Microsyringe-based slug-flow microextraction for rapid and accurate determination of antibiotics in highly saline seawater.

BACKGROUND: Extensive use of antibiotics leads to widespread environmental pollution, endangering ecosystems, and human health. It is particularly concerning, posing global threats requiring urgent attention and action. In this regard, the shift to mass spectrometry in determining antibiotics is highly desirable. Significant progress has been made in analyzing and optimizing the sensitivity of high-salt samples. However, the persistence of cumbersome operational procedures presents a significant challenge to this shift. Thus, the persistence of complex operational procedures needs to be addressed. RESULTS: In this study, a rapid and direct method for determining antibiotics in highly saline environmental water samples using microsyringe-based slug-flow microextraction (MSFME)-droplet spray ionization (DSI) mass spectrometry (MS) has been described. The proposed method successfully detected clarithromycin, ofloxacin, and sulfadimidine in seawater within a linear range of 1-1200 ng mL-1, with low limits of detection of 0.19 ng mL-1, 0.17 ng mL-1, and 0.20 ng mL-1, respectively (Signal/Noise = 3). Additionally, spiked real seawater samples of all three antibiotics demonstrated satisfactory recoveries (95.1-107.5%) and precision (RSD≤8.8%). The MSFME-treated high-salt sample (3.5 wt%) showed a mass spectral response intensity 4-5 orders of magnitude higher than the untreated medium-salt sample (0.35 wt%). Furthermore, exploration of the applicability of MSFME showed that it is suitable not only for high-salinity (3.5 wt%) samples but also for salt-free or low-salt and hard water samples rich in calcium and magnesium ions. SIGNIFICANCE: Comparisons with other methods, complex laboratory setups for sample processing are now simplified to a single step, completing the entire process, including desalination and detection, MSFME-DSI-MS provides faster results in less than 1 min while maintaining sensitivity comparable to that of other detection methods. In conclusion, this advancement provides an exceptionally simplified protocol for the rapid, highly sensitive, and quantitative determination of antibiotics in environmental water samples.

One-step online analysis of antibiotics in highly saline seawater by nano-based slug-flow microextraction.

The transition to mass spectrometry (MS) in the analysis of antibiotics in the marine environment is highly desirable, particularly in the enhancement of sensitivity for high-salinity (3.5 wt%) seawater samples. However, the persistence of complex operational procedures poses substantial challenges to this transition. In this study, a rapid method for the online analysis of antibiotics in seawater samples via nano-electrospray ionization (nESI) MS based on slug-flow microextraction (SFME) has been proposed. Comparisons with other methods, complex laboratory setups for sample processing are now seamlessly integrated into a single online step, completing the entire process, including desalination and detection, SFME-nESI-MS provides faster results in less than 2 min while maintaining sensitivity comparable to that of other detection methods. Using SFME-nESI, six antibiotics in high-salinity (3.5 wt%) seawater samples have been determined in both positive and negative ion modes. The proposed method successfully detected clarithromycin, ofloxacin, and sulfadimidine in seawater within a linear range of 1-1000 ng mL-1 and limit of detection (LOD) of 0.23, 0.06, and 0.28 ng mL-1, respectively. The method recovery was from 92.8% to 107.3%, and the relative standard deviation was less than 7.5%. In addition, the response intensity of SFME-nESI-treated high-salinity (3.5 wt%) samples surpassed that of untreated medium-salinity (0.35 wt%) samples by two to five orders of magnitude. This advancement provides an exceptionally simplified protocol for the online rapid, highly sensitive, and quantitative determination of antibiotics in high-salinity (3.5 wt%) seawater.