Sample components that can interfere with LC-MS results

Overview

Purpose of sample preparation prior to LC-MS is to bring sample to a form that is suitable for chromatography (Dissolved in a solvent & particle free), but sometimes depending on the analytes and matrix components complex sample preparation is required to be performed on these samples. The reason for this is the fact that a lot of sample components can interfere with LC-MS analysis.

Some biological matrices, such as plasma, contain high amounts of phospholipids. If not removed prior to chromatography, separating phospholipids from analytes of interest can require long chromatography run times and high concentrations of organic solvents. Furthermore, phospholipids can build up on analytical column, and unexpectedly elute in future runs.

Drug formulation agents, such as polysorbitans and polyethylene glycol, can also interfere and cause ionization suppression. Polymeric sample contaminants are especially troublesome since they lead to multiple peaks within a mass spectrum which are separated from each other with a constant mass.

Besides sample-derived contaminants, additional sources of contamination are sampling devices, solvent impurities, containers, sample preparation devices, volatile organics introduced as a result of handling personal care products, and even columns themselves.

Plasticizers from labware can interfere with LC-MS, resulting in the need to lengthen the chromatography run in order to resolve these peaks from analyte peaks.

Sample components that can interfere with LC-MS results include:

  • Metabolites
  • Detergents
  • Salts/Buffer components
  • Degradation products
  • Counterions
  • Matrix
Mono-isotopic ion mass (singly charged) Ion type Formula for M or subunit or sequence Compound ID or species Possible origin and other comments
74.06059 [M+H]+ C3H7NO Dimethyl formamide Solvent
102.12827 [M+H]+ C6H15N TEA Triethylamine, buffer
107.0782 [A2B+H]+ [C2H4O]nH2O PEG Polyethylene glycol, ubiquitous polyether
123.09222 [M+H]+ C7H10N2 DMAP Dimethylaminopyridine, solvent
153.13917 [M+H]+ C9H16N2 DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene
214.09018 [M+H]+ C10H15NO2S n-BBS n-butyl benzenesulfonamide, plasticizer
242.28477 M+ C16H36N TBA Tetrabutylammonium, buffer
279.15964 [M+H]+ C16H22O4 Dibutylphthalate Plasticizer, phthalate ester
371.1018 [M+H]+ [C2H6SiO]5 Polysiloxane Polysiloxane, followed by m/z 388
371.31614 [M+H]+ C22H42O4 DEHA Bis(2-ethylhexyl) adipate, plasticizer
391.28484 [M+H]+ C24H38O4 Diisooctyl phthalate Diisooctyl phthalate, plasticizer
445.12060 [M+H]+ [C2H6SiO]6 Polysiloxane Polysiloxane, followed by m/z 462
447.2934 [M+H]+ [C3H6O]nH2O PPG Polypropylene glycol, ubiquitous polyether
515.41341 [M+H]+ C30H58O4S DDTDP Didodecyl 3,3′-thiodipropionate, antioxidant
519.13940 [M+H]+ [C2H6SiO]7 Polysiloxane Polysiloxane, followed by m/z 536
593.15820 [M+H]+ [C2H6SiO]8 Polysiloxane Polysiloxane, followed by m/z 610

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