But most of the drugs has tew fluorescence quantum yield, so some reagents must be added to produce fluorescence. 間接測定法是由於大部分藥物本身無熒光或者在水溶液中的熒光量子產率低，無法直接測定藥物熒光，必須通過加入其它試劑提高藥物的熒光量子產率而建立的熒光分析法。
Covalent bonds between chromogen and macromolecule chains enhance their photochemical stability, increase their whitening performance and fluorescence quantum yield. 發色團與高分子鏈間的共價鍵使其光化學穩定性大大增強，增白性能和熒光量子產率顯著提高。
