You can use additives such as trifluoroacetic acid or formic acid to improve the resolution. A complete range of high purity LC-MS additives is available in bottles or ampoules.
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In reversed-phase HPLC mode gradient, unwanted “ghost peaks” can be a real problem. Quality of your mobile phase (High UV transmittances, low residue on evaporation) and batch-to-batch reproducibility are the key parameters to avoid these unwanted peaks.
LC-MS methods are improving in sensitivity to meet today's demands. The quality of solvent is essential with low level of ionic background, low alkaline metal content, suitable for ULC, UPLC and UHPLC.
LC-MS additives are commonly added to the mobile phase or introduced post column prior to the interface to influence analyte ionisation. A selection of buffers to improve your separation in HPLC.
LC-MS most commonly pre-blended mobile phases solutions prepared with precision and very high quality components to minimize baseline noise. Increase your quality assurance by using these pre-blended mixes.
For HPLC gradient elution, many new ion pair reagents which exhibit minimal extinction in the low UV region and and excellent transparency down to 200 nm.
Safety is essential, discover our complete range of HPLC Solvents packed in aluminium bottles and avoid broken bottles in your lab.
Complete range of HPLC Solvents in stainless steel recycling drums to improve the safety, limit the potential contamination and eliminate waste.
Different grades and packs have been tailored to the requirements of preparative HPLC to facilitate scale-up from analytical to preparative separations. These solvents have an extremely low evaporation residue (< 1 mg/l), low water content and high purity
Merck Supelco® standards and reference materials.
FAQ
What can I do to improve separations in LC-MS?
What is the role of ion pair reagents in HPLC?
Ion pair reagents rely upon the addition of ionic compounds to the mobile phase to promote the formation of ion pairs with charged analytes. These reagents are comprised of an alkyl chain with an ionisable terminus. When used with common hydrophobic HPLC phases in the reversed phase mode, ion pair reagents can be used to selectively increase the retention of charged analytes.
What are the main causes of ghost peaks in gradient HPLC?
- Transition of the sample from an autosampler to an instrument, especially when impurities are absorbed to the inside and outside surfaces of the needle dipped into the vial
- If an impurity in the sample has the same absorption wavelength as the compound of interest
- The water used in the mobile phase is not pure or fresh enough
- Old mobile phase
- Poor quality buffers or additives added in the mobile phase
- Phthalates or plastic additives contained in the plastic containers used during mobile phase preparation
What are the best recommendations for avoiding ghost peaks?
- Try to use pre-mixed solvents
- Use fresh eluants with salts
- Filter your HPLC solvents
- Use high quality water (18,2 mOhm, TOC<5 ppb) or gradient grade water
- Use good quality buffers and salts
- Control glassware cleaning
Why is it important to control the pH in the mobile phase?
When samples contain ionizable compounds, mobile phase pH can be one of the most variable in the control of retention in reversed phase RP HPLC separation. However, if it is not controlled properly, pH can be a source of many problems. Since most compounds analyzed by RP HPLC contain one or more acidic or basic functional groups, most mobile phases require pH control. For this reason, buffers are widely used.
Additional Resources
Explore the full range of chromatography solutions and application notes on our chromatography micro-site.