JP2006292613A - Gas chromatograph device, and data processing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To utilize as a reference an analysis result of a material which is not a reference material not requiring analysis essentially, by imparting interchangeability to a retention index based on a different material. <P>SOLUTION: Three kinds of compounds α, β, γ whose retention indexes based on an n-alkane are known and two kinds of compounds δ, ε whose retention indexes based on a derived fatty acid are known are analyzed in the same analysis condition, to thereby acquire a retention time of each compound (S1, S2). The retention index based on the n-alkane is estimated from each retention time of the compounds δ, ε based on the relation between each retention time and each retention index of the compounds α, β, γ (S3, S4), and a conversion formula showing the relation between a retention index estimated value based on the n-alkane and the retention index based on the derived fatty acid is determined (S5). Each retention index based on the n-alkane can be estimated, relative to all the other compounds whose retention indexes based on the derived fatty acid are known by using the conversion formula (S6). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas chromatograph apparatus for separating and analyzing sample components using a column, and a data processing method for identifying a peak appearing on a chromatogram in the apparatus.

  In general, in gas chromatographic analysis, a retention time, which is a time required for a compound to pass through a column, is used to identify a peak appearing in a chromatogram. However, the retention time is not a value inherent to the component, but is a value that varies depending on various analysis conditions such as carrier gas flow rate, column temperature, column size, and column liquid phase thickness. Therefore, unless these various analysis conditions are the same, it is impossible to accurately identify the peak using the retention time. In addition, even if the analysis conditions as described above are the same in different apparatuses, the retention time is not necessarily the same due to the inter-instrument difference. Therefore, there is a peak identification retention time database created using a certain apparatus. In some cases, it cannot be used in other devices as it is.

  Therefore, a retention index (retention index) is conventionally used as a parameter that does not depend on analysis conditions or instrument differences, unlike the retention time (see, for example, Patent Document 1). The retention index in the GC analysis will be briefly described with reference to FIG. Here, consider the case where the most common n-alkane homologue series is the reference substance.

Now, based on the appearance position of the methane (CH ₄ ) peak in the chromatogram shown in FIG. 6, the retention times of the adjacent C _n and C _{n + 1} peaks of the _n -alkane are t ₁ and t ₂ , respectively. To do. At this time, when the retention time of the substance X existing between C _n and C _{n + 1} is t _x , the retention index RIx of the substance X is defined by the following equation (1) in the isothermal analysis.
RIx = [(logt _x -logt ₁ ) / (logt ₂ -logt ₁ )] × 100 + 100 × n (1)
Further, in the temperature rising analysis (for example, the temperature rising rate: 20 ° C./min), the retention index RIx of the substance X is defined by the following equation (2).
RIx = [(t _x −t ₁ ) / (t ₂ −t ₁ )] × 100 + 100 × n (2)
A retention index database is obtained by performing GC analysis on various compounds together with n-alkanes to obtain respective retention times, calculating retention indices based on the formula (1) or (2), and collecting the retention indices.

  The above-mentioned retention index database using n-alkane as a reference substance is the most common, and retention of various substances under various conditions (for example, the type of column liquid phase) from various research institutions and universities. An indicator database has been announced. In addition, the reference substance of the retention index is not necessarily n-alkane. For example, the retention substance is polycyclic aromatic such as benzene or DIPA [1- (N, N-diisopropyl-amino) -alkane]. An indicator database is also provided.

  When performing peak identification of unknown substances appearing in chromatograms using such a retention index database, there is an advantage that the retention index has little dependency on the equipment and analysis conditions, so there is no need to worry about these factors. On the other hand, it is necessary to analyze the reference material in the retention index database together with the unknown material to be identified under the same conditions. Therefore, for example, even when a holding index database having n-alkane as a reference substance is at hand, if there is no standard sample for n-alkane analysis, peak identification using the holding index database cannot be performed. . Conversely, even when a retention index database using polycyclic aromatics as a reference material is provided, if there is no standard sample for analyzing the reference material, peak identification using the retention index database cannot be performed.

  In addition, when an ion source based on negative chemical ionization (NCI) is used in a gas chromatograph mass spectrometer (GC / MS) using a mass spectrometer as a detector for a gas chromatograph, n-alkane is used due to its characteristics. It cannot be detected. Therefore, in such an analysis, peak identification using a retention index database using n-alkane as a reference substance cannot be performed.

JP-A-11-201960

  The above problems are caused by the incompatibility of retention index databases based on different reference materials. The present invention has been made in view of these points, and the object of the present invention is to associate retention indexes created based on different reference materials and convert them into retention index values based on different reference materials. It is an object of the present invention to provide a gas chromatograph apparatus and a data processing method in the apparatus capable of providing compatibility by performing the above.

A first invention made to solve the above problems is a gas chromatograph apparatus for identifying a peak on a chromatogram using a retention index.
a) a plurality of first substances whose retention indices based on the first reference substance are known, and a plurality of second substances whose retention indices are known based on a second reference substance different from the first reference substance Analyzing execution means for obtaining the retention time of each substance by analyzing under the same analysis conditions;
b) A retention index for estimating a retention index based on the first reference substance from the retention time of the second substance based on the relationship between the retention times of the plurality of first substances and the known retention indices of the respective substances. An estimation means;
c) holding index conversion information acquisition means for obtaining a relationship between the holding index estimated by the holding index estimation means based on the first reference substance of the second substance and the holding index of each substance based on the second reference substance; ,
d) Using the relationship obtained by the retention index conversion information acquisition means, the second reference substance is used as a reference for substances other than the second substance whose retention index is known based on the second reference substance. Holding index conversion means for converting the holding index into a holding index based on the first reference substance;
It is characterized by having.

Further, a second invention made to solve the above problems is a data processing method of a gas chromatograph apparatus for identifying a peak on a chromatogram using a retention index,
A plurality of first substances whose retention indices based on the first reference substance are known, and a plurality of second substances whose retention indices are known based on a second reference substance different from the first reference substance, Analyze under the same analysis conditions to obtain the retention time of each substance,
Based on the relationship between the retention times of the plurality of first substances and the known retention indices of the respective substances, the retention indices based on the first reference substance are estimated from the retention times of the second substances, respectively.
Obtain the relationship between the estimated retention index of the second substance based on the first reference substance and the retention index of each substance based on the second reference substance,
Using this relationship, the retention index based on the second reference substance is used as the reference for the first reference substance for substances other than the second substance whose retention index based on the second reference substance is known. It is characterized by being converted to a retention index.

  In the gas chromatograph apparatus according to the first invention that embodies the data processing method according to the second invention, the analysis execution means includes a plurality of retention indexes whose reference is based on the first reference substance under the same analysis conditions. A GC analysis is performed on the first substance and a plurality of second substances whose retention indices are known based on a second reference substance different from the first reference substance, and a retention time of each substance is obtained. The GC analysis of the first substance and the second substance may be performed simultaneously in one measurement or may be performed at different times. As a result of the GC analysis, the correspondence relationship between the retention times of the plurality of first substances and the known retention indices of the respective substances is clarified. Therefore, the retention index estimating means retains the second substance based on the relations. Retention indices based on the first reference substance are estimated from the time.

  Next, the retention index conversion information acquisition means obtains a correspondence relationship between the estimated retention index based on the first reference substance of the second substance and the known retention index based on the second reference substance of each substance, for example, A conversion formula and conversion table are derived from the relationship. The retention index conversion means uses, for example, this conversion formula or conversion table, with respect to other substances other than the second substance whose retention index based on the second reference substance is known, based on the second reference substance. The retention index is converted into a retention index based on the first reference substance. Thereby, a retention index based on the first reference substance is obtained as an estimated conversion value for each substance for which only the retention index for the second reference substance was previously known.

  As a result, for example, a retention index database based on the second reference substance can be converted into a database of retention index conversion values based on the first reference substance, so that the first reference substance is identified instead of the second reference substance. It becomes possible to identify the unknown substance based on the result of the GC analysis together with the target unknown substance. Therefore, even when it is desired to perform peak identification using the retention index database based on the second reference material, it is not necessary to prepare the second reference material, and the analysis work can be simplified.

  In addition, even when n-alkane cannot be detected as in NCI of GC / MS, a huge retention index database based on n-alkane is used for peak identification using other detectable reference materials. Can do. When n-alkane cannot be detected as in the NCI of GC / MS, the NCI is temporarily replaced with NCI when determining the retention time of a substance whose retention index is known using n-alkane as a reference substance. The GC / MS analysis may be performed using an ionization method capable of detecting n-alkane, for example, an electron impact ionization method (EI).

  Hereinafter, an embodiment of a gas chromatograph apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of a gas chromatograph apparatus according to this embodiment.

  A sample vaporizing chamber 2 is provided at the inlet of the column 5 installed in the column oven 4, and a carrier gas is sent into the column 5 through the sample vaporizing chamber 2 from the carrier gas introduction tube 3 at a constant flow rate. When a small amount of liquid sample is injected into the sample vaporizing chamber 2 from the injector 1 at a predetermined timing, the liquid sample is vaporized in a short time and is carried into the column 5 on the carrier gas. The column 5 is maintained at a constant temperature by the column oven 4 (in the case of constant temperature analysis), or the temperature rise is controlled according to a predetermined temperature rise program (in the case of temperature rise analysis). While passing through the column 5, various compounds contained in the liquid sample are separated in the longitudinal direction of the column 5, eluted from the column 5 with a time lag, and detected by the detector 6.

  The detection signal of the detector 6 is sent to the data processing unit 10, where a chromatogram is created, and further, predetermined data processing is executed to perform qualitative analysis and quantitative analysis. The control unit 7 achieves the GC analysis operation by controlling the operation of the data processing unit 10 and each of the above units. Connected to the control unit 7 are an input unit 8 for an analyzer to give various instructions and set conditions, and a display unit 9 for displaying analysis results and the like. Many of the functions of the control unit 7 and the data processing unit 10 are realized, for example, by operating a predetermined control / processing program on a personal computer. Further, as a characteristic configuration of the present embodiment, the data processing unit 10 includes a holding index conversion processing unit 11 as a part of the function, and the holding index conversion processing unit 11 includes a first holding index database 13 and a preset first holding index database 13. The conversion holding index database 12 is created based on the 2 holding index database 14.

  In this embodiment, the retention index of various compounds with n-alkane as a reference substance is recorded in the first retention index database 13 corresponding to the compound name, and the second retention index database 14 is PFB-Br. Retention indices of various compounds using derivatized fatty acids (hereinafter referred to as “derived fatty acids”) as reference substances are recorded corresponding to the compound names. Since the reference substances are different, the retention index is different even for the same compound.

  Next, the retention index conversion function executed mainly by the retention index conversion processing unit 11 in the gas chromatograph apparatus of the present embodiment will be described with reference to the flowchart of FIG.

  First, under the control of the control unit 7, predetermined analysis conditions for three types of compounds α, β, and γ recorded in the first retention index database 13 and having known retention indices based on n-alkane are known. The GC analysis is executed at (here, temperature rise analysis). By this analysis, a chromatogram as shown in FIG. 3A is acquired, and retention times (RT) a, b, and c of each compound α, β, γ are obtained (step S1). In FIG. 3, the retention index based on n-alkane is described as ◯ RI, and the retention index based on derived fatty acid as ΔRI. For these three compounds α, β and γ, the combination (RT, ○ RI) of the retention time (RT) and the retention index (○ RI) based on n-alkane is (a, A), (b , B), (c, C).

  Next, under the control of the control unit 7, the two compounds δ and ε that are recorded in the second retention index database 14 and whose retention index based on the derived fatty acid is known are the same as in the above analysis. Perform GC analysis under analytical conditions. By this analysis, a chromatogram as shown in FIG. 3B is acquired, and retention times (RT) d and e of the respective compounds δ and ε are obtained (step S2). For these two types of compounds δ, ε, combinations (RT, ΔRI) of retention time (RT) and retention index (ΔRI) based on derived fatty acids are (d, D), (e, E) It becomes.

  The compounds α, β, γ and the compounds δ, ε are not necessarily analyzed in two steps, but may be analyzed at once by using a sample in which all of them are mixed.

  On the graph with (RT, ○ RI) based on the above analysis results for compounds α, β, and γ, with the retention time (RT) on the horizontal axis and the retention index (○ RI) based on n-alkane on the vertical axis Is plotted as points Pa, Pb, and Pc in FIG. Therefore, a line passing through these three points Pa, Pb, and Pc is drawn. In FIG. 4, lines for linearly interpolating two adjacent points Pa and Pb and Pb and Pc are drawn, but for example, assuming an nth order polynomial, the nth order polynomial passes through three points. A polynomial coefficient may be obtained. The line drawn here represents a conversion formula indicating the correspondence between the retention time under the above analysis conditions and the retention index based on n-alkane.

That is, the conversion formula from the holding time (RT) to the holding index (○ RI) is as follows for the holding time p where a ≦ p <b.
P ′ = [(BA) / (ba)] × (pa) + A (3)
For holding time p where b ≦ p ≦ c,
P ′ = [(C−B) / (c−b)] × (p−b) + B (4)
It is. These equations (3) and (4) are conversion equations for obtaining a retention index based on n-alkane from the retention time p (step S3).

  Next, the retention index conversion processing unit 11 applies the retention times d and e obtained by the GC analysis for the compounds δ and ε to the conversion formulas of the above formulas (3) and (4). Estimated values D ′ and E ′ of the holding index are obtained (step S4). For these compounds δ and ε, since the retention index (ΔRI) based on the derived fatty acid is known from the second retention index database 14, for example, the horizontal axis is the retention index ΔRI and the vertical axis is the n-alkane. When the above relationship is plotted on a graph in which the retention index is estimated with reference to, two points Pd and Pe shown in FIG. 5 are obtained. A line passing through these two points Pd and Pe is drawn. In FIG. 5, a line for linearly interpolating between the two points Pd and Pe is simply drawn. However, for example, an nth order polynomial may be obtained by increasing the number of compounds. The line drawn here represents a retention index conversion formula showing a correspondence relationship between a retention index based on n-alkane and a retention index based on derived fatty acid.

That is, the conversion formula from the retention index based on the derived fatty acid (ΔRI) to the retention index based on the n-alkane (◯ RI) is:
X ′ = [(E′−D ′) / (ED)] × (X−D) + D ′ (5)
(Step S5).

  The holding index conversion formula of the formula (5) is established for a compound with D ≦ X ≦ E, but a line obtained by interpolating between two points can be further extrapolated. And all the compounds having the retention index based on the derived fatty acid recorded in the second retention index database 14, or particularly necessary compounds, that is, all the compounds recorded in the second retention index database 14 Can be converted into a holding index based on n-alkane, that is, a converted holding index corresponding to the holding index described in the first holding index database 13 (step S6). Then, the value thus converted is registered in the conversion holding index database 12.

  In this way, the retention indices of all the compounds originally recorded in the second retention index database 14 based on the derived fatty acid are converted into retention indices based on the n-alkane and converted into the converted retention index database 12. Retained. Therefore, when identifying the peak appearing in the chromatogram by GC analysis of the unknown substance, the n-alkane is analyzed under the same conditions, and the peak is obtained from the analysis result, the first retention index database 13 and the reduced retention index database 12. Can be identified.

  In addition, by storing the conversion formula shown by the formula (5), the retention index based on the derived fatty acid can be converted into the retention index based on the n-alkane at any time. It is also possible to construct a retention index database based on an arbitrary reference substance by integrating the retention index databases of three or more different reference substances using the retention index conversion function as described above. .

  It should be noted that the above embodiment is merely an example of the present invention, and it is apparent that modifications and corrections can be made as appropriate within the scope of the present invention. For example, since various detectors can be used in the present invention, for example, the present invention can be applied to a gas chromatograph mass spectrometer combining a gas chromatograph and a mass spectrometer.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the gas chromatograph apparatus by one Example of this invention. The gas chromatograph apparatus of a present Example WHEREIN: The flowchart of the holding | maintenance index conversion function performed centering on a holding | maintenance index conversion process part. Explanatory drawing about the holding | maintenance parameter | index conversion processing operation in the gas chromatograph apparatus of a present Example. Explanatory drawing about the holding | maintenance parameter | index conversion processing operation in the gas chromatograph apparatus of a present Example. Explanatory drawing about the holding | maintenance parameter | index conversion processing operation in the gas chromatograph apparatus of a present Example. Explanatory drawing of a holding | maintenance parameter | index.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Injector 2 ... Sample vaporization chamber 3 ... Carrier gas introduction tube 4 ... Column oven 5 ... Column 6 ... Detector 7 ... Control part 8 ... Input part 9 ... Display part 10 ... Data processing part 11 ... Holding index conversion process part 12 ... Conversion holding index database 13 ... First holding index database 14 ... Second holding index database

Claims (2)

In a gas chromatograph that identifies peaks on a chromatogram using retention indices,
a) a plurality of first substances whose holding index is known based on the first reference substance, and a plurality of second substances whose holding index is known based on a second reference substance different from the first reference substance Analyzing execution means for obtaining the retention time of each substance by analyzing under the same analysis conditions;
b) A retention index for estimating a retention index based on the first reference substance from the retention time of the second substance based on the relationship between the retention times of the plurality of first substances and the known retention indices of the respective substances. An estimation means;
c) holding index conversion information acquisition means for obtaining a relationship between the holding index estimated by the holding index estimation means based on the first reference substance of the second substance and the holding index of each substance based on the second reference substance; ,
d) Using the relationship obtained by the retention index conversion information acquisition means, with respect to other substances other than the second substance for which the retention index based on the second reference substance is known, the second reference substance as a reference Holding index conversion means for converting the holding index into a holding index based on the first reference substance;
A gas chromatograph apparatus comprising: A data processing method of a gas chromatograph apparatus for identifying a peak on a chromatogram using a retention index,
A plurality of first substances whose retention indices based on the first reference substance are known, and a plurality of second substances whose retention indices are known based on a second reference substance different from the first reference substance, Analyze under the same analysis conditions to obtain the retention time of each substance,
Based on the relationship between the retention times of the plurality of first substances and the known retention indices of the respective substances, the retention indices based on the first reference substance are estimated from the retention times of the second substances, respectively.
Obtain the relationship between the estimated retention index of the second substance based on the first reference substance and the retention index of each substance based on the second reference substance,
Using this relationship, the retention index based on the second reference substance is used as the reference for the first reference substance for substances other than the second substance whose retention index based on the second reference substance is known. A data processing method for a gas chromatograph, wherein the data is converted into a retention index.

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