Why Ultrapure Water is Important for Nano-LC/MS Applications

  • Fig.1: Schematic showing the technologies used to produce ultrapure water suitable for nano-LC/MS work. The 0.22 µm point-of-use final filter retains particulates that could clog emitters.Fig.1: Schematic showing the technologies used to produce ultrapure water suitable for nano-LC/MS work. The 0.22 µm point-of-use final filter retains particulates that could clog emitters.

Nano-flow LC (nano-LC) is an important tool in proteomics research and in the measurement of low level biomarkers. To avoid the common problem of emitter clogging, only the highest purity solvents and reagents should be used.

Introduction
Connecting a liquid chromatography (LC) system to a mass spectrometer with an electrospray ionization (ESI) source, LC/MS or LC/MS/MS (MS/MS for tandem mass spectrometry), offers today's laboratories superior sensitivity and dynamic range over other detectors, and provides far more molecularly-specific information [1]. However, minute sample quantities, complex matrices, and very low concentrations (pg/mL) make analysis of endogenous biomolecules found in vivo a challenge. An excellent solution is provided by nanoflow LC (nano-LC) coupled to nano-electrospray ionization (nanospray), which typically utilizes 75 µm ID columns. Nano-LC requires minimal sample loading and results in more concentrated peaks. The very low flow rate (nL/min range) is optimal for nanospray sources. Nanospray ionization increases ionization efficiency, leading to better sensitivity [2-3,4,5,6,7,8].

Nano-LC/MS emitters/sprayers have tips with inner diameters of ~1-30 µm that are prone to clogging [4,9]. It is therefore important to choose not only the most robust emitters, but also the highest purity solvents and reagents. This work uses the separation of neuropeptides by nano-LC/MS to demonstrate that using freshly produced ultrapure water as a solvent component in nano-LC/MS does not clog emitters.

Read more on this within the Application Note.

Authors

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Merck Millipore SAS

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