Multi-measurement flow cell assembly for liquid chromatography

Abstract

A detector for detecting constituents of a liquid for use in liquid chromatography is disclosed. The detector includes a first optical flow cell body and a second optical flow cell body, each having a channel therethrough that allows passage of a liquid from an inlet port to an outlet port. The first and second optical flow cell bodies are arranged in series such that the liquid exiting the outlet port of the first optical flow cell body enters the inlet port of the second optical flow cell body. An insulator resides between the first optical flow cell body and the second optical flow cell body, which is adapted to electrically insulate the first optical flow cell body from the second optical flow cell body while allowing the liquid to pass from the first optical flow cell body to the second optical flow cell body. The first optical flow cell body is adapted to facilitate measurement of absorption by the liquid of a first wavelength of light, and second optical flow cell body is adapted to facilitate measurement of absorption by the liquid of a second wavelength of light. The first and second optical flow cell bodies are further adapted to perform as electrodes for measuring the conductivity of the liquid.

What is claimed is: 
     
         1 . An LED light source for use with a photodetector, comprising:
 two or more LED lights in close enough proximity such that they produce essentially coaxial beams of light that diverge by no more than 5 degrees; and   a light pulsing controller configured to pulse the beams of LED light, wherein the light pulses occur with cycle times between 0.1 and 500 milliseconds, and with the light pulses occurring over less than about 50% of the cycle.   
     
     
         2 . The LED light source of  claim 1 , wherein the light pulsing controller comprises software for controlling the timing and duration of the pulses of light, and the timing and duration of the cycles. 
     
     
         3 . The LED light source of  claim 1 , wherein the light pulsing controller is configured to pulse the beams of LED light, with the light pulses occurring over less than about 25% of the cycle. 
     
     
         4 . The LED light source of  claim 1 , wherein the light pulsing controller is configured to pulse the beams of LED light, with the light pulses occurring over less than about 10% of the cycle. 
     
     
         5 . The LED light source of  claim 1 , operatively arranged with a photodetector to detect constituents of liquid for use in liquid chromatography. 
     
     
         6 . The LED light source of  claim 1 , operatively arranged with a photodetector that is synchronously gated to coincide with the pulses of light. 
     
     
         7 . A system comprising the LED light source of  claim 1 , a flow cell, and a photodetector, wherein the photodetector is synchronously gated to coincide with the pulses of light. 
     
     
         8 . The system of  claim 7 , wherein the photodetector is arranged to receive light passed through the flow cell from the LED light source. 
     
     
         9 . The system of  claim 7 , further comprising a liquid chromatography column arranged to supply an eluent to the flow cell. 
     
     
         10 . The system of  claim 7 , wherein the flow cell comprises a tube comprising two or more spirals, or angled holes, or spiral-forming structures. 
     
     
         11 . A method for transmitting LED light through a flow cell and on to a photodetector, comprising pulsing one or more beams of LED light through a flow cell and on to a photodetector, wherein the light pulses occur with cycle times between 0.1 and 500 milliseconds, and with light pulses occurring over less than about 50% of the cycle. 
     
     
         12 . The method of  claim 11 , wherein the light pulses occur over less than about 25% of the cycle. 
     
     
         13 . The method of  claim 11 , wherein the light pulses occur over less than about 10% of the cycle. 
     
     
         14 . The method of  claim 11 , wherein the duration of the cycles and the duration of the light pulses is controlled using software. 
     
     
         15 . The method of  claim 11 , wherein the method comprising passing two or more beams of LED light through the flow cell to the photodetector, and wherein the pulses for each light beam are fixed so as to minimize any interference between them, and so that both pulses occur within a single cycle. 
     
     
         16 . The method of  claim 11 , wherein the photodetector is synchronously gated with the pulses of light. 
     
     
         17 . The method of  claim 15 , wherein the photodetector is synchronously gated with the pulses of light. 
     
     
         18 . The method of  claim 11 , wherein the method is conducted in a liquid chromatography process. 
     
     
         19 . The method of  claim 15 , wherein the two or more beams of LED light are in close enough proximity so that they produce essentially coaxial beams of light that diverge by no more than 5 degrees 
     
     
         20 . A flow cell comprising a tube comprising two or more spirals, or angled holes, or spiral-forming structures.