Triazine Herbicides Analyzed Using New Magnetic Solid-Phase Extraction Method

A recent study led by Shandong Academy of Sciences personnel in Jinan, China created a new approach for performing magnetic solid-phase extraction on trace triazine herbicides. Their findings were published in the Journal of Chromatography A (1).

Farmer on a tractor with a sprayer makes fertilizer for young vegetable | Image Credit: © Dusan Kostic - stock.adobe.com

Triazine herbicides (THs) were introduced in the 1950s to curb broadleaf weed growth before and after the emergence of crops like corn and sugar cane. By targeting the D1 protein of plant photosystem II (PSII), electron transfers are disrupted, thus inhibiting photosynthesis. Nowadays, they are the most heavily used agricultural chemicals in the United States (2). However, due to large TH use and their long residual half-life in the environment, THs can remain in water, soil, and agricultural products throughout the application process. If this persists, it can lead to what the scientists call “the triple-causing effects of ‘carcinogenicity, teratogenicity, and mutagenesis,’” in addition to irreversible side effects, like endocrine disruption (1). This can cause damage to reproductive systems in frogs, fish, and other wildlife. This, and its potential risk to human health, led to partial bans by the EU in 2005. As a side effect, interest has been renewed in analyzing these compounds.

The U.S. Environmental Protection Agency (EPA) has designated THs like simazine and atrazine as priority pollutants; as such, this includes mandates that the concentration of Atrazine in drinking water must be <3 μg/L, while the concentration of Simazine must be <4 μg/L. Further, there is an urgent demand to exploit quantitative methods for accurate, sensitively, and conveniently capturing TH residues in environmental water samples and agricultural products. However, due to low residue levels and complex matrix effects of THs in actual samples, immediate separation and instrumental TH determination can be difficult. Therefore, sample pretreatment and enrichment are vital to eliminate matrix interference and ensure accuracy and precision of the analysis. Current sample pretreatment methods, such as dispersive solid phase extraction (d-SPE), solid phase extraction (SPE), and solid phase microextraction (SPME), are viewed as knotty and time-consuming. Magnetic solid-phase extraction (MSPE) has attracted interest due to its effectiveness in enriching trace targets in complicated matrices. However, creating magnetic materials with covalent bonding and functionalization to enhance efficiency and recyclability is still challenging.

In this study, the scientists covalently constructed abundant long-chain hydroxyl groups-functionalized magnetic microporous organic networks (MMON-2OH) for detecting eight THs in honey and water samples. This formula owned a high surface area, (287.86 m²/g), enhanced water compatibility, and increased exposure of long-chain hydroxyl groups, significantly improving TH enrichment capacity. Upon creating theoretical analyses and characterization data, interaction mechanisms were revealed, including hydrogen bonds (N-H···O and O-H···N), halogen bond (Cl···N) and π stackings (NH-π, CH-π and π-π).

Regarding TH detection, this approach achieved low limits of detection (LODs) of 0.03–0.6 ng/L for water, and 0.006–0.134 μg/kg for honey. Further, trace concentrations of THs, ranging from 1.0–21.2 ng/L in surface water and 0.1–0.9 μg/kg in honey, were successfully detected. Altogether, the halogen and hydrogen bonding, along with π-stacking interactions of MMON-2OH, show this technique’s potential for analytical applications, especially when considering its straightforward synthesis, rapid MSPE process, and high enrichment sensitivity.

References

(1) Zhang, M.; Liu, L.; Liu, F.; Sun, Q-Y.; Zhao, Y-F.; et al. Hydroxylated Magnetic Microporous Organic Network for Efficient Magnetic Solid Phase Extraction of Trace Triazine Herbicides. J. Chromatogr. A 2025, 1741, 465606. DOI: 10.1016/j.chroma.2024.465606

(2) Triazine Herbicides. AccuStandard 2025. https://www.accustandard.com/triazine_herbicides (accessed 2025-1-14)