Method for phosporous quantitation

Abstract

A method of detecting and measuring phosphorus in samples is disclosed. The measurement of phosphorylation is made with an inductively coupled plasma mass spectrometer (ICP-MS), coupled to a reactive collision cell. The reactive collision cell is employed to ensure in inteference-free detection of phosphorus ions, by the: formation of product ions, with a different mass to charge ratio. Accurate Measurement of phosphorylation in samples is important in proteomics.

1 . A method for detecting and measuring the degree of phosphorylation in a sample, comprising: 
 (i) introducing the sample containing an analyte into an inductively coupled plasma mass spectrometer having a reactive collision cell, and producing analyte ions;    (ii) reacting the analyte ions with a reactive gas, producing product ions with a different mass to charge ratio than the analyte ions which provides interference-free detection;    (iii) detecting and measuring a signal or combination of signals from a product phosphorus-containing ion and a signal or combination of signals from a second ion, wherein the second ion is specific to the sample and is one of an ion and a plurality of ions; and    (iv) computing one of the ratio and plurality of ratios, of the signal or combination of signals from the product phosphorus-containing ions to the signal or combination of signals from the second ions, to determine the degree of phosphorylation in the sample.    
     
     
         2 . The method of  claim 1  wherein the reactive collision cell is a Dynanic Reaction Cell™.  
     
     
         3 . The method of  claim 2  wherein the second ion or plurality of second ions are specific to the sample and are selected from the group consisting of non-phosphorus-containing analyte ions, non-phosphorus-containing product ions, and combinations thereof.  
     
     
         4 . The method of  claim 3  further comprising detecting and measuring a plurality of isotopes of the product phospborus-containing ion and the second ions and computing a plurality of ratios of product phosphorus-containing ions to second ions.  
     
     
         5 . The method of  claim 3  wherein the second ion is selected from the group consisting of sulfur-containing ions and sodium.  
     
     
         6 . The method of  claim 3  wherein the sample is selected from the group consisting of proteins, polypeptides, cells, cell lines, cell lysates nucleic acids, sugars, and mixtures thereof.  
     
     
         7 . The method of  claim 3  wherein the product ions are ions that have been oxidized.  
     
     
         8 . The method of  claim 7  wherein the reactive gas is selected from the group consisting of O 2 , N 2 O and CO 2 .  
     
     
         9 . The method of  claim 3  wherein the product ions are ions that have been fluorinated.  
     
     
         10 . The method of  claim 9  wherein the reactive gas is CH 3 F.  
     
     
         11 . The method of  claim 3  wherein the product ions contain an allyl group.  
     
     
         12 . The method of  claim 11  wherein the reactive gas is selected from the group consisting of CH 4 , C 2 H 4  and C 2 H 6 .  
     
     
         13 . The method of  claim 3  further comprising controlling the pressure and potentials on the field defining elements of the reactive collision cell.  
     
     
         14 . The method of  claim 3  further comprising controlling the axial field in the reactive collision cell such that it is accelerating.  
     
     
         15 . The method of  claim 3  further comprising controlling the axial field in the reactive collision cell such that it is decelerating.  
     
     
         16 . The method of  claim 3  wherein the step of sample introduction comprises laser ablation.  
     
     
         17 . The method of  claim 16  wherein the sample contains SDS denatured proteins and the second ion is Na + .  
     
     
         18 . A system that detects and measures the degree of phosphorylation in a sample, comprising: 
 (i) means for introducing the sample containing an analyte into an inductively coupled plasma mass spectrometer having a reactive collision cell, and producing analyte ions;    (ii) means for reacting the analyte ions with a reactive gas, producing product ions with a different mass to charge ratio than the analyte ions which provides interference-free detection;    (iii) means for detecting and measuring a signal or combination of signals from a product phosphorus-containing ion and a signal or combination of signals from a second ion, wherein the second ion is specific to the sample and is one of an ion and a plurality of ions; and    (iv) means for computing one of the ratio and plurality of ratios, of the signal or combination of signals from the product phosphorus-containing ions to the signal or, combination of signals from the second ions, to determine the degree of phosphorylation in the sample.    
     
     
         19 . Use of an inductively coupled mass spectrometer having a reactive collision cell for the detection and measurement of the degree of phosphorylation in a sample.  
     
     
         20 . The method of  claim 3  further comprising the step of tagging a biologically active material with an element, such that the biologically active material binds with the analyte in the sample.  
     
     
         21 . The method of  claim 3  further comprising the step of tagging the analyte with an element.