Development of an extractive spectrophotometric method for the determination of spermidine in urine samples using cucurbit[7]uril-truxene derivative as a fluorescent extractant

Spermidine has emerged as a promising biomarker for the early-stage diagnosis of cancer in humans. A novel extractive spectrophotometric analytical method has been developed for the determination of spermidine in urine samples. This technique leverages the selective extraction of spermidine from complex matrices using a cucurbit[7]uril-truxene derivative (Q[7]-Cs-Tr) as a fluorescent extractant. The Q[7]-Cs-Tr forms a stable host-guest complex with spermidine, facilitating its extraction from the aqueous phase to the organic phase. The formation of this complex results in a decrease in the fluorescence intensity of the Q[7]-Cs-Tr in the organic phase. Key factors influencing extraction efficiency, including the type of dispersed organic solvent, extractant concentration, solution pH, extraction times, and equilibrium time, were thoroughly investigated. The method demonstrated minimal interference from various metal ions, anions, amino acids, and other biogenic amines. It also exhibited a low limit of detection (8.6 nM), excellent linearity (R 2  = 0.9972), and high repeatability (RSD = 2.4 % intra-day, RSD = 3.6 % inter-day). The proposed method was successfully applied to determine spermidine levels in urine samples, yielding satisfactory recoveries ranging from 96.3 % to 103.5 %. Compared to existing methods, this approach is simple, reliable, highly sensitive, and exhibits low interference, making it a potential robust tool for clinical diagnostics.