FAQ - Frequently Asked Questions
(LCMS) Mobile Phases Suitable for MS
(LCMS) Mobile Phases Suitable for MS
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Answer
The following solvents are generally used for reverse-phase LC/MS (API) systems.
• Water
• Methanol
• Acetonitrile
• Formic acid (< 0.1 %)
• Acetic acid (< 0.1 %)
• Trifluoroacetic acid (< 0.1 %)
• Ammonium acetate (< 10 mM)
• Ammonium formate (< 10 mM)
• Methanol
• Acetonitrile
• Formic acid (< 0.1 %)
• Acetic acid (< 0.1 %)
• Trifluoroacetic acid (< 0.1 %)
• Ammonium acetate (< 10 mM)
• Ammonium formate (< 10 mM)
CAUTION: 100% acetonitrile cannot be used, because it does not provide proton donors.
CAUTION: Ammonium acetate and ammonium formate do not dissolve in acetonitrile.
Solvents indicated in the below either cannot be used or require special precautions.
• Concentrated Sulfuric Acid, Concentrated Nitric Acid, Dichloroacetic Acid, Acetone*, Tetrohydrofuran (THF), Dichloromethane, Chloroform, and Dimethyl Sulfoxide (DMSO)
Do not use.
Do not use.
* Low concentration aqueous solutions with 0.5% or less acetone may be used temporarily, such as to check the gradient performance.
• Mobile Phases Containing Hexafluoroisopropanol (HFIP)
Do not use.
Do not use.
Polymer is used for tubing joints, regardless of the tubing material used. Using such mobile phases could cause solvent to spray out due to lower polymer strength or damage.
• Halogenated Mobile Phases
Using mobile phases with chloroform or other halogen elements can generate corrosive gases at high temperatures during APCI or ESI.
Using mobile phases with chloroform or other halogen elements can generate corrosive gases at high temperatures during APCI or ESI.
Corrosion will occur even at low concentrations of a few percent in mobile phases. Use stainless steel tubing for connections between the high performance liquid chromatograph and other instruments. Using PEEK polymer tubing could cause solvent to spray out from ruptured tubing due to decreased tubing strength.
Black particles can attach to the APCI or ESI units.
Corrosive gases could shorten the time between replacements.
• Buffer Solutions with Low Volatility (Such as Phosphate Buffer Solutions)
Avoid using. They can leave salt deposits at the interface that can decrease sensitivity.
Avoid using. They can leave salt deposits at the interface that can decrease sensitivity.
• Trifluoroacetate (TFA) or Ion Pair Reagents
Prone to carryover in instrument, which could affect other data acquisition.
Prone to carryover in instrument, which could affect other data acquisition.
• Mobile Phases with High or Low pH (>10 or <2)
To prevent corrosion starting on aluminum surfaces, they can require surface-wiping process or even sandpapering in some cases.
To prevent corrosion starting on aluminum surfaces, they can require surface-wiping process or even sandpapering in some cases.
CAUTION: Always use PEEK tubing for connections on the front side of the MS probe. That prevents leakage due to high voltage.
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