Analytical Methodologies for the Detection of Sucralose in Water

Abstract

A detailed evaluation of two liquid chromatography-mass spectrometry techniques, quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS) and triple quadrupole mass spectrometry (LC/MS-MS), was carried out in terms of sensitivity, selectivity, and ionization mode for the detection of sucralose in environmental water samples, which is an important environmental topic in water analysis. Interesting findings were made in regards to fragmentation and sensitivity when both techniques and both ionization modes of operation were compared. In positive ion mode, sucralose was detected by its sodium adduct [M + Na](+) at m/z 419.0038. Fragmentation by MS-MS of the sodiated molecule was possible using either LC/MS-MS or LC/Q-TOF-MS under positive ionization. Accurate mass measurements provided exact structural confirmation of the sodiated fragments obtained (m/z 221.0187 and m/z 238.9848). In negative ion mode, the deprotonated molecule was observed ([M - H](-) at m/z 395.0073), and fragmentation by MS-MS yielded two characteristic fragment ions (m/z 359.0306 and m/z 34.9694). Because sucralose contains three chlorine atoms, time-of-flight analyses provided a valuable amount of isotopic accurate mass information for its detection. With LC/MS-MS, the sensitivity was 10 times higher in positive ion mode than in negative ion mode, with limits of detection of 15 ng/L. Similarly, when time-of-flight mass spectrometry was used, the sensitivity was slightly better in positive ion mode, with limits of detection of 400 ng/L. Matrix effects were observed for surface and wastewater samples; thus the use of a deuterated standard (sucralose-d6) was crucial for precise quantitation. The most sensitive analytical methodology for the analysis of sucralose in water samples was LC/MS-MS using triple quadrupole under positive ion mode.