Waters 2998 Overview And Maintenance Manual page 91

C.9.3 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 (
as the molar absorptivity (
operating wavelength for a particular analysis. Because of the diversity possible within a given
sample, scanning over a range of wavelengths may be necessary to determine the best
wavelength for a particular analysis.
Table C–4:
Chromophore
Ether
Thioether
Amine
Thiol
Disulfide
Bromide
Iodide
Nitrile
Acetylide
Sulfone
Oxime
Azido
Ethylene
Ketone
Thioketone
Esters
Aldehyde
Carboxyl
Sulfoxide
Nitro
Nitrile
Azo
Nitroso
Nitrate
Allene
Allene
) of each group. Use this information as a guide to select the optimal
max
Electronic absorption bands of representative chromophores *
Chemical
Configuration
—O—
—S—
—NH 2
—SH
—S—S—
—Br
—I
—CN
—CC—
—SO 2 —
—NOH
>C=N—
—C=C—
>C=O
>C=S
—COOR
—CHO
—COOH
>S—O
—NO 2
—ONO
—N=N—
—N=O
—ONO 2
—(C=C) 2 —
(acyclic)
—(C=C) 3 —
December 5, 2017, 715004753 Rev. B

 max
(nm)
max
(L/m/cm)
185 1000
194 4600
195 2800
195 1400
194 5500
208 300
260 400
160 —
175-180 6000
180 —
190 5000
190 5000
190 8000
195 1000
205 strong
205 50
210 strong
200-210 50-70
210 1500
210 strong
220-230 1000-2000
285-400 3-25
302 100
270 12
(shoulder)
210-230 21,000
260 35,000
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 ), as well
max
 
max max
(nm) (L/m/cm)
215 1600
255 400
270-285 18-30
280-300 11-18
300-400 10