Apparatus and method for ion mobility spectrometry and sample introduction

Abstract

The IMS apparatus and methods described in this invention involve setting the ion detector at the highest potential of the drift tube and setting the ionization source at ground or near ground potential. The methods allow significantly simple sample introduction without the limitation of the high potential (voltage) concern of the front end sample delivery. The invention also describes bringing samples directly into the ion mobility drift tube. The invention further describes using single syringe for sample introduction via an electrospray ionization method. In addition, automation of the direct spray needle can be achieved by setting up array of the spray needles that are loaded in a manner that rotates and/or moves to the next spray needle in the ESI source region.

What is claimed is: 
     
         1 . An auto injector apparatus comprising:
 a) an electrospray needle that introduces a sample into an analytical instrument, where the sample is ionized via electrospray ionization process; the electrospray needle is part of a syringe that contains the sample;   b) a pump that pushes on the syringe, causing the sample to reach the electrospray needle;   c) a mechanism that automatically switches among multiple electrospray needles with syringes.   
     
     
         2 . The auto injector apparatus of  claim 1 , wherein the mechanism involves moving one electrospray needle to the next electrospray needle; 
     
     
         3 . The auto injector apparatus of  claim 1 , wherein the mechanism involves rotating the electrospray needles. 
     
     
         4 . The auto injector apparatus of  claim 1 , where the needle is a reusable electrospray needle. 
     
     
         5 . The auto injector apparatus of  claim 1 , where the electrospray needle is a disposable electrospray needle. 
     
     
         6 . The auto injector apparatus of  claim 1 , further comprise packed material in the electrospray needle. 
     
     
         7 . The auto injector apparatus of  claim 6 , wherein the packed material is to aid in desalting, sample cleanup or separation of the sample compounds. 
     
     
         8 . The auto injector apparatus of  claim 1 , wherein the analytical instrument is an ion mobility spectrometer. 
     
     
         9 . The auto injector apparatus of  claim 8 , wherein the ion mobility spectrometer comprises:
 a) the electrospray needle is placed in front of a negative flow curtain gas section;   b) the negative flow curtain gas section bringing the charged particles or ions into a desolvation region is located between the electrospray needle and the desolvation region, wherein the negative flow curtain gas section has a first opening to the electrospray needle allowing charged particles or ions to enter, a second opening to the desolvation region, and a third opening where gas flows are exhausted;   c) an ion gate that is located between the desolvation region and a drift region of the spectrometer; and   d) gas flow around the electrospray needle flows through the first opening into the negative flow curtain gas section; a high temperature desolvation gas flows from the desolvation region through the second opening into the negative flow curtain gas section; and both gas flows are exhausted through the third opening.   
     
     
         10 . The auto injector apparatus of  claim 9 , wherein
 a) an ion detector of the ion mobility spectrometer is set at a high potential of the spectrometer by connecting to a high voltage power supply; and   b) the electrospray needle is set at a low potential of the spectrometer.   
     
     
         11 . The auto injector apparatus of  claim 10 , wherein the high potential is either positive or negative potential. 
     
     
         12 . The auto injector apparatus of  claim 9 , further comprises a sample inlet where a gas sample is introduced, and then ionized via a secondary electrospray ionization process. 
     
     
         13 . The auto injector apparatus of  claim 10 , wherein the low potential is the lowest potential for the spectrometer at ground or near ground potential. 
     
     
         14 . The auto injector apparatus of  claim 1 , wherein the electrospray needle is used both for sampling and as the spray needle. 
     
     
         15 . The auto injector apparatus of  claim 9 , where the curtain gas section further includes a first plate and a second plate, each of which has an opening in the center, and wherein the plates are set at different potentials that guide ions entering the first plate toward the second plate. 
     
     
         16 . The auto injector apparatus of  claim 9 , wherein the third opening is used as a gas inlet at a different time period for a cooling gas flow, and both the cooling gas flow and the high temperature desolvation gas that flows from the desolvation region through the second opening into the curtain gas section are exhausted from the first opening to the electrospray needle. 
     
     
         17 . An auto injector method comprising:
 a) Introducing a sample into an analytical instrument using an electrospray needle, where the sample is ionized via electrospray ionization process; the electrospray needle is part of a syringe that contains the sample;   b) Pushing on the syringe using a pump, causing the sample to reach the electrospray needle;   c) Automatically switching among multiple electrospray needles with syringes.   
     
     
         18 . The auto injector method of  claim 17 , wherein the automatically switching of the electrospray needles with syringes involves moving one electrospray needle to the next electrospray needle. 
     
     
         19 . The auto injector method of  claim 17 , wherein the automatically switching of the electrospray needles with syringes involves rotating the electrospray needles. 
     
     
         20 . The auto injector method of  claim 17 , further comprise desalting, cleaning up or separating sample compounds in a packed material in the electrospray needle.