Liquid chromatographic analysis of carboxylic acids using N-(4-aminobutyl)-N-ethylisoluminol as chemiluminescent label: determination of ibuprofen in saliva.
N-(4-Aminobutyl)-N-ethylisoluminol was used for labelling of carboxylic acids. The derivatization reaction was carried out with 1-hydroxybenzotriazole as pre-activator of the carboxylic acid function and N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide as the coupling reagent. Optimum conditions for the derivatization were determined by using factorial design analysis, with ibuprofen as the test compound. Chemiluminescence detection was carried out using a post-column on-line electrochemical hydrogen peroxide generation system and the addition of microperoxidase as the catalyst. The detection limit of derivatized ibuprofen in human saliva was 0.7 ng per 0.5 ml of saliva, with a recovery of 96.1 +/- 1.3%. The method was linear over at least three decades (2.5 ng to 2.5 micrograms) and the repeatability was satisfactory (R.S.D. = 5.2% at the 25 ng level; n = 4).
Department of Analytical Chemistry, Free University, Amsterdam, Netherlands.
O M
OM
Steijger
H
H
Lingeman
U A
UA
Brinkman
J J
JJ
Holthuis
A K
AK
Smilde
D A
DA
Doornbos
D001798:Blood Proteins / Q000378:metabolism; D002264:Carboxylic Acids / Q000032:analysis*; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis; D007052:Ibuprofen / Q000032:analysis*; D007202:Indicators and Reagents; D008163:Luminescent Measurements; D008165:Luminol / Q000031:analogs & derivatives*; D009195:Peroxidase / Q000737:chemistry; D011485:Protein Binding; D012463:Saliva / Q000737:chemistry*
D001798:Blood Proteins; D002264:Carboxylic Acids; D007202:Indicators and Reagents; D008165:Luminol; C031912:6-(N-(4-aminobutyl)-N-ethyl)amino-2,3-dihydrophthalazine-1,4-dione; D006861:Hydrogen Peroxide; D009195:Peroxidase; D007052:Ibuprofen