Determination of Impurities in Solvent Ink by Gas Chromatography

Some solvent-based inks have a problem of slow dryness in the packaging and printing. The technician thinks that high-boiling solvents may be mixed. For this purpose, we determined the high-boiling impurities content of this solvent ink by gas chromatography.
1, the experimental part:
1.1, the main instruments and reagents:
Instrument: One-tenth of the analytical balance and PYE104 gas chromatograph produced by PYE, UK, using a hydrogen flame ion detector, color-filled glass column specification: 2000mm×3mm, stationary phase: 10% PEG-20M, support For the 100-120 mesh, the 807-IT type integrator manufactured by JASCO Corporation was used.
Reagents: Petroleum ether 30-60°C (Analytical Pure), A Solvent (Analytical Pure), B Solvent (Analytical Pure), C Solvent (Analytical Pure), Measured Solvent (Analytical Pure).
1.2. Pretreatment of samples:
Take a 10ml vial, add 5ml (30-60°C) of analytical pure petroleum ether at boiling point, add about two grams of ink sample, and stir well to make the solid components in the ink settle out. Then seal the cap and seal it. Yes, use it. During the measurement, take the solution in the bottle as a sample and measure the gas chromatogram. Petroleum ether is an additional precipitant. When calculating the measured solvent content, the content of petroleum ether should be reduced. With the solid content of the ink, the actual content of the solvent dissolved in the ink can be measured.
1.3, the production of standard samples:
Take 10ml vials, add analytical pure solvents A, B, and C in order, their weight ratios are prepared according to the actual proportion in the ink, and then the analytically measured solvent is added, and the ratio is as close as possible to the sample. The above four solvents were accurately weighed using an analytical balance. Then, pure petroleum ether was sampled and analyzed at a temperature of 30-60°C, and its weight ratio was also as close as possible to the sample. After configuration, seal and shake the vial and set it aside. When measuring, take the prepared solution as a standard and measure the gas chromatogram.
1.4, chromatographic conditions:
The carrier gas is high purity nitrogen with a flow rate of 40 ml/min; the column temperature is 90°C, the detector temperature is 150°C, the vaporization chamber temperature is 200°C, the amplifier attenuation is 16×10, and the integrator attenuation is 16mV The injection volume was 0.2 μl. Quantitative, using external standard method, with a single point correction.
1.5, sample determination:
(1) Determination of standard samples:
Take 0.2 μl of the prepared standard sample and inject it into the inlet of the gas chromatograph. For accurate measurement, inject the sample three times and take the average value.
Spectra and data of the first needle of the standard (RUN 227)




The calculation result of 0.5054% is the measured solvent proportion of the total solvent in the tested ink, and should also be converted into the proportion in the ink. For example, if the solvent accounts for 60% of the weight of the ink, the measured solvent content of the tested ink is:
0. 5054%×60%=0.30324%≈0.3%
2 Description:
2.1: For quantitative determination, we use a single point calibration of the external standard method. This method is easy to calculate and does not require correction factors. The single point calibration method is suitable for the case where the concentration of the component to be measured does not change much. It is also required to prepare a standard sample that has a very close content with the component to be measured. The injection volume of the standard sample and the sample should also be the same. The single-point calibration method also requires stable operating conditions and good reproducibility of injection volume. Otherwise, it will have a greater impact on the analysis results. The above requirements require attention during operation.
2.2: With our current sample pretreatment method, although the impurity content can be measured, it is contaminated with the GC column. Because the compounds in the sample are not necessarily all vaporized, the unvaporized components will remain in the column and contaminate the column. Therefore, the column needs to be processed, which is also worth noting.