TY - JOUR
T1 - Investigation of photochemical reactions of saccharides during direct ultraviolet absorbance detection in capillary electrophoresis
AU - Schmid, Thomas
AU - Himmelsbach, Markus
AU - Oliver, James D.
AU - Gaborieau, Marianne
AU - Castignolles, Patrice
AU - Buchberger, Wolfgang
PY - 2015
Y1 - 2015
N2 - Direct UV detection of saccharides in capillary electrophoresis is possible due to a base-catalyzed con-version into UV absorbing substances initiated by the light of the UV detector lamp. In the present studythe compounds formed during this reaction were investigated with capillary electrophoresis using anadditional UV lamp for online irradiation at a certain distance before the detector resulting in a separa-tion of the conversion products. It was found that for all investigated saccharides (glucose, ribose andsucrose) the major portion of the UV absorption in direct UV detection resulted from one and the samesubstance. By CE-UV, CE-MS as well as HPLC-MS measurements this substance was demonstrated tobe malondialdehyde, present as its conjugate base malonenolate under alkaline conditions. Additionalexperiments revealed that the conversion reaction is highly sensitive to the residence time under theUV light as malondialdehyde can further degrade into non-UV absorbing products. NMR measurementsshowed that under alkaline conditions this degradation proceeds slowly even without UV irradiation.
AB - Direct UV detection of saccharides in capillary electrophoresis is possible due to a base-catalyzed con-version into UV absorbing substances initiated by the light of the UV detector lamp. In the present studythe compounds formed during this reaction were investigated with capillary electrophoresis using anadditional UV lamp for online irradiation at a certain distance before the detector resulting in a separa-tion of the conversion products. It was found that for all investigated saccharides (glucose, ribose andsucrose) the major portion of the UV absorption in direct UV detection resulted from one and the samesubstance. By CE-UV, CE-MS as well as HPLC-MS measurements this substance was demonstrated tobe malondialdehyde, present as its conjugate base malonenolate under alkaline conditions. Additionalexperiments revealed that the conversion reaction is highly sensitive to the residence time under theUV light as malondialdehyde can further degrade into non-UV absorbing products. NMR measurementsshowed that under alkaline conditions this degradation proceeds slowly even without UV irradiation.
UR - http://handle.uws.edu.au:8081/1959.7/565171
U2 - 10.1016/j.chroma.2015.02.030
DO - 10.1016/j.chroma.2015.02.030
M3 - Article
SN - 0021-9673
VL - 1388
SP - 259
EP - 266
JO - Journal of Chromatography A
JF - Journal of Chromatography A
ER -