Electromembrane extraction of salivary polyamines followed by capillary zone electrophoresis with capacitively coupled contactless conductivity detection

Electromembrane extraction (EME) as a novel sample preparation technique was firstly applied for the purification and enrichment of four polyamines mainly present in saliva samples. These four target analytes, putrescine, cadaverine, spermidine, and spermine, were directly determined by CZE with capacitively coupled contactless conductivity detection (CZE-C4D) after EME procedure. Several factors affecting extraction efficiency, electrophoretic separation, and detection were investigated. Under the optimum conditions, four polyamines were baseline separated within 22 min, exhibiting a linear calibration over three orders of magnitude (r>0.999); the highest enrichment factor could reach 106-fold (for spermidine), and the LODs were in the range of 1.4–7.0 ng mL−1. The proposed EME/CZE-C4D method has been successfully applied to analyze human saliva samples with recoveries in the range of 78–97%.