introduction
Carbaryl, Carbofuran (named Carbofuran), bentazone and 2,4-D (2,4-D) are the four widely used pesticides, both of which are water soluble (especially Carbofuran, The water solubility is 700 mg / L), so the residual period in the soil is longer. Due to surface runoff, surface water and other drinking water sources are likely to cause pollution, which leads to more opportunities for entering the human body from the environment. The "Surface Water Environmental Quality Standards" [1] and the "Sanitary Standards for Drinking Water" [2] Appendix A both stipulate that the limit of carbaryl is 0.05 mg / L, and the international daily allowable intake (ADI value) is 0.02. Mg / kg / day [3] , GB 5749-2006 Sanitary Standard for Drinking Water The limits for herbicides and 2, 4-D in drinking water are 0.3 mg/L and 0.03 mg/L, respectively. At present, the detection methods for the four kinds of pesticide residues in China are mainly gas chromatography [4] , liquid chromatography [5] , and ion chromatography [6] , but most of these methods need to be pre-concentrated and derivatized before they can be carried out. Analysis and testing, the operation is a bit cumbersome. High-performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS), high-selective reaction detection mode (H-SRM) was used to directly complete carbinol, carbofuran, and bentazone in water. Qualitative and quantitative analysis of 2,4-D, the method is simple, sensitive and accurate, and meets the needs of actual sample detection.
Experimental part
1.1 Instruments and reagents
Chromatography system: Thermo Accela HPLC system;
Mass Spectrometry System: Thermo TSQ Quantum Access Max Triple Quadrupole Mass Spectrometry System;
Ultrapure water preparation system: Thermo Barnstead Diamond II water machine;
Carbaryl, carbofuran, bentazone and 2, 4-dip standard: SigmaAldrich;
Chromatographic Pure Methanol: Fisher Scientific; Ammonium Acetate: Fisher Scientific
1.2 Sample preparation
Preparation of standard solution: Prepare a concentration of 0.05μg/L, 0.1μg/L, 0.2μg/L, 0.5μg/L, 1μg/L, 10μg/L, 50μg/L, 100μg/L, 200μg/L Budweiser, carbaryl, bentazone and 2, 4-drop standard solution.
Actual sample: laboratory tap water
1.3 liquid chromatography conditions
Column: Syncronis C18, 100mm x 2.1mm, 5μm;
Mobile phase A: 5 mmol/L NH4 AC aqueous solution; mobile phase B: methanol; flow rate: 400 μL/min; injection volume: 20 μL; gradient as follows:
1.4 Mass spectrometry conditions
Thermo Scientific TraceFinderTM software features new and improved mass spectrometry methods, a built-in compound database, a convenient data browsing interface, library search capabilities, and the ability to export intelligent analysis reports based on built-in templates, so you can quickly create methods that are fast and easy. Output reports, greatly improving the analytical processing power. In addition, the software has developed a range of analytical methods, such as pesticides, environmental, antibiotics, and standard analytical methods for industrial chemicals in areas such as melamine-based food safety.
2 Results and discussion
2.1 Chromatogram
The standard chromatogram of the four pesticides at a concentration of 1 μg/L is shown in Figure 3. The signal acquisition method is H-SRM mode at 0.4Da resolution (quantitative ion pair: chlorpyrifos: 238.9 → 175.0; 2,4-D: 218.8) →160.9; Carbide: 221.9→165.0; Carbaryl 201.9→145.0). The retention times of bentazone, 2, 4-d, carbofuran and carbaryl were: 3.23, 4.05, 4.38 and 4.48 min, respectively.
2.2 linear range
Under the set chromatographic conditions, take 20 μL of the mixed standard solution separately, and analyze the injection. Take the concentration of the pesticide as the abscissa and the corresponding peak area as the ordinate. Use the edited TraceFinder quantitative method to make the working curve and get the four. The working curve equation of a pesticide.
2.3 Detection limit
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TIC diagram of 0.025μg/L carbofur | TIC diagram of 0.1μg/L bentazone |
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TIC map of 0.1μg/L carbaryl | 0.1μg / L 2,4- drop the TIC |
2.5 Detection of actual samples
The sample taken in the experiment was tap water in the demonstration laboratory, from which no pesticide residues were detected, as shown in Figure 4 .
3 conclusions
Experimental use Thermo Scientific TSQ Quantum AccessMax triple quadrupole LC-MS system and Thermo Scientific TraceFinder TM 2 is built up a body of water, 4 drops, bentazone, carbaryl and carbofuran four kinds of pesticide residues in quantitative methods The sensitivity, linearity and precision of the method were investigated based on the standard products, and four pesticide residues in the tap water of the laboratory were tested. The experimental results show that the TSQ Quantum Access Max triple quadrupole LC/MS system is equipped with a heated electrospray ionization source, a focused ion beam lens assembly, a 90- degree bending collision cell, and a high selective reaction detection mode (0.4Da , 0.7). Da resolution is adjustable , etc., which can effectively improve the signal response and reduce the neutral noise. It has the advantages of high sensitivity and good specificity in detecting actual samples containing matrix compounds.
references
1.GB5749 - 2006 , National Standard Sanitary Standard for Drinking Water [S]
2. GB3838 - 2002 , Surface Water Environmental Quality Standard [S] .
3. Ministry of Environmental Protection of the People's Republic of China . Safe Use and Prevention of Chemicals for Sanitary Killing in Earthquake-Stricken Areas [M].2008 .
4. Peng Min, Liu Zhuansheng solid phase extraction - precolumn derivatization - gas chromatography - mass spectrometry bentazone and 2,4-D in water [J] Physical Testing - Chemical Analysis, 2009, 45 (7): 791- 793.
5. Chen Yan deceive, Zhongshu Ting, Ganfeng Juan, and other ultra-high performance liquid chromatography tandem mass spectrometry atrazine in drinking water and bentazone [J] Chinese Journal of Health Laboratory, 2008, 18 (4): 590-592 .
6. Su Yuliang , Wu Jie , Fang Li . Collaborative analysis of 2, 4- D , glyphosate and bentazone in water by ion chromatography [J]. Water Purification Technology , 2008, 27(3): 51-52.
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