By murugan.R on Thursday, November 27, 2003 - 03:38 am:

In LC/MS/MS quadrupole techniqes,which materials are coated on the quadrupole.Normally which one is suitable for good resolution.

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By Anonymous on Friday, December 19, 2003 - 01:08 am:

We are looking for an LC/MS/MS instrument. Is triple quadrupole or iontrap more suitable for quantification of biomarkers in human plasma?

Thanks!

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By Anonymous on Wednesday, April 7, 2004 - 02:21 pm:

Hello there,
I am planning to buy a Iontrp system for our lab. We are pretty much sure that We will either buy a Agilent LCMSD SL or Bruker Esquire 4000.
Any peace of advice on those two systems? What would be the proper price range?

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By Anonymous on Friday, April 16, 2004 - 04:52 am:

Ion Traps are generally not used in quantitative applications. The Quadrupole would be preferred in that it tends to give improved precision and sensitivity vs. IonTrap

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By Anonymous on Thursday, April 29, 2004 - 05:17 am:

Hello,

our LCQ Deca XP shows intense ions at m/z 391. This behaviour was observed during the installation of the MS and intense cleaning of removable parts did not change the intensity of these ions at all. m/z 391 is a phthalate that must be present elsewhere in the interior of the instrument. The occurance of the ions is related to the temperature of the heated capillary. We assume that the coating of the heater cables or the heater itself could be the source of the contamination and that a chemical ionisation reaction occurs. No ions if the orifice is closed.
Did anybody observe the same issue with his LCQ and could anybody solve the problem ?

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By Bharat kumar Agarwal on Thursday, May 6, 2004 - 04:21 am:

Is there any difference between FAB Mass spectra and EIMS spectra ?

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By Bharat kumar agarwal on Thursday, May 6, 2004 - 04:25 am:

I have to validate a TLC method(or HPLC method) for limitative test for an unknown impurity in a bulk drug substance.Which parameters I should verify?

If a drug is a water soluble in that situation which mobile phase is select for TLC and how we develop it, please tell me the stationary phase also.

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By neil on Thursday, May 6, 2004 - 09:43 am:

hello , i am using a lcq deca xp coupled to a switchos and famos hplc . for some reason the ms and ms/ms data seems to be really noisy , even when running a blank , we have tried cleaning everything , nothing seems to help . any ideas

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By MG on Thursday, May 6, 2004 - 01:10 pm:

On FAB vs. EI: I have not personally done FAB, but my understanding is that yes, it is different. With FAB, you get (M+H)+, that is an even electron ion. With EI, you get a radical cation (odd electron), and the fragmentation reactions would be different. Someone with experience in FAB could provide more details.

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By Goran Mitulovic on Friday, May 7, 2004 - 02:07 am:

The noise observed in MS when using UltiMate Nano HPLC System for sample separation and introduction, is usually due to four factors:

1. Poor water quality. We observed that the HPLC an even HPLC -MS water form many producers is not suitable and here the MilliQ water is especially not recommended for use. Some water (declared as LC-MS) showed very intense PEG signals (m/z difference of 22 and 44 Da). We did some tests with water from several suppliers and found that the Sigma "Water LC-MS Chromasolv" showed the best performance with the very low background. Also, the acetonitrile quality is very often questionable. Try to vacuume filter it through a 20 um filter and a lot of material will be detected.

2. Poor He quality. UltiMate uses He for degassing the mobile phase. If the He is contaminated, the impurity will be constantly introduced into the mobile phase and into the mass spectrometer. If any organic solvent ever rich the He tubing, it will cause a serious damage to the line and will release a lot of softeners, which will be then blown into the mobile phase and into the mass spectrometer.

3. Nano needles. These needles can be contaminated from the very beginning. It is strongly recommended to wipe the needle tip with some acetone.

4. Ion pairing reagent. To have proper HPLC performance and proper binding of peptides or proteins ion pairing agents such as formic acid and TFA are used. These agents vary in their quality very strong, even those declared as high quality and originating from the same supplier. The purity of the ion pairing agent will drastically influence the quality of mass spectrometry data and will add a very significant amount of "trash" ions to the background noise. Please use only high purity reagents and keep them, if possible, under inert gas atmosphere. Once the impurities are in the mobile phase, they will continuously be introduced into the mass spectrometer.

Almost always, 1 and 4 apply and almost always they are the major reason for noisy MS spectra and poor sensitivity.

Concluding: the FAMOS and Switchos are most likely not the source of the noise observed. It is recommended to check the water and the ion pairing agent and flush the complete system with clean solvents, and then also check the He quality and the quality of the connecting lines.

Best regards

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By Anonymous on Monday, June 21, 2004 - 03:25 am:

Hello, I am looking for general informatin about hplc/ms and hplc/ms/ms. i would like to write a short info-paper about this technics... pls if you can send me some links or some documents which i can use I will be appreciate mjb142@wp.pl

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By Anonymous on Wednesday, June 23, 2004 - 03:26 am:

Dear Anonymous (mjb142),

This website may give a clear picture in LCMS.

http://www.forumsci.co.il/HPLC/program.html

Have a nice reading...

Siva

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By jack on Wednesday, July 14, 2004 - 07:24 pm:

is anyone have some idea to extract streptomycin in honey matrix and then run on lc/ms/ms, please help

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By Anonymous on Monday, December 30, 2002 - 02:08 am:

hi folks,
i am new to LC-MS and wish to buy a LC-MS system for my lab to do impurity profiling and charecterization ( Drugs and peptides ), can u pls let me know about the best and worst instruments available for this kind of job and kind of mass detector required. i also wish to know whether LC-MS is sufficient ot LC-MS-MS.

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By L.Kalyanaraman on Tuesday, December 31, 2002 - 04:05 am:

For Impurity profiling LCMSMS will be an ideal machine. The advantage of LCMSMS over LCMS is the additional fragmentation information which is vital for structure elucidation along with other technique like NMR.

Quadrupole mass spectrometers will serve your purpose. But a QTRAP (Quadrupole combine with a Iontrap detector) will be more suitable for your work. Excellent machines are available with Applied biosystems and Waters Micromass.

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By Anonymous on Tuesday, December 31, 2002 - 06:32 am:

What you need to do is invest in a book and do some reading. The following title outlines very nicely the pros and cons of each style of MS and the uses they are best suited for.

A Global View of Lc/MS: How to Solve Your Most Challenging Analytical Problems -- by Ross Willoughby, et al; Paperback
Buy new: $49.95 @ Amazon.com

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By Anonymous on Tuesday, February 25, 2003 - 01:01 am:

What kind of ionization source is more suitable for analysis of common drugs? APCI or ESI?
Thank you

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By Anonymous on Thursday, March 13, 2003 - 10:10 pm:

My laboratory wants to buy an LC/MS/MS system. The question is: for analytical and structural analysis purposes, what m/z range is optimal? I saw at Micromass and at Applied Biosystems m/z range 2-1800, and at Agilent m/z range 50-2200. Is-there an disadvantage for Agilent system?
Regards

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By Anonymous on Friday, March 14, 2003 - 06:57 am:

The range depends on what you want to analyze. If you are looking for most pharmaceutical compounds or pesticides, you will seldom look outside of the range of 100-600.
As for the disadvantange of Agilent, I have never used their MS/MS systems, but I have used their single quads, and they are not very reliable. The newer ones seem to be worse than the older ones. (We brought in a plastic lemon and placed in on whichever of the two new instruments was broken that week.) I had such a bad experience with the last one, that I would never recommend purchasing one. Micromass, Sciex, and Finnegan all produce good triple quads. I have never used Applied Biosystems.

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By Beppe on Friday, March 14, 2003 - 07:53 am:

Some clarifications :
- MS/MS can be done on to kinds of instruments : triple quad and ion trap; Finnigan have both, Agilent only ion trap, Micromass (now Waters) and Applied Biosystems have triple quad, unsure if they have ion trap.
- Applied Biosystem MS are those manufactured by Sciex
- I work with an Agilent simple quad that never caused me a serious problem.

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By Anonymous on Wednesday, April 16, 2003 - 03:56 am:

Ms/MS is more suited for your application. Personally I have worked on Micromass Triple Quad Machine and have served my purpose.

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By M.Steel on Monday, May 12, 2003 - 11:28 am:

If you are still looking, we are selling our ThermoFinnigan LCQ DECA XP LC/MS/MS at an excellent price. It was originally purchased in 2001. www.mckscientific.com

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By Anonymous on Thursday, June 5, 2003 - 02:05 pm:

I found this course which offers a loads of information on LC/MS systems: Applying LC-MS to
Pharmaceutical Analysis.

http://www.pti-international.com/LC-MS/

Hope you all found this site helpful!

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By Anonymous on Thursday, June 26, 2003 - 04:28 am:

Are there any LC-MS courses in Europe?

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By Tomasz on Thursday, July 31, 2003 - 02:52 am:

Hello,
I want to buy an MS analyzer for structural analyses (structural elucidation) of organic compounds, unknown drugs metabolites and quantification of pharmaceuticals in serum. A local sale agent of a MS manufacturer told me that their single quad instrument can satisfy these needs due of CID phenomena, which is responsible by some in source fragmentation of compounds. I have seen some MS “spectraâ€