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Method for predicting multi-order temperature programming retention time according to nonlinear plate theory

A technology of programmed temperature rise and retention time, applied in the field of chromatography, can solve the problems of cumbersome determination and calculation process

Active Publication Date: 2012-05-09
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Although this method can predict the retention time more accurately, it needs to accurately measure the initial viscosity of the carrier gas, correct the viscosity of the carrier gas in different constant temperature sections, and measure the pressure at the inlet and outlet of the chromatographic column to calculate the carrier gas viscosity. The pressure drop at different positions in the column, and the pressure needs to be corrected, this measurement and calculation process is very cumbersome

Method used

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  • Method for predicting multi-order temperature programming retention time according to nonlinear plate theory
  • Method for predicting multi-order temperature programming retention time according to nonlinear plate theory
  • Method for predicting multi-order temperature programming retention time according to nonlinear plate theory

Examples

Experimental program
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Effect test

Embodiment 1

[0070] Instruments: HP6890 gas chromatograph, hydrogen flame ionization detector, 6890 gas chromatograph workstation;

[0071] Chromatographic column: non-polar HP-5 (5% phenylmethyl polysiloxane) column;

[0072] Conditions: The temperature of the detector is 250°C, and the temperature of the injection port is 250°C;

[0073] 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;

[0074] Injection method: split injection, the split ratio is 50:1, each injection volume is 0.2ul, the initial concentration C S00 = 1 μg / ml;

[0075] (1) Select isoamyl acetate as the compound to be tested, and measure its retention time at six constant temperatures of 30°C, 50°C, 100°C, 150°C, 200°C and 250°C on the HP-5 column, which are respectively 34.41min, 13.50min, 3.90min, 2.63min, 2.24min and 2.04min;

[0076] (2) Get virtual dea...

Embodiment 2

[0091] The process and condition of the present embodiment are identical with embodiment 1, and difference is:

[0092] (1) virtual dead time τ becomes 0.05min by 1.85min, calculates the retention factor of isoamyl acetate under six constant temperatures according to formula 1, they are respectively: 687.20, 269.00, 77.00, 51.60, 43.80 and 39.80; Then use Equation 2 fits the curves of the relationship between the retention factor and the temperature at six constant temperatures, and obtains the parameters a, b, c and d, which are respectively: -6×10 -7 , 0.0009, -0.4014 and 66.091; thus the relationship between the retention factor and the temperature of each compound during the temperature programming process

[0093] lnk=-6×10 -7 T 3 +0.0009T 2 -0.4014T+66.091

[0094] Choose from six different temperature programs, which are:

[0095] A program temperature rise 30°C (hold 2min) → 5°C / min → 70°C (hold 1min) → 25°C / min → 250°C;

[0096] B Program temperature rise 30°C (...

Embodiment 3

[0106] (1) Select ethanol as the compound to be tested, and measure its retention time at six constant temperatures of 30°C, 50°C, 100°C, 150°C, 200°C and 250°C on the HP-5 column, and they are 4.74min, 2.89min, 1.74min, 1.50min, 1.39min and 1.36min;

[0107] (2) Get τ=1.00min, calculate the retention factor of ethanol under six constant temperatures according to formula 1, they are respectively: 3.74, 1.89, 0.74, 0.50, 0.39 and 0.36; Then use formula 2 to the retention under six constant temperatures The curve of the relationship between the factor and the temperature is fitted to obtain the parameters a, b, c and d, which are respectively: -3×10 -7 , 0.0005, -0.2407 and 38.011; thus the relationship between the retention factor and temperature of each compound during the temperature programming process

[0108] lnk=-3×10 -7 T 3 +0.0005T 2 -0.2407T+38.011

[0109] Choose from three different temperature programs, which are:

[0110] D program temperature rise 30°C (hold...

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Abstract

The invention discloses a method for predicting multi-order temperature programming retention time according to a nonlinear plate theory. The method comprises the following steps of: determining the retention time of a compound to be determined at six constant temperatures, and determining virtual dead time; computing retention factors of the compound to be determined at six constant temperatures, and determining a corresponding retention factor at any jump in a column according to a cubic equation between the retention factors and a temperature relation; and computing the concentration in the mobile phase of a last column plate at any jump of the compound to be determined, and computing time needed by jumping which serves as the retention time. In the invention, the retention time can bepredicted by only optionally setting the virtual dead time, so that the prediction process is very simple and convenient; and meanwhile, the influences of temperature on entropy and enthalpy are considered, so that the method has a wide application range and high prediction accuracy.

Description

technical field [0001] The invention relates to a method for predicting the retention time of multi-stage temperature programming by using nonlinear plate theory, and belongs to the technical field of chromatography. Background technique [0002] Chromatography is a very efficient technique for separating the components of complex compounds. However, for complex compounds with a wide range of boiling point composition, temperature programming is required for separation, and it is very time-consuming to select appropriate chromatographic separation conditions. Retention time is an important parameter for the qualitative analysis of chromatography and the thermodynamic properties of the chromatography process. For temperature-programmed gas chromatography, knowing the retention behavior of sample components is the basis for optimizing operating conditions. Therefore, the prediction of retention time becomes an important step in the optimization of temperature-programmed opera...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/02
Inventor 范国樑皇甫旭丹张兰兰敖敏
Owner TIANJIN UNIV
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