Overcoming UV-Absorbing Mobile Phases

The UV absorption spectrum of some solvents overlaps with the product they dissolve, meaning that fraction collection processes cannot distinguish between solvent and product. The phenomenon, especially when applied to mobile phase gradients, can also result in drifting baselines and, in a worst case, swamp the sample out completely. Luckily, there is technology that solves this problem.

In this application note, it is shown shows a drifting baseline can be completely eliminated in UV detected purification by the use of advanced baseline correction features. Certain flash systems automatically organize real blank runs for the chemist to create true background spectra and ensure maximum fidelity of the resulting baseline data, enabling almost any UV absorbing solvent combination to be used for flash purification.

Baseline correction chromatogram with Isolera Spektra

Results of purification runs. System used: Isolera™ One running Spektra 2.0. UV-detector: 200–400 nm. Solvent A: Toluene; Solvent B: Acetone. Wavelengths used: 220 nm and 280 nm. Cartridge: Biotage® SNAP KP-Sil, 25 g. Sample: Nitronaphthalene, 2-Nitroaniline, 3-Nitroaniline (1.1:1 in acetone, 0.6 g/ml) 1 ml sample gives 2.4 % loading.
a) Example purification @ 265 and 280 nm detection [baseline correction off].
b) Example purification [λ-All: ON, baseline correction on].

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Using UV detection with UV absorbing mobile phases

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