High-intensity focused ultrasound (HIFU) is a noninvasive soft tissue ablation technique, which utilizes ultrasound energy to induce thermal coagulation necrosis in targeted tissues. Whether this high energy causes side effects in vivo, such as the formation of peptide bonds, has not been fully investigated. Glycylglycine is the simplest dipeptide and hence is often used as a model compound for peptide studies. In this study, we developed and validated a sensitive quantification method based on ion-exchange solid-phase extraction, liquid chromatography, and tandem mass spectrometry (SPE-LC-MS/MS) for the analysis of glycylglycine without derivatization, and then used it to evaluate whether HIFU promoted peptide bond formation in aqueous solution (without enzymes) and plasma (with enzymes). The results showed that strong cation exchange SPE significantly reduced the matrix effect and improved the sensitivity of the LC-MS/MS method. No formation of glycylglycine in the aqueous solution or plasma was observed following HIFU irradiation.
Shuang Chen,Yue Qiao,Youwei Jiang,Wei Qiu,Shuang Zang,Jing Zhang,Xianshi Wang,Jun Ma
Halogenated aromatic disinfection byproducts (DBPs) are gradually receiving attention due to their high detection frequency and usually higher toxicity than regulated DBPs. In this study, we established a solid phase extraction (SPE)-LC-MS/MS method to simultaneously trace analyze 59 halogenated aromatic DBPs. The limits of detection and limits of quantification of halogenated aromatic DBPs ranged from 0.03 ng/L to 135.23 ng/L and 0.1 ng/L to 450.76 ng/L, respectively. The range of recoveries and relative standard deviation (RSD) in river water were between 72.41 % to 119.54 % and 1.86 % to 16.03 %, respectively. Therefore, this method can be used to accurately analyze trace levels of halogenated aromatic DBPs in drinking water. The occurrence and transformation of halogenated aromatic DBPs were explored based on this method. In the chlorinated simulated source water and chlorinated river water, 20 and 45 halogenated aromatic DBPs were determined, respectively. The active halogen species (HOCl, HOBr, and HOI) first reacted with natural organic matter (NOM) to form halogenated aromatic DBPs. Then, chlorine further reacted with the halogenated aromatic DBPs to convert them into small-molecule halogenated aliphatic DBPs through oxidation, electrophilic substitution, and hydrolysis reaction, etc. In the chlorinated simulated source water, chlorinated river water, and tap water, the toxicity contribution of bromoacetic acids (Br-HAAs) accounted for the majority (> 71.16 %). Given that halogenated aromatic DBPs are intermediate products of halogenated aliphatic DBPs, controlling the formation of halogenated aromatic DBPs is beneficial in decreasing the formation of halogenated aliphatic DBPs, thereby diminishing the toxicity of drinking water.
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