Method and device for solid phase microextraction and desorption

Abstract

A device for carrying out solid phase microextraction is a fiber contained in a syringe. The fiber can be solid or hollow. The syringe has a barrel and a plunger slidable within the barrel, the plunger having a handle extending from one end of the barrel. A hollow needle extends from an end of the barrel opposite to the plunger. The fiber is contained in the needle. When the plunger is depressed, the fiber extends beyond a free end of the needle and when the plunger is in a withdrawn position, the fiber is located within the needle. The syringe protects the fiber from damage. When it is desired to analyze a sample in a bottle having a septum, the needle is inserted through the septum and the plunger is depressed so that the fiber will extend into the sample. After one or two minutes, the plunger is moved to the withdrawn position so that the fiber will return to the needle and the syringe is withdrawn from the sample bottle. The syringe is then inserted through a septum in a gas injection port of a gas chromatograph. The plunger is again depressed so that the fiber will extend into the gas chromatograph and an analysis of the components on the fiber is carried out. Then, the plunger is moved to the withdrawn and the syringe is withdrawn from the injection port. Previously, samples were analyzed using liquid-liquid extraction or using cartridges. Both of these methods are relatively expensive and time consuming. Both of these methods also require the use of solvents which can be difficult and expensive to dispose of.

I claim:  
     
         1 . A device for carrying out solid phase microextraction of components contained in a fluid carrier including: 
 (a) a tubular member having an extracting phase coating on an inner surface thereof;    (b) a member supporting said tubular member at one end thereof for flow of carrier fluid through the tubular member in contact with the extracting phase coating when an opposite end of the tubular member is placed in contact with a fluid carrier, said support member having a passageway in communication with said one end of said tubular member for permitting the fluid carrier to pass into and out of said support member through said tubular member.    
     
     
         2 . A device as claimed in  claim 1  wherein said passageway is a pressure source associated with said support member for creating a pressure differential through said tubular member and said support member to force said fluid carrier through said tubular member.  
     
     
         3 . A device as claimed in any one of claims  1  or  2  wherein said tubular member is a hollow fiber.  
     
     
         4 . A device for carrying out solid phase microextraction of components contained in a fluid carrier including: a hollow needle for insertion through a septum; a surface disposed within the needle; an extracting phase coating on said surface; a member supporting said needle at one end thereof for flow of carrier fluid through the needle in contact with the extracting phase coating when an opposite end of the needle is passed through a septum and placed in engagement with a body of fluid carrier.  
     
     
         5 . A device as claimed in  claim 4  wherein said needle is part of a syringe having a barrel, a plunger and a needle, the plunger being movable inside the barrel and the needle being mounted at one end to the barrel and an opposite end being insertable through a septum into engagement with a body of fluid carrier;  
     
     
         6 . A device as claimed in any one of claims  4  or  5  wherein the extracting phase coating is located on a tubular member within the needle.  
     
     
         7 . A method of carrying out solid phase microextraction of components contained in a fluid carrier using a surface having an extracting phase coating thereon, said carrier containing at least two different analytes, a member supporting said surface having a passageway, said surface having a free end, said method comprising inserting an end of said surface into a fluid carrier to allow contact with the extracting phase coating for sufficient time to allow microextraction to occur between said fluid carrier and said coating, subsequently removing said surface from the fluid carrier and inserting said surface into an inlet of an analysis instrument, desorbing the components from the coating into the instrument and determining the concentrations of said at least two different analytes in said carrier from the amount of said at least two different analytes in said coating.  
     
     
         8 . A method as claimed in  claim 7  wherein said surface is placed in contact with the fluid carrier until the components of the carrier reach equilibrium with said extracting phase coating.  
     
     
         9 . A method as set forth in  claim 8  wherein the surface is located on one of an element, a longitudinal element, a tubular element, a capillary and a channel.  
     
     
         10 . A method as claimed in any one of claims  7  or  8  including the steps of determining the concentration of said two different analytes in said carrier from the volume of the coating and the distribution constant between the coating and the carrier for that particular analyte.  
     
     
         11 . A method as claimed in any one of claims  7  or  8  including the steps of determining the concentration of said two different analytes in said carrier from the concentration of the particular analytes in the coating and the distribution constant between the coating and the carrier for each of said two different analytes.  
     
     
         12 . A method as claimed in any one of claims  7  or  8  including the steps of determining the concentration of said two different analytes in said carrier from the concentration of said two different analytes in the coating and the distribution constant between the coating and the carrier for each of said two different analytes from the equation:  
       
         n 
         c 
         =KV 
         c 
         C 
         s  
         where n c  is the number of moles of said particular analyte in the coating;  
         K is the distribution constant of said particular analyte;  
         V c  is the volume of the coating; and  
         C s  is the concentration of said particular analyte in the sample.