Prepared concentration (ng/mL) Period after preparation (day)

0                          1                        2                                  3     
2 2.3 2.0 2.6 2.1
40 38.5 42.1 38.9 40.0
Data is the average of 3 samples
Table 6: Stability of ameziniummetilsulfate (AM) in autosampler.