(152b) Simultaneous Detection of Harmful Herbicides with Lateral Flow Immunoassay Catalyzed By Palladium@Platinum Nanoparticles

In this presentation, we will show a method for simultaneously detecting two herbicides, atrazine and acetochlor, in real samples obtained from fruits and vegetables. These herbicides may be detected by lateral flow immunoassay (LFIA) using platinum coated over palladium (Pd@Pt) nanoparticles as a signal-amplifying agent. For validation, the results are compared with those obtained using a conventional HPLC analysis.

LFIA, also known as a test strip or an immunochromatographic assay, is an increasingly common immunoanalytical method for on-site screening because it is rapid, portable, inexpensive, and reagents are stable. LFIA has been applied in diverse areas such as medical diagnostics, drugs-of-abuse testing, environmental monitoring, and food safety. This study involves the use of LFIA for environmental monitoring and food safety, focusing especially on the detection of herbicides, since the capability of detecting these chemicals in the environment and in foods is crucial due to their potential hazards, from skin irritation to cancer. Atrazine is one of the most widely used herbicides in the United States, with 70 million pounds applied annually, as reported by the United State Geological Survey (USGS); however, the Environmental Protection Agency (EPA) has set the maximum contamination level in drinking water at 3 ng/mL for atrazine, and several studies have reported that atrazine has the potential to impact reproductive hormone levels in humans, rats, and amphibia. Acetochlor is another widely used herbicide, with an estimated 35 million pounds applied per year, as reported by the USGS; it is sometimes used instead of atrazine because of its superior biodegradability and higher maximum contamination level for drinking water, which is set at 20 ng/mL according to the Minnesota Department of Health. However, acetochlor is sited for its potential toxicity in rats and humans and has been noted by the EPA as having “Suggestive Evidence of Carcinogenic Potential.”

Plans are underway to apply our previously developed dual-LFIA method, which employs a triangular sample pad combined with two test strips, to detect atrazine and acetochlor simultaneously in real samples of fruits and vegetables. We expect to be able to detect two herbicides near or below the maximum contamination levels set by the EPA and obtain recoveries between 80 – 120 %. The mesoporous Pd@Pt nanoparticle was used as the signal-amplifying agent because of its electrochemical activity as a peroxide conversion catalyst which allows for quantitative detection. Moreover, its high surface area increases its sensitivity, and its pH- and thermo-stability make it suitable for use with real samples. For validation, we detected the two herbicides simultaneously with HPLC and obtained a limit of detection of 10 ng/mL for atrazine and 50 ng/mL for acetochlor. We spiked apple and watermelon juices with 50, 80, and 100 ng/mL of atrazine and 100, 150, and 200 ng/mL of acetochlor, and obtained recoveries between 99.7 – 100 % when compared to an HPLC analysis. Laboratory experiments are planned for detecting the two herbicides in blended fruits, apples and grapes, and blended vegetables, corn and cabbage. We expect LODs near EPA limits and will report on the most recent progress. We expect our findings will suggest that innovations in efficiency, sensitivity, and stability are possible in tests for harmful chemicals in the environment and in food by use of the Pd@Pt nanoparticle enhanced immunoassays.