Direct Detection of Textile Dyes in Environmental Samples by LDI and MALDI FT-ICR MS

Dye contamination poses a serious problem in some developing countries, which often lack the facilities for effective analysis. International shipment of samples for high-resolution mass spectrometry is hindered by strict regulations and high costs. Therefore, there is a need for a direct, low-volume analytical method. To address this challenge, we present a direct, preparation-free method for the identification of various textile dye compounds in environmental samples using LDI and MALDI FT-ICR MS. This method requires only 2 μL of sample water without any pretreatment, making it highly efficient in terms of both sample volume and preparation time. A comprehensive MS and MS/MS database of 58 standard dye compounds was constructed, showcasing the ability of LDI and MALDI to ionize dyes that are traditionally difficult to analyze. We applied this method to water samples from the Loji River in Indonesia, where 12 dyes were identified by comparing the results with the database. Notably, 7 dyes were newly identified compared to previous results obtained using LC-FT-ICR MS, demonstrating the enhanced sensitivity and specificity of the LDI/MALDI FT-ICR MS approach. The results highlight the significant advantages of this method, including minimal sample consumption, rapid analysis, and the elimination of sample preparation steps, positioning it as a powerful tool for environmental monitoring. Furthermore, the development of a dye identification database is an essential scientific contribution that will facilitate more efficient environmental monitoring in diverse settings.