Methods of determining the dose of UVC light delivered to a sample comprising a low optical transmission complex fluid are provided. Also provided are methods of inactivation of an organism, such as a spore, a bacteria or a virus, in a sample comprising dose of UVC light delivered to a sample comprising a low optical transmission complex fluid.提供判斷傳遞至樣品(包含低光學傳輸複合流體)之UVC光劑量的方法。亦提供使樣品中之有機體(諸如孢子、細菌或病毒)不活化之方法,其包含向包含低光學傳輸複合流體之樣品傳遞一定劑量之UVC光。