Determination of trace glyphosate in water with a prism coupling optical waveguide configuration

• Glyphosate detection limits below1.4 nmol/L with a prism coupling optical waveguide configuration.
• Discussing a prism coupling hollow-core metal-cladded waveguide (HCMW) sensor.
• HCMW sensor that uses ultrahigh-order modes (UHM) for sensitive absorption detection of glyphosate.
• High sensitivity, low consumption and solution-free operation were experimentally demonstrated.

We herein discuss a prism coupling hollow-core metal-cladded waveguide (HCMW) sensor that uses ultrahigh-order modes (UHM) for sensitive absorption detection of glyphosate. In our method, modified chromogenic glyphosate in the hollow-core serves as guiding medium for high-power wave propagation. Prism coupling is employed to generate attenuated total reflection (ATR) dips of the UHM. The depths of the dips are closely related to the extinction coefficient of chromogenic glyphosate. A glyphosate detection limit below1.4 nm/l is experimentally demonstrated with low consumption and solution-free operation. The calibration curve has been found linear in the concentration range of 0.0−5.0 nm/l.