To achieve high sensitivity , the minimum concentration of analyte detectable should be reproducibly measured by a signal distinguishable from the background , i . e . , noise at zero dose of analyte ( 38 ) 為了達到高靈敏度,通過產生的信號與背景不同,即0劑量分析物的噪音,應該可重復的測到能檢測到的最小分析物濃度。
Abstract : methanesulfonic acid method was used to prepare five acylated chitins . except heptanoyl chitin , four of them , i . e . acetyl chitin , propionyl chitin , butyryl chitin and hexanoyl chitin , had high degree of substitution ( from 1 . 5 to 2 . 0 ) and exhibited lyotropic liquid crystalline behavior and cholesteric phase . as the length of the side chain increased the critical concentration ( w / w ) somewhat increased from 0 . 21 to 0 . 26 because the chain rigidity dropped . the critical concentration values of all the four derivatives were much higher than that of chitin ( 0 . 12 ) due to the decrease of intramolecular hydrogen bonds . the four acylated chitin can form typical banded texture after being sheared . there minimum concentrations to form banded texture of them were evidently different , varied from 0 . 25 ( for acetyl chitin ) to 0 . 37 ( for hexanoyl chitin ) . these results further indicated that liquid crystallinity decreased while the length of flexible side substituents increased 文摘:四種羧?;讱に丶匆阴;?、丙?;?、丁?;图乎;讱に卦诙纫宜崛芤褐芯尸F膽甾型溶致液晶相.臨界濃度隨側基長度增加而略有增加,衍生物的臨界濃度明顯都比原甲殼素高許多,這些規(guī)律都可以用鏈剛性的變化來解釋.四種羧酰化甲殼素在剪切時均能形成條帶織構,而且能形成條帶織構的最低濃度有明顯差別,隨側基長度增加而提高,進一步表明側基較長,液晶性減少