I am confused about the method I found in the study. It does not state the type of mass analyzer I should use. Please help me understand this method:
Flavonoid analyses from FIII and from isolated flavonoids
were carried out on an HP 1100 liquid chromatograph
system equipped with a PDA detector (Agilent
Technologies, Waldbronn, Germany) and interfaced with
a Finnigan LCQ (San Jose, CA) mass spectrometer
equipped with an API-ES ionization chamber. Separation
was performed on an AQUA C18 reverse phase column,
150 46 mm 5 lm (Phenomenex, Torrance, CA, USA) at
25 C, using 2.5% aqueous acetic acid (A), 2.5% aqueous
acetic acid–acetonitrile 90:10 (B) and acetonitrile (C) as
mobile phase. The gradient profile used was 0–100% B in
A (0–5 min), 0–15% C in B (5–30 min), 15–50% C in B
(30–35 min) and 50% C in B (35–40 min) isocratically, at
a flow rate of 0.5 ml min1. The first detection was done
with a PDA detector in a wavelength range 250–600 nm,
followed by a second detection in the mass spectrometer.
Mass analyses were obtained in the negative ion mode.
The mass spectrometer was programmed to perform three
consecutive scans: full mass (m/z 125–1500), MS2 of the
most abundant ion in the full mass and MS3 of the most
abundant ion in the MS2. Source voltage was 2.5 kV and
the capillary voltage and temperature were 10 V and
175 C. Nitrogen was used as sheath and auxiliary gas at
flow rates of 1.2 and 6 l/min, respectively. The normalised
energy of collision was 45%, using helium as collision gas.
Does it mean the author used a tandem MS since he did 3 consecutive scans? Also, if I use other mass analyzer how will it impact my readings? We only have a quadrople type of mass analyzer in the college I believe. Can I adjust this method to fit the instrument available?
The answer to your own questions ["I am confused about the method I found in the study. It does not state the type of mass analyzer I should use. & "What mass analyzer should I choose for LC-PDA-ESI-MS?""] are in fact in the text you copied and posted here. They used an ion trap LC-MS with API-ES source. *As you are a student, new to HPLC and LC-M, please contact the professional chromatographer at your school to assist you with your sample analysis.
As William Letter indicated this is a kind of trap instrument. Therefore MSn application could be accomplished. A hyphenated platform was used. After chromatographic separation probably each UV-active substance (in this case flavonoids) were identified in terms of their molecular weights. In this scenario, MS capability was only used for MW determination rather than quantitative approach due to consecutive scanning mode. You can only perform MSn (three-stage scanning) experiments with the trap-based mass analyzers. Regarding to your question you can conduct flavonoid analysis with quadrupole mass analyzers. You may both transfer the obtained masses to tandem ms (quadrupole) method acquisitions or experimentally infuse the reference standard of flavonoid of interest to find out the mass transitions.
As William Letter indicated the LCQ instrument mentioned in the manuscript is an ion trap mass spectrometer that allows more than two consecutive scans (MSn). I presume that the analysis on a conventional LC triple quad (LC-MS-MS) with single reaction monitoring should be more than sufficient.
The need for asecond detection done with a PDA detector should be investigated, it might not be necessary for flavonoid analyses ....
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