A method for detecting paraquat in water using a Raman signal amplification surface technique employing a colloid of silver nanosheets.

Abstract

------25 / 06 / 2569------(OCR) OCR 09WP This invention reveals a method for detecting paraquat in water using a Raman signal amplification surface technique with a colloid of silver nanosheets in conjunction with a Raman spectrometer. When the colloid of silver nanosheets is mixed with the water sample to be tested at a ratio of 1:1 by volume, the optimal mixing time is 10 minutes. A dry drop of 0.02 ml of the mixture is then placed on a glass slide, and the Raman signal is measured using a Raman spectrometer with a wavelength of 785 nm. Comparing the principal Raman signal at wavenumber 1651 cm, the Raman signal of the paraquat solution can be amplified up to 200 times compared to measurements without the colloid of silver nanosheets. A standard curve is obtained for determining the concentration of residual paraquat in water. This method can quantify the minimum concentration of paraquat in water to 6.46 x 10⁻¹⁷ molar. And the detector was able to distinguish 4.62 x 10⁻¹⁷ molar.

Claims

------25 / 06 / 2569------(OCR) OCR 09WP1. The method for detecting paraquat in water using the Raman spectroscopy technique with a colloidal silver nanosheet is as follows: a. Add 0.1 ml of the water sample to be tested to 0.1 ml of the colloidal silver nanosheet (or a 1:1 ratio by volume). Immediately shake the mixture for 30 seconds. Then, let the mixture stand for 10 minutes. After 10 minutes, shake the mixture again for 30 seconds. Then, use a syringe to draw 0.02 ml of the mixture and drop it onto a glass slide, allowing it to dry. b. Examine the prepared slide using a Raman spectrometer with a laser beam of wavelength 785 nm, power 3.2 mW, and magnification 50x. The laser beam duration is 5 seconds, with an average of 2 measurement cycles. The main Raman wavenumber used for detection is 1651 per centimeter. c.The concentration of paraquat in a water sample is calculated by substituting the Raman signal intensity at 1651 cm² into the y-value in the standard linear equation. The concentration ranges are as follows: for concentrations greater than 2,146, use the equation y = 5,686x + 24,721; for concentrations less than 2,146, use the equation y = 633.75x + 4,868, where x is the logarithm of the concentration (x = log c). The value is then converted back to the normal concentration of paraquat in molar units.

2. Method for detecting paraquat in water using Raman signal amplification surface technique with silver nanoplate colloid, as per claim 1, where in the mixing step (step A), the silver nanoplate colloid used is a photosynthesis-based colloid with a triangular plate shape exhibiting vibration when an electric field is applied in two directions.

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