Rapid screening and determination of 105 pesticide residues in apple juice concentrate

Summary

In recent years, China has made great progress in the series of determination of various pesticide residues, and has issued four national standard methods. For example, GB/T 19648-2005, Method for Determination of 446 Pesticide Multi-residues in Fruits and Vegetables. Source: Food Safety Monitoring Technology (Chemical Industry Press)

Operation method

Gas Chromatography Mass Spectrometry

Materials and Instruments

Apple juice
Dichloromethane-hexane Distilled water
Beaker, glass rod, diatomaceous earth column, gas chromatograph.

Move

1. Pre-processing

Accurately weigh 50.0 g of apple juice concentrate in a 250 mL beaker, accurately add an equal amount of distilled water for dilution, stir well with a clean glass rod, accurately aspirate 20 mL of the diluted sample solution onto a diatomaceous earth column, and after all the liquid was fed into the column, continue to let it stand for 20 min, and then rinse the sample with dichloromethane-hexane (1:1, v/v/v) at a flow rate of 160 mL, and collect the effluent in a 200 mL concentration flask, concentrate it in a 40°C water bath until nearly dry, and then fix it accurately with hexane to 1 mL for gas chromatography detection. The flow rate was controlled to be 5 mL/min, and the effluent was collected in a 200 mL concentration flask, concentrated to near dryness in a water bath at 40°C, and then accurately diluted to 1 mL with hexane for detection by gas chromatograph.

2. Gas chromatographic conditions

Carrier gas: helium (99.999%)

Column flow rate: 1 mL/min

Inlet temperature: 250 ℃

Injection mode: pulse split injection; injection volume 1uL

Column temperature program: initial temperature 80 ℃, hold for 1 min, warm up to 160 ℃ at the rate of 10 ℃ / min, hold for 5 min, warm up to 240 ℃ at the rate of 3 ℃ / min, then warm up to 280 ℃ at the rate of 25 ℃ / min, hold for 10 min.

3. Mass spectrometry conditions

Interface temperature: 280 °C

Ion source temperature: 230 ℃

Quadrupole temperature: 150 ℃

Ionization method: EI Electron energy: 70 eV

Mass spectrometry detection method: Selected Ion Detection (SIM).

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