JP2012163475A - Content determination method in gas chromatography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively measure the existence of a substance to be regulated contained in a component and concentration thereof to enable a content determination to be performed.SOLUTION: Provided is a method for determining a content of a predetermined substance to be analyzed in an object to be measured with a gas chromatograph analyzer. The method uses a column capable of securing a target detection lower limit, derives a peak start time of the substance to be analyzed from a chromatogram obtained by measuring a standard substance of the substance to be analyzed, and detects a peak where a start time, near the peak start time of the substance to be analyzed, is in a chromatogram obtained by analyzing the object to be measured. A content determination of the substance to be analyzed in the object to be measured is performed by comparing the detected peak start time of the object to be measured with the peak start time of the substance to be analyzed, and a content concentration thereof is calculated when the existence of a content is determined.

Description

  The present invention relates to a gas chromatography that allows easy determination of the content of a target substance in an object to be measured, and also relates to a gas chromatograph analyzer having a function that can easily determine the content.

  In gas chromatography, a mixture of various substances is gasified, and the mixture gas is passed through a tube (column) in which a thin film is formed on the inner wall. This is an analytical method for grasping the contents by sequentially separating the substance as it progresses through the column and detecting in order with a detector installed at the end of the column.

  Gas chromatography is used in various fields, and in particular, as environmental awareness has increased, there has been an active movement to regulate and investigate the use of hazardous substances in industrial products. For the purpose of investigation, analysis by gas chromatography is frequently performed.

  For the identification of substances in gas chromatography, use the time (holding time) from the start of analysis until it is detected by the detector, and analyze the target standard in advance to determine the holding time of the target substance. The substance is identified by comparison with the time. The analytical column can be said to be the heart of the analysis that greatly affects the separation performance of the analysis target substance, and various types of columns having different lengths, inner diameters, inner film thicknesses and types are commercially available. Analysts select a column that matches the type of analyte and sample volume with the goal of obtaining a peak with a shape close to a normal distribution in order to obtain accurate results. If there is a sample load exceeding 1, the peak shape becomes distorted. In particular, when a sample with a large sample load coexists, a phenomenon in which the retention time important for substance identification shifts backward (referred to as “reading”) occurs, and accurate determination is often impossible.

  In Patent Document 1, the rise of a peak detected in the vicinity of the peak start time of the standard substance of the analysis target substance is grasped, and the gain of the detector that detects the peak is changed, so that a low concentration and a high concentration are obtained. A method is disclosed in which the gains of detectors that match each other are ensured even when they are mixed, and the concentrations of both are accurately detected.

JP-A-6-148165

  When performing analysis by gas chromatography on a vast number of parts used in industrial products, the content of analytes contained in the measurement object and the presence of coexisting substances that affect the results are often unknown. .

  By the way, grasping how the peaks detected near the peak start time of the standard substance of the analysis target substance are grasped, and the gain of the detector that detects the peak is changed, so that a low concentration and a high concentration are mixed However, in the method of detecting the concentration by ensuring the detector gain that matches each, if the sample load greatly exceeds the allowable amount of the column (reading occurs), the detector gain is optimized. Even if it is set to a value, the retention time depends on the performance of the column. Therefore, the retention time, which is a determination criterion for inclusion, is shifted in the direction of increasing, and the substance cannot be identified by the retention time. Therefore, the analysis must be performed again by changing the injection amount to the analysis condition reduced to the sample allowable amount of the column, resulting in a loss of measurement time and sample preparation. Furthermore, since there is an apparatus limitation in adjusting the injection amount, when the content of the target substance greatly exceeds the sample load on the column, the sample is injected beyond the adjustment range. In that case, it is necessary to replace the column with a large sample capacity in order to perform accurate identification, and a time loss of more than half a day due to the replacement of the column occurs.

  As a result, there is a problem that the measurement efficiency of regulated substances such as harmful substances contained in industrial product components is lowered.

  An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to enable the content determination by efficiently measuring the presence / absence and concentration of a regulated substance in a part.

  In order to solve the above problems, the present inventor has conducted various experimental studies. As a result, when the sample loading amount is injected exceeding the column allowable amount, the retention time of the detection peak depends on the sample loading amount. The peak start time was not affected by the sample loading, and was found to be constant as long as the analysis conditions and column were not changed.

  Therefore, the present invention uses a column that can ensure the target lower detection limit, derives the peak start time of the analyte from the chromatogram obtained by measuring the standard substance of the analyte, In the chromatogram obtained by analyzing the peak, the peak having a start time near the peak start time of the analyte to be analyzed is detected, and the peak start time of the detected analyte and the peak start time of the analyte are determined. By comparing, the content determination of the substance to be analyzed in the object to be measured is performed, and when the content is determined to be included, the content concentration is calculated.

  In addition, in order to make it easier for the measurer to easily understand the peak start time of the standard substance to be analyzed and the peak start time on the chromatogram obtained from the object having a start time in the vicinity, A device having a function of simultaneously displaying the peak start time of the target standard substance and the peak start time existing in the vicinity thereof is used.

  According to the content determination method in the gas chromatography of the present invention, even when a sample exceeding the allowable load of the analytical column is injected, re-measurement by changing the analytical conditions or change of the column type is performed. In addition, it is possible to efficiently determine the content of a regulated substance in a part and measure its concentration.

Schematic of the gas chromatograph analyzer in one embodiment of the present invention The flowchart which shows the content determination method of the target substance to the to-be-measured object in one embodiment of this invention The figure showing the peak start time of the analysis target standard substance in one embodiment of the present invention The figure showing the peak start time on the chromatogram of the to-be-measured object in one embodiment of this invention

  Hereinafter, a content determination method in gas chromatography according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the configuration of a gas chromatograph analyzer for carrying out the content determination method in gas chromatography of the present invention.

  In FIG. 1, a sample introduction unit 1 heats and vaporizes a solution of a sample piece to be analyzed and a standard substance. Next, the vaporized gas is separated in the process of passing through the column 2, and the peak is detected by the detector 3 provided at the column outlet. The apparatus control unit 4 controls the series of analysis operations so as to satisfy preset conditions, and the data analysis unit 5 calculates a peak area and the like from the obtained results. Moreover, it has the display part 6 for seeing a control state and data, and the input part 7 for performing the setting of an analysis condition, a change of a result display form, etc.

  The flow chart of FIG. 2 shows steps for performing a content determination of a predetermined target substance in the object to be measured.

  As shown in FIG. 2, the target substance content determination method in the present invention includes a step (S1) of determining the peak start time of the analysis target substance by measuring the standard substance of the analysis target substance, and the object to be measured is gas chromatograph. Step (S2) for extracting the peak start time detected in the vicinity of the peak start time of the analyte in the chromatogram obtained by analyzing with the graph, and the peak start time extracted in step S2 and the step S1 A content determination step (S3) for comparing the peak start time and determining the result.

  In such a step, the step of grasping the peak start time of the substance to be analyzed will be described.

  Measurement is performed with a gas chromatograph analyzer using a solution or solid (referred to as a standard substance) whose concentration of an analysis target substance to be contained is known, and a chromatogram peak of the standard substance is obtained.

  FIG. 3 shows an example of a peak in the chromatogram of the standard substance of the analysis target substance. In FIG. 3, a tangent line with respect to the slope of the detection peak is drawn at a portion where the half value width 36 of the peak of the standard substance is reached, and an intersection of the tangent extension line 34 and the base line 35 is defined as a peak start time 32. Further, the time at the highest position of the peak is set as the retention time 33 of the peak. The peak retention time 33 is constant when it is within the range of the allowable sample load of the analytical column used, but when the upper limit of the allowable sample load is exceeded, the retention time becomes longer as the sample load increases. Although shifting in the direction, the peak start time 32 is constant.

  Next, the peak start time detected in the vicinity of the peak start time of the substance to be analyzed in the chromatogram of the object to be measured is extracted.

  A part to be measured is placed in a cup and loaded into the sample introduction unit 1 and heated using a heating wire or the like to gasify the contained components. The heating temperature may be about the same as the boiling point of the substance to be analyzed. As a method for gasifying the substance to be analyzed, in addition to the method of heating the object to be measured in the solid state as described above, a material completely dissolved in a solvent in advance may be injected into the sample introduction unit 1. In the chromatogram of the object to be measured, a peak having a starting point is extracted in the vicinity of the peak starting time of the target substance ascertained in advance. Here, the vicinity may be approximately ± 0.2 min, although it varies depending on the analysis conditions.

  FIG. 4 shows an example of a chromatogram obtained by analyzing an object to be measured that contains a large amount of the substance to be analyzed. A tangent to the slope of the detected peak is drawn at a portion where the detected peak has a half-value width 44, and the intersection of the tangent extension 41 and the base line 42 is defined as a peak start time 43.

  Next, a content determination step is performed.

  The peak start time 32 of the analysis target standard substance obtained in the above step is compared with the peak start time 43 in which the start point is detected in the vicinity of the peak start time of the analysis target standard substance in the chromatogram obtained by actual measurement. If both times match, it is determined that the target substance is contained, and if both times do not match, it is determined that the target substance is not contained.

  By taking the above steps, it is possible to easily determine whether the substance to be analyzed is contained in the object to be measured without remeasurement or replacement of the column.

  As described above, according to the present invention, it is a method for determining the content of a target substance determined in advance using gas chromatography in a measurement object, using a column that can ensure a target lower detection limit, Deriving the peak start time of the analyte from the chromatogram obtained by measuring the standard substance of the analyte, and the peak of the analyte in the chromatogram obtained by analyzing the analyte The sample load tolerance of the column used is determined by performing the steps of detecting a peak with a start time near the start time and comparing the peak start time of the detected analyte with the peak start time of the analyte. Over time, the loss of time due to reanalysis and column exchange with adjusted sample volume can be eliminated, greatly improving analysis efficiency. It can be achieved.

  Further, by having means for simultaneously displaying on the display unit 6 of the gas chromatograph analyzer the peak start time of the standard substance to be analyzed and the peak start time on the chromatogram obtained from the measurement object having a start time in the vicinity thereof. In the content determination work, the measurer can easily compare the peak start time of the target standard substance with the peak start time in the chromatogram obtained by measuring the measurement object without switching the screen. Therefore, the work efficiency can be improved.

  In addition, as a method of displaying the retention time on the display unit 6 of the chromatograph analyzer, the chromatogram of the target standard substance and the chromatogram of the object to be measured may be displayed so as to overlap each other with the peak start time as the center, Only both peak start times may be displayed on the screen.

  As described above, according to the present invention, it can be used for content determination of a substance to be analyzed using a gas chromatograph in a part or member used for an industrial product or the like and measurement of the content concentration.

DESCRIPTION OF SYMBOLS 1 Sample introduction part 2 Column 3 Detector 4 Apparatus control part 5 Data analysis part 6 Display part 7 Input part 32 Peak start time 33 Detection peak retention time 43 Peak start time

Claims (2)

A method for determining the presence of a predetermined target substance in a measurement object using a gas chromatograph analyzer, and measuring the standard substance of the target substance using a column that can ensure the target lower detection limit From the obtained chromatogram, the peak start time of the analyte is derived, and the peak with the start time near the peak start time of the analyte is detected in the chromatogram obtained by analyzing the measurement object. In addition, by comparing the peak start time of the detected analyte with the peak start time of the analyte, the content determination of the analyte in the analyte is performed. The content determination method in the gas chromatography characterized by calculating a density | concentration. The gas chromatograph analyzer has means for simultaneously displaying a peak start time of a standard substance to be analyzed and a peak start time on a chromatogram obtained from an object having a start time in the vicinity thereof. The content determination method in the gas chromatography of Claim 1.

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