Four laboratories from New Zealand, Ireland, Singapore and
China using the described method observed variable between-day
intermediate precision (RSDiR) ranging from 5.38 to 12.9% (Table 2).
As indicated by HorRat values, three of the laboratories were in the
upper range of acceptability, reflecting the difficulty of the derivatisations.
However, the method is deemed to have sufficient
long-term stability to be considered fit-for-purpose for quality
control purposes in the dairy industry. Removal of three statistical
outliers from Lab 1 reduced RSDiR to 8.7%.