JP5423601B2 - Headspace sampling device - Google Patents

Description

  The present invention relates to a headspace sample collection device that collects a sample gas volatilized from a sample solution contained in a sealed container and introduces the sample gas into a gas chromatograph device.

  One of the gas chromatography analysis methods is headspace analysis. In this analysis method, a sample gas is generated from a sample solution stored in an airtight container, and the sample gas collected in the upper space (head space) of the container is collected and introduced into a gas chromatograph for analysis (Patent Document) 1). Usually, the sample liquid is heated to a predetermined temperature to promote the generation of the sample gas. In this case, it is necessary to collect the sample gas after the gas-liquid equilibrium is reached at the predetermined temperature and the concentration of the sample gas is stabilized. .

  In general, the headspace sampling device is provided with a device that vibrates a sample container so that a gas-liquid equilibrium state can be realized at an early stage and analysis can be started at an early stage. For example, by inserting a sample container containing the sample liquid into a holding hole formed in the upper surface of the metal block and reciprocating it with a drive motor while heating the block with an electric heater or the like, the sample liquid in the sample container Is vibrated in the container.

Japanese Patent Laid-Open No. 11-72421

  The time until the sample liquid in the sample container and the sample gas in the upper space reach an equilibrium state and reach a uniform concentration (equilibrium arrival time) can be shortened by vibrating the sample container. It is generally not known if such a situation has been reached at that time. The equilibrium arrival time varies depending on the volume of the sample container, the amount of the sample liquid, the viscosity of the sample liquid, and the like. In the conventional headspace sampling device, the frequency of the sample container is set in advance in a plurality of stages (for example, “strong”, “medium” within the range applicable in most cases from the upper and lower limits of those parameters assumed. ”And“ Weak ”), and the user selects an appropriate frequency from among them.

  However, as described above, since there is actually no appropriate method for confirming whether the sample has reached a vapor-liquid equilibrium state, in many cases, the user has selected a higher frequency in anticipation of safety. As a result, there is a problem that the time until the start of analysis becomes longer than necessary. Conversely, if an appropriate frequency is selected incorrectly, the sample gas may be sucked before the gas-liquid equilibrium state is reached, and an incorrect sample may be analyzed.

  The present invention has been made in view of such points, and the object of the present invention is to accurately set the conditions for vibrating the sample container so that the time to reach equilibrium is as short as possible. It is to provide a headspace sampling device.

The headspace sampling device according to the present invention, which has been made to solve the above problems,
a) Condition input means for allowing the user to input a parameter value including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid;
b) Frequency determining means for determining the frequency for vibrating the sample container based on the value of the parameter input by the condition input means;
c) Vibrating means for vibrating the sample container according to the value of the frequency determined by the frequency determining means.

  Here, the frequency is the number of times the vibration of the sample container is repeated per unit time. The value is desirably set to a natural frequency when the liquid level of the sample liquid resonates in the sample container or a value close thereto. In addition, the frequency value depends on the temperature of the sample liquid in addition to the values of the three types of parameters, the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid. Good.

  The condition input means is not limited to direct input of the parameter value to the user, but presents a plurality of parameter value candidates to the user and allows the user to select a parameter value. Also good. Alternatively, a plurality of analysis method candidates previously associated with the parameter value may be presented to the user, and the user may be allowed to input the parameter value by selecting the analysis method.

  The frequency determining means may calculate and determine the frequency by performing a predetermined calculation based on the value of the parameter input by the condition input means. Further, a table in which the parameter value and the vibration frequency are associated in advance is built in, and the vibration frequency is extracted and determined from the table based on the parameter value input by the condition input means. Also good.

  In the case where the condition input means presents a plurality of parameter value candidates to the user in advance and allows the user to select a parameter value from among them, the parameter value candidates are not subdivided, but are roughly divided. It is desirable to select a correct value. For example, the types of sample containers are classified into large / small or large / medium / small grades prepared as standard. The amount of the sample liquid in the sample container may be three levels of many / medium / small and two levels of many / small. The types of sample liquids are classified according to their viscosities, and it is desirable to classify them as high viscosity / medium viscosity / low viscosity or high viscosity / low viscosity. The temperature of the sample liquid can also be classified into simple categories of high temperature / medium temperature / low temperature or high temperature / low temperature.

  In the headspace sampling device according to the present invention, the frequency determining means is based on the value of the parameter including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid input by the condition input means. The vibration frequency is determined, and the vibration means vibrates the sample container with the vibration frequency. As described above, by determining the frequency based on the parameters relating to the sample container and the sample solution, it is possible to accurately set the vibration condition for shortening the equilibrium arrival time. In addition, by resonating the sample liquid in the sample container at the natural frequency, the uniformity of the liquid phase and gas phase of the sample can be improved more effectively, and the time to reach equilibrium can be shortened. it can.

1 is a schematic configuration diagram of a headspace sampling apparatus according to an embodiment of the present invention. The top view of a metal block. The figure which shows the relationship between the angular velocity of a metal block and time, and the mode of the liquid level in a sample container.

  Hereinafter, a headspace sampling apparatus according to an embodiment of the present invention will be described with reference to the drawings. The headspace sample collection device 10 of the present embodiment is a device for collecting a sample gas volatilized from a sample solution stored in a sample container 20 with a syringe 18 and introducing the sample gas into a gas chromatograph device (see FIG. 1). The sample container 20 set in the apparatus is a general vial having a cylindrical inner wall and a flat bottom, and its mouth is sealed with a rubber septum.

  The headspace sampling apparatus 10 includes a metal block 11 that holds a plurality of sample containers 20. A plurality of holding holes 111 into which the sample containers 20 are inserted are formed on the same circumference on the upper surface of the metal block 11 (see FIG. 2). The metal block 11 rotates around the rotation shaft 112 while holding each sample container 20. A through-hole 113 through which a pin 171 (to be described later) can be passed is formed in the bottom surface of each holding hole 111.

  The through hole 113 revolves in a horizontal plane as the metal block 11 rotates. A pin 171 is disposed below a predetermined position in the movement path, and the pin 171 moves up and down by the air cylinder 17. A syringe 18 is disposed further above the sample container 20 held in the holding hole 111 above the air cylinder 17, and the syringe 18 has a sampling needle 181 protruding downward.

  A heater 12 is attached to the metal block 11. The heater 12 is a planar heater attached to the outer periphery of the metal block 11 in this embodiment, but may be a coiled heater built in the metal block 11 or the like.

  A drive motor 13 that rotates the metal block 11 via a rotating shaft 112 is disposed below the center of the metal block 11. The rotation angle of the drive motor 13 is controlled by the control unit 14.

  The control unit 14 includes a CPU, a memory, and the like, and is a computer that controls the drive motor 13, the air cylinder 17, and the syringe 18 based on a predetermined program. The display unit 15 and the operation unit 16 are connected to the control unit 14. The control unit 14 includes a condition input unit 141 and a frequency determination unit 142. The drive motor 13 corresponds to the vibration means in the present invention.

  The condition input unit 141 allows the user to input parameter values including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid. When the user directly inputs the parameter value, the parameter input screen is displayed on the display unit 15 and the user is made to input the parameter value by the operation unit 16.

  The condition input unit 141 is not limited to the parameter input directly input by the user as described above, and a plurality of parameter value candidates are presented to the user, and the parameter value is selected by the user from among them. It may be made to do. In this case, it is desirable to select a rough value instead of subdividing candidate values for each parameter. For example, the types of sample containers are classified into large / small or large / medium / small grades prepared as standard. The amount of the sample liquid in the sample container may be three levels of many / medium / small and two levels of many / small. The types of sample liquids are classified according to their viscosities, and it is desirable to classify them as high viscosity / medium viscosity / low viscosity or high viscosity / low viscosity. Furthermore, in addition to the above three parameters, the temperature of the sample solution may be input. The temperature of the sample liquid can also be classified into simple categories of high temperature / medium temperature / low temperature or high temperature / low temperature. Thus, the operability is improved by allowing the user to select a rough value.

  In addition, the condition input unit 141 presents a plurality of analysis method candidates previously associated with the parameter value to the user, and allows the user to select the analysis method to input the parameter value. Also good. In addition, the analysis method candidate not only defines the type of sample container to be used, the amount of sample liquid stored in the sample container, the parameter value including the type of sample liquid, but also the natural frequency. Also good. The analysis method may be a standard method defined by JIS or the like, or may be one uniquely set by the user.

  When the parameter value candidate or the analysis method candidate is selected by the user to input the parameter value, the condition input unit 141 displays the parameter value candidate or the analysis method candidate on the display unit 15. By causing the user to select a parameter value by the operation unit 16, the parameter value is input.

When a parameter value is input to the condition input unit 141, the frequency determining unit 142 sets a frequency for vibrating the sample container based on the parameter value. The frequency determining unit 142 determines the natural frequency ω _n by using the following equation, for example, using the value of the parameter relating to the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid.
R ・ (ω _n ) ² / g = k _ns・ tanh (k _ns・ h / R)
(J _n '(k _ns ) = 0; n, s = 1, 2,…)
R: radius of cylindrical container
h: Liquid depth
g: Gravity acceleration
J _n : n-th order Bessel function of the first kind
J _n ': Derivative of J _n
k _ns : J _n '(k _ns ) = 0 positive real root The above equation is a theoretical formula for calculating the natural frequency ω _n when water undergoes liquid level oscillation (sloshing) in a cylindrical container.

  The frequency determining unit 142 may determine the theoretical value of the natural frequency derived from the above theoretical formula as the frequency for vibrating the sample container as it is, but the actual experimental results and the fluid characteristics (dynamics of the sample liquid) The correction value obtained by correcting the theoretical value of the natural frequency may be determined as the frequency for vibrating the sample container by using a correction coefficient or the like built in the frequency determination unit 142 in advance in consideration of the viscosity and the like.

  The frequency determination unit 142 may perform calculation based on a theoretical formula based on the parameter value input by the condition input unit 141 and calculate and determine the frequency each time. It is also possible to incorporate a table associating the value and the vibration frequency, and extract and determine the vibration frequency from the table based on the parameter value input by the condition input unit 141.

  The condition input unit 141 is configured to present analysis method candidates to the user and to select parameter values by selecting them, and the analysis method candidates include the type of sample container to be used, the sample container In the case where not only the parameter value including the amount of the sample liquid stored in the container and the type of the sample liquid but also the natural frequency is specified, the frequency determining unit 142 is selected by the condition input unit 141. The natural frequency specified in the analysis method is determined as the frequency for vibrating the sample container as it is.

  Next, the operation of the head space sampling device 10 will be described. The following is a configuration in which the condition input unit 141 presents analysis method candidates to the user, and allows the user to select an analysis method from among them. The analysis method candidates are included in the type of sample container to be used and the sample container. This is an example in which not only the values of parameters including the amount of sample liquid to be stored and the type of sample liquid but also the natural frequency are specified.

  First, the user encloses a predetermined amount of sample solution in the sample container 20 according to the definition of the analysis method to be used, and inserts the sample container 20 into the holding hole 111 of the metal block 11. Then, the user selects an analysis method to be used using the operation unit 16 from the analysis method candidates displayed on the display unit 15 by the condition input unit 141.

  In this embodiment, since the natural frequency is defined for the analysis method candidate, the frequency determining unit 142 determines the natural frequency as it is as the frequency for vibrating the sample container. And the control part 14 drives the drive motor 13, and vibrates the metal block 11 currently heated with the heater 12 with the said natural frequency. Thereby, the sample liquid in the sample container 20 resonates in the container. By this resonance, the uniformity of the liquid phase and the gas phase of the sample can be effectively increased, and the time to reach equilibrium can be shortened.

  In the present embodiment, the control unit 14 intermittently rotates the metal block 11 in one direction in order to vibrate the sample liquid in the sample container 20. Specifically, as shown in FIG. 3, the angular velocity is changed in a trapezoidal wave shape. In this case, when the metal block 11 is stationary, the liquid level of the sample liquid is horizontal (state A). When the metal block 11 is rotated (accelerated) from this state, the liquid level of the sample liquid is tilted ( State B). After the angular velocity reaches a predetermined value, when the metal block 11 is moved at a constant speed while maintaining the angular velocity, the liquid level starts to return to the original horizontal state and becomes horizontal after a certain time (state C). After the liquid level becomes horizontal, the metal block 11 is decelerated. At this time, the liquid level is inclined in the opposite direction (state D). Then, when the metal block 11 is stopped, the liquid level starts to return to the original horizontal state and becomes horizontal after a certain period of time (state A '). Thereafter, similarly, the angular velocity is periodically changed, and the sample liquid is changed in the order of states A ′, B ′, C ′, D ′, A ″,... By making the reciprocal of the natural frequency determined in 142, the sample liquid can be resonated in the sample container 20. The rotation angle of one cycle of the metal block 11 is arbitrary, for example, 60 ° to 90 °. It can be.

  The control unit 14 vibrates the metal block 11 for a predetermined time, and then controls the rotation angle of the metal block 11 to move the sample container 20 to be sampled directly below the syringe 18 (directly above the air cylinder 17). Next, the control unit 14 drives the air cylinder 17 to insert the pin 171 into the through hole 113 to lift the sample container 20, and pierce the sampling needle 181 through the septum of the sample container 20. In this state, the syringe 18 is operated to collect the sample gas accumulated in the head space of the sample container 20 and introduce it into the gas chromatograph apparatus.

  It should be noted that the above embodiment is merely an example, and it is obvious that modifications and corrections can be made as appropriate in accordance with the spirit of the present invention. For example, in the above embodiment, the sample container 20 is vibrated by intermittently rotating the metal block 11 in one direction, but the sample container 20 may be vibrated by reciprocating rotation. Further, the sample container 20 may be vibrated by rotating the metal block 11 so that the angular velocity draws a continuous curve (for example, a sine curve). Furthermore, the sample block 20 may be vibrated by moving the metal block 11 linearly.

DESCRIPTION OF SYMBOLS 10 ... Head space sampling device 11 ... Metal block 111 ... Holding hole 112 ... Rotating shaft 113 ... Through-hole 12 ... Heater 13 ... Drive motor 14 ... Control part 141 ... Condition input part 142 ... Frequency determination part 15 ... Operation part 16 Display unit 17 Air cylinder 171 Pin 18 Syringe 181 Sampling needle 20 Sample container

Claims (7)

a) Condition input means for allowing the user to input a parameter value including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid;
b) Frequency determining means for determining the frequency for vibrating the sample container based on the value of the parameter input by the condition input means;
c) A head space sampling device comprising: vibration means for vibrating the sample container according to the frequency value determined by the frequency determination means.   2. The headspace sampling apparatus according to claim 1, wherein the frequency is a natural frequency when the liquid surface of the sample liquid resonates in the sample container.   The condition input means presents to the user the values of a plurality of parameter candidates including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid, and allows the user to select a parameter value. The head space sampling device according to claim 1, wherein the head space sampling device is provided.   The condition input means presents to the user a plurality of analysis method candidates associated with parameter values including the type of the sample container, the amount of the sample liquid in the sample container, and the type of the sample liquid, and the analysis method is presented to the user. The headspace sampling apparatus according to claim 1 or 2, wherein the parameter value is input by selecting.   The analysis method candidate is further associated with a frequency at which the sample container is vibrated, and the condition input means causes the user to select an analysis method, thereby further inputting a frequency value as the parameter value. 5. The headspace sampling apparatus according to claim 4, wherein the frequency determining means determines the value of the frequency input by the condition input means as a frequency for vibrating the sample container.   The frequency determination means calculates and sets the frequency by performing a predetermined calculation based on the parameter value input by the condition input means. 5. The headspace sampling apparatus according to any one of 4 above.   The frequency determining means incorporates a table in which the parameter value and the frequency are associated with each other, and extracts the frequency from the table based on the information input by the condition input means, thereby calculating the frequency. The headspace sampling device according to any one of claims 1 to 4, wherein the headspace sampling device is set.

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