Table 2.

Repeatability and intra-day and inter-day precision of the LC/APCI-MS/MS method, calculated at 25 nM. Results are expressed as % relative standard deviation (% RSD)

Compound	Repeatabilitya %	Intra-dayb %	Inter-day %c
MDA	1.3	5.2	6.9
Acrolein	2.7	3.5	7.5
4-HHE	2.6	4.4	6.9
4-HNE	2.1	2.6	7.8
n-hexanal	2.2	4.7	7.4
n-heptanal	4.4	7.9	9.9
n-nonanal	3.6	6.2	8.5

^an = 12.

^bn = 24; four derivatized samples, each injected twice, at the beginning, in the middle and at the end of the working session.

^cn = 24; solutions of aldehydes were prepared daily from the 5 mM solution in acetonitrile and derivatized.