Waters 2489, Operator'S Manual

Page: 217 / 234

Wavelength selection D-11
Wavelength selection for chromophore detection
Certain functional groups found in most compounds absorb light selectively.
These groups, known as chromophores, and their behavior can be used to
categorize the detection of sample molecules.
The table below lists some common chromophores, and their detection
wavelengths (
λ
max
), as well as the molar absorptivity (
ε
max
) of each group. Use
this information as a guide to select the optimal operating wavelength for a
Wavelength cutoffs for different mobile phases
Mobile Phase
UV
Cutoff
(nm)
Mobile Phase
UV
Cutoff
(nm)
Acetic acid, 1% 230 Sodium chloride, 1 M 207
Ammonium acetate,
10 mM 205 Sodium citrate, 10 mM 225
Ammonium bicarbonate,
10 mM 190 Sodium dodecyl sulfate 190
BRIJ 35, 0.1% 190 Sodium formate, 10 mM 200
CHAPS, 0.1% 215 Triethyl amine, 1% 235
Diammonium phosphate,
50 mM 205 Trifluoracetic acid, 0.1% 190
EDTA, disodium, 1 mM 190 TRIS HCl, 20 mM, pH 7.0,
pH 8.0 202, 212
HEPES, 10 mM, pH 7.6 225 Triton-X™ 100, 0.1% 240
Hydrochloric acid, 0.1% 190
Waters PIC
®
Reagent A,
1 vial/liter
200
MES, 10 mM, pH 6.0 215 Waters PIC Reagent B-6,
1 vial/liter 225
Potassium phosphate,
monobasic, 10 mM
dibasic, 10 mM
190
190
Waters PIC Reagent B-6,
low UV, 1 vial/liter 190
Sodium acetate, 10 mM 205 Waters PIC Reagent D-4,
1 vial/liter 190