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Gas Chromatography / Triple Quadrupole Mass Spectrometry ( TSQ8000 ) Internal Standard Method for Detection and Analysis of 17 Phthalates in Alcohol Products
Li Chunli
Thermo Fisher Scientific (China) Co., Ltd.
1 Introduction
In recent years, Phthalic Acid Esters (PAEs) have become one of the most common contaminants in the world due to their widespread use worldwide. PAEs are not food additives and are strictly prohibited from being added to food. In the announcement No. 16 of 2011 issued by the Ministry of Health, phthalate esters have been included in the sixth batch of blacklists of “non-edible substances that may be illegally added in foodâ€. A large number of studies have confirmed that the residues of PAEs in the human body will seriously affect the human reproductive system, immune system and nervous system, so that the hormones in the organism can not be secreted normally, leading to cell mutation, teratogenicity and carcinogenesis.
This paper uses the new generation of triple quadrupole gas chromatography mass spectrometer (TSQ 8000) internal standard method of Thermo Fisher Scientific to analyze and detect 17 phthalates in wine products. The effect of background interference in complex matrix samples is greatly reduced by the two-dimensional mass spectrometry scanning, and the detection sensitivity of the target compound is improved. The isotope internal standard method can reduce the influence of the stability of the instrument and offset the interference effect of the extraction process. The method has detection limit. Low, good stability, wide linear range and so on.
2. Experimental part
2.1 Instruments and reagents
Instrument: TSQ8000 Gas Chromatography - Triple Quadrupole Mass Spectrometer (Thermo Fisher Scientific, USA)
Column: TR-5MS 30m × 0.25mm × 0.25μm capillary column
Reagents: n-hexane, pesticide residue grade.
Liquor: purchased from the supermarket
2.2 Instrument method
Gas phase method:
Column oven: 60 ° C for 1 min, at 20 ° C / min to 220 ° C, for 1 min, then at 5 ° C / min to 290 ° C, for 3 min; inlet: splitless injection, no split time 1min, inlet temperature is 250 °C; carrier gas: constant current, 1ml / min; transmission line: 280 ° C
Mass spectrometry method:
The ion source temperature is 280 ° C, using the Acquisition-Timed method, SRM scanning, the specific detection ion pair is shown in Table 1:
Table 1.17 Mass spectrometry conditions for phthalate and 2 internal standards
Where DINP and DIDP are multimodal
2.3 Pre-processing methods
Weigh 2 g of the alcohol sample, add 1 ml of ethyl acetate: ether = 1 : 1 solution, shake well. Then add 4 ml of water, shake for 3 minutes, add 3 g of anhydrous sodium chloride, mix and centrifuge on a 5000r/min centrifuge for 3 minutes, remove the supernatant and dry with anhydrous sodium sulfate, and blow nitrogen. To the dry. Then reconstituted with 1 ml of n-hexane, passed through a 0.22 um filter, and analyzed by GCMSMS.
Note: The entire process must be carried out in a glass container. It is strictly forbidden to use plastic products to prevent the incorporation of phthalate esters from non-samples during sample processing.
3. Analysis of experimental results
3.1 chromatographic separation results
Since the ion information of the 17 phthalates is somewhat similar, we have chosen a weakly polar column with good resolution to ensure that the 17 phthalates are separated on the chromatogram. In order to make qualitative quantification more accurate. The chromatographic separation of 19 phthalates (including 2 internal standards) is shown in Figure 1:
Figure 1.1 Chromatogram of 19 mg/L phthalate (with internal standard)
3.2 standard curve and minimum limit of quantitation
The standard curve was set with n-hexane as solvent. The concentration range was 0.1 mg~1 mg/L. The standard curve of each compound is shown in Figure 2. The correlation coefficient R2 is greater than 0.99, indicating that the standard curve of these 17 compounds is linear.
Figure 2.17 Linear correlation diagram of phthalates
3.3 actual sample testing
According to the above pretreatment method, the commercially available 21 kinds of wine products were subjected to analysis and detection of phthalate residue. Some products of DMP, DEP, DIBP, DBP, DMEP and DEHP are positive results. Due to the fact that there is no corresponding national standard for the plasticizer in the current wine products, it is impossible to explain whether it exceeds the standard.
in conclusion:
The use of triple quadrupole mass spectrometry to determine the residues of phthalate esters in alcoholic products has the advantages of convenient operation, good selectivity, high sensitivity, wide linear range, etc., which was previously used by Thermo Fisher Scientific. It has been reflected in the application article. The isotope internal standard method used in this paper to quantify the phthalate in wine can correct and eliminate the influence of operating conditions on the analysis results and improve the accuracy of the analysis results. In the process of quantifying plasticizer by external standard method, due to the influence of plasticizer residue, some phthalate products are linearly poor, especially DBP and DEHP. In this paper, the isotope internal standard calibration of these two substances is used. The good linearity coefficient of 17 kinds of phthalate was obtained, which ensured accurate quantitative results and greatly solved the difficulty of analyzing the presence of phthalate by gas chromatography tandem mass spectrometry.