LC-MS Solvents
Liquid Chromatography-Mass Spectrometry (LC-MS) is an analytical technique that integrates the physical separation capabilities of liquid chromatography (LC) with the mass analysis capabilities of mass spectrometry (MS). This method is widely used to differentiate compounds with similar chemical properties and to analyze a broad range of substances, including small molecules, peptides, proteins, and metabolites.
LC-MS is rapidly becoming a standard tool in modern analytical laboratories. With its increasing use, ongoing advancements in instrumental, chemical, and database techniques are enhancing the sensitivity, specificity, and speed of analysis. Innovations such as new ion sources, high-resolution LC systems, and rapid mass spectrometers with improved ion optics and detectors have significantly lowered detection limits while raising the purity expectations for reagents used in sample preparation, mobile phases, and additives.
However, certain compound classes, such as alkali ions, plasticizers, and surfactants, can pose challenges in LC-MS analysis. These compounds are prevalent and can interfere with results by forming adducts, increasing background noise, and leading to signal suppression.
Products
LC-MS grade solvents
LC-MS solvents are high-purity solvents specifically designed to meet the stringent requirements of LC-MS applications, ensuring baseline stability, minimal impurities, and high UV transmittance.
These solvents are available under two premium product lines: OmniSolv® solvents (available only in the US and Canada) and LiChrosolv® solvents. Additionally, the Supelco® portfolio caters to regulated and accredited application fields, while the Sigma-Aldrich® portfolio is intended for research purposes. The solvents undergo microfiltration to 0.2 μm, effectively removing particulates that could interfere with the chromatography process. This level of filtration is essential for maintaining stable flow and preventing clogging within the system.
The solvents exhibit a clean UV impurity profile, maximizing sensitivity near the UV cut-off and reducing background noise during detection. This allows for clearer and more accurate measurements of target analytes. Furthermore, low levels of particulates and non-volatile impurities enhance the longevity of columns and systems. These solvents form minimal mass spectrometry adducts, improving the accuracy and reliability of analysis, and demonstrate excellent lot-to-lot reproducibility, ensuring consistent performance across different batches.
LC-MS Reagents and Additives
LC-MS reagents and additives are introduced to the mobile phase or post-column to enhance ionization and improve the resolution of the analytical signal. These reagents are formulated with low levels of inorganic and organic impurities, specifically designed for accurate and rapid LC-MS applications.
Acid Additives
Volatile, low molecular weight organic acids such as formic acid, acetic acid, or novel difluoroacetic acid (DFA), significantly enhance ionization and resolution across a wide range of molecules. The incorporation of organic acids into the mobile phase can effectively counteract the ionization-suppressing effect of trifluoroacetic acid (TFA), which is commonly found in the mobile phases used for protein and peptide analysis.
Neutral Salts
Neutral volatile salts, such as ammonium acetate or ammonium formate, are commonly used as buffer compounds to control the ionization state of the analytes and phases. This control plays a crucial role in influencing LC-MS separation and performance.
Sodium Adduct Formation
Alkali adducts can diminish instrument sensitivity. When the tendency for adduct formation is strong, adding defined amounts of sodium ions (mostly pre-column) can help achieve uniform and stable molecular ions for detection in LC-MS.
LC-MS Blends
LC-MS Blends consist of a range of high-purity solvents that are pre-blended with reagents, including acetic acid, formic acid, or trifluoroacetic acid. These blends offer convenient, ready-to-use mobile phases specifically designed for accurate LC-MS applications. By using pre-blended solvents, users can save time, reduce the risk of contamination, and minimize exposure to hazardous chemicals.
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