Study on the inclusion interaction of cucurbit[n]urils with sanguinarine by spectrofluorimetry and its analytical application

The characteristics of host–guest complexation between cucurbit[n]uril (CB[n], n = 5, 6, 7, 8) and sanguinarine (SA) were investigated by spectrofluorimetry. The result showed that CB[n] (n = 5, 6, 7, 8) reacted with SA to form an inclusion complex. At the optimum reaction conditions, the rectilinear calibration graphs were obtained in the range from 0.1 to 2800 ng mL−1 for the investigated drug, with correlation coefficients 0.9998, 0.9997, 0.9999 and 0.9997 and detection limits 0.052, 0.26, 0.03 and 0.058 ng mL−1 using CB[5], CB[6], CB[7], and CB[8], respectively. The apparent association constants of the complexes were 1.23 × 104, 6.73 × 103, 4.53 × 104 and 1.21 × 104 L mol−1, for the reagents in the same order. The result demonstrated that CB[7] exhibited a higher fluorescence signal than CB[5], CB[6], and CB[8]. The proposed method was successfully applied for the determination of the drug in human urine and serum samples.