Wavelength cutoffs for mixed mobile phases

Wavelength cutoffs for mixed mobile phases
Topic LCI-USG-0088, Last Updated 11/08/2024

Consult this table to obtain the approximate wavelength cutoff values for solvents, buffers, detergents, and mobile phases.

The solvent concentrations represented are those most commonly used. If you want to use a different concentration, you can determine approximate absorbance using Beer’s law, because absorbance is proportional to concentration.

Notes:
  • λ (or UV) cutoff is the wavelength at which the absorbance of the solvent equals 1 AU.
  • Operating at a wavelength near or below the cutoff increases baseline noise because of solvent absorbance.
Table 1. Wavelength cutoffs for various mobile phases
Mobile phase λ cutoff (nm)
Acetic acid, 1% 230
Ammonium acetate, 10 mM 205
Ammonium bicarbonate, 10 mM 190
3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 0.1% 215
Diammonium phosphate, 50 mM 205
Disodium EDTA, 1 mM 190
4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), 10 mM, pH 7.6 225
Hydrochloric acid, 0.1% 190
2-(N-Morpholino)ethanesulfonic acid (MES), 10 mM, pH 6.0 215
4-Octylphenol polyethoxylate (Triton X-100), 0.1% 240
Polyoxyethylene (35) lauryl ether (Brij 35), 0.1% 190
Potassium phosphate, dibasic, 10 mM 190
Potassium phosphate, monobasic, 10 mM 190
Sodium acetate, 10 mM 205
Sodium chloride, 1 M 207
Sodium citrate, 10 mM 225
Sodium dodecyl sulfate, 0.1% 190
Sodium formate, 10 mM 200
Triethylamine, 1% 235
Trifluoroacetic acid, 0.1% 190
Tris(hydroxymethyl)aminomethane hydrochloride (Tris HCl), 20 mM, pH 7.0 202
Tris HCl, 20 mM, pH 8.0 212
Waters Paired-Ion Chromatography (PIC) Reagent A, 1 vial/liter 200
Waters PIC Reagent B-6, 1 vial/L 225
Waters PIC Reagent B-6, low UV, 1 vial/L 190
Waters PIC Reagent D-4, 1 vial/L 190

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