Salicylic acid is an emerging environmental contaminant, usually found at ng L concentrations in natural waters. It quantification usually involves LC-MS/MS, which require complex and costly instrumentation as well as time-consuming sample pretreatment, typically involving large solvent volumes. In this work, sequential injection chromatography was exploited to develop a fast, green, cost-effective, and highly sensitive procedure for fluorimetric determination of salicylic acid in natural waters. Analyte preconcentration directly on the chromatographic column (on-column preconcentration) was exploited to improve detectability, yielding an enrichment factor of 122 (1.75 mL of sample) and taken only 8.5 min per determination. A detection limit of 20 ng L , a linear response range from 0.06 to 5.00 μg L , coefficients of variation lower than 3.0 % (n = 10), and recoveries within 86 and 114% were estimated. The procedure was applied for the analyses of freshwater samples and results agreed with those obtained by LC-MS/MS at the 95% confidence level. The proposed procedure encompasses in-line concentration, isolation/separation, and detection, without the need for sample clean-up, thus minimizing the consumption of organic solvents and risks of analyte losses. This article is protected by copyright. All rights reserved.