Making Lowry Measurements - Thermo Scientific NanoDrop 1000 V3.7 User Manual

Section 11-Protein Lowry
Reset all Standards (F11): clears all replicates of all standards.
Reset 1 Standard (F12): clears all replicates of the selected
standard.
Absorbance at 650 nm: the Cu-complex's absorbance at 650 nm for
the 1mm pathlength.
Cursor λ and Absorbance: this feature allows the user to adjust the
cursor wavelength and view the corresponding absorbance. The
cursor wavelength can be set by the user. Note: The user-selected
wavelength and absorbance are not utilized in any calculations.
mg/ml: the concentration of the sample (unknown).

Making Lowry Measurements

A standard curve is required every time the Modified Lowry assay is
run. Although curves can be saved and reloaded in the NanoDrop
1000 Spectrophotometer software, it is recommended that the user
follow manufacturers' guidelines and generate fresh standard curves
for each assay. Additionally, a standard curve 'set-up' may be
reloaded. This feature will recall the respective standard series used
in a previously saved standard curve. Both single and multi-point
standard curve generation is incorporated into the software. A
standard curve can be developed using a reference (Modified Lowry
reagent only – no protein) and a single replicate of one standard. The
multi-point standard curve generator allows a maximum of five
replicates for up to seven different standards. There is no set order in
which standards must be run.
A blank must be measured before the standard curve may be
generated. It is advisable to use water as the blank and use the dye
reagent without any protein added as the "0" or reference sample.
There are three general procedural steps to unknown protein
concentration measurements. The requisite order, including
generating the standard curve, is as follows:
11-3