The limit of detection (LOD)10 for the proteinogenic amino acids was
0.8 pmol/L (16). The LOD and the limit of quantification for L-theanine
and ethylamine were calculated according to the derivation of the
German Research Foundation (17). The LOD was 0.01 mmol/L for
L-theanine and 0.08 mmol/L for ethylamine (signal to noise ratio = 2.5:1).
The corresponding limit of quantifications were 0.02 and 0.12 mmol/L,
respectively. The standard curve of L-theanine and ethylamine was linear
between 0.005 and 50 mmol/L (r > 0.95). Inter- and intra-assay variances
were