Interactive Variable Pathlength Device

Abstract

This disclosure relates generally to a sampling device, and more particularly, a sampling device that facilitates spectroscopic measurements with a variable path length and the necessary software controlled algorithms and methods for such a device.

We claim: 
     
         1 . A method of determining the concentration of a sample comprising:
 (a) placing the sample in a vessel;   (b) placing a probe within sample;   (c) taking an absorbance reading;   (d) moving the probe relative to the vessel by a predetermined increment taking an absorbance reading at a predetermined wavelength;   (e) repeating step (d) one or more times;   (f) generating a regression line from the absorbance values such that a slope of the regression line is obtained; and   (g) determining the concentration of the sample by dividing the slope of the regression line by the extinction coefficient of the sample.   
     
     
         2 . A method of determining the concentration of a sample comprising:
 (a) placing the sample in a vessel;   (b) moving a probe relative to the vessel such that the probe makes contact with the bottom of the vessel   (c) moving the probe relative to the vessel such that the probe moves from the bottom of the vessel through the sample by a predetermined increment such that a preselected path length through the solution is obtained;   (d) taking an absorbance reading at a predetermined wavelength;   (e) repeating steps (c) and (d) sequentially one or more times;   (f) generating a regression line from the absorbance and path length such that a slope of the regression line is obtained; and   (g) determining the concentration of the sample by dividing the slope of the regression line by the extinction coefficient of the sample.   
     
     
         3 . The method of  claim 1  wherein the predetermine increment is the same for each iteration. 
     
     
         4 . The method of  claim 1  wherein the predetermined increment is from about 0.005 mm to about 50 mm. 
     
     
         5 . The method of  claim 1  wherein the predetermined increment is from about 0.0002 mm to about 10 mm. 
     
     
         6 . The method of  claim 2  wherein the predetermine increment is the same for each iteration. 
     
     
         7 . The method of  claim 2  wherein the predetermined increment is from about 0.005 mm to about 50 mm. 
     
     
         8 . The method of  claim 2  wherein the predetermined increment is from about 0.0002 mm to about 10 mm. 
     
     
         9 . The method of  claim 1  wherein the regression line has an R 2  value of from around 0.99950 to about 0.99999. 
     
     
         10 . The method of  claim 2  wherein the regression line has an R 2  value of from around 0.99950 to about 0.9999. 
     
     
         11 . The method of  claim 1  wherein the regression line has an R 2  value of from around 0.99990 to about 0.99999. 
     
     
         12 . The method of  claim 2  wherein the regression line has an R 2  value of from around 0.99990 to about 0.99999. 
     
     
         13 . A method of determining the extinction coefficient of a sample at a wavelength where the extinction coefficient is not known comprising:
 (a) placing the sample in a vessel;   (b) placing a probe within the sample;   (c) taking an absorbance reading at a first predetermined wavelength where the extinction coefficient is known and a second predetermined wavelength where the extinction coefficient is not known;   (d) repeating step (c) one or more times to determine the ratio of the absorbance to the path length at the first wavelength and the second wavelength;   (e) calculate the extinction coefficient at the second wavelength from the ratios of the absorbance to path length at both wavelengths and the extinction coefficient for the first wavelength.   
     
     
         14 . An instrument for determine the concentration of a sample at multiple path lengths comprising:
 (a) a light source operably linked to a probe   (b) a sample vessel that can contain the sample;   (c) a motor operably linked to the sample vessel such that the sample vessel can be moved relative to the probe to provide variable path lengths;   (d) a probe that can carry electromagnetic radiation that can be moved relative to the sample vessel by the motor;   (e) a universal sliding mechanism;   (f) a detector that can detect electromagnetic radiation disposed such that the detector is substantially perpendicular to the electromagnetic radiation emanating from the probe; and   (g) software for calculating the concentration of the sample based on the information provided by the detector at the predetermined path lengths.   
     
     
         15 . The instrument of  claim 14 , wherein the universal sliding mechanism is passively locked. 
     
     
         16 . The instrument of  claim 14 , wherein the universal sliding mechanism is actively locked by a user. 
     
     
         17 . The instrument of  claim 14 , wherein the universal sliding mechanism is operably linked to the probe. 
     
     
         18 . The instrument of  claim 14 , wherein the universal sliding mechanism is operably linked to the sample vessel. 
     
     
         19 . The instrument of  claim 14 , wherein the path lengths are between about 0.2 μm to about 1.0 mm 
     
     
         20 . The instrument of  claim 14 , wherein the path lengths are between about 0.2 μm to about 1.0 μm 
     
     
         21 . The instrument of  claim 14 , wherein the motor is operably linked to the sample vessel though a sample vessel stage. 
     
     
         22 . The instrument of  claim 14 , wherein the motor is computer controlled. 
     
     
         23 . The instrument of  claim 14 , wherein the software can calculate the concentration based on deriving the slope of a line based on the ratio of path length to absorbance values. 
     
     
         24 . The instrument of  claim 23 , wherein the slope of the line is derived while the values are being measured.