Thermo Scientific NanoDrop One, User Manual

Page: 66 / 328

7
Measure Protein A280
60 NanoDrop One User Guide Thermo Scientific
Each sample type applies a unique extinction coefficient to the protein calculations. If the
extinction coefficient of the sample is known, choose the

+ MW (molar) or

1% (mass)
option and enter the value. Otherwise, calculate the extinction coefficient or choose the
option that best matches the sample solution. If you only need a rough estimate of protein
concentration and the sample extinction coefficient is unknown, select the 1 Abs=1 mg/mL
sample type option.
Tip Ideally, the extinction coefficient should be determined empirically using a solution of
the study protein at a known concentration using the same buffer.
Setting Available Options
Mass Ext. Coefficient
(L/gm-cm)
Description
Sample type
a
1 Abs = 1 mg/mL General reference 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.,

1% = 10.
BSA 6.67 Calculates BSA (Bovine Serum Albumin) protein
concentration using mass extinction coefficient (

) of
6.67 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
-1
cm
-1
.
IgG 13.7 Suitable for most mammalian antibodies (i.e.,
immunoglobulin G or IgG). Calculates protein
concentration using mass extinction coefficient (

) 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
-1
cm
-1
.
Lysozyme 26.4 Calculates lysozyme protein concentration using mass
extinction coefficient (

) 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
-1
cm
-1
and 39,000 M
-1
cm
-1
.