Determination of Formaldehyde by CdTe Quantum Dots Fluorescence Quenching Method

Water-soluble CdTe quantum dots (QDs) modified with N-acetyl-L-cysteine (NAC) are synthetized by one-step hydrothermal method. Based on the fluorescence quenching of formaldehyde to NAC-CdTe QDs, fluorescence spectrometry for determination of formaldehyde was developed. Formaldehyde with different mass concentration was added into the system with 7.5×10^-8mol·L^-1 NAC-CdTe and 0.01 mol·L^-1 Tris-HCl (pH 6.0). After reaction for 10 min, the fluorescence intensity (I) of the system was measured at 567 nm with the excitation wavelength of 400 nm. Linear relationship was found between the value of I₀/I (I₀ was the fluorescence intensity of the system without formaldehyde) with the mass concentration of formaldehyde in the range of 5.0×10^-6-1.0×10^-1 g·L^-1, with detection limit (3s/k) of 1.3×10^-6g·L^-1. The poposed method was applied to detemination of formaldehyde in water sample, giving results in consistent with those obtained by acetylacetone spectrophotometric method. Recovery rates obtained by standard addition method were in the range of 98.0%-102%, and RSDs (n=5)were in the range of 1.4%-4.1%.