Abstract:
Method and apparatus for analyzing a breath sample provide user-friendly operation and analysis. The method and apparatus provide automatic operation and coordination of operation of an absorbent sample tube, including desorbing means, a chromatographic precolumn, a chromatographic main column, a detector, a data processor, a sample receiving tube for receiving exhaled breath sample, a sample loop for aspirating a prescribed quantity of breath sample from the sample receiving tube, a sample valve, a standard gas reservoir, and a standard gas valve. All of the foregoing are operated automatically in such that start cycles, detector cycles, fault detection cycles, standardizing, analysis, shutdown and end cycles are performed in a way which allows straightforward and simple measurement of breath sample by a user.

Description:
RELATED APPLICATION 
     This application is a divisional of application Ser. No. 08/910,113, Aug. 13, 1997, allowed now U.S. Pat. No. 6,148,657 granted Nov. 21, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method and an apparatus for analyzing constituents contained in a breath sample by means of gas chromatograph. 
     DESCRIPTION OF THE RELATED ART 
     There is conventionally available an apparatus for analyzing a breath sample based on detection of alcohol. On the other hand, analysis of constituents of a sample by the use of a gas chromatograph is popularly applied. The conventional chromatograph is used by researchers or engineers well versed in handling of the equipment. There is available no apparatus for automatically starting a gas chromatograph, analyzing and testing a sample, and then completing. For many of the users, therefore, the conventional chromatographic analysis apparatus is hard to use. 
     There is known no apparatus serving for clinical tests in the medical area by analyzing breath constituents. A breath analyzing apparatus for such medical tests should preferably be easily and automatically used by a test operator. 
     SUMMARY OF THE INVENTION 
     The present invention has an object to provide breath analyzing apparatus and method for analyzing a breath sample by means of a gas chromatographic column. 
     Another object of the invention is to provide breath analyzing apparatus and method which permit automatic and easy breath analysis of a low-concentration constituent such as pentane. 
     Further, another object of the invention is to provide breath analyzing apparatus and method which permit analysis of low-concentration constituents and high-concentration constituents by the use of a single main column and a detector. 
     Further, another object of the invention is to provide breath analyzing method and apparatus which permit perfect automation of start processing until the analyzing apparatus is ready to analyze. 
     Further, another object of the invention is to provide breath analyzing method and apparatus which permit perfect automation of shutdown processing upon completion of analysis and until supply of a carrier gas is discontinued. 
     Further, another object of the invention is to provide breath analyzing method and apparatus which permit automatic testing of deterioration of the column. 
     Furthermore, the present invention has an object to provide a breath analyzing method and a compact apparatus for the application thereof, which permit automation of various steps, completion of analysis in a shorter period of time of analysis and is easy to use in the area of clinical testing having needs different from those of laboratories. 
     Another object of the invention is to provide breath analyzing apparatus and method for carrying out measurement of a room interior environment, detection of a narcotic drug in vivo, and investigation of a cause of fire. 
     To achieve these objects of the invention, the apparatus of the invention comprises desorbing means for desorbing a breath sample absorbed into an absorbent sample tube, a chromatographic precolumn for passing the breath sample desorbed from the absorbent sample tube in a retention time prescribed for each constituent, a chromatographic main column for passing the breath sample having passed through the precolumn, in a retention time prescribed for each constituent, a detector for detecting constituents having passed through the main column, and a data processor for generating a chromatograph for the constituents detected by the detector. As a result of presence of the precolumn, when there are two constituents having different retention times, there remains, after passage of one constituent, for example pentane, through the main column, the other constituent such as hexane in the precolumn, thus permitting earlier completion of analysis by purging the main column and the precolumn. Presence of the desorbing means permits satisfactory detection of low-concentration constituents contained in the breath such as pentane, dimethyl sulfide and isoprene. 
     Further, the apparatus of the invention comprises a sample receiving tube for receiving the exhaled breath sample, a sample loop for aspirating a prescribed quantity of breath sample from the sample receiving tube, and a sample valve which connects the sample loop and the main column when a breath sample is aspirated into the sample loop. This makes it possible to sample a high-concentration constituent in the breath such as acetone directly from the sample receiving tube and analyze the sampled constituent by means of the main column. 
     The apparatus of the invention further comprises a standard gas bottle for supplying a standard gas, and a standard gas valve which connects the standard gas bottle and the sample loop when testing sensitivity of said-column. This permits automatic testing of the column. 
     In a preferred embodiment, the apparatus of the invention comprises an interface having various buttons and a controller controlling start, analysis, testing and shutdown of the apparatus in response to an instruction to the interface. 
     In another preferred embodiment, there is disclosed a method necessary for separating isoprene and pentane by the use of the foregoing apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a configurational view of an embodiment of the present invention; 
     FIG. 2 is the same view as FIG. 1 in which the sample valve is changed; 
     FIG. 3 illustrates the relationship between the controller and the individual heaters; 
     FIGS.  4 (A) and  4 (B) are schematic sectional views of the sampling valve; 
     FIG. 5 is a configurational view of absorbing means; 
     FIG. 6 is a block diagram illustrating the configuration of another embodiment of the invention; 
     FIG. 7 is a block diagram illustrating the configuration of the controller; 
     FIG. 8 is a block diagram illustrating the configuration of temperature control means; 
     FIG. 9 is a block diagram illustrating the configuration of channel switching means; 
     FIG. 10 is a flowchart illustrating a typical start processing using the time; 
     FIG. 11 is a flowchart illustrating a typical and processing using the time; 
     FIG. 12 is a time chart of the processing shown in FIGS. 10 and 11; 
     FIG. 13 is a flowchart illustrating another example of start processing using the time; 
     FIG. 14 is a flowchart illustrating another example of end processing using the time; 
     FIG. 15 is a time chart of the processing shown in FIGS. 13 and 14; 
     FIG. 16 is a flowchart illustrating an example of start processing using the time; 
     FIG. 17 is a flowchart illustrating an example of end processing using the time; 
     FIG. 18 is a time chart of the processing shown in FIGS. 16 and 17; 
     FIG. 19 is a flowchart illustrating an example of test processing; 
     FIG. 20 is a graph illustrating typical conditions for conditioning; 
     FIG. 21 is a time chart; 
     FIG. 22 is a flowchart illustrating a typical analysis processing; 
     FIG. 23 is a flowchart illustrating an example of desorbing processing; 
     FIG. 24 is a chromatograph illustrating retention times for pentane and hexane; 
     FIGS.  25 (A)- 25 (D) are descriptive views illustrating examples of backlash; 
     FIG. 26 is a configurational view of other embodiment of an apparatus not having a sample receiving tube; 
     FIG. 27 is a view similar to FIG. 26, in which the sample valve is changed; 
     FIGS.  28 (A) and  28 (B) are schematic sectional views of the sampling valve; 
     FIGS.  29 (A) and  29 (B) are chromatographs for illustrating resolutions R 12 , R 23  and R 34 ; 
     FIG. 30 is a graph illustrating retention times for the individual constituents relative to temperature of the capillary column in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.]; 
     FIG. 31 is a graph illustrating retention times for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 10 [m] with a capillary column temperature kept constant at 110° C.; 
     FIG. 32 is a graph illustrating retention times for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 10 [m] with a capillary column temperature kept constant at 130° C.; 
     FIG. 33 is a graph illustrating resolutions for the individual constituents relative to capillary column temperature in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.]; 
     FIG. 34 is a graph illustrating resolutions for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 10 [m] with a capillary column temperature kept constant at 110° C.; 
     FIG. 35 is a graph illustrating resolutions for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 10 [m] with a capillary column temperature kept constant at 130° C.; 
     FIG. 36 is a graph illustrating relative retention times for the individual constituents relative to capillary column temperature in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.]; 
     FIG. 37 is a graph illustrating retention times for the individual constituents relative to capillary column temperature in a capillary column haviang a length of 25 [m] with a carrier gas flow rate kept constant at 5 [ml/min.]; 
     FIG. 38 is a graph illustrating retention times for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 25 [m] with a capillary column temperature kept constant at 100° C.; 
     FIG. 39 is a graph illustrating retention times for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 25 [m] with a capillary column temperature kept constant at 110° C.; 
     FIG. 40 is a graph illustrating resolutions for the individual constituents relative to capillary column temperature in a capillary column havinag a length of 25 [m] with a carrier gas flow rates kept constant at 5 [ml/min.] ; 
     FIG. 41 is a graph illustrating resolutions for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 25 [m] with a capillary column temperature kept constant at 100 ° C.; 
     FIG. 42 is a graph illustrating resolutions for the individual constituents relative to carrier gas flow rate in a capillary column having a length of 25 [m] with a capillary column temperature kept constant at 110° C.; and 
     FIG. 43 is a graph illustrating relative retention times for the individual constituents relative to capillary column temperature in a capillary column having a length of 25 [m] with a carrier gas flow rate kept constant at 5 [ml/min.] . 
     FIG. 44 is a chromatograph in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.] and a capillary column temperature kept constant at 90° C.; 
     FIG. 45 is a chromatograph in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.] and a capillary column temperature kept constant at 110° C.; 
     FIG. 46 is a chromatograph in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.] and a capillary column temperature kept constant at 130° C.; 
     FIG. 47 is a chromatograph in a capillary column having a length of 10 [m] with a carrier gas flow rate kept constant at 5 [ml/min.] and a capillary column temperature kept constant at 150° C.; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Overview 
     Referring to FIG. 1, the breath analyzing apparatus  12  of the invention comprises a main column  14  and a precolumn  16  for passing a breath sample A therethrough and separating constituents contained in the breath sample A, and a detector  56  for detecting the constituents separated by the precolumn  16  and the main column  14 . The detector  56  may be any of ones detecting mass, thermal conductivity, and ion current. 
     The apparatus  12  further comprises an absorbent sample tube  22  absorbing the breath sample A in the interior thereof, and desorbing means  20  desorbing the breath sample A absorbed in the absorbent sample tube  22 . Low-concentration constituents contained in the breath sample are introduced from the desorbing means into the column. The apparatus  12  is further provided with a sample receiving tube  32  receiving a breath B breathed out by a subject, a sample loop  18  aspirating the breath B in a certain quantity, and a pump  66  aspirating the breath B in the sample receiving tube  32  though the sample loop  18 . High-concentration constituents of the breath sample are introduced from the sample receiving tube and the sample loop into the column  14 . 
     The apparatus  12  further comprises a standard gas bottle  62 . The standard gas bottle  62  is filled with a standard gas S comprising known constituents. The standard gas is a mixture of, for example, helium with isoprene and pentane. Isoprene and pentane should have the same concentrations as in desorbing the breath sample at the desorbing means  20   f . Standard gas storing means  69  is a storage vessel for storing the standard gas in a certain quantity (for example, 500 ml) to ensure smooth supply of the standard gas S. Bringing the standard gas into contact with the breath analyzing apparatus is useful for testing resolution of the column or for confirming the retention time. 
     The breath analyzing apparatus of the invention further comprises channel switching means  40 . The channel switching means  40  has a sample valve  42 , a standard gas valve  43 , solenoid valves  46 ,  48  and  50 , and a controller for switching over the individual solenoid valves  46 ,  48  and  50  and the individual valves  42  and  43 . The controller  44  may be one comprising manual switches, one comprising relays and timers, or one comprising a microcomputer and programs thereof. A carrier gas bottle  60  filled with a carrier gas C is connected through a reducing valve  68  to the channel switching means  40 . Air, hydrogen, nitrogen, helium or argon is usually used as a carrier gas C. 
     The sample valve  42  selects any one of the desorbing means  20  and the sample receiving tube  32 . The sample valve has a plurality of ports serving as outlets, ten ports in the example shown in FIG.  1 . The sample valve has two operating positions: FIG. 1 shows the first operating position and FIG. 2 shows the second operating position. In FIG. 1, the port  1  is connected to the port  2 , the port  3  is connected to the port  4 , and similarly all the ports up to the port  10  are sequentially connected. In FIG. 2, on the other hand, the port  2  is connected to the port  3 , the port  4  is connected to the port  5 , and all the ports are sequentially connected by shifting by one from the first operating position. 
     The standard gas valve  43  comprises an inlet connected to the sample receiving tube  32 , an inlet connected to the standard gas bottle  62 , an outlet connected to the sample valve  42 , and a line connecting any one of the inlets to the outlet by switching. 
     The desorbing means  20  comprises an absorbent sample tube support  24  supporting the absorbent sample tube  22 , a secondary concentrating tube  26  absorbing the breath sample A in the interior thereof, and a secondary concentrating tube support  28  supporting the secondary concentrating tube  26 . The absorbent sample tube support  24  has a built-in absorbent sample tube heater, described further in connection with FIG. 5 for desorbing the breath sample A absorbed in the absorbent sample tube  22 . The secondary concentrating tube support  28  has a secondary concentrating tube cooler  26 H for absorbing the breath sample A desorbed from the absorbent sample tube  22  into the secondary concentrating tube  26 , and a secondary concentrating tube heater, described further in connection with FIG. 5, for desorbing the breath sample A absorbed in the secondary concentrating tube  26  by heating the secondary concentrating tube  26 . The heater is for example an electric heater, and the cooler performs cooling by the use of liquid nitrogen for example. 
     A capillary tube having an inside diameter within a range of from 0.5 to 1.0 mm is used as the secondary concentrating tube  26 . The material should preferably be the same as, or equivalent in properties with, that of the main column  14 . The secondary concentrating tube  26  should be coated with a liquid absorbent to improve efficiency of secondary concentration. 
     The sample receiving tube  32  has a breath discharging port  34  and a breath blowing port  36 . The subject attaches a disposable mouth piece  38  to the breath blowing port  36 , presses the mouth piece  38  against his or her mouth, and blows a breath B into the sample receiving tube  32 . The sample receiving tube support  39  supports the sample receiving tube  32 , and has a receiving tube heater for heating the breath B or the like. 
     Referring again to FIG. 1, the breath analyzing apparatus  12  has a breath sucking line for sucking a breath breathed out by the subject through the ports  5  and  6  into the sample loop, to analyze the breath breathed out by the subject. 
     Referring to FIG. 2, the apparatus  12  has a first carrier gas line carrying the breath sucked into the sample loop to the sample valve  42 , the main column  14 , and the detector  56  by means of a pump. When the solenoid valve  46  is open, the first carrier gas line sends the carrier gas through the ports  7  and  6  to the sample loop, and sends the blown out breath through the ports  3  and  2  to the main column. 
     As shown in FIG. 1, the apparatus  12  has a second carrier gas line for carrying the breath sample desorbed from the absorbent sample tube  22  to the sample valve  42 , the precolumn  16 , the main column  14  and the detector  56 , to analyze the breath sample concentrated in the absorbent sample tube  22 . When the solenoid valve  50  is open, the carrier gas line sends the carrier gas from the desorbing means  20  to the ports  10  and  9 , the precolumn  16 , the ports  1  and  2  and the main column  14 . 
     The first carrier gas line serves also as a third carrier gas line for carrying the standard gas sucked into the sample loop  18  to the sample valve  42 , the main column  14  and the detector  56 . 
     Referring to FIG. 2, the apparatus  12  is further provided with a fourth carrier gas line C 2  which carries the constituents having passed through the precolumn  16  of the breath sample desorbed from the absorbent sample tube  22  to the sample valve  42 , and the main column  14 , and a fifth carrier gas line C 3  which purges the constituents not having passed through the precolumn  16  of the breath desorbed from the absorbent sample tube  22  from the sample valve  42 . When performing backflash, the second carrier gas line C 1  shown in FIG. 1 is switched over to the fourth and the fifth carrier gas lines C 2  and C 3  shown in FIG.  2 . 
     Referring to FIG. 3, the apparatus  12  is further provided with a column heater  14 H heating the column  14 , a detector heater  56 H heating the detector  56 , a sample receiving tube heater  32 H heating the sample receiving tube  32 , and a thermostatic oven  42 H heating the sample loop  18  and the sample valve  42 . The controller  44  controls temperature of the individual heaters. A display  34  for displaying the test result or the completion of start processing using the standard gas is connected to the foregoing controller  44 . 
     Referring to FIG. 4, the sampling valve  42  is a rotary valve having ten ports  1  to  10 . FIG. 4 is a schematic sectional view illustrating an example of sampling valve  42 . In FIG. 4, the sampling valve  42  is composed of a fixed body  42 A having ports  1  to  10 , a rotating body  42 B having communicating vessels a to e, and an actuator (not shown) such as a solenoid for rotating the rotating body  42 B. FIG.  4 (A) illustrates a first operating position shown in FIG. 1, and FIG.  4 (B) illustrates a second operating position shown in FIG.  2 . 
     Referring again to FIG. 1, a piping  1   a  connected to an end of the precolumn  16  is connected to the port  1 . A piping  2   a  connected to an end of the main column  14  is connected to the port  2 . A piping  3   a  connected to an end of the sample loop  18  is connected to the port  3 . A piping  4   a  connected to the pump  66  is connected to the port  4 . A piping  5   a  connected to the sample receiving tube  32  is connected to the port  5 . A piping  6   a  connected to the other end of the sample loop  18  is connected to the port  6 . A piping  7   a  for introducing the carrier gas C 2  through the solenoid valve  46  is connected to the port  7 . A piping  8   a  (vent) for discharging the carrier gas C 3  having passed through the desorbing means  20  and the precolumn  16  is connected to the port  8 . A piping  9   a  connected to the other end of the precolumn  16  is connected to the port  9 . A piping  10   a  introducing the carrier gas C 1  and C 3  having passed through the desorbing means via a filter  20  is connected to the port  10 . 
     Referring to FIG. 5, the breath concentrating/absorbing unit  80  for absorbing the breath sample A into the absorbent sample tube  22  comprises a Teddler bag  72  filled with breath A, the absorbent sample tube  22  connected to the Teddler bag  72 , and a pump  84  for sucking the breath A in the Teddler bag  72  into the absorbent sample tube  22 . 
     Further, the breath concentrating/absorbing unit  80  is provided with a mass flowmeter  86  for measuring a mass flow rate f of the breath A passing through the absorbent sample tube  22 , a manometer  81  for measuring pressure p of the breath A in the Teddler bag  72 , an absorption control means  90  for stopping the pump  84  when pressure p of the breath A measured by the manometer  81  is under a prescribed value pF, a thermostat  92  for keeping a constant temperature T of the absorbent sample tube  22 , and a water absorbing filter  94  provided in the channel of the breath A between the absorbent sample tube  22  and the pump  84 . 
     The Teddler bag  72 , a tee  881  of the manometer  81 , the absorbent sample tube  22 , the water absorbing filter  94 , the pump  84  and the mass flowmeter  86  are individually connected by flexible tubes  95   a  to  95   e.    
     The absorbent tube  22  has an absorbent  23  for absorbing the breath sample A. The Teddler bag  72  has a breath inlet port  74  and a breath discharging port  78 . A stop valve capable of being manually opened and closed is provided for each of the breath discharging port  78  and the breath inlet port  76 . The subject previously attaches the disposable mouth piece  74  to the breath inlet port  76 , presses his or her mouth against the mouth piece  74 , and blows breath A into the Teddler bag  82 . The mass flowmeter  86  is a common flowmeter for gas such as a mass flowmeter. The manometer  81  utilizes the piezo-electric effect in which voltage is generated by applying a pressure onto a piezo-electric element. 
     According to the result of an experiment, pressure p during sucking is, for example, −0.05 kgf/cm 2 , and pressure p upon completion of sucking is, for example, within a range of from −0.3 to −0.4 kgf/cm 2 . To determine the completion of sucking, pressure is measured with the manometer  81 . The thermostat  92  is composed of a heating/cooling unit  96  and a temperature control unit  97 . The heating/cooling unit  96  can be divided into an upper portion  98  and a lower portion  99 , and the upper portion  98  and the lower portion  99  hold the absorbent sample tube  22  in between. The upper portion  98  has a heat insulating member  98 A and a heat conducting member  98 B. The lower portion  99  has a heat insulating member  99 A, a heat conducting member  99 B, a Peltier element  99 C and a radiation fin  99 D. 
     A thermocouple  97 A is provided in the heat conducting member  992 . The thermocouple  97 A provides an output of voltage corresponding to temperature T of the absorbent sample tube  22  to the temperature control means  97 . The temperature control means  97  controls feeding of power to the Peltier element  99 C so that temperature T of the absorbent sample tube  22  as given by an output from the thermocouple  97 A is constant at a certain value TC. When the certain value TC is over room temperature, a simple electric heater or the like may be provided in place of the Peltier element  99 C. The water absorbing filter  94  is filled with a hygroscopic agent  93  such as silica gel or calcium carbide. 
     When the pump  84  is operated, the breath A is sucked from the Teddler bag  82  through the absorbent sample tube  22 . As a result, the breath constituents A are concentrated and caught by the absorbent  141  of the absorbent sample tube  22 . At this point, pressure p upon sucking is measured by the manometer  88 , and mass flow rate is measured by the mass flowmeter  86 . When the Teddler bag  82  becomes empty, pressure p reaches the level of a certain value pF, and the main control means  90  causes stoppage of the pump  84 . The mass flow rate f upon completion of sucking is provided from the mass flowmeter  86  to the sucking control means  90 . The sucking control means  90  therefore calculates the quantity of breath A concentrated in the absorbent sample tube  22 . 
     Referring to FIG. 6, in the breath analyzing apparatus  12  of the invention, the desorbing means  20 , the precolumn  16  and the main column  14  are connected for analysis of the concentrated breath sample. The sample receiving tube and the sample loop  18  are connected as well to sample the breath exhaled by the subject. Further, the sample loop  18  and the main column  14  are connected to analyze the breath sample sucked into the sample loop  18 . Then, the standard gas bottle  62 , the sample loop  18  and the main column  14  are connected to test sensitivity of the detector  56  and calculate a resolution representing the column performance by the use of the standard gas. 
     Constituents of the standard gas, the breath breathed out by the subject or the breath concentrated in the absorbent sample tube are detected in the same main column  14  and detector  56 , and analyzed in the data processing means  72 . Adoption of the configuration shown in FIG. 6 makes it possible to analyze low-concentration and high-concentration breath constituents, and makes it easier to carry out a test by the use of the standard gas. 
     The precolumn  16 , being provided for backflash, is not used for sampling breath from the sample receiving tube. When conducting backflash, the carrier gas should be sent to the main column while purging constituents remaining in the precolumn. When sampling breath with the sample receiving tube, the breath should be sucked into the sample loop by means of the pump at an end, and then sent to the main column by means of the carrier gas. The configuration shown in FIGS. 1 and 2 is an embodiment permitting achievement of the steps mentioned above, but any other configuration may be adopted, such as one based on opening/closing of the solenoid valve. 
     Referring to FIG. 7, the controller  44  comprises a main controller  100 , temperature controller  102  for controlling the individual heaters, and line controller (channel controller)  104  for controlling switching of the channels. Further, in this embodiment, the apparatus comprises start controller  106  for controlling the breath analyzing apparatus from stationary to a state capable of accomplishing analysis, analysis controller  108  for controlling analyzing operations, shutdown controller  110  for discontinuing operation of the breath analyzing apparatus upon completion of analysis, and test controller for testing performance of the breath analyzing apparatus by the use of the standard gas. 
     Further, an interface  120  is connected to the controller  44 . The interface  120  comprises a start button  122  for user&#39;s instructing start of the breath analyzing apparatus, an analysis start button  124  for instructing start of analysis, an end button for instructing end of analysis, and a test button  128  for instructing testing. A button for switching over between concentrated and non-concentrated types, or setting an object to be analyzed may be provided. 
     Referring to FIG. 8, the temperature control means  102  is provided with preselected temp. recorder  130  for storing set temperature and a heater driver  132 . The recorder  130  stores temperatures forming conditions for analysis such as a column temperature set in response to the material to be breath-analyzed. The heater driver  132  is connected to the column heater  14 H, the detector heater  56 H, the absorbent sample tube heater  22 H, the secondary concentrating tube heater  26 H and the thermostatic oven  42 H. 
     Referring to FIG. 9, the line controller  104  is connected to the sample valve  42 , the first carrier gas solenoid valve  50 , the second carrier gas solenoid valve  46 , the standard gas valve  51  and the standard gas switching valve (select valve)  43 . 
     The controller  44  controls start, shutdown, testing and analysis of the breath analyzing apparatus by performing control with reference to the temperature and the switching time. 
     Operation 
     Start processing using time: 
     Referring to FIG. 10, when the subject presses the start button  122 , start operation by the controller  44  is started. First, the controller  44  selects a channel for startup, and opens the carrier gas solenoid valves  50  and  46  (S1). The channel for starting purges the main column  14  and the detector  56 , and serves also as a channel for purging the desorbing means (FIG.  2 ). Referring again to FIG. 2, the carrier gas, which is introduced from the desorbing means into the precolumn, may be purged in the reverse direction from the port  8 , i.e., from the precolumn  16  to the desorbing means  20 . 
     The timing when the solenoid valve  50  is opened is regarded as the starting point, i.e., 0 minute. Thereafter, it is determined whether or not a certain period of time a has elapsed (S2). As a result, the carrier gas C purges the main column  14  and the detector  56 , and then, the precolumn  16  and the desorbing means  20 . This certain period of time a is for example three minutes. 
     After the lapse of the certain period of time a, the detector heater  56 H is turned on (S3; lapse of three minutes). Then, it is determined whether another certain period of time b has elapsed (S4). After the lapse of the certain period of time b, the column heater  14 H is turned on (S5; lapse of ten minutes). The certain period of time b is set by comparing heating properties of the detector heater  56 H and the column heater  14 H so that the detector temperature is always higher than the column temperature. The certain period of time b is for example seven minutes. 
     Further, it is determined whether or not a certain period of time c has elapsed (S6). After the lapse of the certain period of time c, the ionization lamp  58  of the detector is turned on (S7; lapse of 13 minutes). The certain period of time c should be set at a value not reducing the period of time available for the ionization lamp  58  by stabilization of operations of the ionization lamp  58  before operations of the detector  56  are not as yet stabilized. The certain period of time c is for example three minutes. 
     Further, when an output signal from the detector  56  shows a value under a prescribed value (3 V for example), confirmation of slope sensitivity is started, and it is determined whether or not the slope sensitivity takes a value under a certain value (200 μV/min for example) (S8). When the slope sensitivity becomes under a certain value, a preparation completion signal is issued (S9; lapse of 43 minutes). As a result, preparation completion is displayed on the display  34 . A slope sensitivity under the certain value means that residual constituents leaving the main column decrease and operation of the detector  56  has become stable. 
     Shutdown processing using time: 
     Referring to FIG. 11, when the operator presses the shutdown button  126 , the end operation by the controller  44  is started. The controller  44  selects a channel for starting and finishing from among the various channels for analysis. It further turns off the ionization lamp  58 , and turns off the column heater  14 H (S10). The moment when the column heater  14 H is turned off is regarded as 0 minute. Then, it is determined whether or not a certain period of time d has elapsed (S111). Upon the lapse of the certain period of time d, the detector heater  16 H is turned off (S12; lapse of one minute). The certain period of time d is set by comparing cooling properties between the detector heater  16 H and the column heater  14 H so that the detector temperature is always higher than the column temperature. The period of time d is for example one minute. 
     Then, it is determined whether or not a certain period of time e has elapsed (S13). Upon the lapse of the certain period of time e, the solenoid valve  18  is closed (S14; lapse of 36 minutes). The certain period of time e is set by taking account of the cooling property of the detector heater  16 H so as to cause degradation of performance of the detector  56  as a result of the high-temperature detector  56  coming into contact with the open air. The certain period of time e is for example 35 minutes. 
     More specifically, the controller  44  controls the solenoid valve, the detector heater, the column heater and the ionization lamp in accordance with the time chart shown in FIG. 12, thereby achieving the foregoing flowchart. 
     Another example of start or end control using time: 
     Referring to FIG. 13, upon starting, the controller  44  turns on the ionization lamp simultaneously with turn-on of the detector heater (S23). In the example shown in FIG. 13, the startup time can be reduced. Referring to FIG. 14, the controller  44  turns off the ionization lamp simultaneously with turn-off of the detector heater (S33). This flowchart is achieved by the controller  44  operating in accordance with the time chart shown in FIG.  15 . 
     Start processing using temperature: 
     Referring to FIG. 16, when the operator presses the start button  122 , the start operation by the controller  44  is started. First, the controller  44  selects the channel for starting and opens the solenoid valve (S41). The moment when the solenoid valve opens is regarded as 0 minute. Then, it is determined whether or not a certain period of time has elapsed (S42). The certain period of time is for example three minutes. Upon the lapse of the certain period of time, the detector heater  16 H is turned on (S43; lapse of three minutes), and it is determined whether or not the detector  56  temperature has reached a certain percentage of the set detector temperature (S44). The set detector temperature is stored in the set temperature storing means  130 . When the temperature has reached a certain percentage, the column heater  14 H is turned on (S45; lapse of eight minutes). The set detector temperature is 120° C., and the certain percentage is 60% corresponding to about 70° C. This certain percentage is set at a value such that the temperature of the column  14  becoming higher than that of the detector  56  does not impair accuracy of the detector  56 . 
     Then, it is determined whether or not temperature of the column  14  has reached the certain percentage of the set temperature (S46), and upon reaching the certain percentage, the ionization lamp  58  is turned on (S47; lapse of ten minutes). The set column temperature is 100° C., and the certain percentage is 80% corresponding to 80° C. This certain percentage is set at such a value that the available period of time for the ionization lamp  58  is never reduced by the stabilization of operation of the ionization lamp  58  before stabilization of operation of the detector  56 . 
     Then, when the output signal of the detector  56  shows a value under a certain value (3 V for example), confirmation of slope sensitivity is started, and it is determined whether or not the slope sensitivity has become under a certain value (S48). When the slope sensitivity becomes under the certain value, a preparation completion signal is generated for output (S49; lapse of 37 minutes). As a result, preparation completion is displayed on the display. 
     Shutdown processing using temperature: 
     Referring to FIG. 17, when the operator presses the shutdown button  126 , end operation by the controller  44  is started. First, the controller  44  selects a channel for start and end, turns off the ionization lamp  58 , and turns off the column heater  14 H (S51). This is regarded as the starting point, i.e., 0 minute. Then, it is determined whether or not temperature of the column  12  has reached a certain percentage of the set column temperature (S52), and when it decreases to the certain percentage, the detector heater  56 H is turned off (S53; lapse of one minute). The set column temperature is 100° C., and the certain percentage is 70% corresponding to 70° C. This certain percentage is set at such a value that accuracy of the detector  56  is never degraded by the temperature of the detector  56  becoming lower than that of the column  12 . 
     Then, it is determined whether or not temperature of the detector  56  has decreased to the certain percentage of the set detector temperature (S 54 ). When it decreases to the certain percentage, it is determined whether or not a certain period of time has elapsed (step S 55 ; lapse of 31 minutes). Upon the lapse of the certain period of time, the solenoid valve is closed (S 56 ; lapse of 36 minutes). The set detector temperature is 120° C., and the certain percentage is about 17% corresponding to 20° C. The certain period of time is five minutes. The certain percentage and the certain period of time are set at such values that performance of the detector  56  is never degraded by the high-temperature detector  56  exposed to the open air. Start and end control using temperature results in a time chart for example as shown in FIG.  18 . 
     Concentrated type test processing: 
     Referring to FIG. 19, when the test button  128  is pressed, the controller  44  tests the column  14  and the detector  56 . First, the valve  42  is driven to the second operating position as shown in FIG. 2, and the solenoid valve is opened. Then, the carrier gas C is sent through the sample loop  18  to the main column  14  and the detector  56 . Then, slope sensitivity of the detector  56  is measured (S 61 ). Typical test conditions include a column  12  temperature of 80° C., a detector  56  temperature of 120° C. and a carrier gas C comprising helium at 6 ml/min. 
     Then, the sample valve  42  is switched over to the first operating position as shown in FIG.  1 . The standard gas valve  43  is switched over and the solenoid valve  48  is opened to standard gas in a certain quantity is introduced into the sample loop  18 . Further, the sample valve  42  is switched over to the second operating position as shown in FIG.  2 . Then, the solenoid valve  46  is opened to send the standard gas S introduced into the sample loop to the main column  14  and the detector  56 . 
     Since the standard gas contains pentane and isoprene in concentrations contained in the breath sample desorbed in the desorbing means  22 , the main column  14  separates these constituents in response to the respective retention times. The detector  56  generates electric signals dependent on the content of each constituent by ionizing the breath constituents by irradiating, for example, the ionization lamp  58 . Further, the data processor  72  calculates resolutions from chromatographs of pentane and isoprene (S 62 ). 
     Referring to FIG. 20, the extent of separation of the two constituents cannot be known from the separation coefficient k (the keeping ratio of the latter constituent relative to the former constituent, k&gt;1) and the steepness of peaks of both constituents (theoretical number of steps, N) alone. An extent of separation can be expressed by a resolution R. In FIG. 20, R is given by: 
     
       
           R= 2( tr   2 − tr   1 )/( w   1 − w   2 )  
       
     
     The following formula can be derived as a formula correlating R with N, k and k′ on the assumption of w 1 =w 2 : 
     
       
           R= ( N   1 /2/4)[ k− 1)/α[ k′/ ( k′+ 1)] 
       
     
     When R&lt;0.5, two peaks almost overlap each other, R=1 leads to partial overlap of 2%, and R=1.25, to overlap of 0.5%. With R=1.5, separation is substantially complete. 
     Then, it is determined whether or not sensitivity of the detector  56  and resolution of the column  12  are normal (S 63 ). A sensitivity of the detector  56  as represented by a slope sensitivity under a certain value (200 μV for example) is normal, and one over the certain value is abnormal. A column  12  resolution of over a certain value is normal, and one under the certain value is abnormal. The certain value for resolution is equal to a threshold value of 1.5 when the standard gas comprises a combination of helium with isoprene and pentane. 
     If sensitivity of the detector  56  or resolution of the column  14  is abnormal, the column  14  and the detector  56  are conditioned (S 64 ). Conditioning is carried out by supplying the carrier gas for a certain period of time while heating the main column  14  and the detector  56 . Referring to FIG. 21, the carrier gas is supplied for 960 minutes. In this supply, temperature of the column  14  is varied within a range of from 50° C. to near the maximum temperature. Temperature of the detector  56  is kept constant. Of the carrier gas C, helium is supplied at 6 ml/min. 
     Upon completion of this conditioning, sensitivity of the detector  56  is tested again (S 65 ), and resolution of the column  12  is tested (S 66 ), to determine whether or not sensitivity of the detector  56  and resolution of the column  12  are normal (S 67 ). When sensitivity of the detector  56  or resolution of the column  12  is abnormal, this is displayed on the display  34  (S 68 ). The display tells, when sensitivity of the detector  56  is abnormal, that “The detector may deteriorate. Check or replace the detector.” and when resolution of the column  12  is abnormal, that “The column may deteriorate. Check or replace the column.” As required, execution of automatic end causes end of all the operations (S 69 ). 
     When no abnormality is found in steps S 64  and S 67 , execution of automatic end (S 69 ) causes end of all the operations. 
     In an embodiment, timing of starting test is not only pressing the test button  128 , but the column  14  and the detector  56  are tested at every lapse of a prescribed period of time or every end of a prescribed number of analyzing runs. The prescribed period of time in this case is for example one day, and the prescribed number runs of analysis is for example one span. One span means a number of runs of analysis when continuously analyzing the same constituent, or when continuously analyzing under the same conditions. A test may be carried out upon every end processing. 
     Concentrated type analyzing processing: 
     Prior to starting analysis, the operator should previously cause the absorbent sample tube  22  to absorb the breath sample A by means of the breath concentrating/absorbing apparatus  80  shown in FIG.  5 . Then, the absorbent sample tube  22  is attached to the desorbing means  20 . When the operator presses the analysis start button, the controller  44  starts breath analysis. When startup has not as yet been conducted, the start processing is performed first. Upon completion of startup, the carrier gas flows constantly to purge the column  14  and the detector  56 . The detector  56  always provides an output of detection signal of constituents to the data processor  72 . Referring to FIG. 22, upon starting analysis, a start signal is sent to the data processor  72  (S 71 ). Then, the data processor  72  stores the output signal from the detector  56 . 
     Then, the controller switches over the channel from the purging channel to that shown in FIG. 1 (S 72 ). Then, the breath sample absorbed in the absorbent sample tube is desorbed. Appearance of a peak in the chromatograph varies with the manner of desorbing. That is, a gradual desorbing result in an excessively wide band, preventing satisfactory quantitative determination. In this embodiment, therefore, a secondary concentration is performed. 
     Referring to FIG. 23, the desorbing processing S 73  comprises heating the absorbent sample tube  22  for example to 250° C. (S 81 ), and at the same time, cooling the secondary concentrating tube  26  for example to a temperature within a range of from −130 to −180° C. (S 82 ). When the carrier gas C is passed from the absorbent sample tube  22  to the secondary concentrating tube  26 , the breath sample A leaves the absorbent sample tube  22 , is further concentrated, and absorbed by the secondary concentrating tube  26 . Upon completion of absorption of the breath sample A into the secondary concentrating tube  26 , i.e., upon the lapse of a certain period of time j (S 83 ), the secondary concentrating tube  26  is heated for example to 190° C. (S 84 ). 
     Referring again to FIG. 1, at this point, the solenoid valve  46  is closed to saving the carrier gas C. The carrier gas C 1  therefore flows through the solenoid valve  50 , the desorbing means  20 , the filter  30 , the ports  10  and  9 , the precolumn  16 , the parts  1  and  2 , the main column  14 , and the detector  56 , and then discharged. The breath sample A flow as well with the carrier gas C, and passes through the precolumn  16 , the main column  14  and the detector  56 . Constituents contained in the breath sample A are separated in the precolumn  16  and the main column  14 , and are thus detected by the detector  56  with time changes. 
     In the concentrated type, it is possible to detect low-concentration high-boiling-point constituents (such as hexane) which cannot be detected in the non-concentrated type. However, ordinary high-boiling-point constituents have a long retention time in the precolumn  16  and the main column  14  (delay in retention). As a result, the time required for analysis, which is for example 15 minutes in the non-concentrated type, is more than an hour in the concentrated type. 
     Referring to FIG. 24, pentane P is detected in about six minutes from the start of analysis, and hexane H is detected in about 30 minutes. Even when only pentane P must be detected, therefore, it is necessary to continue analysis for a long period of time for discharging hexane. To pass a high-boiling-point constituent such as hexane through the main column  14  and the detector  56  may lead to contamination or deterioration of these components. 
     For the purpose of reducing the analyzing time and preventing contamination and deterioration, therefore, backflash is conducted. As shown in FIG.  25 (A), when the carrier gas C 1  begins flowing through the precolumn  16  and the main column  14 , pentane P and hexane H, which are constituents of the breath sample A, enters the precolumn  16 . Pentane P which is harder to be held in the precolumn  16  than hexane H passes through the precolumn  16  before hexane as shown in FIG.  25 (B). As time passes and even when pentane P has advanced considerably into the main column  14 , hexane still remains in the precolumn  16 , as shown in FIG.  25 (C). If the carrier gas C 1  continues to flow in this state, it takes a long time for hexane H to leave the main column  14 . Therefore, the precolumn  16  and the main column  14  are separated, and a carrier gas C 3  in the reverse direction to the carrier gas C 1  is caused to flow in the precolumn  16 . The carrier gas C 2  is caused to flow in the same direction as that of the carrier gas C 1  in the main column  14 . As a result, pentane P is detected upon leaving the main column  14 , and hexane H is purged from the precolumn  16 , as shown in FIG.  25 (D). 
     When the column length, temperature thereof and the carrier gas flow rate are constant, the retention time of the breath constituents in the column is also constant. Purging of the precolumn shown in FIG.  25 (D) is accomplished upon the lapse of a certain period of time g from the start of desorption. 
     Referring again to FIG. 22, upon the lapse of this certain period of time g (S 74 ), pentane P stays in the main column  14 , and hexane H, in the precolumn  16 . The valve  42  is changed from FIG. 1 to FIG. 2 (S 75 ). Upon further lapse of a certain period of time h, for example in the case shown in FIG. 24, the channel is switched over to that for purging the main column  14  and the detector  56  when three minutes have elapsed from the change into the backflush channel and eight minutes from the start of analysis (S 77 ). In the example shown in FIG. 2, purging is accomplished by causing the carrier gas to flow without changing the channel. 
     In the detector  56 , a qualitative analysis is carried out on the basis of the capacity (holding capacity) of carrier gas or the time (retention time) thereof before formation of discriminating bands of the individual constituents after pouring of the breath sample A, and a quantitative analysis, on the basis of the peak area or the peak height. 
     Non-concentrated type test processing: 
     First, the sample receiving tube  32  is heated for example to 40° C., and the channel shown in FIG. 1 is selected. When the subject presses the analysis start button and blows breath B into the sample receiving tube  32 , the pump  66  operates only for a prescribed period of time in response thereto. In this case, the breath B flows through the sample receiving tube  32 , the ports  5  and  6 , the sample loop  18 , the ports  3  and  4 , and the pump  66 , and is then discharged. As a result, the sample loop  18  is filled with the breath B as the breath sample A. 
     When the breath is sucked into the sample loop  18 , the channel shown in FIG. 2 is selected to cause the carrier gas to flow therethrough. As the solenoid valve  46  is open at this point, the carrier gas C 2  flows through the solenoid valve  46 , the ports  7  and  6 , the sample loop  18 , the ports  3  and  2 , and the main column  14  and the detector  56 , and is then discharged. The breath sample A filling the sample loop  18  flows together with the carrier gas C 2 , and passes through the main column  14  and the detector  56 . The constituents contained in the breath sample A are detected by the detector  56  with time changes as a result of separation in the main column  14 . 
     Analytical conditions: 
     Concentration of dimethyl sulfide in the breath is believed to increase as a result of hepatocirrhosis or the like. Isoprene is a precursor of cholesterol, and the concentration thereof in breath is said to increase as a result of diabetes mellitus, hypertension diseases, cholelithiasis or arteriosclerosis. In pregnant intoxication, diabetes mellitus and arteriosclerosis, lipid peroxidation causes an increase in the pentane concentration in breath. By conducting concentration, using a PLOT (porous layer open tubular) column having a high liquidus polarity (for example, poraplot U), and setting the following conditions including a column temperature, a column length and a carrier gas flow rate, it is possible to satisfactorily separate pentane, isoprene and dimethyl sulfide in the foregoing breath analyzing apparatus. 
     The conditions for the main column  14  include, for example, a material comprising molten silica, an inside diameter within a range of from 0.3 to 1.0 [mm], a length of from about 10 to 25 [m], a coating layer thickness of from 10 to 20 [μm], a coating layer material comprising divinylbenzene ethylene glycol dimethacrylate. A layer length of the main column generally leads to a better resolution, but on the contrary, to a longer period of time required for analysis. A length within a range of from 10 to 25 [m] is therefore appropriate. As the detector  56 , a flame ionization detector (FID) or a thermal conductivity detector (TCD) may be used. 
     The breath analyzing apparatus shown in FIGS. 1 and 2 is employed. Since detection of pentane, dimethyl sulfide and isoprene should preferably be conducted after concentration, the sample receiving tube  32  or the sample loop  18  is not necessary for analyzing these three substances alone. A breath analyzing apparatus not having a sample receiving tube  32  is illustrated in FIGS. 26 and 27. In this example, a sampling valve  42  having eight ports is used. The carrier gases C 1  to C 3  upon backflash are shown in FIGS. 26 and 27. Referring to FIG. 28, the sectional view of the sampling valve  42  is substantially the same as that shown in FIG.  4 . 
     Referring to FIG. 29, E represents a peak of ethanol, D, dimethyl sulfide, P, pentane, and I, isoprene (the same applies hereafter also in the following chromatograms). In FIG. 29, for pentane and dimethyl sulfide, the retention times become reverse under some conditions. FIG.  29 [ a]  illustrates a case where the retention time for pentane is longer than that for dimethyl sulfide, and FIG.  29 [ b]  covers a case where the retention time for pentane is shorter than that for dimethyl sulfide. 
     As is clear from FIG. 29, R 12  indicates resolution for ethanol and dimethyl sulfide or pentane, R 23 , resolution for dimethyl sulfide and pentane, and R 34 , resolution for dimethyl sulfide or pentane and isoprene. As described above, reversal of the retention time between dimethyl sulfide and pentane does not affect calculation of resolution R 23 . 
     Pentane, main column length of 10 m: 
     Referring to FIG. 30, a higher column temperature results in a shorter retention time for all the three constituents. Referring to FIG. 31, with a column temperature of 110° C., a higher flow rate leads to a shorter retention time for all the three constituents. Referring to FIG. 32, with a column temperature of 130° C., a higher flow rate brings about a sudden decrease in the retention time for all the three constituents. Referring to FIG. 33, resolution of each constituent varies with the column temperature. 
     Referring to FIG. 33, according to the analysis of pentane, the main column temperature should preferably be within a range of from 125 to 135° C., or more preferably, 130° C. Within this temperature range, the retention time of dimethyl sulfide is longer than that of pentane (FIG.  36 ), this corresponding to the chromatogram shown in FIG. 29 [b].  Therefore, R 12  is the resolution for ethanol and pentane, and R 23  is the resolution for pentane and dimethyl sulfide. The lower limit value is set at 125° C. because a temperature under 125° C. leads to an R 23  of under 1.3, although R 12  is over 1.5 as shown in FIG.  33 . The upper limit value is set at 135° C. because a temperature over 135° C. results in an R 12  value under 1.3 although R 23  is over 1.5, as shown in FIG.  33 . 
     Referring to FIG. 35, the carrier gas flow rate should preferably be within a range of from 3 to 6 [ml/min.], or more preferably, 5 [ml/min.]. At a temperature of 130° C., the retention time of dimethyl sulfide is longer than that of pentane as shown in FIG. 36, taking the form of the chromatogram shown in FIG. 29 [b].  Therefore, R 12  is the resolution for ethanol and pentane, and R 23  is the resolution for pentane and dimethyl sulfide. The lower limit is set at 3 [ml/min.] because a value under 3 [ml/min.] leads to an R 12  of under 1.5 and an R 23  of under 1.4 as shown in FIG.  35 . The upper limit value is set at 6 [ml/min.] because a value of over 6 [ml/min.] results in an R 23  of under 1.4 although R 12  is over 1.5, as shown in FIG.  35 . 
     FIG. 36 is a graph illustrating relative retention times for the individual constituents relative to the main column temperature. The term relative retention time as used herein means the retention time for each constituent on the assumption of a retention time of ‘1’ for ethanol. 
     Pentane, main column length of 25 m: 
     Referring to FIG. 37, the retention time is reduced by increasing the column temperature also in the case of a column length of 25 m. Similarly, referring to FIG. 38, an increased flow rate results in a shorter retention time. Referring to FIG. 39, a higher flow rate leads to a shorter retention time also in the case of a column temperature of 110° C. 
     Referring to FIG. 40, resolution varies with the column temperature on the assumption of a column length of 25 m and a flow rate of 5 [ml/min.]. When analyzing pentane with a column length of 25 m, the main column temperature should preferably be within a range of from 85 to 115° C., or more preferably, from 90 to 110° C. Within this temperature range, the retention time of pentane is longer than that of dimethyl sulfide as shown in FIG. 43, resulting in a chromatogram as shown in FIG.  29 [ a].  Therefore, R 23  is the resolution for dimethyl sulfide and pentane, and R 34  is the resolution for pentane and isoprene. The lower limit value is set at 85° C. because a value under 85° C. is found to tend to result in an R 34  of under 1.5 although R 23  is oven 2.0 as shown in FIG.  40 . The upper limit value is set at 115° C. because a temperature of over 115° C. leads to an R 23  of under 1.6 although R 34  is over 2.4. 
     The carrier gas flow rate should preferably be different between a main column temperature range of from 85 to 105° C. and a main column temperature range of from 105 to 115° C. Within the main column temperature range of from 85 to 105° C., as shown in FIG. 40, the carrier gas flow rate should preferably be within a range of from 2 to 25 [ml/min.], or more preferably, from 5 to 20 [ml/min.]. 
     The upper limit value is set at 25 [ml/min.] because a flow rate of over 25 [ml/min.] causes a decrease in R 23  and R 34 , as shown in FIG.  41 . Within the main column temperature range of from 105 to 115° C., the carrier gas flow rate should preferably be within a range of from 2 to 10 [ml/min.], or more preferably, 5 [ml/min.], as shown in FIG.  42 . The upper limit value is set at 10 [ml/min.] because a flow rate of over 10 [ml/min.] leads to an R 23  of under 1.4 although R 34  is over 2.0 as shown in FIG.  42 . 
     Dimethyl sulfide, main column length of 10 m: 
     Referring again to FIG. 33, when analyzing dimethyl sulfide with a main column length of 10 m, the main column temperature should preferably be within a range of from 125 to 140° C., or more preferably, 130° C. Within this temperature range, the retention time of dimethyl sulfide is longer than that of pentane as shown in FIG. 36, resulting in a chromatogram as shown in FIG.  29 [ b] . Therefore, R 23  is the resolution for pentane and dimethyl sulfide, and R 34  is the resolution for dimethyl sulfide and isoprene. In order to ensure clear separation of dimethyl sulfide, both R 23  and R 34  must be at least certain values. The lower limit value is set at 125° C. because a value of under 125° C. results in an R 23  of under 1.3 as shown in FIG.  33 . The upper limit value is set at 140° C. because a value of over 140° C. leads to an R 34  of under 1.3 as shown in FIG.  33 . 
     In this case, the carrier gas flow rate should preferably be within a range of from 3 to 6 [ml/min.], or more preferably, 5 [ml/min.]. The lower limit value is set at 3 [ml/min.] because a value of under 3 [ml/min.] results in an R 23  of under 1.4 as shown in FIG.  35 . The upper limit value is set at 6 [ml/min.] because a value of over 6 [ml/min.] leads to an R 23  of under 1.4 as shown in FIG.  35 . 
     Dimethyl sulfide, main column length of 25 m: 
     Referring again to FIG. 40, when analyzing dimethyl sulfide with a column length of 25 m, the main column temperature should preferably be within a range of from 80 to 115° C., or more preferably, from 90 to 110° C. Within this temperature range, the retention time of pentane is longer than that of dimethyl sulfide as shown in FIG. 43, resulting in a chromatogram as shown in FIG. 29 [a] . Therefore, R 12  is the resolution for ethanol and dimethyl sulfide, and R 23  is the resolution for dimethyl sulfide and pentane. In order to ensure clear separation of dimethyl sulfide, both R 12  and R 23  must be at least certain values. The lower limit value is set at 80° C. because a temperature of under 80° C. tends to give an R 12  of under 1.5 as shown in FIG.  40 . The upper limit value is set at 115° C. because a temperature of over 115° C. results in an R 23  of under 1.6. 
     When analyzing dimethyl sulfide with a column length of 25 m, the carrier gas rate should preferably vary between the main column temperature range of from 80 to 105° C. and the range thereof of from 105 to 115° C. At a main column temperature within the range of from 80 to 105° C., the carrier gas flow rate should preferably be within a range of from 2 to 25 [ml/min.], or more preferably, from 5 to 20 [ml/min.] as shown in FIG.  41 . At a temperature of 100° C. as shown in FIG. 23, the retention time of pentane is longer than that of dimethyl sulfide as shown in FIG. 43, resulting in a chromatogram as shown in FIG.  29 [ a] . Therefore, R 12  is the resolution for ethanol and dimethyl sulfide, and R 23  is the resolution for dimethyl sulfide and pentane. To ensure clear separation of dimethyl sulfide, both R 12  and R 23  must be at least a certain value. The lower limit value is set a 2 [ml/min.] because a flow rate of under 2 [ml/min.] cannot give a sufficient signal intensity. The upper limit value is set at 25 [ml/min.] because a flow rate of over 25 [ml/min.] tends to give an R 23  of under 1.5 as shown in FIG.  41 . At a main column temperature within the range of from 105 to 115° C., the carrier gas flow rate should preferably be within a range of from 2 to 10 [ml/min.], or more preferably, 5 [ml/min.] as shown in FIG.  42 . The upper limit value is set at 10 [ml/min.] because a flow rate of over [ml/min.] results in an R 23  of under 1.4. 
     Isoprene, main column length of 10 m: 
     Referring again to FIG. 33, when analyzing isoprene with a column length of 10 m, the main column temperature should preferably be within a range of from 20 to 140° C., or more preferably, from 30 to 130° C. Within this temperature range, as shown in FIG. 36, the retention time of isoprene is always longer than that of dimethyl sulfide or pentane, resulting in a chromatogram shown in FIG.  29 [ a]  or  29   [b] . Therefore, R 34  is the resolution for isoprene and dimethyl sulfide or pentane. To ensure clear separation of isoprene, R 34  must be at least a certain value. The lower limit value is set at 20° C. (room temperature) because a lower temperature only leads to a longer retention time as shown in FIG. 30, and is not considered to affect separation of isoprene from the other constituents as shown in FIG.  30 . The upper limit value is set at 140° C. because a temperature of over 140° C. leads to an R 34  of under 1.3 as shown in FIG.  33 . 
     As shown in FIG. 35, the carrier gas flow rate should preferably be within a range of from 2 to 10 [ml/min.], or more preferably, 6 [ml/min.]. At a temperature of 130° C. as shown in FIG. 35, the retention time of dimethyl sulfide is longer than that of pentane as shown in FIG. 36, resulting in a chromatogram shown in FIG. 29 [b] . Therefore, R 34  is the resolution for dimethyl sulfide and isoprene. To ensure clear separation of isoprene, R 34  must be at least a certain value. The lower limit value is set at 2 [ml/min.] because a flow rate of under 2 [ml/min.] leads to an R 34  of under 1.6 as shown in FIG.  35 . The upper limit value is set at 10 [ml/min.] because a flow rate of over 10 [ml/min.] leads to an R 34  of under 1.6 as shown in FIG.  35 . 
     Isoprene, column length of 25 m: 
     Referring again to FIG. 40, when analyzing isoprene in a main column having a length of 25 m, the main column temperature should preferably be within a range of from 80 to 150° C., or more preferably, from 90 to 110° C. Within this temperature range, as shown in FIG. 43, the retention time of isoprene is always longer than that of dimethyl sulfide or pentane, resulting in a chromatogram shown in FIG.  29 [ a]  or  29 [ b] . Therefore, R 34  is the resolution for isoprene and dimethyl sulfide or pentane. To ensure clear separation of isoprene, R 34  must be at least a certain value. The lower limit value is set at 80° C. because a temperature of under 80° C. tend to give an R 34  of under 1.5 as shown in FIG.  40 . The upper limit value is set at 150° C. because a value of over 150° C. gives an R 34  of under 1.6 as shown in FIG.  40 . 
     As shown in FIG. 41, the carrier gas flow rate should preferably be within a range of from 2 to 25 [ml/min.], or more preferably, from 5 to 20 [ml/min.]. At a temperature of 100° C. as shown in FIG. 22, the retention time of pentane is longer than that of dimethyl sulfide as shown in FIG. 43, resulting in a chromatogram as shown in FIG. 29 [a] . Therefore, R 34  is the resolution for pentane and isoprene. To ensure clear separation of isoprene, R 34  must be at least a certain value. The lower limit value is set at 2 [ml/min.] because a flow rate of under 2 [ml/min.] leads to unavailability of a sufficient signal intensity. The upper limit value is set at 25 [ml/min.] because a value of over 25 [ml/min.] tends to give an R 34  of under 1.6 as shown in FIG.  22 . 
     Referring to FIGS. 44 to  47 , it is possible to obtain a satisfactory chromatogram at a temperature set in response to the particular use. 
     The results of optimization of analytical conditions have been described above for cases where main columns  14  having lengths of 10 [m] and 25 [m] are used. When considering the difference in performance of the main column  14  based on the difference in length of the main column  14 , results similar to those obtained with the main column  14  having a length of 10 [m] are considered to be available under the foregoing analytical conditions even when using a main column having a length within a range of from 8 to 12 [m], and even for a main-column having a length within a range of from 20 to 30 [m], similar results as those of the main column  14  having a length of 25 [m] are considered to be available under the foregoing analytical conditions. 
     The above-mentioned temperature and flow rate are controlled by means of the controller  44 . 
     The entire disclosure of Japanese patent Applications: 
     No. 7-270533 filed on Sep. 25, 1995; 
     No. 7-319553 filed on Nov. 14, 1995; 
     No. 8-073208 filed on Mar. 4, 1996; 
     No. 8-191342 filed on Jul. 2, 1996; 
     No. 8-231371 filed on Aug. 13, 1996; 
     No. 8-231372 filed on Aug. 13, 1996; and 
     No. 9-145846 filed on May 20, 1997, 
     including the specification, claims, drawings and summary are incorporated herein by reference in its entirety.