Quantification of iprodione in dry basil using silica gel supported titanium dioxide.

Iprodione is an agricultural fungicide that is difficult to detect in foods by HPLC because it coelutes with natural compounds in the food. We previously showed that food matrix could be degraded with titanium dioxide powder (TP). Here we describe an improved method for detection of iprodione using silica gel supported titanium dioxide (SGT). To synthesize SGT, titania-sol was mixed with diethanolamine, 2-propanol, and titanium tetraisopropoxide. After titania-sol was infiltrated into the silica gel (particle diameter 4 mm), the mixture was dried and then heated. Crude basil extract containing iprodione was mixed with SGT in a quartz vial, and the vial was irradiated with a UV light to selectively decompose the matrix interfering with the iprodione determination. In HPLC chromatograms of the treated solution, the interference peak decreased 35 times faster with SGT than with TP. When SGT (11 g) was added to the extract (20 mL) of dry basil (2 g), black light irradiation for 30 min was enough to quantify iprodione. The recovery rate of iprodione was 99.1%. Thus, the photocatalytic cleanup method using SGT is effective for analyzing residual iprodione in dry basil.