TY - JOUR
T1 - Hydroxycarbonyl anion (m/z 45), a diagnostic marker for α-hydroxy carboxylic acids
AU - Bialecki, Jason B.
AU - Axe, Frank U.
AU - Attygalle, Athula B.
PY - 2009/2
Y1 - 2009/2
N2 - Collision-induced dissociation mass spectra of anions derived from α-hydroxy carboxylic acids (AHAs) show a diagnostic peak at m/z 45. Product ion spectra recorded from this m/z 45 ion confirm that it represents the hydroxycarbonyl anion (⊖COHO) and not the formate anion (C - HOO⊖) as sometimes described in the literature. For example, the formate anion is not only defiant to further fragmentation but is also unreactive toward CO2. In contrast, the hydroxycarbonyl anion easily fragments to produce a peak at m/z 17 for the hydroxyl anion, and also readily reacts with CO2 to produce a peak at m/z 61 for the bicarbonate anion. The hydrogen atom in the hydroxycarbonyl anion and that in the formate anion are not mobile within the skeletal framework of the ions, since the two ions did not manifest any interconversion under the conditions and time scales of our mass spectrometric experiments. The other significant product ion peak in the spectra of deprotonated AHAs represents a 46-Da loss. MS/MS data from appropriately deuteriated compounds confirmed that one hydrogen atom from the C-2 position, and the other from the hydroxy group are specifically removed for this loss of elements of formic acid. Moreover, the two oxygen atoms eliminated for the HCOOH loss originate exclusively from the carboxylate group.
AB - Collision-induced dissociation mass spectra of anions derived from α-hydroxy carboxylic acids (AHAs) show a diagnostic peak at m/z 45. Product ion spectra recorded from this m/z 45 ion confirm that it represents the hydroxycarbonyl anion (⊖COHO) and not the formate anion (C - HOO⊖) as sometimes described in the literature. For example, the formate anion is not only defiant to further fragmentation but is also unreactive toward CO2. In contrast, the hydroxycarbonyl anion easily fragments to produce a peak at m/z 17 for the hydroxyl anion, and also readily reacts with CO2 to produce a peak at m/z 61 for the bicarbonate anion. The hydrogen atom in the hydroxycarbonyl anion and that in the formate anion are not mobile within the skeletal framework of the ions, since the two ions did not manifest any interconversion under the conditions and time scales of our mass spectrometric experiments. The other significant product ion peak in the spectra of deprotonated AHAs represents a 46-Da loss. MS/MS data from appropriately deuteriated compounds confirmed that one hydrogen atom from the C-2 position, and the other from the hydroxy group are specifically removed for this loss of elements of formic acid. Moreover, the two oxygen atoms eliminated for the HCOOH loss originate exclusively from the carboxylate group.
KW - CID
KW - Even-electron ions
KW - Formate anion
KW - Fragmentation
KW - Hydroxycarbonyl anion
KW - Ion-neutral complex
KW - Negative ions
KW - α-hydroxy carboxylic acids
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U2 - 10.1002/jms.1504
DO - 10.1002/jms.1504
M3 - Article
C2 - 19034891
AN - SCOPUS:59949100822
SN - 1076-5174
VL - 44
SP - 252
EP - 259
JO - Journal of Mass Spectrometry
JF - Journal of Mass Spectrometry
IS - 2
ER -