Determination of Organochlorine Pesticides in Soil

This solution refers to the methods “HJ 835-2017 Determination of Organochlorine Pesticides in Soil and Sediment by Gas Chromatography-Mass Spectrometry” and "HJ 783-2016 Extraction of Organic Matter from Soil and Sediment by Pressurized Fluid Extraction". It briefly introduces a complete set of methods for extracting 15 kinds of organochlorine pesticides from soil using the Raykol HPFE high-throughput pressurized fluid extractor, purifying with the Fotector Plus high-throughput automatic solid-phase extraction instrument, and detecting with the gas chromatography-mass spectrometry after concentration by the MPE series high-throughput vacuum parallel concentrator. The experimental method is simple, with a high recovery rate and good parallelism, suitable for the detection of 15 kinds of organochlorine pesticides in soil.

Sample Pretreatment

>Standard Solution Preparation

The AP 300 liquid sample processing workstation can be used to prepare mixed standard working solutions. Standard solutions of organochlorine pesticides and substitutes with concentrations of 50μg/L, 100μg/L, 200μg/L, 500μg/L, and 1000μg/L are prepared using n-hexane solution, and an appropriate amount of internal standard solution is added to achieve a standard curve with a concentration of 200μg/L in the standard solution.

AP 300 Automatic Liquid Sample Processing Workstation 

>Extraction

Take 20g of the sieved environmental soil sample, add an appropriate amount of diatomaceous earth and mix evenly, then fill it into a 34mL extraction pool. Fill six extraction pools in the same way. Place the prepared samples in the HPFE for two rounds of extraction, collect the extract, and remove the water with anhydrous sodium sulfate.

HPFE Series High Throughput Pressurized Fluid Extractor

>Concentration

Place the collection tube in the MPE series high-throughput vacuum parallel concentrator, with a concentration temperature of 40°C. Use n-hexane to transfer the solvent during the concentration process, finally replace the solvent with n-hexane, and concentrate the sample volume to about 2mL.

MPE Series High Throughput Vacuum Parallel Concentrator

>Purification

Cleaning: Clean the sample channel, first clean the sample needle with n-hexane and acetone (9:1)

Activation: Enrich and purify with Florisil small column (1g/6mL). Wash with acetone (9:1), followed by activation with n-hexane.

Sampling: Sample at a flow rate of 0.5mL/min, collect the solution.

Cleaning: Clean the sample bottle with n-hexane, collect the solution.

Elution: 8mL n-hexane and acetone (9:1)

Concentration and volume adjustment: Concentrate the collected solution to 0.5mL with the MPE high-throughput vacuum parallel concentrator, add 20μL of 10μg/mL internal standard solution, adjust the volume to 1mL with n-hexane, and the sample to be tested is subjected to gas quality detection.

Fotector Plus High Throughput Fully Automatic Solid Phase Extractor 

Sample Spiking Treatment

Add 100μL, 300μL, and 500μL of 1 ppm organochlorine pesticide standard solution to the soil samples respectively, then carry out the experiment, add 20μL of 10μg/mL internal standard solution, and finally adjust the volume to 1mL with n-hexane, to determine the spike recovery rate.

Gas Chromatography-Mass Spectrometry Conditions

Results and Discussion

Summary

The Raykol AP 300 automatic liquid sample processing workstation can assist laboratory personnel in easily preparing mixed standard working curves.

The Raykol HPFE series high-throughput pressurized fluid extraction instrument, as an essential device for soil extraction, can extract six samples simultaneously in 30 minutes. According to the working time of 8 hours, the daily processing capacity can reach 96. The instrument is easy to operate and can be controlled by a touch screen. It can be operated with one button. New laboratory personnel can start operating immediately. The instrument has four solvents, which can be extracted in different proportions without manual preparation.

The Raykol MPE series high-throughput vacuum parallel concentrator can concentrate 20 large-volume samples or 48 small-volume samples in half an hour, greatly improving the efficiency of sample pretreatment.

The Raykol Fotector Plus high-throughput automatic solid-phase extraction instrument can simultaneously process 6 samples and automatically continuously process 60 samples. All basic commands from activation, sampling, rinsing to elution are fully automated, greatly improving the accuracy and reliability of the instrument and ensuring the recovery rate.