I will be buying a reference standard fpr my LC MS analyses. Most of he standards in sigma aldrich is available in 1 mg only. I am not sure if this is enough for my LC-MS analyses. At what concentrations should reference standards be injected in the LC MS? I will be using the ff standards: quercetin, apigenin, caffeic acid, pcoumaric acid, syringic acid, isoorientin.
This is included in the procedure :
An injection volume of 100 μl will be used for all standards and samples (prepared with 1.8 mg of extract dissolved in 1 ml of methanol-water 1:1 ratio).
It is not clear to me whether the concentration of the standards be the same wit the sample extract. Thank you!
There are no universal answers to such questions. Impossible to say until the actual method has been developed, but why not start with 1 or 2 mg of pure std, each.
Detection limits vary for ALL compounds, detectors, modes, the specific sample properties and the actual LC-MS method used for analysis (of which there are millions of permutations). However, 1 or 2 mg of each pure std should provide enough material to perform some initial infusion studies to find the detection settings and develop an LC-MS method. Those are the basic steps to take with any new LC-MS method (or sample type) to find the best settings and conditions to use.
2 to mg of standard you would need for an LC MS analysis.
Check https://www.rsc.org/images/AMC%20LCMS%20Guide_tcm18-240030.pdf
Hello Duri,
Check on this work
https://www.mdpi.com/1420-3049/22/1/174/pdf
Dissolve 1-2 mg sample in methanol/ethanol/water and centrifuge. After that filter it through syringe filter. Your sample is ready for LCMS analysis.
If you will prepare the standard solution by weighing, 10 mg at least is required to minimize balance error.
1.0 mg is enough if you directly solve the standard by washing its container and diluting it to a total volume. But you should check the uncertainty of standard from its certificate.
In the instrumental part, start with 1.0 ppm solution and check the signal intensities, because it strongly depends on the analyte structure.
Elif and William replied well. For LC-MS, 1 mg standard will be enough. About concentrations range, it also depends on machine, scan mode as well. If you are using MRM mode in QQQ, you need very less concentrations, if it is simple MS2 scan then you required higher than used in MRM scan mode. Likewise, QTOF etc. If it is simple LC-MS single quadrupole, then it will roughly 0.1 ug to maximum 500 ug/mL. It is my rough estimations.
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