Development and validation of an analytical procedure for quantitation of surfactants in dishwashing detergents using ultra-performance liquid chromatography-mass spectrometry.

The detection of surfactants in dishwashing detergents is challenging because the detergents tend to create a lot of foam. The aim of this study was therefore to develop a simple and robust procedure for simultaneous identification and quantification of multiple surfactants in dishwashingdetergents using standard addition method and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The results contain the method validation for 11 surfactants (linear alkylbenzene sulfonates, PPG-9-ethylhexeth-5, sodium lauryl polyoxyethylene ether sulfate, alkyl polyglucoside, sodium C14-16 olefin sulfonate, cocamide diethanolamine, cocamide monoethanolamine, lauryldimethylamine oxide, cocamidopropyl betaine, nonylphenol, and nonylphenol ethoxylate). The correlation coefficients of the linear calibration curves were larger than 0.98. The limits of detection and quantification were in the ranges of 0.43-8.0 µg/mL and 1.42-26.4 µg/mL, respectively. The precision ranged from 1.72% to 11.70%. The recoveries were within the range of 84-115%. The validation criteria were fulfilled for the 11 tested surfactants. The analytical procedure was applied to the analysis of 20 dishwashing detergent products collected from markets. The surfactants labeled on 13 out of the 20 products were consistent with the test results. Two surfactants, nonylphenol and nonylphenol ethoxylate, are relatively toxic to aquatic plants, fish, and aquatic invertebrates. These two surfactants were not detected among the 20 dishwashing detergent products, indicating that they were likely not added to the dishwashing detergent products. The developed UPLC-MS-based analytical procedure can be effectively applied to surfactant identification and quantification in dishwashing detergent products.

Identification of tyrosine-phosphorylated proteins associated with lung cancer metastasis using label-free quantitative analyses.

Lung cancer is a lethal disease, and early metastasis is the major cause of treatment failure and cancer-related death. Tyrosine phosphorylated (P-Tyr) proteins are involved in the invasive and metastatic behavior of lung cancer; however, only a limited number of targets were identified. We attempt to characterize P-Tyr proteins and events involved in the metastatic process. In a previous work, we have developed a strategy for identification of protein phosphorylation. Here, this strategy was used to characterize the tyrosine phosphoproteome of lung cancer cells that have different invasive abilities (CL1-0 vs. CL1-5). Using our analytical strategy, we report the identification of 335 P-Tyr sites from 276 phosphoproteins. Label-free quantitative analysis revealed that 36 P-Tyr peptides showed altered levels between CL1-0 and CL1-5 cells. From this list of sites, we extracted two novel consensus sequences and four known motifs for specific kinases and phosphatases including EGFR, Src, JAK2, and TC-PTP. Protein-protein interaction network analysis of the altered P-Tyr proteins illustrated that 11 proteins were linked to a network containing EGFR, c-Src, c-Myc, and STAT, which is known to be related to lung cancer metastasis. Among these 11 proteins, 7 P-Tyr proteins have not been previously reported to be associated with lung cancer metastasis and are of greatest interest for further study. The characterized tyrosine phosphoproteome and altered P-Tyr targets may provide a better comprehensive understanding of the mechanisms of lung cancer invasion/metastasis and discover potential therapies.