Table 2.

Relative intensities of peaks of ions a ([HC≡N–CH₃]⁺, m/z 42) and b ([CF₃–C≡N⁺–CH₃], m/z 110) in the spectra of methyl esters of N-methyl-N-TFA derivatives of l-glycine (I), l-alanine (II), l-phenylalanine (III), l-valine (IV), l-leucine (V), l-isoleucine (VI), l-serine (VII), l-threonine (VIII), l-cysteine (IX), l-methionine (X), l-lysine (XI), l-glutamic acid (XII) and l-aspartic acid (XIII).

Compound	Im/z42	Im/z110	Compound	Im/z42	Im/z110	Compound	Im/z42	Im/z110
I	22	33	VI	37	24	XI	29	31
II	24	39	VII	16	14	XII	14	29
III	48	20	VIII	50*	7	XIII	90	69
IV	52	45	IX	33	16
V	44	31	X	34	14

^*May contain a contribution from an oxonium ion fragment.