Highly sensitive detection for tetracycline residues in water based on its decreasing effect on photocurrent of AgInS2 quantum dots

Water-soluble AgInS2 quantum dots (AIS QDs) stabilized by thioglycollic acid (TGA) were prepared through hot-injection method. Based on the decreasing effect of tetracycline (TC) on the photocurrent of as-prepared AIS QDs, a highly sensitive photoelectrochemical (PEC) method for TC detection was developed. The standard curve was established between relative decrease value of photocurrent (ΔI/I0) and the logarithm of TC concentration. The linear range of TC concentration was 1.3 × 10−9 - 1.0 × 10−4 mol·L−1, r = 0.9998, and the detection limit (LOD) (3 S/N) was 6.0 × 10−10 mol·L−1 (n = 5). The average addition standard recovery of TC in the water of Erhai Lake was 99.55%- 103.25%. The method proposed in this work had a wide detection range (spanning almost 5 orders of magnitude), a low detection limit, a high accuracy, a low cost and easy operability, which could be applied to detect TC residues in water environments. A possible mechanism involving ·O2- acts as a strong oxidant, participating in the redox processes of TC, thus decreasing the photocurrent of AIS QDs was proposed.