Rapid Identification of Unknown Organic Iodine in Small-Volume Complex Biological Samples Based on Nanospray Mass Spectrometry Coupled with in-Tube Solid Phase Microextraction.

A new method for rapid screening of unknown organic iodine (OI) in small-volume complex biological samples was developed using in-tube solid phase microextraction (SPME) nanospray mass spectrometry (MS). The method proposed a new identification scheme for OI based on nanospray high-resolution mass spectrometry (HR-MS). The mass ranges of OI ions were confirmed using the t-MS scan mode first; then, the possible precursor ions of OI were selected and identified orderly in full MS/ddMS and t-MS scan modes. Besides, in-tube SPME was used for the pretreatment of small-volume biological samples, and it was the first time in-tube SPME combined with nanospray MS for OI identification. The whole analysis procedure took only 8 min and consumed 50 μL per sample. Using the new method, six kinds of OI added to urine and an unknown OI CHOI in human milk were successfully identified. Moreover, the proposed identification scheme is also suitable for other ambient mass spectrometry (AMS) to determine unknown compounds with characteristic fragment ions.