I tried analyzing VOCs metabolites using various published methods. I got recovery of most of the analytes correct but still getting aberrant recoveries for some of the analytes (CEMA,HPMA, HEMA, MHA, DHBMA,PHEMA,SPMA,BPMA, HPMMA ).
Did anybody in past also had similar issues with VOCs metabolites recovery in SRMs ?
Hello, I think something wrong with your SRM? Usually no problem with VOC recovery.
these are mercapturic acid metabolites of VOCs. Is your matrix urine? If so, spike the known amount of the analytical standard one of these metabolites into SRM and calculate the recovery. You can identify whether this is a matrix or sample prep dependent issue. You can fix this by using an internal standard normalization approach. If the problem is at your SRM sample then with a known amount of spiking and quantifying the target can show the source of the problem.
Mr. Pal,
I would like, in particular, to focus your attention on our most recently developed innovative stochastic dynamic concept and own-authored (mine and my co-author's) formulas for exact or absolute quantification of analytes in complex mixture by means of mass spectrometry. The method has been tested studying mixtures of organics at pg.(mL)-1 and ng.(L)-1 concentrationlevels, showing coefficients of correlations between theory and experiment within /r/ = 0.99997 - 1. It has been validated by means of chromatographic analyses, as well.
Please, consider, references [1,2].
A set of advantages of our method can be underlined, amongst many others. These are, for instance: (i) It is applicable to direct analysis without sample pretreatment steps; (ii) it operates without internal standard; (iii) the method is not only highly precise, accurate and sensitive, but also selective one; and (iv) it operates without isotope labeling, respectively.
[1] Steroids, 164 (2020) 108750
Stochastic dynamic mass spectrometric quantification of steroids in mixture — Part II; Bojidarka Ivanova, Michael Spiteller
[2] B.Ivanova, M. Spiteller, Stochastic dynamic mass spectrometric approach to quantify reserpine in solution, (2020) in press.
Since, work [2] is still unavailable online, due to delay in its publishing, please consider some chemometric data shown as graphical abstract, herein. As can be seen the reliability in this case is /r/ = 0.99994.
Generally there is no problem with VOC recovery, but depends on the used analytical technique used for extraction and analysis. For VOCs analysis you certainly used GC-MS. What extraction technique you used?
Regards
JSCamara
I have tried analysing various sets of SRMs (fresh and new) for VOCs metabolites recovery. Additionally for other classes of organics(like Pthaltes etc.), recovery is coming good in SRMs. Karen A. Darbinyan,since other classes of organics are showing good recovery. I think SRMs are fine.
José Câmara We are analysing VOCs metabolites instead of parent VOCs. We are using CDC/Alwis et., al 2012 LC-MS/MS method(DOI: 10.1016/j.aca.2012.04.009) for VOCs metabolites in urine, which is a direct dilute and shoot.
İsmail Emir Akyildiz Yes we are using Internal Standards for reference. I have tried spiking SRMs at low and high concentrations(0.1,0.2,0.5,1,2,5,10,20,50,100 ppbs) and recovery for VOCs metabolites are good. This rules out that this is not a matrix or SRM dependent issue. Since its a direct dilute and shoot method it involves no as such sample preparation.
Dear Vineet, you use Lc-MS/MS for volatile metabolites? It is not, at all, the most adjusted way to analyse volatiles. LC-MS/MS is adequate for analysis of non-volatile metabolites or thermally labile compounds. For volatile metabolites you must to use GC-MS. By sure!!
Regards
JSCamara
Please look at the following below attached papers which may help you in your analysis.
Thanks
Dear José Câmara The parent VOCs are volatile while its metabolites are non-volatile.That's why it's good idea to use LC-MS/MS for VOCs metabolites, if it would have been Parent VOCs then definitely GC-MS is the first choice. It would be great if can you please share any recent paper who have measured VOCs metabolites using GC-MS.
Currently, I am following CDC's validated method for VOCs metabolites using LC-MS/MS (DOI: 10.1016/j.aca.2012.04.009, PMID: 23062436).
Thanks
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