Method for calibrating mass spectrometers with trityl mass-tags

Abstract

The subject invention relates to processes of measuring molecular mass by mass spectrometry, in particular to methods of precise calibration of mass spectrometeres, and to kits and systems for use in calibrating mass spectrometeres.

We claim:  
     
         1 . A method of measuring the molecular mass of a compound Y of unknown molecular mass by mass spectrometry, comprising 
 providing a sample of compound Y,    providing samples of at least two different compounds each of Formula (I), R—X in which R is a trityl group and X is cleavable to form a charged species for mass spectrometry,    and recording the molecular mass of compound Y and the at least two compounds of Formula (I) in a mass spectrometer.    
     
     
         2 . The method, according to  claim 1 , in which R is R 1 R 2 R 3 C— wherein R 1 , R 2  and R 3  are the same or different and each is a monocyclic or fused ring aromatic group that is substituted or unsubstituted.  
     
     
         3 . The method, according to  claim 2 , in which at least one of R 1 , R 2  and R 3  carries a substituent selected from the group consisting of substituted or unsubstituted C 1 -C 20  alkoxy and hydrocarbyl.  
     
     
         4 . The method, according to  claim 3 , in which the alkoxy or hydrocarbyl is substituted by a substituent selected from the group consisting of carboxylic acid, sulphonic acid, nitro, cyano, hydroxyl, thiol, primary, secondary or tertiary amino, primary or secondary amido, anhydride, carbonyl halide and active ester.  
     
     
         5 . The method, according to any of  claim 2 , in which each of R 1 , R 2  and R 3  is aryl.  
     
     
         6 . The method, according to  claim 5 , wherein said al is phenyl.  
     
     
         7 . The method, according to  claim 1 , in which the trityl group R has at least two amide substituents.  
     
     
         8 . The method, according to  claim 7 , wherein said trityl group R has at least four amide substituents.  
     
     
         9 . The method, according  claim 2 , in which R 1 , R 2  and R 3  together carry at least two amide groups and/or at least two reactive groups for coupling.  
     
     
         10 . The method, according to  claim 9 , wherein said groups are N-hydroxy succinimide ester groups.  
     
     
         11 . The method, according to  claim 1 , in which X is halide or tosylate.  
     
     
         12 . The method, according to  claim 1 , comprising providing at least five compounds of Formula (I) and recording their molecular masses in a mass spectrometer.  
     
     
         13 . The method, according  claim 1 , in which the group X is photocleavable to form a charged species for mass spectrometry.  
     
     
         14 . The method, according to  claim 1 , additionally comprising estimating the molecular mass of unknown compound Y as M y  and providing at least one compound of Formula (I) which has known molecular mass M 1  below My and at least one different compound of Formula (I) which has molecular mass M 2  above My.  
     
     
         15 . The method, according to  claim 14 , wherein the difference between My and each of M 1  and M 2  is not more than ±50%.  
     
     
         16 . The method, according to  claim 1 , additionally comprising providing a sample of at least one further compound Z of unknown molecular mass and measuring the molecular mass of compound Z.  
     
     
         17 . Use of a compound of Formula (I) R—X in which R is a trityl group and X is cleavable to form a charged species for mass spectrometry as a calibration compound for mass spectrometry.  
     
     
         18 . A kit for the production of calibration compounds for mass spectrometry comprising: 
 (a) at least one base reactant of Formula (I) R—X where R is a trityl group and X is cleavable to form a charged species for mass spectrometry; and    (b) at least two different amine compounds which are of different molecular masses and which are each capable of reacting with the base reactant;    wherein the base reactant (a) is packaged separately from amine compounds (b).    
     
     
         19 . The kit, according to  claim 18 , additionally comprising instructions to select at least two desired molecular masses M 1  and M 2  for the calibration compounds and to choose one or more amines for reaction with the base reactant so as to obtain compounds of the desired predetermined molecular masses M 1  and M 2 , and instructions to use the compounds in mass spectrometry.  
     
     
         20 . A set of calibration compounds for mass spectrometry comprising at least two separately packaged mixtures (a) and (b), wherein 
 mixture (a) comprises at least two different compounds each of formula (I) R—X and having different molecular masses, and    mixture (b) comprises at least two further compounds of formula (I) R—X having different molecular masses and wherein R is a trityl group and X is cleavable to form a charged species for mass spectrometry.    
     
     
         21 . The set, according to  claim 20 , in which the lowest molecular mass in mixture (a) is lower than the lowest molecular mass in mixture (b) and the highest molecular mass in mixture (a) is lower than the highest molecular mass in mixture (b).  
     
     
         22 . The set, according to  claim 20 , in which each of mixtures (a) and (b) contains at least five different compounds of different molecular masses.  
     
     
         23 . The set, according to  claim 22 , in which each of mixtures (a) and (b) contains at least 10 different compounds of different molecular masses.  
     
     
         24 . The set, according to  claim 20 , comprising at least three separately packaged mixtures of compounds.  
     
     
         25 . The set, according to  claim 24 , comprising at least five separately packaged mixtures of compounds.  
     
     
         26 . A kit for the production of a set of calibration compounds comprising a first package comprising a base reactant of Formula (I) R—X, in which R is a trityl group and X is cleavable to form a charged species for mass spectrometry, and at least two separate second packages (a) and (b), each containing a mixture of at least two amine compounds which have different molecular masses and which are capable of reacting with the base reactant.  
     
     
         27 . The kit, according to  claim 26 , in which the lowest molecular mass in mixture (a) is lower than the lowest molecular mass in mixture (b) and the highest molecular mass in mixture (a) is lower than the highest molecular mass in mixture (b).  
     
     
         28 . The kit, according to  claim 26 , in which each of mixtures (a) and (b) contain at least five different amine compounds of different molecular masses.  
     
     
         29 . The kit, according to  claim 28 , wherein each of mixtures (a) and (b) contain at least ten different amine compounds of molecular masses.  
     
     
         30 . The kit, according to  claim 26 , comprising at least three mixtures of amine compounds.  
     
     
         31 . The kit, according to  claim 30 , comprising at least five mixtures of amine compounds.  
     
     
         32 . A method of measuring the molecular mass of a compound Y of unknown molecular mass comprising 
 estimating the expected molecular mass of compound Y, selecting at least one calibration compound of Formula (I) R—X having molecular weight close to the expected molecular weight of the compound Y, in which R is a trityl group and X is cleavable to form a charged species for mass spectrometry    and subjecting both compounds to mass spectrometry simultaneously.    
     
     
         33 . The method, according to  claim 32 , in which the calibration compound R—X is provided by selecting a base reactant R—X and selecting an amine reactant of appropriate molecular mass and reacting the amine reactant and the base reactant.  
     
     
         34 . A mixture of at least two compounds of Formula (I) R—X in which R is a trityl group and X is a group cleavable to give a charged species for analysis by mass spectrometry.  
     
     
         35 . The mixture, according to  claim 34 , comprising at least five different compounds of Formula (I).  
     
     
         36 . The mixture, according to  claim 35 , comprising at least ten different compounds of Formula (I).  
     
     
         37 . A method of mass spectrometry comprising subjecting simultaneously to mass spectrometry at least two different compounds of Formula (I) R—X in which R is a trityl group and X is cleavable to give a charged species for analysis by mass spectrometry.