Analysis of Herbicide Atrazine and Its Degradation Products in Agricultural Soil by Ultra-Performance Liquid Chromatography‒Mass spectrometry
Abstract
A novel ultra -performance liquid chromato graphy‒mass spectrometry ( UPLC‒MS) method was developed for the determination of herbicide atrazine (ATR) and its principal metabolites namely deisopropylatrazine (DIA) , deethylatrazine (DEA) and hydroxyatrazine (HA) in soils. The limit of detection ranged from 0.06 μg kg‒1 (DEA) to 0.25 μg kg‒1 (HA). Recoveries for the four target analytes at three spiked levels ranged from 73.2 to 110% with relative standard deviation of 5.1‒8.1%. In the cases of the three control soil samples spiked with ATR were treated for 60d, the sum content of the three degraded products is 3, 6.4, and 6.8 times greater than ATR residue, respectively. Analyzing 80 soil samples from four counties evaluated this method. ATR of 1.1‒125 μg kg‒1 in 80 of 80 samples, ATR of 0.5‒7.8 μg kg‒1 in 39 of 80 samples, and DIA of 0.5 and 0.6 μg kg‒1 in 2 of 80 samples were found. The proposed method can ensure the rapid and highly sensitive analysis of atrazine and its degradation products in soil, and can provide a direction for proper application of atrazine and a base for evaluating their hazards to the environment.
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Introduction
Herbicide atrazine (ATR) is a pollutant of environmental concern due to acute toxicity, relatively stable nature in environments, Several epidemiological cancer studies concerning ATR and its possible association with carcinogenic effects in humans are being reviewed.1 The acute toxicity of its metabolites such as deethylatrazine (DEA) and deisopropylatrazine (DIA) was found to be twice as that of ATR.2 Their presence in the environment has caused public concerns owing to their toxicity to human health. Therefore, it is important to develop a sensitive and accurate analytical method for detecting ATR residue and its degradation products in the environment.
Chromatography was an effective analytical tool for single residue and multi-residue triazine in the environment.3,4 Currently, gas chromatography (GC) methods5 and high performance liquid chromatography (HPLC)6-8 have been used for the determination of triazines in environment and food samples. However, GC or HPLC is not enough to match the routine analysis of interested trace herbicides in complex matrix due to the lack of high detection sensitivity and high identification certainty. In comparison with GC/HPLC, GC/HPLC–mass spectrometry (GC-MS/HPLC–MS) was more frequently used for multi-residue analysis of triazine in the environment. However, there was relative lack of reports for studying the degradation products of ATR herbicide.
ATR and its some degradation products were determined in water.9-13 A few of works were reported for the determination of ATR and its some degradation products in soil. Hrdlička and Dolinová 14 presented an automated hot solvent extraction and HPLC method for the determination of atrazine and its degradation products in soil from maize fields, with detection limit (LOD) of 4 μg kg‒1 for ATR and 2 μg kg‒1 for DEA and DIA. Min et al. 15 reported a sensitive GC-MS method for the determination of ATR in soil, with quantification limit (LOQ) of 0.3 μg kg‒1 for ATR, 1.0 μg/kg‒1 for DIA, and 0.8 μg kg‒1 for DEA. The content of ATR ranged from 0.77 to 10.83 μg kg‒1, but DEA and DIA were not detected. Recently, Amadori et al.16 reported a HPLC method with LOQ of 50 μg kg‒1 for investigating the content change of ATR, DEA and DIA in the soil spiked with an initial ATR content of 2500 μg kg‒1 after 15, 30, 45 and 60 days of treatment time under controlled conditions, but no data for content of DEA and DIA in real agricultural soil were reported.
In our previous work, an UPLC–MS method was described for the determination of 50 hebicides in soil sample,17 but it is unsuited to analyze ATR and its degradation products. The purpose of this paper is to develop a new sensitive UPLC–MS method for effective separation and simultaneous determination of ATR, HEA, HIA and HA. Linearity, sensitivity, precision, and accuracy of the method were validated. To assess its applicability, the proposed method was applied for the analysis of soil. The detection limits, repeatability, and recoveries achieved meet the needs of trace level monitoring of these compounds in soil.
Conclusion
Using acetonitrile can effectively extract atrazine and its degradation products from soil. Using a BEH C18 stainless -steel cartridge column and isocratic elution mode with acetonitrile –water (v/v, 80:20) as a mobile phase can achieve effective chromatographic separation within 5min. The validated method can ensure the rapid and highly sensitive analysis for atrazine and its degradation products in soil. The sum content of the three degraded products (DEA, DIA and HA) is 3‒6.4 times greater than atrazine residue. This should be caused for m ore concern due to that these degraded products have similar or higher toxicity than atrazine residue. The developed method provides an effective, sensitive and accurate analytical base for investigating their distribution and degradation as well as evaluating their hazards to the environment and human health.
