

1NanoDrop Lite Plus User Guide
Nucleic Acid Measurements
12 NanoDrop Lite Plus User Guide Thermo Scientific
c = (A *CF)/b
where,
c= the nucleic acid concentration in ng/μL
A= the sample absorbance
CF = the conversion factor in ng-cm/μL
b= the pathlength in cm
The generally accepted conversion factors for nucleic acids are:
• Double-stranded DNA: 50 ng-cm/μL
• Single-stranded DNA: 33 ng-cm/μL
• RNA: 40 ng-cm/μL
Table 3.Nucleic acid concentration range
Sample
Type
Lower
Detection
Limit
Upper
Detection
Limit
Typical reproducibility;
based on 10 replicates
(SD = ng/µL; CV=%)
dsDNA 2.0 ng/μL 1500 ng/μL ±2.0 ng/μL for sample
concentrations between 2.0 and
100 ng/μL samples; ±2% for
samples >100 ng/μL
ssDNA 1.3 ng/μL 990 ng/μL ±2.0 ng/μL for sample
concentrations between 2.0 and
100 ng/μL samples; ±2% for
samples >100 ng/μL
RNA 1.6 ng/μL 1200 ng/μL ±2.0 ng/μL for sample
concentrations between 2.0 and
100 ng/μL samples; ±2% for
samples >100 ng/μL
Note Absorbance reported is normalized to a 1.0 cm (10.0 mm) pathlength for
all measurements.

1 NanoDrop Lite Plus User Guide
Protein Measurements
Thermo Scientific NanoDrop Lite Plus User Guide 13
Protein Measurements
Purified protein samples can be quantified on the NanoDrop Lite Plus
spectrophotometer. To measure the concentration of a protein sample, select the
Protein application from the Home screen and then select the appropriate assay
type (1 Abs= 1 mg/mL, IgG, Lysozyme, BSA, or Other Protein).
Making a Measurement
1. Select Protein from the Home screen.
2. Select the appropriate assay type: 1Abs=1mg/mL, IgG, Lysozyme, BSA, or
Other Protein.
3. Following the on-screen instructions, establish a blank by pipetting 2 μL of the
blanking buffer onto the bottom pedestal, lower arm and select Blank.
4. When measurement is complete, raise the arm and wipe the buffer from both the
upper and lower pedestals using a dry laboratory wipe.
5. Confirm Blank by pipetting a fresh aliquot of blanking buffer onto the bottom
pedestal, lower the arm and select Measure. The resulting absorbance at the
analysis wavelength should be no more than 0.04 A. If your absorbance does
not meet this criteria, establish a new blank with a fresh aliquot of buffer.
6. When measurement is complete, raise the arm and wipe the buffer both the
upper and lower pedestals using a dry laboratory wipe.
7. Measure sample by pipetting 2 μL of sample onto the bottom pedestal, lower
arm and select Measure.
8. Wipe the upper and lower pedestals using a dry laboratory wipe and the
instrument is ready to measure the next sample.
When working with protein samples it is recommended that a 2 μL sample volume
be used to ensure that a liquid column is formed between the upper and lower
pedestals. This is especially true for concentrated samples or samples that contain
detergents. “Sample Volume Requirements” on page 17.
Note Use a fresh aliquot of sample for each measurement.

1NanoDrop Lite Plus User Guide
Protein Measurements
14 NanoDrop Lite Plus User Guide Thermo Scientific
Protein Measurement Screen
Protein Calculations
Proteins, unlike nucleic acids, exhibit considerable diversity. The Protein A280
application is indicated for purified proteins that contain Trp, Tyr residues or Cys-Cys
disulphide bonds and exhibit absorbance at 280 nm. The Protein A280 application
measures sample absorbance at 280 nm (A280) and calculates the concentration
(mg/mL) using the selected extinction coefficient. The Protein A280 application does
not require generation of a standard curve.
The NanoDrop Lite Plus should be used to measure the concentration of purified
protein samples. Direct protein concentration measurements assume a highly
purified sample as all absorbance at 280 nm is included in the calculation of the
protein concentration. Carryover of starting materials, purifying reagents, and cell
material into the measured protein sample will result in an artificially high protein
concentration.
Measure sample
solution
Sample name
Run blank Print
Sample measurement screen
Sample measurement data
Return to Home
Application

1 NanoDrop Lite Plus User Guide
Protein Measurements
Thermo Scientific NanoDrop Lite Plus User Guide 15
Protein concentration is calculated using the Beer-Lambert equation:
c = A/e*b
where,
c= the protein concentration
A= the sample absorbance
e= the protein specific mass extinction coefficient
b= the pathlength in cm
The protein specific concentration measurement options are:
1 Abs= 1 mg/mL: Recommended when extinction coefficient is unknown and
rough estimate of protein concentration is acceptable for a solution with no other
interfering substances. Assumes 0.1% (1 mg/mL) protein solution produces 1.0A at
280 nm (where pathlength is 10 mm), i.e., E1% = 10.
IgG: Suitable for most mammalian antibodies (i.e., immunoglobulin G or IgG).
Calculates protein concentration using mass extinction coefficient (E) of
13.7L/gm-cm at 280 nm for 1% (i.e., 10 mg/mL) IgG solution. Assuming MW is
150,000 Da, molar extinction coefficient at 280 nm for IgG is approximately
210,000M-1cm-1.
BSA: Calculates BSA (Bovine Serum Albumin) protein concentration using mass
extinction coefficient (E) of 6.7 L/gm-cm at 280 nm for 1% (i.e., 10 mg/mL) BSA
solution. Assuming MW is 66,400 daltons (Da), molar extinction coefficient at
280nm for BSA is approximately 43,824 M-1cm-1
Lysozyme: Calculates lysozyme protein concentration using mass extinction
coefficient (E) of 26.4 L/gm-cm at 280 nm for 1% (i.e., 10 mg/mL) lysozyme solution.
Assumes molar extinction coefficient for egg white lysozyme ranges between 36,000
M-1cm-1 and 39,000 M-1cm-1.
Other protein (E &MW): User entered molar extinction coefficient and molecular
weight. Assumes protein has known molar extinction coefficient (E) and molecular
weight (MW), where:
(Emolar)*10=(Epercent)*(MWprotein)
Enter MW in kiloDaltons (kDa) and molar extinction coefficient (E) in M-1cm-1 divided
by 1000 (i.e., E/1000). For example: For protein with molar extinction coefficient of
210,000 M-1cm-1, enter 210.
Other Protein (E 1%): User entered mass extinction coefficient. Assumes protein
has known mass extinction coefficient (E). Enter mass extinction coefficient in
L/gm-cm for 10 mg/mL (E1%) protein solution.

1NanoDrop Lite Plus User Guide
Transferring Data From Instrument to Computer
16 NanoDrop Lite Plus User Guide Thermo Scientific
Transferring Data From Instrument to Computer
The NanoDrop Lite Plus automatically stores the last 1000 measurements in the
internal memory. A USB memory device can be used to transfer these
measurements from the NanoDrop Lite Plus to a computer for archival or further
analysis.
The internal software of the NanoDrop Lite Plus does not support connecting the
NanoDrop Lite Plus to an external hard drive. Only USB memory devices (memory
sticks) should be used to transfer data.
Sample data is automatically saved on the instrument.
To transfer data from the instrument to a USB memory device:
1. Insert the device.
2. From the Home screen, select History.
3. Select Export.
This file is a .csv format and can be transferred to a computer to be opened in
Microsoft Excel® or other compatible application.
Table 4.Protein Concentration Range
Sample
Type
Lower
Detection
Limit
Upper
Detection
Limit
Typical reproducibility
(10 replicates, SD = mg/mL; CV=%)
BSA 0.06 mg/mL 45 mg/mL ±0.10 mg/mL (for 0.10-10 mg/mL
samples); ±2% for samples
>10 mg/mL
IgG 0.03 mg/mL 22 mg/mL ±0.10 mg/mL (for 0.10-10 mg/mL
samples); ±2% for samples
>10 mg/mL
Lysozyme 0.015
mg/mL
11.4
mg/mL
±0.10 mg/mL (for 0.10-10 mg/mL
samples); ±2% for samples
>10 mg/mL
Note Absorbance reported is normalized to a 1.0 cm (10.0 mm) pathlength for
all measurements.
NOTICE A maximum of 1000 measurements will be saved in the instrument
and are available to be transferred to a USB memory device at any time.
Measurement #1001 will replace #1.

1 NanoDrop Lite Plus User Guide
Helpful Information for Measuring Samples
Thermo Scientific NanoDrop Lite Plus User Guide 17
Helpful Information for Measuring Samples
Sample Volume Requirements
Sample volume is important because it is essential that a proper liquid column is
formed and that the path between the upper and lower pedestals is bridged with
liquid sample which is held in place by surface tension.
The dominant factor determining the surface tension of a droplet is the hydrogen
bonding of the lattice of water molecules in solution. Generally, all solutes (including
protein, DNA, RNA, buffer salts and detergents) can reduce the surface tension by
interfering with the hydrogen bonding between water molecules. Although 1 μL volumes
are usually sufficient for most sample measurements, increasing the sample size to 2 μL
will ensure proper column formation for samples with reduced surface tension.
This is particularly true when working with protein samples which may contain
detergents. Such samples do not "bead" on the pedestal but tend to spread across
the measurement surface. To ensure that a liquid column forms in the gap between
the upper and lower pedestals, a 2 μL volume is indicated for such samples.
Protein samples, especially those containing detergents, are subject to bubble
formation. Extra care is required while pipetting onto the pedestal to ensure bubbles
are not present into the light path of the spectrophotometer.
Field experience indicates that the following volumes are sufficient to ensure
reproducibility: Aqueous solutions of nucleic acids: 1 μL
Aqueous solutions of purified protein: 2 μL
It is best to use a precision pipettor (0-2 μL) with precision tips to ensure that
sufficient sample (1-2 μL) is delivered. Lower precision pipettors (0-10 μL and larger)
are not as good at delivering 1 μL volumes to the lower pedestal. If the user is unsure
about the sample characteristics or pipettor accuracy, a 2 μL sample volume is
recommended.
Sample Measurement Accuracy and Reproducibility
Sample or aliquot heterogeneity and/or liquid column breakage may result in
erroneous or non-reproducible results. Follow the recommendations below to ensure
accurate and reproducible results:
• Ensure the pedestal surfaces are clean. A dirty pedestal (i.e., a pedestal with
sample dried on it) may cause erroneous absorbance readings (even negative
values) and signal saturation. It is good practice to clean the pedestal surfaces
with deionized water prior to starting a measurement.
Note Do not use a squirt or spray bottle to apply de-ionized water.

1NanoDrop Lite Plus User Guide
Helpful Information for Measuring Samples
18 NanoDrop Lite Plus User Guide Thermo Scientific
• Use a 1.5-2 μL sample volume. Unexpected results can occur when the liquid
sample column is not completely formed during a measurement. During the
measurement, visually confirm that the liquid column is formed. Also, proteins
and solutions containing surfactants are known to “un-condition” the pedestal
surfaces so that the liquid column does not form. If this occurs, use the Thermo
Scientific Pedestal Reconditioning compound (PR-1) to recondition the
pedestals. Refer to “Reconditioning” on page 30 for more details.
• Heat high molecular weight DNA samples to 63 °C and gently vortex before
measurement. Due to the small volumes required by the NanoDrop Lite Plus, it is
important to ensure that the sample being measured is homogeneous. Field
experience has shown that samples containing large molecules such as
genomic or lambda DNA are particularly susceptible to heterogeneity.
• Ensure that a fresh aliquot of blanking solution is used for the blank confirmation
prior to making a sample measurement.
• Confirm that blank and sample buffer are the same pH and ionic strength. Some
buffer components absorb in the UV range, therefore, it is critical to blank the
instrument with the same solution (buffer from the same bottle if possible) in
which the sample is suspended.
• Confirm that the sample is not too dilute or too concentrated. Analyzing samples
at or near the detection limit will result in variable measurements. Refer to
Table 3 and Table 4 for guidance on detection limits.
• Confirm instrument is working within specifications with PV-1. PV-1 is a liquid
photometric standard available from Thermo Fisher Scientific and its distributors.
It is recommended that the performance verification be performed every six
months with a fresh vial of PV-1 to confirm that the instrument is performing
within specifications.
Sample Homogeneity
Sampling from heterogeneous solutions, particularly when using small volumes, may
result in poor data reproducibility regardless of the technology being used to make
the measurement. Genomic DNA, lambda DNA and viscous solutions of highly
concentrated nucleic acids or proteins are common examples that require careful
attention to ensure homogeneity before sampling. Proteins are subject to
denaturation, precipitation, and aggregation and therefore also require special
handling to ensure homogeneity before sampling.
Sample Carryover
Wiping of the upper and lower pedestal with a clean, dry laboratory wipe is sufficient
to eliminate carryover between samples differing in concentration by as much as
three orders of magnitude.

1 NanoDrop Lite Plus User Guide
Helpful Information for Measuring Samples
Thermo Scientific NanoDrop Lite Plus User Guide 19
A260/A280 Ratio
Some researchers may encounter a consistent A260/A280 ratio change when
switching from a standard cuvette spectrophotometer to the NanoDrop Lite Plus.
The three main causes for this are:
Change in sample acidity - Small changes in solution pH will cause the A260/A280
ratio to vary. Acidic solutions will under-represent the A260/A280 ratio by 0.2-0.3,
while a basic solution will over-represent the ratio by 0.2-0.3. When comparing the
NanoDrop Lite Plus to other spectrophotometers, it is important to ensure that the
pH of an undiluted sample measured on the NanoDrop Lite Plus is at the same pH
as the diluted sample measured on the second spectrophotometer.
Wavelength Accuracy of the Spectrophotometers - Although the absorbance of a
nucleic acid at 260 nm is generally on a plateau, the absorbance curve at 280 nm is
quite steeply sloped. A slight shift in wavelength accuracy will have a large effect on
A260/A280 ratios. For example, a + 1 nm shift in wavelength accuracy will result in a
+0.2 change in the A260/A280 ratio. Since many spectrophotometers claim a 1 nm
accuracy specification, it is possible to see as much as a 0.4 difference in the
A260/A280 ratio when measuring the same nucleic acid sample on two
spectrophotometers that are both within wavelength accuracy specification.
The difference in the A260/A280 ratio is important when comparing measurements
taken on the NanoDrop Lite Plus to measurements made on other
spectrophotometers.
Nucleotide Mix in Your Sample - The five nucleotides that comprise DNA and RNA
exhibit widely varying A260/A280 ratios. The following represent the A260/A280
ratios estimated for each nucleotide if measured independently:
Adenine: 4.50
Cytosine:1.51
Guanine: 1.15
Thymine:1.47
Uracil: 4.00
The resultant A260/A280 ratio for the nucleic acid being studied will be
approximately equal to the weighted average of the A260/A280 ratios for the four
nucleotides present. It is important to note that the generally accepted ratios of 1.8
and 2.0 for DNA and RNA are “rules of thumb.” The actual ratio will depend on the
composition of the nucleic acid.
Note RNA will typically have a higher A260/A280 ratio due to the higher ratio of
Uracil compared to that of Thymine.

1NanoDrop Lite Plus User Guide
Helpful Information for Measuring Samples
20 NanoDrop Lite Plus User Guide Thermo Scientific
Run a Blanking Cycle
Run a blanking cycle to verify the following:
• instrument is operating normally (with flat baseline)
• pedestals are clean (i.e., no dried-down sample material on pedestals)
• absorbance contribution of buffer solution you plan to use for sample analyses
Supplies needed
• lint-free laboratory wipes
• calibrated precision pipettor (0–2 μL)
• buffer solution for evaluation
To run a blanking cycle
1. From the Home screen, select an application.
2. Lift the instrument arm and clean the upper and lower pedestals with a
laboratory wipe.
3. Measure a water blank:
– Pipette exactly 1 μL deionized water (DI H2O) onto the lower pedestal and
lower the arm.
– Tap Blank and wait for the measurement to complete.
– Lift the arm and clean both pedestals with new laboratory wipe.
4. Measure the buffer solution:
– Pipette 1-2 μL buffer solution onto the pedestal, lower the arm, and tap
Measure
– Wait for measurement to complete.
The resulting absorbance should vary no more than 0.04A at the analysis
wavelength.
If your spectrum does not meet these criteria, repeat steps 2–4.
If spectrum is still outside specifications, see “Solutions for blanking problems”
on page 21
NOTICE
• Do not use a squirt or spray bottle on or near the instrument as liquids will
flow into the instrument and may cause permanent damage.
• Do not use hydrofluoric acid (HF) on the pedestals. Fluoride ions will
permanently damage the quartz fiber optic cables.