Agilent Technologies 1100 Series Manual de servicio descargar pdf (Pagina 37)

1100 Series DAD and MWD Reference Manual 37

How to optmize the Detector 2

Signal A in the detector default method is set to sample 250,100, reference

360,100, that is, the average absorbance from 200 – 300 nm minus the average

absorbance from 300 – 400 nm. As all analytes show higher absorbance at

200 – 300 nm than at 300 – 400 nm, this signal will show you virtually every

compound which can be detected by UV absorbance.

Many compounds show absorbance bands in the spectrum. Figure 10 shows

the spectrum of anisic acid as an example.

To optimize for lowest possible detectable concentrations of anisic acid, set

the sample wavelength to the peak of the absorbance band (that is, 252 nm)

and the sample bandwidth to the width of the absorbance band (that is,

30 nm). A reference of 360,100 is adequate. Anisic acid does not absorb in this

range.

If you work with high concentrations, you may get better linearity above

1.5 AU by setting the sample wavelength to a valley in the spectrum, like

225 nm for anisic acid.

Figure 10 Optimization of Wavelength Setting

Reference bandwidth 100 nm

Reference wavelength 360

Wavelength (nm)

Absorbance (mAU)

sample wavelength 252 nm

30 nm

bandwidth

Anisic acid

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Agilent Technologies 1100 Series Manual de servicio Pagina 37