N-doped carbon dots fluorescence sensor for simultaneous detection of Cd2+ and Hg2+ in food samples

Overview

This method paper reports the synthesis of nitrogen-doped carbon dots (N-CDs) as a dual-channel fluorescence sensor for simultaneous detection of cadmium (Cd²⁺) and mercury (Hg²⁺) ions in food samples. The sensor exploits differential quenching and enhancement effects on the carbon dot fluorescence signal to distinguish and quantify both analytes in a single measurement. The method was validated using spiked apple and cabbage matrices, with recovery rates and limits of detection reported.

Key numbers

• LOD: 0.20 µM for Cd²⁺; 0.188 µM for Hg²⁺.
• Recovery rates: 86.44–109.40% for Cd²⁺ in spiked food samples; 86.62–115.32% for Hg²⁺.
• Validated matrices: apple (fruit) and cabbage (vegetable).
• Linear detection range reported for both analytes.

Methods (brief)

N-doped carbon dots synthesised from citric acid and urea via hydrothermal route. Dual fluorescence channel: Cd²⁺ enhances one emission peak; Hg²⁺ quenches another. Spiked food matrices prepared by adding known Cd and Hg concentrations to apple and cabbage digests. No LOQ reported separately. ICP-MS used for cross-validation in some samples. Total Hg measured; speciation not performed.

Implications

Testing: Provides an alternative low-cost optical method for simultaneous Cd and tHg screening in fruit and vegetable matrices; LOD is in µM range, which may be less sensitive than ICP-MS at regulatory threshold levels (ppb range). Courses: Illustrates the fluorescence sensor approach for food metal detection; useful for training on emerging detection technologies. App: Validates that both Cd and Hg are measurable in apple and cabbage food matrices; this is a method paper, not an occurrence survey.

Wiki pages updated on ingest

• fluorescence-sensors
• Cadmium

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