Matrix effects: Do they differ between SFC/ESI-MS and LC/ESI-MS

• Introduction (120 ord)Supercritical fluid chromatography (SFC) is increasingly used in many fields following the new generation of instruments available on the market, often combined with electrospray ionization mass spectrometry (ESI/MS). New methods are developed and validated, often for samples of complex matrices. Thus, measurements of the matrix effects are sometimes included. Comparisons between SFC/ESI/MS and LC/ESI/MS have previously been performed, often focusing on e.g. sensitivity and separation. However, a systematic and qualitative investigation of the matrix effects achieved using same ion source and mass spectrometer, but different types of chromatography, i.e. SFC or LC, is so far lacking. Methods (120 ord)Effluent wastewater was collected and 100.0 ml was extracted using a generic SPE method (Oasis MCX), evaporated and redissolved in 1.0 ml of water:ACN (1:1). A 10 min gradient was developed for each technique, separating eight compounds chosen for being low molecular weight drugs with varying hydrophobicity and proteolytic properties. The mixture of compounds was then added to the ESI make-up solvent (MeOH) for the SFC/ESI/MS method. The extracted wastewater was injected without added compounds, and the SRM channel for each compound was monitored using tandem quadrupole MS (Quattro Micro, Waters®). The same interface and settings were used for LC, but an infusion of compounds was performed through a post-column syringe pump since no make-up flow was used. Preliminary data – Limit 300 wordsThe retention times for the eight model compounds were evenly spread over the chromatographic time scale for both chromatographic methods. When applying the continuous compound infusion through the make-up solution (SFC/ESI/MS) or through a syringe pump (LC/ESI/MS), a stable signal was observed for all compounds. Injection of the extracted wastewater affected the signal in comparison with the blank. The difference in the signal profiles were however larger between LC and SFC than between blank and extracted wastewater. The two separation techniques also gave different levels of noise and variations in the SRM-channels for the different compounds, and occurred at differently time points during the gradients for both the techniques. In summary, the matrix effects seem to affect the detection differently depending on what chromatographic technique that is used. With increased knowledge about this, it could help future method development to minimize the matrix effects.     Novel aspect – Limit 20 wordsThe first systematic comparison between SFC and LC in terms of matrix effects for ESI-MS/MS using qualitative methods (infusion).

Ämnesord

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

Nyckelord

Analytical Pharmaceutical Chemistry

Analytisk farmaceutisk kemi

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