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Alan Nanders

What are the differences between LC/MS and LC/MS/MS ?

David Daminic  Follow

Dear Sir,
We done our ESI-MS of our novel recombinant protein sample and found varying color (green,red,yellow) of peptide when matching to our known protein sequence (isolated and purified from plant source its ms spectra have identified 7 peptide and expressed it recombinantly). I have found all the peptide matching in our ESI-MS of recombinant protein with native protein ms (out of 7 peptide we have found 3 green 1 yellow and 3 red peptide). please clarify should i consider it my recombinant protein is have same sequence as native plant protein. Secondly what could be the reason of getting varying colour peptide.
Please clarify the significant of peptide deduced in sequence represented with varying color like green,Red and yellow. Could you please elaborate the percentage of similarity level of green, yellow and green peptides????
Thanks
Regards

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Bennison Denny Overton  Follow

I need a standard laboratory where I can send plant samples to for extraction and phtyhormone analysis using LC-MS/MS. Any suggestion will be appreciated.

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Chris Johnston  Follow
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Daniel Toth  Follow

Hi! I start to work with proteomic. And I`m having difficult to understand one information that is um my mzML file. What means the msLevel?

Thanks

Regards

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AFZAAL AGHA  Follow

MS only measures the m/z of a compound. Whereas, MS/MS measures the m/z of the compound as well as its intermediates (by-products).
1. MS/MS filters the compound you target
2. then breaks it down into small intermediate compounds
3. then filters these intermediates and detect them
That provides extra precision and higher sensitivity

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Chris Robinson  Follow

Hello, dear maam. Do you mean programming or genome work?

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Affan Khadir  Follow

An LC-MS/MS is useful for fine-tuning the separation further and improving the resolution of ions segregated by single quadrupole instruments. Multiple reaction monitoring using LC-MS/MS offers many-fold selectivity improvements over single ion monitoring (SIM) using a single quadrupole LC-MS.
I hope it helps.
Regards.
Zeeshan

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Chris Frost  Follow

Hi Mohammed,
LC-MS and LC-MS/MS are the combination of liquid chromatography (LC) with mass spectrometry (MS). MS means you only analyze your precursor ion (as generated in the source) for example in an iontrap, a quadrupole or time-of-flight Massspec. MS/MS is the combination of two mass analyzers in one mass spec instrument. The first MS filters for the precursor ion followed by a fragmentation of the precursor ion with high energy and e.g. nitrogen gas. A second mass analyzer is then filtering for the product ions, generated by the fragmentation. This is usually done in a triple quadrupole MS (QQQ) or a QTOF. The advantages of MS/MS is the increased sensitivity (in the QQQ, due to reduction of noise) and you can gain more structural information on your analyte (QTOF) based on the fragmentation pattern.
I hope that helps
Cheers
Stefanie

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Brianna Cashaw  Follow

Harun, any type of sample can be analyzed by MS/MS as long as it can be fragmented to generate product ions. It increases specificity, sensitivity and confidence in the data.

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Alapa Osayande Wisdom  Follow

Hi
1) In LC/MS, the effluent from the LC is ionized, and the ions are directed into a mass spectrometer. The spectrometer generally records all ions within the set range. You can collect all ions within the working range and plot the total ion chromatograph (TIC). If the analyte that you are observing has a unique mass, you can get better resolution of that analyte by performing SIM, single ion monitoring, where you only monitor the specific ion.You would use MS/MS if you need to confirm that the mass you are monitoring belongs to the analyte of interest. You could for instance monitor anisole at m/z 108. You would detect all ions at this m/z ratio, including other ions of other molecules such as benzyl alcohol, or fragments formed from degradation of larger molecules. You can perform MS/MS however. With the first mass separation, collect only m/z 108 ions. Then you would allow this ion to fragment and perform mass separation and look for a fragment with m/z 65 (C5H5+). That will give you further confirmation of the analyte's structure.2)Some molecules form anions easier than cations, and vice versa. Sometimes you get more structural information using positive mode than negative mode, etc. Use the mode that is better suited for your analyte and your separation conditions.

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BJ Chippindale  Follow

Sanjib Meitei Thanks for the help.

Regards


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All Things Addiction  Follow

Pamela C Lukasewicz Ferreira
msLevel gives you information on whether a scan is MS1 or MS2 or higher in case of multi stage mass spectrometry ( ion trap based workflows).

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