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Method for forecasting retention time of gas chromatography under temperature programming after shortening of chromatographic column

A technology of retention time and temperature programming, applied in the field of chromatographic analysis, can solve problems such as high cost, inability to be widely used, and great differences in measurement results

Inactive Publication Date: 2012-06-20
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

That is, the retention time of all samples decreased by at least 40% compared with before the column broke, which shows two problems: first, the two measurement results are very different; second, the reduction of retention time is not only affected by the column length, but also by the column length. Influence of internal flow and pressure change
However, this method is too expensive to be widely used

Method used

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  • Method for forecasting retention time of gas chromatography under temperature programming after shortening of chromatographic column
  • Method for forecasting retention time of gas chromatography under temperature programming after shortening of chromatographic column
  • Method for forecasting retention time of gas chromatography under temperature programming after shortening of chromatographic column

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0111] Instruments: HP6890 gas chromatograph, hydrogen flame ionization detector, 6890 gas chromatograph workstation;

[0112] Chromatographic column: non-polar HP-5 (5% phenylmethyl polysiloxane) column;

[0113] Original length, HP-5 (Crosslinked 5% PH ME Siloxane, 30m×0.32mm×0.25μm);

[0114] After shortening, HP-5 (Crosslinked 5% PH ME Siloxane, 22m×0.32mm×0.25μm);

[0115] Conditions: The temperature of the detector is 250°C, and the temperature of the injection port is 250°C;

[0116] Carrier gas: use high-purity nitrogen gas (purity not less than 99.999%), constant flow operation mode, that is, the carrier gas is at the outlet of the column, and the mass flow rate is kept constant at 1ml / min;

[0117] Injection method: split injection, the split ratio is 50:1, each injection volume is 0.2μl, the initial concentration C M00 = 1 μg / ml;

[0118] Programmed heating conditions: Programmed temperature start temperature T 0 =30°C, heating rate v=5°C / min, termination tempe...

Embodiment 2

[0140] The process and condition of the present embodiment are identical with embodiment 1, and difference is:

[0141] Programmed heating conditions: Programmed temperature start temperature T 0 =30°C, heating rate v=25°C / min, termination temperature T f = 250°C;

[0142] (1) only need to change the parameter value of the programmed temperature rise rate of the input of step (nine) in embodiment 1 into temperature rise rate v=25 ℃ / min; All the other parameter values ​​and prediction process are identical with embodiment 1;

[0143] (2) In order to verify the predicted value, it is necessary to start temperature T at the programmed temperature 0 =30°C, heating rate v=25°C / min, termination temperature T f =250°C, measure the real retention time of the three components on the shortened 22m HP-5 chromatographic column.

[0144] The error analysis between the predicted value and the measured value of the three substances under the above-mentioned programmed temperature rise cond...

Embodiment 3

[0148] The process and condition of the present embodiment are identical with embodiment 1, and difference is:

[0149] Samples: butyric acid, formaldehyde, heptane, methane, benzene;

[0150] (1) the process of step (1) in embodiment 1 is exactly the same;

[0151] (2) the process of step (2) in embodiment 1 is exactly the same;

[0152] (3) Respectively call the retention times of formaldehyde, heptane and standard substance benzene in the original length of 30m HP-5 column at 30°C, 50°C, 100°C, 150°C, 200°C and 250°C at six temperature points, they are respectively corresponds to:

[0153] 3.31min, 3.04min, 2.63min, 2.36min, 2.17min and 2.01min;

[0154] 8.43min, 5.17min, 3.00min, 2.46min, 2.19min and 2.01min;

[0155] 6.74min, 4.53min, 2.89min, 2.41min, 2.17min and 2.00min;

[0156] Because the retention time of butyric acid at low temperature is longer than 1 hour, the analysis time is too long, so only five temperatures of 50°C, 100°C, 150°C, 200°C and 250°C for but...

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Abstract

The invention discloses a method for forecasting retention time of gas chromatography under temperature programming after shortening of a chromatographic column. The method includes the steps: firstly, determining dead time and capacity factors corresponding to optional temperature points of an original chromatographic column and correcting the number of column plates of the shortened chromatographic column by using benzene as a standard substance; secondly, forecasting the retention time of components in the shortened chromatographic column under temperature programming; thirdly, measuring the retention time of the components in the shortened chromatographic column according to the determined temperature programming in the forecasting step; and fourthly, computing the relative deviation of the forecasted retention time of the components, and judging that forecasting precision meets requirements when the absolute value of the relative deviation is smaller than 2%. The method has the advantages that experimental cost is saved, the working intensity of analysis is reduced, practical ways are provided for selecting optimal separation conditions of the gas chromatography of the short column, the forecasting process is clear, and the method is applicable to wide-range popularization and application.

Description

technical field [0001] The invention relates to a method for predicting the retention time of gas chromatography under programmed temperature rise after the chromatographic column is shortened, and belongs to the technical field of chromatographic analysis. Background technique [0002] Chromatographic retention time is the basis of chromatographic analysis and an important basis for identifying the best separation conditions for compounds. At present, the prediction methods of retention time all use constant temperature data to predict the retention time of the same chromatographic column with the same column length under certain temperature, pressure or flow program conditions. However, with the frequent use of the chromatographic column, the column efficiency is damaged, and the improper replacement of different types of chromatographic columns during the experimental operation leads to the breakage of the column, which makes the length of the chromatographic column signi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/86
Inventor 范国樑张兰兰皇甫旭丹敖敏
Owner TIANJIN UNIV
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