Preparation of titanium (IV)-immobilized covalent organic polymer and use for simultaneous enrichment of nucleotides and catecholamines at weakly acidic pH.

Simultaneous analysis of catecholamines (CAs) and nucleotides (NTs) is very important for early diagnosis of diseases and physiological function monitoring. In this study, a titanium (IV)-immobilized affinity adsorbent, TpBD-(COOH)@AS@Ti, was prepared by functionalizing hydroxyl bearing covalent organic polymer (COP) with alendronate, and the adsorbent was used for simultaneous enrichment of CAs and NTs under weakly acidic conditions (pH 6.0), which can prevent the oxidation of CAs and improve the accuracy of their analysis. Selective adsorption is primarily driven by Ti⁴⁺-mediated coordination. Extraction parameters were systematically optimized, and analytical methods for determination of CAs and NTs in human urine have been established by coupling the TpBD-(COOH)@AS@Ti based dispersive solid phase extraction (dSPE) with HPLC equipped with two tandem detectors of ultraviolet (UV) and fluorescence (FL). With the UV detector, the limits of detections (LODs) of CAs and NTs were 0.17-3.97 ng/mL and 0.32-1.46 ng/mL, respectively. The recoveries in spiked urine were 73.8 %-116.1 % with relative standard deviations (RSDs) below 15 %. Meanwhile, CAs achieved higher sensitivity with LODs of 0.24-0.79 ng/mL when using the FL detector. Therefore, this study has important application potential for providing more comprehensive clinical diagnostic information and early diagnosis of diseases.