Rapid and in-situ detection of iodine and potassium ferrocyanide in table salt using enhanced-Multipass cavity Raman scattering

The excess of iodine (I₂) and potassium ferrocyanide (K₄[Fe(CN)₆]) to table salt are harmful to both human health and environment. To date, there are still a lack of suitable methods for simple, rapid and in-situ to detect the I₂ and K₄[Fe(CN)₆] contents in table salt. Herein, we employ a highly sensitive Raman spectroscopy, which is based on multiple reflection cavities and multi-directional signal collection optical systems, to detect the concentration of trace ions in table salt. The detection limit of our technology is less than 1 mg/kg in salt solutions, signifying that the corresponding quantitative detection limit in table salt is 3.45 mg/kg. Simultaneously, the relative Raman intensity of the ion exhibits a highly linear correlation with concentration (R² = 0.999), rendering it a molecular probe for I₂ and K₄[Fe(CN)₆] within table salt. The accuracy of this molecular probe for I₂, K₄[Fe(CN)₆], and sulfate (SO₄²⁻) content in different salts is 87.2 %, 89.6 % and 95.6 % respectively.Compared with the traditional method, this method has the advantages of low sample consumption (1g of salt), fast detection speed (10 min), and the measured sample can be saved.