Isomeric reagent tags for differential mobility spectrometry
Methods and systems for separating and/or quantifying compounds, using differential mobility spectrometry (DMS) are provided herein. In accordance with various aspects of the applicants' teachings, the methods and systems can provide for the quantification of one or more compounds, for example, using isomeric labels that can be less costly to produce relative to conventional tags that incorporate stable-isotope labels. The present teachings can quantify the relative amount of a compound based on the effect of using an easily charged functional group as well as a functional group positioned at a resonant or non-resonant position through a DMS. In some aspects, methods and systems in accordance with various aspects of the present teachings provide for the detection and/or quantification of the analytes labeled with isomeric tags that can be differentiated via a DMS upstream of a first stage mass analyzer and/or prior to fragmentation of the labeled analyte, for example.
1. A method of analyzing a plurality of samples, comprising:
separately reacting first and second samples containing or suspected of containing an analyte of with different isomeric labels so as to differentially label the analytes from each sample, thereby generating a plurality of differentially labeled analytes, wherein the different isomeric labels are different in the locations of binding of a functional group, wherein the functional group is at a resonant position on one species of the isomeric label and at a non-resonant position on another species of the isomeric label;
mixing the differentially labeled analytes;
ionizing the mixture of differentially labeled analytes so as to generate ionized labeled analytes; and
performing ion mobility spectrometry on the ionized labeled analytes.
2. The method of claim 1 , further comprising performing liquid chromatography on the mixture of differentially labeled analytes prior to performing ion mobility spectrometry.
3. The method of claim 1 , wherein the ion mobility spectrometry is performed with a differential mobility spectrometer and wherein the method further comprises adjusting at least one of a compensation voltage and a separation voltage of the differential mobility spectrometer to maximize transmission therethrough of one species of the ionized labeled analytes relative other species of the ionized labeled analytes.
4. The method of claim 1 , further comprising adding a chemical modifier to a carrier gas of the ion mobility spectrometer to maximize transmission therethrough of one species of the ionized labeled analytes relative other species of the ionized labeled analytes.
5. The method of claim 1 , wherein the functional group is an electron donating group selected from the group consisting of NH 2 , OCH 3 , OH, and CH 3 or an electron withdrawing group selected from the group consisting of F, Cl, Br, I, NO2, and CN.
6. The method of claim 1 wherein the different isomeric labels are fluorine-substituted N-alkyl-pyridinium compounds or substituted 2-methyl-quinolin-8-ols compounds.