Distribution of Tamiflu in Surface Water of the Sagami River System

Concentrations of tamiflu (Oseltamivir phosphate) in surface water of Sagami River system were investigated. Analytical method of tamiflu for environmental water with solid phase extraction and LC/MS/MS was developed. Using this method, recovery and determination limit were 94.9% and 0.1ng/L respectively. In surface water of Sagami River, concentration of tamiflu was increased (from ‹0.1ng/L to 1.1ng/L) by confluence of tributaries contaminated by tamiflu. This observation suggests that tamiflu detected within tributaries could be from houses not connected to sewage. Seasonal variation of tamiflu from September, 2006 to January, 2010 followed to the transition of influenza cases very well after a delay of about one month.