Abstract:
A measuring method including the steps of providing a chamber, drawing a vacuum in the chamber, placing a sample into the chamber, heating the sample to desorb a target species from the sample, passing a carrier gas through the chamber, the carrier gas mixing with the desorbed target species to form a mixture, and analyzing the mixture.

Description:
FIELD 
     This application relates to the measurement of the content of a particular species in a sample and, more particularly, to the measurement of hydrogen content in high-strength structural materials, such as high-strength steels and titanium alloys, for the evaluation of hydrogen embrittlement potential. 
     BACKGROUND 
     Structural aircraft components, such as landing gear, are subjected to significant stresses while in use. Therefore, structural aircraft components are typically constructed from high-strength structural materials, such as high-strength steels and titanium alloys. To inhibit environmental corrosion, high-strength steels are typically plated with a corrosion-resistant coating. Typical corrosion-resistant coatings include titanium-cadmium coatings and zinc-nickel coatings. 
     It has long been known that hydrogen diffuses through high-strength structural materials, thereby resulting in hydrogen embrittlement (i.e., the hydrogen-induced reduction in ductility that renders materials relatively more brittle than materials that have not been exposed to hydrogen). The process of plating high-strength structural materials with corrosion-resistant coatings has been known to significantly contribute to hydrogen embrittlement due to the evolution of hydrogen that occurs at the plating cathode. 
     Thus, prior to being deployed, high-strength structural materials are typically evaluated for hydrogen embrittlement. For example, ASTM F326 is a standard test method for the electronic measurement of hydrogen embrittlement potential resulting from cadmium electroplating processes. However, the ASTM F326 standard test method is not suitable for measuring hydrogen embrittlement potential resulting from zinc-nickel electroplating processes. As another example, ASTM F519 is a standard test method for the mechanical measurement of hydrogen embrittlement potential resulting from various electroplating processes. However, the ASTM F519 standard test method requires over 200 hours and, therefore, significantly increases overall production time. 
     Accordingly, those skilled in the art continue with research and development efforts in the field of hydrogen detection. 
     SUMMARY 
     In one embodiment, the disclosed measuring method may include the steps of (1) providing a chamber, (2) drawing a vacuum in the chamber, (3) placing a sample into the chamber, (4) heating the sample to desorb a target species from the sample, (5) passing a carrier gas through the chamber, the carrier gas mixing with the desorbed target species to form a mixture, and (6) analyzing the mixture. 
     In another embodiment, the disclosed measuring method may include the steps of (1) providing a chamber, (2) drawing a vacuum in the chamber, (3) placing a sample into the chamber, (4) heating the sample to desorb hydrogen from the sample, (5) passing a carrier gas through the chamber, the carrier gas mixing with the hydrogen to form a mixture, and (6) analyzing the mixture. 
     In another embodiment, the disclosed measuring system may include (1) a thermal desorption chamber, (2) a vacuum pump in selective fluid communication with the thermal desorption chamber, (3) a heating element received in the thermal desorption chamber, (4) a carrier gas source in selective fluid communication with the thermal desorption chamber, and (5) a detector in selective fluid communication with the thermal desorption chamber. 
     In yet another embodiment, the disclosed measuring system may include (1) a thermal desorption chamber, (2) a vacuum pump in selective fluid communication with the thermal desorption chamber, the vacuum pump being configured to draw a vacuum in the thermal desorption chamber, (3) a heating element received in the thermal desorption chamber, the heating element being configured to heat a sample housed in the thermal desorption chamber to desorb hydrogen from the sample, (4) a detector in selective fluid communication with the thermal desorption chamber, and (5) a carrier gas source in selective fluid communication with the thermal desorption chamber to carry the desorbed hydrogen to the detector. 
     Other embodiments of the disclosed system and method for detecting hydrogen content in a sample (or the content of other target species in a sample) will become apparent from the following detailed description, the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram depicting one embodiment of the disclosed system for detecting hydrogen content in a sample; 
         FIG. 2  is a flow chart depicting one embodiment of the disclosed method for detecting hydrogen content in a sample; and 
         FIG. 3  is a schematic diagram depicting an alternative embodiment of the disclosed system for detecting hydrogen content in a sample. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed are systems and methods for detecting the hydrogen content of a sample. The sample may be a sample of a structural material, such as high-strength steel or a titanium alloy. Optionally, the sample may have been chemically treated or plated with a corrosion-resistant coating material, such as a titanium-cadmium coating or a zinc-nickel coating, using, for example, an electroplating process. Therefore, it may be desirable to know the amount of hydrogen, such as diffusible hydrogen, within the sample and, thus, the hydrogen embrittlement potential of the sample. 
     While reference is made herein to the detection of hydrogen content in a sample, it is also contemplated that the disclosed systems and methods may be used to detect the presence and/or the concentration of other species within a sample. Furthermore, while reference is made herein to hydrogen embrittlement potential, the disclosed systems and methods may be used to detect the content of hydrogen (or other species) for a variety of reasons, not just for determining hydrogen embrittlement potential. 
     Referring to  FIG. 1 , one embodiment of the disclosed system for detecting hydrogen content in a sample, generally designated  10 , may include a thermal desorption chamber  12 , a sample introduction chamber  14 , a detector  16 , a first vacuum pump  18 , a second vacuum pump  20  and a carrier gas source  22 . An optional processor  24  may also be provided to operate the system  10 , monitor temperature and pressure, and receive and process data from the detector  16 . 
     Thus, a sample may be introduced to the thermal desorption chamber  12 , such as by way of the sample introduction chamber  14 , such that the sample may be heated to desorb hydrogen from the sample. The carrier gas source  22  may supply a carrier gas to the thermal desorption chamber  12  to carry the desorbed hydrogen to the detector  16  where the desorbed hydrogen may be measured. Background hydrogen, which may compromise the measurements taken at the detector  16 , may be minimized by evacuating the thermal desorption chamber  12  and the sample introduction chamber  14  using the pumps  18 ,  20  prior to introducing the sample to the thermal desorption chamber  12 . 
     The thermal desorption chamber  12  may be a rigid, heat-resistant enclosure capable of maintaining a vacuum (i.e., substantially gas-tight). For example, the thermal desorption chamber  12  may be a vessel constructed to withstand internal pressures of 10 −8  Torr or lower. However, thermal desorption chambers  12  configured to operate at higher pressures (e.g., 10 −7  Torr, 10 −6  Torr, 10 −5  Torr, 10 −4  Torr, 10 −3  Torr, 10 −2  Torr or higher) may be used without departing from the scope of the present disclosure. 
     The size of the thermal desorption chamber  12  may be dictated by, among other things, the maximum sample size intended to be evaluated using the disclosed system  10 . For example, the thermal desorption chamber  12  may be sufficiently large to receive the same sample required for the ASTM F519 test method. Therefore, using the same samples, correlations may be made between the results of the ASTM F519 test method and the measurements obtained using the disclosed system  10 . 
     The thermal desorption chamber  12  may be constructed from a heat-resistant and substantially rigid material that is capable of withstanding vacuum pressures. Examples of suitable materials for constructing the thermal desorption chamber  12  include metals, such as steel (e.g., mild or stainless), brass and aluminum, and non-metals, such as ceramic materials, composite materials and polymeric materials. 
     It is noted that aluminum has roughly seven orders of magnitude less hydrogen than stainless steel. Therefore, without being limited to any particular theory, it is believed that constructing the thermal desorption chamber  12  from low hydrogen aluminum may contribute to a reduction in background hydrogen and, thus, improve overall performance of the disclosed system  10 . A suitable aluminum thermal desorption chamber  12 , or at least the components thereof, may be obtained from Atlas Technologies of Port Townsend, Wash. 
     A heating element  26  may be provided to heat the thermal desorption chamber  12  (or at least the sample housed within the thermal desorption chamber  12 ) to desorb hydrogen from the sample. For example, the heating element  26  may include one or more heating lamps (e.g., a halogen heating lamp), and the heating lamps may be supplied with electrical energy by way of an electrical power line  28 . While use of a heat lamp is specifically disclosed, those skilled in the art will appreciate that various heating elements  26  (e.g., heating cartridges) may be used to heat the sample within the thermal desorption chamber  12  without departing from the scope of the present disclosure. 
     A temperature sensor  30 , such as a thermocouple, may be provided to detect the heat generated within the thermal desorption chamber  12 . The temperature sensor  30  may be in communication with the processor  24  by way of communication line  32 . Therefore, the processor  24  may control the heating element  26  to heat the sample within the thermal desorption chamber  12  to the desired temperature (e.g., at least 150° C.) based on temperature signals received from the temperature sensor  30 . 
     Optionally, an ultraviolet lamp  34  may be provided within the thermal desorption chamber  12 . The ultraviolet lamp  34  may be supplied with electrical energy by way of an electrical power line  36 , and may emit light having a wavelength ranging from about 200 to about 400 nanometers. 
     Without being limited to any particular theory, it is believed the ultraviolet light may excite water molecules (a background hydrogen source), thereby preventing the water molecules from attaching to the walls of the thermal desorption chamber  12 . Therefore, the ultraviolet lamp  34  may be actuated when the thermal desorption chamber  12  is being purged to minimize background hydrogen, as discussed in greater detail herein. 
     Vacuum gauges  38 ,  40  may be coupled to the thermal desorption chamber  12  to monitor the pressure within the thermal desorption chamber  12 . For example, vacuum gauge  38  may be an ion gauge configured to measure pressures between 10 −4  and 10 −10  Torr, while vacuum gauge  40  may be a thermocouple gauge configured to measure pressures between about 1 atm and 10 −4  Torr. The vacuum gauges  38 ,  40  may optionally be in communication with the processor  24  such that the processor  24  may control the pressure within the thermal desorption chamber  12 . 
     The sample introduction chamber  14  may be a load lock chamber selectively coupled to the thermal desorption chamber  12 . Therefore, the sample introduction chamber  14  may be a rigid enclosure capable of maintaining a vacuum (e.g., pressures of 10 −4  Torr or lower), and may be sized and shaped to receive the sample. 
     A vacuum gauge  15  may be coupled to the sample introduction chamber  14  to monitor the pressure within the sample introduction chamber  14 . For example, the vacuum gauge  15  may be a thermocouple gauge configured to measure pressures between about 1 atm and 10 −4  Torr. The vacuum gauge  15  may optionally be in communication with the processor  24  such that the processor  24  may control the pressure within the sample introduction chamber  14 . 
     When the sample introduction chamber  14  is used, the sample may first be introduced to the sample introduction chamber  14  and a vacuum may be drawn on the sample introduction chamber  14 . Then, the sample introduction chamber  14  may be fluidly coupled with the thermal desorption chamber  12  (e.g., by way of valve  42 ) such that the sample may be transferred to the thermal desorption chamber  12 . For example, once the sample introduction chamber  14  is fluidly coupled to the thermal desorption chamber  12 , a push rod (not shown) or the like may be used to transfer the sample from the sample introduction chamber  14  to the thermal desorption chamber  12 . 
     Thus, use of the sample introduction chamber  14  to introduce the sample to the thermal desorption chamber  12 , rather than directly introducing the sample to the thermal desorption chamber  12 , may minimize the amount of ambient air (a background hydrogen source) introduced to the thermal desorption chamber  12  during introduction of the sample to the thermal desorption chamber  12 . 
     The first vacuum pump  18  may be selectively coupled to both the thermal desorption chamber  12  and the sample introduction chamber  14  by way of valves  44 ,  46 . Therefore, by selectively opening and closing the valves  44 ,  46 , the first vacuum pump  18  may be actuated to draw a vacuum in either the thermal desorption chamber  12  or the sample introduction chamber  14 . 
     The first vacuum pump  18  may be a low vacuum pump, and may be used to draw an initial vacuum within the thermal desorption chamber  12  and the sample introduction chamber  14 . In one particular implementation, the first vacuum pump  18  may be capable of drawing a vacuum of at least about 10 −3  Torr in both the thermal desorption chamber  12  and the sample introduction chamber  14 . 
     As an example, the first vacuum pump  18  may be a mechanically-actuated positive displacement pump. Since oil may be a background hydrogen source, the first vacuum pump  18  may optionally be an oil-free pump, such as a diaphragm, peristaltic or scroll pump. 
     A vacuum gauge  48  may be mounted on the fluid line  50  that couples the first vacuum pump  18  with the sample introduction chamber  14  and the thermal desorption chamber  12  to monitor the vacuum created by the first vacuum pump  18 . For example, the vacuum gauge  48  may be a thermocouple gauge configured to measure pressures between about 1 atm and 10 −4  Torr. The vacuum gauge  48  may optionally be in communication with the processor  24  such that the processor  24  may control the vacuum generated by the first vacuum pump  18 . 
     The second vacuum pump  20  may be selectively coupled to the thermal desorption chamber  12  by way of valve  52 , and may be connected in series between the first vacuum pump  18  and the thermal desorption chamber  12 . Valve  54  may be positioned between the second vacuum pump  20  and the first vacuum pump  18 . Therefore, with valves  52 ,  54  open, the second vacuum pump  20  may be actuated, either alone or in combination with the first vacuum pump  18 , to draw a vacuum in the thermal desorption chamber  12 . 
     The second vacuum pump  20  may be a high vacuum pump, and may be used to draw high vacuum within the thermal desorption chamber  12 . In one particular implementation, the second vacuum pump  20  may be capable of drawing a vacuum of at least about 10 −9  Torr in the thermal desorption chamber  12 . 
     As an example, the second vacuum pump  20  may be a high vacuum cryopump or a turbomolecular pump, both of which generally do not produce background hydrogen (or hydrogen-containing compounds). However, other high vacuum pumps may also be used without departing from the scope of the present disclosure. 
     Thus, the first vacuum pump  18  may be actuated to draw a vacuum within the sample introduction chamber  14  after the sample has been placed into the sample introduction chamber  14 , thereby minimizing the amount of ambient air that will be introduced to the thermal desorption chamber  12  with the sample. The first and second vacuum pumps  18 ,  20  may be actuated to draw a high vacuum within the thermal desorption chamber  12 , thereby significantly minimizing the amount of background hydrogen (or hydrogen-containing compounds) within the thermal desorption chamber  12 . 
     The detector  16  may be any analytical apparatus or system capable of measuring the content of a target species (e.g., hydrogen) within the thermal desorption chamber  12 . The detector  16  may include a sampling probe  56  that extends into the thermal desorption chamber  12  to couple the detector  16  with the thermal desorption chamber  12 , particularly with the gaseous fluid within the thermal desorption chamber  12 . 
     The detector  16  may be a mass spectrometer. Since the target species (e.g., hydrogen) will be carried to the detector  16  in a carrier gas, the mass spectrometer may be capable of sampling under system conditions, such as at elevated temperatures and within the viscous flow regime (i.e., not high vacuum). 
     In one particular construction, the detector  16  may be an atmospheric ionization mass spectrometer (i.e., a mass spectrometer capable of sampling at atmospheric pressure). One example of suitable atmospheric ionization mass spectrometer is the HPR-20 QIC TMS gas analyzer, commercially available from Hiden Analytical Ltd. of Warrington, England. In one variation, the detector  16  may be a mass spectrometer capable of sample at pressures above 10 −4  Torr. In another variation, the detector  16  may be a mass spectrometer capable of sample at pressures above 10 −3  Torr. In yet another variation, the detector  16  may be a mass spectrometer capable of sample at pressures above 10 −2  Torr. 
     The carrier gas source  22  may be a source of carrier gas, and may be fluidly coupled with the thermal desorption chamber  12  by way of fluid line  58 . A valve  60  may be provided to control the flow of the carrier gas from the carrier gas source  22  to the thermal desorption chamber  12 . 
     The carrier gas may be an inert gas or a mixture of inert gasses. For example, the carrier gas may be argon or helium, though other gases, including other inert gases, may be used as the carrier gas without departing from the scope of the present disclosure. Without being limited to any particular theory, the selection of a carrier gas that is substantially free of hydrogen, whether free hydrogen or hydrogen compounded with other elements, may result in significantly more accurate measurements. 
     Optionally, the system  10  may also include a calibration gas source  60  fluidly coupled with the thermal desorption chamber  12  by way of fluid line  62 . The calibration gas source  60  may include a calibration gas having a known concentration of the target species (e.g., hydrogen) in a carrier gas (e.g., argon). 
     Thus, by selectively opening/closing valves  64 ,  66 ,  68 , the calibration gas may be passed from the calibration gas source  60  to the thermal desorption chamber  12  by way of fluid line  62 . From the thermal desorption chamber  12 , the calibration gas may pass to the sampling probe  56  such that it may be analyzed by the detector  16 , thereby facilitating calibration of the detector  16 . 
     Accordingly, the disclosed system  10  may be used to detect the content of hydrogen (or other species) in a sample. The first and second pumps  18 ,  20 , as well as the ultraviolet lamp  34 , may be employed to minimize background hydrogen within the thermal desorption chamber  12 . The sample introduction chamber  14  may be used to introduce a sample to the thermal desorption chamber  12  without introducing a significant amount of ambient air (a background hydrogen source). The sample placed in the thermal desorption chamber  12  may be heated by the heating element  26  to desorb hydrogen from the sample. The carrier gas source  22  may supply a carrier gas (e.g., argon) to the thermal desorption chamber  12  to transport the desorbed hydrogen to the detector  16 . The detector  16 , which may be a mass spectrometer, may measure the amount of desorbed hydrogen in the carrier gas stream. 
     Referring to  FIG. 2 , also disclosed is a method, generally designated  200 , for detecting hydrogen content in a sample. However, the disclosed method  200  may also be used for detecting the content of species other than hydrogen in a sample without departing from the scope of the present disclosure. 
     At step  202 , the method  200  may begin with the step of providing a thermal desorption chamber. For example, the thermal desorption chamber may be the thermal desorption chamber  12  ( FIG. 1 ) described in greater detail above. 
     At step  204 , the thermal desorption chamber may be purged to minimize background hydrogen. The purging step may include drawing a high vacuum within the thermal desorption chamber to reduce to a minimum any background hydrogen within the thermal desorption chamber. Optionally, ultraviolet light may be emitted within the thermal desorption chamber (e.g., by way of ultraviolet lamp  34  shown in  FIG. 1 ) to detach any hydrogen or hydrogen-containing compounds (e.g., water) from the walls of the thermal desorption chamber. 
     At this point, those skilled in the art will appreciate that minimizing background hydrogen within the thermal desorption chamber during the purging step  204  may result in more accurate measurements of the hydrogen content within the sample. Therefore, the purging step  204  may be limited by cost considerations. Nonetheless, in one particular implementation of the disclosed method  200 , the purging step  204  may reduce background hydrogen down to at most about 10 parts per million, such as at most about 1 part per million or at most about 10 parts per billion. 
     At step  206 , a sample may be introduced to the thermal desorption chamber. For example, the sample may be a piece of high-strength structural material, such as high-strength steel. Optionally, the sample may be plated, such as with a titanium-cadmium coating or a zinc-nickel coating. 
     The introducing step  206  is shown in  FIG. 2  being performed after the purging step  204 . For example, the thermal desorption chamber may be purged, and the sample may be introduced to the purged thermal desorption chamber by way of a sample introduction chamber (e.g., chamber  14  in  FIG. 1 ). However, the purging step  204  may be performed after the introducing step  206 , or both before and after the introducing step  206 , without departing from the scope of the present disclosure. 
     At step  208 , the sample within the thermal desorption chamber may be heated, thereby desorbing hydrogen from the sample. For example, the heating step  208  may be performed by actuating a heating element  26  ( FIG. 1 ) within the thermal desorption chamber. 
     At step  210 , a carrier gas (e.g., argon) may be introduced to the thermal desorption chamber to mix with any hydrogen that desorbs from the sample. The carrier gas may increase the pressure within the thermal desorption chamber, thereby allowing flow (e.g., creating a viscous flow regime) within the thermal desorption chamber. For example, the flowing carrier gas may increase the pressure within the thermal desorption chamber to about 10 −2  Torr or above. Therefore, the carrier gas may carry to the detector (detector  16  in  FIG. 1 ) any hydrogen that desorbs from the sample. 
     At step  212 , the hydrogen content of the desorbed hydrogen-carrier gas mixture may be measured. For example, the measuring step  212  may be performed by a mass spectrometer, thereby providing an actual measurement of hydrogen content. 
     Accordingly, the disclosed method  200  may be used to obtain a direct measurement of hydrogen (or other species) within a sample. 
     Referring to  FIG. 3 , one alternative embodiment of the disclosed system for detecting hydrogen content in a sample, generally designated  300 , may include a thermal desorption chamber  302 , a detector  304 , a vacuum pump  306 , a carrier gas source  308  and one or more heating elements  310 . A sample probe  312  may be enclosed within the thermal desorption chamber  302 . 
     The thermal desorption chamber  302  may be a rigid, heat-resistant enclosure capable of maintaining a vacuum. For example, the thermal desorption chamber  302  may be constructed from low hydrogen aluminum. The thermal desorption chamber  302  may be sized and shaped to receive the sample probe  312  therein. 
     The thermal desorption chamber  302  may include a sealing flange  314  and a sealing plate  316  sealingly connected to the sealing flange  314  to enclose the thermal desorption chamber  302 . Through-holes may be formed in the sealing plate  316  to facilitate coupling the thermal desorption chamber  302  with the detector  304 , the vacuum pump  306  and the carrier gas source  308 , while maintaining the thermal desorption chamber  302  as a substantially gas-tight enclosure. 
     The sample probe  312  may be connected to the sealing plate  316  and enclosed within the thermal desorption chamber  302 . 
     In one particular expression, the sample probe  312  may include a hollow tubular body  318  that defines an internal bore  319 , and that includes a first end  320  connected to the sealing plate  316  and a sealed (e.g., capped) second end  322 . For example, the sample probe  312  may be a length of 4130 stainless steel tubing (e.g., 0.5 inch diameter), similar to the immersion probe used in the ASTM F326 standard test for the electronic measurement of hydrogen embrittlement potential resulting from cadmium electroplating processes, and may be used to test other chemical processes. 
     Optionally, at least a portion of the outer surface  324  of the body  318  of the sample probe  312  may include plating  326 . For example, the plating  326  may be a titanium-cadmium material or a zinc-nickel material. Those skilled in the art will appreciate that hydrogen may desorb from both the sample probe  312  and the plating  326 . Therefore, the sample probe  312  and/or the plating  326  may be the sample analyzed by the system  300 . 
     The heating elements  310  may be enclosed within the thermal desorption chamber  302 , and may be arranged to heat the sample probe  312  to desorb hydrogen from the sample probe  312 . For example, the heating elements  310  may be heating lamps, such as halogen heating lamps, and the heating lamps may be supplied with electrical energy by way of an electrical power line  328 . 
     A temperature sensor  311 , such as a thermocouple, may be provided to detect the heat generated by the heating elements  310  within the thermal desorption chamber  302 . Therefore, the temperature of the sample probe  312  may be controlled by controlling the heating elements  310  based on signals received from the temperature sensor  211 . 
     The vacuum pump  306  may be selectively coupled to the thermal desorption chamber  302  by way of a valve  332 . The vacuum pump  306  may be actuated to draw a vacuum in the thermal desorption chamber  302 . 
     Optionally, a vacuum gauge  330  may be coupled to the thermal desorption chamber  302  (or one of the fluid lines in communication with the thermal desorption chamber  302 ) to monitor the pressure within the thermal desorption chamber  302 . Therefore, the pressure within the thermal desorption chamber  302  may be controlled by controlling the vacuum pump  306  based on signals received from the vacuum gauge  330 . 
     Thus, the vacuum pump  306  may be actuated to draw a vacuum within the thermal desorption chamber  302 , thereby significantly minimizing the amount of background hydrogen within the thermal desorption chamber  302 . 
     The carrier gas source  308  may be a source of a carrier gas, such as argon, and may be fluidly coupled with the thermal desorption chamber  302 . A first fluid line  340  may feed the carrier gas into the thermal desorption chamber  302  outside of the sample probe  312  and a second fluid line  342  may feed the carrier gas into the internal bore  319  of the sample probe  312 . Therefore, the carrier gas may be used to sample hydrogen desorbed externally to the sample probe  312  and/or desorbed hydrogen that diffused into the sample probe  312 . The flow of carrier gas from the carrier gas source  308  through the fluid lines  340 ,  342  may be controlled by valves  344 ,  346 . 
     The detector  304 , which may be a mass spectrometer, as discussed above, may be in fluid communication with the thermal desorption chamber  302 . A first fluid line  348  may couple the detector  304  with the thermal desorption chamber  302  outside of the sample probe  312  and a second fluid line  350  may couple the detector  304  with the internal bore  319  of the sample probe  312 . 
     Thus, the carrier gas may pass from the carrier gas source  308  into the thermal desorption chamber  302  where it may mix with any hydrogen desorbed from the sample probe  312 . The resulting desorbed hydrogen-carrier gas mixture may flow to the detector  304  by way of fluid lines  348 ,  350 . The flow of the desorbed hydrogen-carrier gas mixture to the detector  304  may be controlled by valves  352 ,  354 . 
     Accordingly, the disclosed system  300  may be used to detect the content of hydrogen (or other species) in the sample probe  312 . Absolute measurements of hydrogen (or other species) content may be obtained. Furthermore, since the sample probe  312  may also be the immersion probe used in the ASTM F326 standard test for the electronic measurement of hydrogen embrittlement potential resulting from cadmium electroplating processes, two different analyses (e.g., the disclosed method and the ASTM F326 standard test method) may be performed on the same sample probe, thereby allowing for correlation between results (e.g., determining the absolute quantity of hydrogen that corresponds to a failure in the ASTM F326 standard test method). 
     Although various embodiments of the disclosed system and method for detecting hydrogen content in a sample have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.