How to open an Agilent DAD1.UV file and view the spectra

DAD1.UV holds the complete diode-array record of a run: absorbance at every wavelength, at every time point. It is where you go back to when you need a spectrum for peak identity or purity, or a wavelength you did not set as a signal.

What the file contains

A matrix of time × wavelength. A typical run is a few thousand spectra across 190 to 400 nm or wider, at 1, 2 or 4 nm steps. Values are in mAU. ChemStation stores it compressed; OpenLab writes a variant (OL DATA FILE) with the values stored uncompressed.

View it in your browser

1. Open Nagura Lab and drop the .D folder, or the DAD1.UV file on its own.
2. The spectrum map shows the whole run: time across, wavelength up, absorbance as color. Hover to read any point.
3. Click a peak on the map to see the full UV spectrum at that time next to it.
4. Press Download spectra matrix to save every spectrum as CSV: one row per time, one column per wavelength.

Nothing is uploaded; the file is decoded on your computer.

In Python

import rainbow as rb

uv = rb.read("sample.D").get_file("DAD1.UV")
print(uv.data.shape)        # (times, wavelengths)
print(uv.ylabels[:5])       # wavelengths in nm
uv.export_csv("DAD1_spectra.csv")

Reading the spectrum map

• Color scale. The map runs from zero to the 99.9th percentile, so a few very tall peaks do not wash everything else out. The legend marks where it clips.
• Dark band at the bottom. Below about 200 nm, solvent absorbance and low lamp energy give noisy or negative values. Expected, not an error.
• No DAD1.UV in your folder? Spectra are only stored when the DAD method has spectrum storage switched on. Otherwise only the single-wavelength .ch signals exist.