This study proposes a new strategy to determine ultra-trace Ti in human serum using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). The human serum samples were diluted with 1% (v/v) HNO3, followed by the determination of ultra-trace Ti using ICP-MS/MS. In the MS/MS mode, a small amount of H2 was mixed with O2 (the reaction gas) in a collision reaction cell (CRC) to form an O2/H2 reaction mixture, and then, the conversion of Ti+ to TiO+ was determined by the O2 mass shift method. High concentrations of Ca, S, and P in human serum were ionized in plasma, and the formed Ca+, SO+, and PO + reacted with O2 in CRC to form CaO+, SO2+, and PO2+ to interfere with the determination of TiO+. We employed the mass shift reaction of H2 and oxide ions to eliminate this interference. This method was evaluated using the human serum sample spike recovery experiment and comparative analysis by sector field (SF)-ICP-MS. The results showed that using reaction gas mixture O2/H2 reduced the background equivalent concentration (BEC) of Ti and improved sensitivity. The values determined by this method were consistent with the SF-ICP-MS values, which confirmed its accuracy and reliability. The limit of detection (LOD) of Ti was 0.78-7.20 ng L-1, the recovery was 96.0%-104%, and the relative standard deviation (RSD) was 2.0%-4.2%. This method has solved the problem that the determination of ultra-trace Ti in human serum cannot be accurately determined using O2 reaction mode. It realizes the interference-free and highly sensitive determination of the ultra-trace Ti in samples with high levels of Ca, S, and P and provides a new technique for high-throughput and accurate determination of ultra-trace Ti in human serum.
Keywords: Human serum; Inductively coupled plasma tandem mass spectrometry; Interference; Mixture reaction gas O(2)/H(2); Titanium.
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