Abstract:
An apparatus and method for determining a concentration of an additive in a mixture is provided. The apparatus for determining the concentration of an additive in a mixture comprises a distillation system, a filtration system, a detection system and a fluid transportation system. An alternative apparatus is a portable apparatus comprising a distillation system, a filtration system, a detection system and a fluid transportation system removably coupled to a portable container. A method for determining the concentration of the additive in the mixture includes concentrating the additive in the mixture, removing the additive from a fraction of the mixture and measuring a spectral signature of both the non-additive fraction of the mixture and the mixture. A spectral signature value of the non-additive fraction of the mixture to the mixture is determined and then compared to spectral signatures of a plurality of reference mixtures containing known concentrations of the additive.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to an apparatus and method for analyzing a mixture containing an additive, and more particularly, to a system for calculating the concentration of a fuel additive in a fuel using a differential spectroscopic analysis combined with a filtration step. 
     BACKGROUND OF THE INVENTION 
     Use of spectrometry for analysis of liquid mixtures, such as fuel, is known in the art. For example, U.S. Pat. No. 5,262,645 describes a method for measuring alcohol concentration in an alcohol/gasoline mixture by passing light through the mixture at a first wavelength that is strongly absorbed by the alcohol and weakly absorbed by the gasoline and at a second wavelength that is weakly absorbed by the alcohol and strongly absorbed by the gasoline. An absorbance ratio based upon absorbance measurements taken of the mixture at both wavelengths is computed. From this ratio and fuel temperature the concentration of alcohol in the fuel is determined. 
     There are two major difficulties associated with measuring additive concentrations in fuels using infrared (IR) spectroscopy. A fuel additive&#39;s spectral signature at its characteristic transmission peak can be extremely small. As a result, concentration of a fuel additive in a mixture can be at or below the detection threshold. Also, the background spectral variation of the fuel mixture is typically large compared to the spectral signature of the fuel additive, leading to interference in the spectral signature of the fuel additive. 
     SUMMARY 
     The present invention is directed to a method and apparatus for determining the concentration of an additive in a mixture. More particularly, the present invention is directed to a method and apparatus for determining the concentration of a fuel additive, such as a corrosion inhibitor, a static dissipater, an icing inhibitor, a thermal stability improver, an antioxidant, a metal deactivator, and/or an ignition improver, in a fuel mixture such as gasoline, diesel fuel and jet fuel. 
     According to one aspect of the invention, there is provided a method for calculating the concentration of an additive in a mixture, the method including removing the additive from a portion of the mixture to create a first sample of the mixture with an approximate concentration of zero for the additive. A plurality of reference mixtures is then selected with each reference mixture containing a known quantity of the additive. Each reference mixture is separated into a pair of reference samples with each pair of reference samples including a first reference sample and a second reference sample. Thereafter, the additive is removed from each of the first reference samples, and the absorption spectrum of the first sample, the mixture, each of the first reference samples and each of the second reference samples is measured. An absorption spectrum ratio for the first sample and the mixture is computed, as well as an absorption spectrum ratio for the first reference sample and the second reference sample for each pair of reference samples. The absorption spectrum ratio for the first sample and the mixture is compared to the absorption spectrum ratio for each pair of reference samples to calculate the concentration of additive in the mixture. Optionally, the concentration of the additive in the mixture can be increased prior to creating the first sample. This may be required if the concentration of the additive in the mixture is substantially small thereby requiring detection capabilities at lower concentration thresholds. 
     When analysis of the mixture in the field is desired, the steps of increasing the additive concentration, removing the additive from the mixture and measuring an absorption spectrum of the first sample and the mixture are carried out using an instrument that integrates an additive concentration device, an additive removal device, a transmission spectrometer and a fluid transport system. For portability purposes, such an instrument can be coupled to and housed within a readily portable, carrying case weighing under fifteen pounds. 
     According to another aspect of the invention, there is provided a method for calculating an additive concentration in a mixture, the method including directing a first sample of the mixture through a fluid transportation system to an additive removal device that removes the additive from the first sample, followed by directing the first sample from the additive removal device and through the fluid transportation system to a first beam of light transmitted by a transmission spectrometer. A second sample of the mixture is directed through the fluid transportation system to a second beam of light transmitted by the transmission spectrometer. The transmission spectra information for the first sample and the second sample is measured, followed by calculating a ratio based upon the transmission spectra information for the first sample and the second sample. The concentration of the additive in the mixture is then computed by comparing the ratio based upon the transmission spectra information for the first sample and the second sample to transmission spectra information of other mixtures containing known quantities of the additive. Optionally, the additive in the mixture is concentrated prior to removing the additive from the first sample and prior to directing the second sample through the fluid transportation system to the second beam of light. 
     According to yet another aspect of the invention, there is provided a method of calculating an additive concentration in a mixture, the method including measuring a first transmission spectrum of a first sample of the mixture, wherein the first sample excludes an additive, measuring a second transmission spectrum of a second sample of the mixture, wherein the second sample includes the additive, and calculating a spectrum transmission ratio based upon the first transmission spectrum and the second transmission spectrum. Thereafter, the spectrum transmission ratio is compared to a plurality of transmission spectrum ratios obtained from other mixtures containing known quantities of the additive. 
     The mixtures containing known quantities of the additive can be prepared in any number of ways know in the art. In many instances, these mixtures are prepared by obtaining a fraction of the mixture, removing essentially all of the additive from the fraction to form an additive-free mixture, separating the additive-free mixture into a plurality of samples, and adding varying, predetermined amounts of the additive to the plurality of samples. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic view of a system for measuring the concentration of an additive in a mixture. 
         FIG. 2  is a perspective view of a distillation apparatus for use in the system of  FIG. 1 . 
         FIG. 3  is a partial, perspective view of a top of the distillation apparatus of  FIG. 2 . 
         FIG. 4  is a perspective view of a filtration apparatus for use in the system of  FIG. 1 . 
         FIG. 5  is a top plan view of a detection apparatus for use in the system of  FIG. 1 . 
         FIG. 6  is a perspective view of a portable case for containing the system of  FIG. 1 . 
         FIG. 7  is a flowchart depicting a method for determining the concentration of an additive in a mixture. 
         FIG. 8  is a graph depicting the primary wavelength for detection of a corrosion inhibitor additive in a fuel mixture. 
     
    
    
     DETAILED DESCRIPTION 
     The present apparatus and method are used to determine the concentration of an additive in a mixture. The components of the apparatus act in concert to first concentrate the additive in the mixture, then remove the additive from a fraction of the mixture thereby creating a first sample without additive and a second sample with additive. Transmission spectra are then determined for the first and the second samples, which are used to compute a transmission spectra ratio. The transmission spectra ratio is then compared to transmission spectra of a plurality of reference mixtures with known amounts of additive in the reference mixtures to determine the concentration of the additive in the original mixture. 
       FIG. 1  depicts an overview of an apparatus  10  used to measure the concentration of an additive in a mixture. Apparatus  10  includes a distillation system  12 , a filtration system  14 , a detector system  16 , and a fluid transportation system for coupling systems  12 ,  14  and  16  to one another, all of the systems being in communication with a control unit  37  and an associated processing unit  39 . Control unit  37  and processing unit  39  allow a user to control and monitor the temperature of distillation system  12 , the flow rate of fluid through the fluid transportation system, the flow rate of air and all operations of apparatus  10 . The system further includes an air pump  22 , a peristaltic pump  11 , a waste receptacle  13 , an input for filtration system  14  and a pair of reservoirs  28  and  34 . 
     When the apparatus is in use, a mixture containing an additive is distilled after being injected into distillation system  12 . The concentrated mixture containing the additive is sent to an input  26  of the filtration system  14 , where it then enters a first reservoir  28 . Sample 1, a first fraction of the concentrated mixture, is sent from first reservoir  28  through filter  32  where the additive of sample 1 is removed by an additive-removing substrate located in the interior of filter  32 . After sample 1 is filtered, it is sent through a second reservoir  34  to detector system  16  where detector  83  measures the transmission spectra for sample 1. Sample 1 is then sent to waste receptacle  13 . Once sample 1 is moved out of detector system  16 , sample 2, a second fraction of the concentrated mixture, is sent from first reservoir  28  to second reservoir  34 , bypassing filter  32  and retaining the additive in sample 2. Sample 2 is then sent to detector system  16  and detector  83  measures the transmission spectra for sample 2. The transmission spectra of both sample 1 and sample 2 is transmitted from detector  83  to processing unit  39  which then calculates the transmission spectra ratio for sample 1 to sample 2. This transmission spectra ratio of sample 1 to sample 2 correlates to the concentration of the additive in the original mixture. 
     Use of distillation system  12  is required if the concentration of the additive in the mixture is at or below the detection threshold of detector system  16  or is so low as to be masked by background interference from the mixture. More particularly referring to FIGS.  1  and  2 , distillation system  12  includes a condensation chamber  15  in communication with a distillation chamber  38 . Distillation chamber  38  consists of three contiguous chambers: an upper chamber  46 , a conic transition chamber  48  and a lower chamber  50 . Upper chamber  46  and lower chamber  50  are cylindrical with upper chamber  46  having a larger diameter than lower chamber  50 . Conic transition chamber  48  connects upper  46  to lower chamber  50 . Opening  44  of lower chamber  50  is contiguous with an outlet, the outlet being coupled to a stopcock  54 . Stopcock  54  allows a user to start and/or stop liquid exiting lower chamber  50 . 
     For air flow into and out of distillation chamber  38 , air pump  22  moves air from a first tube  18   a  through a first switch valve  20   a  and a second tube  18   b  where second tube  18   b  is removably coupled to via a splitter  17 . Splitter  17  allows the air flow to be split from second tube  18   b  into two tubes, a third tube  18   c  and a fourth tube  18   d , each removably coupled to distillation chamber  38 . More particularly referring to  FIGS. 1 and 3 , third tube  18   c  is removably coupled to a first opening  56  located on a top side  42  of distillation chamber  38  allowing air flow into distillation chamber  38 . Fourth tube  18   d  is removably coupled an air bubbler that extends into the interior of distillation chamber  38  through a second opening  76 . A side port  64  located on a lateral side of a third opening  60  of top side  42  is removably coupled to condensation chamber  15 , providing an outlet for vapor to be moved from distillation chamber  38  to condensation chamber  15  via a tube  66 . 
     Referring to  FIG. 3 , third inlet  60  on top side  42  of distillation chamber  38  houses a detachable cartridge heater  62 . Detachable cartridge heater  62 , connected to a power source via a power cord  68 , raises the temperature of upper chamber  46  to a desired temperature range for distillation. The desired temperature range is chosen to be high enough to vaporize higher vapor pressure liquids but low enough to be below the vaporization temperature of the additive. To monitor the temperature of cartridge heater  62  either manually or via processing unit  39 , a first thermocouple is coupled with cartridge heater  62 . 
     Alternatively, cartridge heater  62  can be replaced by a plurality of heating coils  70  or other materials capable of raising the temperature of upper chamber  46 . For example, heating coils  70  can be removably affixed about the outer circumference of upper chamber  46 . In this embodiment, the first thermocouple is coupled to heating coils  70  to monitor temperature of heating coils  70 . 
     Third opening  60  on top side  42  of distillation chamber  38  also functions as a sample inlet. A syringe or other conventional method is temporarily coupled to third opening  60  to inject the mixture containing the additive into distillation chamber  38 . 
     A second thermocouple  74  is removably coupled to a fourth opening  72  of top side  42  of distillation chamber  38 . A user can monitor the temperature of the mixture containing the additive in upper chamber  46  of distillation chamber  38  via second thermocouple  74  and maintain the temperature of the mixture containing the additive within the desired temperature range. Processing unit communicates with cartridge heater  62  or alternate heating method in such a way as to be able to adjust the temperature of cartridge heater  62  or alternate heating method to remain in the desired temperature range. 
     Referring to  FIGS. 1 and 4 , distillation system  12  communicates with input  26  of filtration system  14 . Input  26  is removably coupled to first reservoir  28  at an inlet  41  by a fifth tube  18   e . An outlet  49  of first reservoir  28  is removably coupled to a first end  47  of filter  32 . Filter  32  is composed of a tube filled with a substrate chosen to target and remove an additive in a mixture. As those familiar in the art understand, complete removal of the additive from the mixture by filtration requires both a substrate that attracts and separates, thereby retaining, the additive, allowing an additive-free mixture to exit the filtering mechanism and sufficient time for the additive in the mixture to be exposed to the substrate. Time of exposure to the substrate is controlled by flow rate of the mixture containing the additive and the length of the filter  32 . A second end  49  of filter  32  is coupled to an inlet  51  of second reservoir  34 . An outlet  53  of second reservoir  34  is coupled to a first inlet  55  of third switch valve  20   c  by a sixth tube  18   f.    
     A second outlet  69  of first reservoir  28  is removably coupled to a second inlet  57  of third switch valve  20   c  by a seventh tube  18   g . An outlet  59  of third switch valve  20   c  is coupled to an inlet  61  of fourth switch valve  20   d  via an eighth tube  18   h.    
     A first opening  65  of fourth switch valve  20   d  is coupled to waste receptacle  13  via a ninth tube  18   i . Peristaltic pump  11  facilitates the movement of a waste product from detector system  16  through fourth switch valve  20   d  and then to waste receptacle  13 . 
     Referring to  FIGS. 4 and 5 , filtration system  14  is coupled to detector system  16  between a second opening  65  of fourth switch valve  20   d  and a cuvette  80  of detector system  16  via a tenth tube  183 . Referring more particularly to  FIG. 5 , detector system  16  comprises a light source  82 , a lens  84 , a moveable reference mirror  86 , a constant temperature cold plate  88 , cuvette  80 , a multi-position filter wheel  81  and a detector  83 . Detector system  16  measures a transmission or absorbance spectra for a sample by passing a first light beam from light source  82  through lens  84  and then through the sample in cuvette  80 . The first light beam is then focused onto multi-position filter wheel  81  and sent to detector  83  where detector  83  determines the transmission or absorption spectra of the sample. 
     To correct the transmission or absorption spectra of the sample for any background interference, detector system  16  adjusts reference mirror  86  so that reference mirror  86  reflects a second light beam to constant temperature cold plate  88 . Constant temperature cold plate  88  sends the second light beam to multi-position filter wheel  81  and detector  83 , where detector  83  measures a transmission or absorption spectra for the background where the second light beam carries no information of the sample. To determine a corrected transmission or absorption spectra for the sample, the transmission or absorption spectra for the sample is mathematically corrected with the transmission or absorption spectra for the background by any conventional method. 
     Referring to  FIG. 6 , a portable container  90  contains distillation system  12 , filtration system  14 , detection system  16  and all or part of the fluid transportation system. Portable container  90 , in a closed state, forms a hollow, approximately square or rectangular-shaped body. Portable container  90  is composed of a first hard shell  92  and a second hard shell  94 . First hard shell  92  has two end walls  96   a  and  b , two side walls  100   a  and  b  and a back wall  102 . Second hard shell  94  has two end walls  104   a  and  b , two side walls  106   a  and  b  and a back wall  108 . First  92  and second hard shell  94  are coupled in any conventional manner as to allow first  92  and second hard shell  94  to meet where end walls  98   a  and  b  of first hard shell  92  align with end walls  104   a  and  b  of second hard shell  94  and side walls  100   a  and  b  of first hard shell  92  align with side walls  106   a  and  b  of second hard shell  94  when portable container  90  is in the closed state. First  92  and second hard shell  94  can be composed of rigid plastic or any other conventional materials available. Portable container  90  can be secured in its closed position by at least one latch using any conventional manner in which to secure a container. 
     Within the open space of the interior of portable container  90 , the distillation system  12 , filtration system  14  and detector system  16  can be removably coupled to portable container  90 . Distillation system  12 , filtration system  14  and detector system  16  can be removably coupled to interior side of back wall  102  of first hard shell  92  either directly with any conventional means or indirectly by removably coupling each system  12 ,  14  and  16  to a body of material, such as a board, that is able to be placed inside portable container  90 . The body of material can then be removably coupled to the interior space of portable container  90  by epoxy, screws or other conventional means. The body of material can be composed of a at least one of a plurality of materials, including wood, plastic, acrylic or any conventional materials available now. 
     Distillation system  12  is removably coupled to the interior side of back wall  102  of first hard shell  92  where top side  42  of distillation chamber  38  is oriented toward end wall  98   a  of first hard shell  92  and condensation chamber  15  is adjacent to side wall  100   a . Filtration system  14  is removably coupled to the interior side of back wall  102  of first hard shell  92  whereby filtration system  14  is adjacent to distillation system  12 . Input  26  of filtration system  14  is adjacent to end wall  98   a  of first hard shell  92  and filter  32  is adjacent to side wall  100   b . Detector system  16  is removably coupled to interior back wall  108  of second hard shell  94 . 
     As illustrated in  FIG. 7 , a method for measuring a concentration of an additive in a mixture is executed as described below. 
     The mixture containing the additive is collected  112  and placed  114  in distillation chamber  38  by injecting the mixture containing the additive through third opening  60  on top side  42 . Cartridge heater  62  is removably coupled to third opening  60  then turned on and set at a level to bring the temperature of upper chamber  46  into a desired temperature range that vaporizes higher vapor pressure liquids but is low enough to not vaporize the additive  116 . Second thermocouple  74  is removably placed into fourth opening  72  of top side  42 . Second thermocouple  74  is turned on and set up to communicate with processing unit  39 , allowing a user to monitor the temperature in distillation chamber  38 . The first thermocouple removably coupled to cartridge heater  62  is turned on and set up to communicate with processing unit  39 , allowing the user to monitor the temperature of the cartridge heater  62 . 
     Air pump  22  is turned on, providing air flow into distillation chamber  38  and apparatus  10 . Air flow is pumped from air pump  22  into first opening  56  of top side  42  to the interior of distillation chamber  38 , thus facilitating temperature stabilization of distillation chamber  38  as well as forcing vapor containing vaporized higher vapor pressure liquids out of distillation chamber  38  and into condensation chamber  40 ,  118 . Air flow from air pump  22  is moved to fourth tube  18   d  removably coupled to an air bubbler that extends through second opening  76  and into the interior of distillation chamber  38 . The air flow flowing through the air bubbler agitates the mixture containing the additive in distillation chamber  38  during the time required to reach the desired concentration of the additive for distillation. The mixture containing the additive is distilled  116  for the period of time required to reach the desired concentration of the additive in the mixture. 
     At the conclusion of the time required to reach the desired concentration of the additive in the mixture  116 , cartridge heater  62  is turned off and the concentrated mixture containing the additive in distillation chamber  38  is allowed to cool. The stopcock  54  of distillation chamber  38  is opened and the concentrated mixture containing the additive is moved from distillation chamber  38  through open end  50 . The volume of the concentrated mixture containing the additive is determined  120 . 
     As stated above, air flow is started through apparatus  10  by air pump  22  prior to distillation or introducing a sample into filtration system  14 . The air flow moves  122  the concentrated mixture into input  26  of filtration system  14  from distillation system  12 . The concentrated mixture containing the additive in input  26  is then sent to first reservoir  28 . Sample 1, a fraction of the concentrated mixture containing the additive, is moved  124  from first reservoir  28  to filter  32 . Filter  32  removes the additive from sample 1 of the concentrated fuel mixture as it moves from first end  47  of filter  32 , through filter  32  and exiting second end  49  of filter  32 . Sample 1 is then sent to second reservoir  34 . 
     From second reservoir  34 , sample 1 is sent to detector system  16  via third switch valve  20   c  and fourth switch valve  20   d . Upon moving into detector system  16 , sample 1 is deposited into cuvette  80  of detector system  16 . A transmission spectra for sample 1 is made with reference mirror  86  in a position to allow a first light beam from a light source  82  to pass through cuvette  80  and sample 1. The first light beam is then focused on multi-position wheel  81  and sent to detector  83  where detector  83  measures the first transmission spectra for sample 1. A transmission spectra is determined for the background with reference mirror  86  in a position to cause a second light beam to hit reference mirror  86 , but not cuvette  80 . Reference mirror  86  reflects the second light beam to constant temperature cold plate  88 . The second light beam then is focused on multi-position filter wheel  81  and sent to detector  83  where detector  83  measures the transmission spectra for the background. The transmission spectra for sample 1 and the transmission spectra for the background are sent to processing unit  39  where processing unit  39  determines a transmission spectra for sample 1 correcting for the background  126 . 
     After the transmission spectra is determined for sample 1, sample 1 is sent from cuvette  80  to fourth switch valve  20   d  and then deposited in waste receptacle  13 . Sample 2, the remaining fraction of the concentrated fuel mixture in first reservoir  28 , is moved from first reservoir  28  to third switch valve  20   c . From third switch valve  20   c , sample 2 is sent to fourth switch valve  20   d  and then to cuvette  80  of detector system  16 , thereby bypassing filter  32  leaving the additive intact in sample 2, 128. 
     With sample 2 in cuvette  80 , a transmission spectra for sample 2 is made with reference mirror  86  in a position to allow a first light beam from a light source  82  to pass through cuvette  80  and sample 2, 130. The first light beam is then focused on multi-position wheel  81  and sent to detector  83  where detector  83  measures the transmission spectra for sample 2. A transmission spectra is determined for the background with reference mirror  86  in a position to cause a second light beam to hit reference mirror  86 , but not cuvette  80 . Reference mirror  86  reflects the second light beam to constant temperature cold plate  88 . The second light beam then is focused on multi-position filter wheel  81  and sent to detector  83  where detector  83  measures the transmission spectra for the background. The transmission spectra for sample 2 and the transmission spectra for the background are sent to processing unit  39  where processing unit  39  determines a transmission spectra for sample 2 correcting for the background. Sample 2 is then sent from cuvette  80  to fourth switch valve  20   d  and then to waste receptacle  13 . 
     A transmission spectra ratio for sample 1 to sample 2 is then determined  132 . A plurality of transmission spectra ratios for a plurality of reference mixtures with each reference mixture containing a known concentration of the additive are determined as with the above method. To calculate the concentration of the additive in the mixture, the transmission spectra ratio for sample 1 to sample 2 is mathematically compared to the plurality of transmission spectra ratios for the plurality of reference mixtures using a means such as partial least squares regression  134 . 
     A mathematical relationship between the transmission spectra of sample 1 and sample 2 can be determined  132  in ways other than a ratio, including, but not limited to, subtraction, weighted subtraction, mathematical modeling, parametric or nonparametric statistical analysis or with the use of any other mathematical or statistical tool. Additionally, the mathematical or statistical relationship between the plurality of transmission spectra for the plurality of reference mixtures with each reference mixture containing a known concentration of the additive can be determined in other ways, including, but not limited to, subtraction, weighted subtraction, mathematical modeling, parametric or nonparametric statistical analysis or with the use of any other mathematical or statistical tool. To compute the concentration of the additive in the mixture, the mathematical or statistical tool chosen to compute the mathematical relationship between the transmission spectra value for sample 1 and sample 2 must be used for calculation of the mathematical relationships for the plurality of transmission spectra for the plurality of reference mixtures. To calculate the concentration of the additive in the mixture, the transmission spectra relationship between sample 1 to sample 2 is then compared to the plurality of transmission spectra relationships for the plurality of reference mixtures using a mathematical or statistical means  134  (e.g. partial least squares regression). 
     The following Example is for illustrative purposes only and does not necessarily limit this invention. 
     EXAMPLE 
     The concentration of a corrosion inhibitor additive in a fuel mixture was determined for a plurality of fuel mixtures collected from at least one fuel distribution point. Cartridge heater  62  from third opening  60  of distillation chamber  38  was removed to place a fuel mixture containing the corrosion inhibitor additive in distillation chamber  38 . Using a syringe, 15 ml of the fuel mixture was injected into distillation chamber  38  aiming the syringe straight down so that the fuel mixture did not hit a sidewall of distillation chamber  38 . After injection, cartridge heater  62  was reinserted to third opening  60  of distillation chamber  38 . Once cartridge heater  62  was fully seated, creating a seal, care was taken so cartridge heater  62  was not in direct contact with second thermocouple  74 . 
     Air pump  22  was turned on to allow air flow to distillation chamber  38 . Second thermocouple  74  was placed into fourth opening  72  of top side  42  of distillation chamber. Second thermocouple  74  was turned on and set up to communicate with processing unit  39 . The first thermocouple removably coupled to cartridge heater  62  was turned on and set up to communicate with processing unit  39 . A first air flow controller associated with distillation system  12  was oriented to send air flow to an air bubbler removably coupled to second opening  76  of distillation chamber  38  so the air flow from the air bubbler mixed the fuel mixture during distillation. Airflow is sufficient for mixing if the bubble path is random, but does not continuously splash the fuel mixture onto interior top side  42  of distillation chamber  38 . A second airflow controller associated with distillation system  12  was oriented to send air flow into first opening  56  of distillation chamber  38  providing air movement in distillation chamber  38 , facilitating the movement of vaporized higher vapor pressure liquids out of distillation chamber  38  and into condensation chamber  40  while assisting in the stabilization of the temperature of distillation chamber  38 . 
     After air flow from air pump  22  began flowing into distillation chamber  38 , cartridge heater  62  was turned on. The first thermocouple removably coupled to cartridge heater  62  provided continuous measurements of cartridge heater&#39;s  62  temperature which was recorded and monitored by processing unit  39 . Processing unit  39  adjusted cartridge heater  62  to maintain a desired temperature range in distillation chamber  38 . 
     Second thermocouple  74  provided continuous measurements of the interior temperature of upper chamber  46  of distillation chamber  38  which was monitored and maintained between 180° C. and 190° C. by processing unit  39 . As this present Example entailed the distillation of a fuel mixture, for safety considerations, processing unit  39  was programmed to deactivate cartridge heater  62  if second thermocouple  74  reached a temperature reading for the interior of distillation chamber  38  exceeding 285° C. Once temperature stabilized between 180° C. and 190° C., distillation of the fuel mixture containing the corrosion inhibitor additive continued for approximately another 6 minutes. At approximately 6 minutes, cartridge heater  62  was turned off. The first air flow controller for the air bubbler coupled to distillation chamber  38  was oriented to stop air flow to the air bubbler. After distillation, approximately 3 ml of the now concentrated fuel mixture containing the corrosion inhibitor additive remained in lower chamber  50  of distillation chamber  38 . An exact volume of the concentrated fuel mixture containing the corrosion inhibitor additive was measured. 
     From distillation system  12 , the concentrated fuel mixture containing the corrosion inhibitor additive was sent to input  26  of filtration system  14 . The concentrated fuel mixture containing the corrosion inhibitor additive was then moved from input  26  and into first reservoir  28 . Processing unit  39  then directed sample 1, approximately 1.2 ml of the concentrated fuel mixture containing the corrosion inhibitor additive, from first reservoir  28  into filter  32 . Filter  32  was a tube approximately 18 to 24 inches in length and packed with a steel grit. The steel grit was chosen for this present Example as it targets and removes the corrosion inhibitor additive from the fuel mixture. The steel grit has a particle diameter averaging 300 microns and is composed of carbon, silicon, manganese and iron. 
     Sample 1 was sent through the steel grit of filter  32  into second reservoir  34 . Once sample 1 exited filter  32 , the air flow was stopped as air pump  22  was turned off by processing unit  39 . Action from peristaltic pump  11  sent sample 1 from second reservoir  34  to third switch valve  20   c  then to fourth switch valve  20   d  and then to cuvette  80  of detector system  16 . 
     For this present Example, we used a 10-position filter wheel in the detector system  16 . For detection of the corrosion inhibitor additive in the concentrated fuel mixture, the primary wavelength was 5.84 μm as seen in  FIG. 8  and was one position on the 10-position filter wheel. The remaining wavelengths on the 10-position filter wheel were chosen to characterize the signals from a plurality of chemicals or compounds in the concentrated fuel mixture that might interfere with the determination of the transmission spectra of the corrosion inhibitor additive at its primary wavelength. This characterization allowed for correction of possible interference by the plurality of chemicals or compounds in the concentrated fuel mixture at the primary wavelength of 5.84 μm. 
     Once sample 1 was deposited into cuvette  80 , a first light beam transmitted by light source  82  moved through lens  84  and then through cuvette  80 . The first light beam then moved to the spinning 10-position filter wheel and then to detector  83 . The detector  83  determined the transmission spectra for sample 1. 
     Upon completion of the transmission spectra for sample 1, reference mirror  86  slid into position while the 10-position filter wheel stopped spinning. After approximately a half-second pause, the 10-position filter wheel began spinning again. A second light beam from light source  82  was reflected by reference mirror  86  to constant temperature cold plate  88 , thus bypassing cuvette  80 . From constant temperature cold plate  88 , the second light beam focused on the 10-position filter wheel and was sent to detector  83 , where detector  83  determined the transmission spectra for the background. Detector  83  sent the transmission spectra for sample 1 and the transmission spectra for the background to processing unit  39 . Processing unit  39  computed a corrected transmission spectra for sample 1 correcting for the background. Sample 1 was moved from cuvette  80  to waste receptacle  13 . 
     After sample 1 was deposited in waste receptacle  13 , processing unit  39  directed sample 2, approximately 0.8 ml of the concentrated fuel mixture, from first reservoir  28  directly to third switch valve  20   c , bypassing filter  32 . Sample 2 then moved from third switch valve  20   c  to fourth switch valve  20   d  and then was deposited into cuvette  80 . Once sample 2 was deposited in cuvette  80 , the transmission spectra for sample 2 and for the background was determined in the same manner as above for sample 1. A corrected transmission spectra for sample 2 correcting for the background was then computed. 
     A corrected transmission spectra ratio for sample 1 to sample 2 was computed and stored by processing unit  39 . The corrected transmission spectra ratio for sample 1 to sample 2 was then compared to a plurality of corrected transmission spectra ratios for a plurality of reference mixtures containing a range of known concentrations of the corrosion inhibitor additive. In this present Example, partial least squares regression was used to determine the concentration of the corrosion inhibitor additive in the fuel mixture by relating the corrected transmission spectra ratio for sample 1 to sample 2 to the plurality of corrected transmission spectra ratios for a plurality of reference samples containing a range of known concentrations of the corrosion inhibitor additive. 
     As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.