Polydispersity Index
This index is a number calculated from a simple 2 parameter fi t to the
correlation data (the cumulants analysis). The Polydispersity Index is
dimensionless and scaled such that values smaller than 0.05 are rarely
seen other than with highly monodisperse standards. Values greater
than 0.7 indicate that the sample has a very broad size distribution and
is probably not suitable for the dynamic light scattering (DLS) technique.
The various size distribution algorithms work with data that falls between
these two extremes. The calculations for these parameters are defined in
the ISO standard document 13321:1996 E and ISO 22412:2008.
脂质体的分散性可以用PDI来表征，PDI的计算可以按照相应的ISO标准得到。好的脂质体分散性PDI值通常小于0.10，但正如上面说的，PDI要小于0.05是很罕见的。PDI与脂质体的处方以及工艺密切相关，是脂质体物理稳定性的一个重要考察指标。
