RESUMO
The synthesis of a new acridinium sulphonylamide label for the liquid chromatographic determination of carboxylic acids is described. The label 10-methyl-N-(p-tolyl)-N-(p-iodoacetamidobenzenesulphonyl)-9-acr idi nium carboxamide iodide is synthesized from 9-acridine-carboxylic acid by a seven-step reaction. Ibuprofen, used as test compound, is coupled to the reactive iodoacetamide group of the label by means of an alkylation reaction in dry acetonitrile for 20 min at 50 degrees C in the presence of 18-crown-6 and potassium carbonate as base catalyst. The reaction mixture is injected into a liquid chromatographic system with chemiluminescence detection. Separation is performed on a Zorbax C18 column with acetonitrile-water-tetrahydrofuran (39:57:4, v/v/v) containing 10 mmol/L TBABr and 0.035% H2O2 as the mobile phase at a flow rate of 1.0 ml/min. Chemiluminescence detection is achieved by the post-column addition of 200 mmol/L potassium hydroxide dissolved in methanol-water (1:1, v/v) at a flow rate of 20 microL/min. The detection limit (S/N = 3) of derivatized ibuprofen is 60 pg (3 pg injected).
Assuntos
Acridinas/química , Ácidos Carboxílicos/análise , Sondas Moleculares/química , Sulfonamidas/química , Acridinas/síntese química , Cromatografia Líquida/métodos , Hidróxidos/química , Ibuprofeno/análise , Medições Luminescentes , Sondas Moleculares/síntese química , Compostos de Potássio/química , Solventes , Sulfonamidas/síntese químicaRESUMO
Column liquid chromatography with chemiluminescence detection is used to determine oestradiol in serum. Oestradiol is labelled by means of a two-phase derivatization procedure with either dansyl chloride or laryl chloride. After derivatization the excess reagent is removed on a short amino-bonded column: the sulphonyl chloride functional group reacts with the amino groups causing removal of the label; the oestradiol derivatives are not retained. Chromatography of oestradiol derivatives is performed with methanol-water mixtures as eluent. Chemical excitation is carried out by adding bis(2-nitrophenyl)oxalate and hydrogen peroxide dissolved in acetonitrile to the column eluate. Linearity is observed (r = 0.9998; n = 7) over at least three decades (10(-6)-10(-9) M) for both dansyl chloride and laryl chloride. A detection limit of 5 x 10(-10) M (50 fmol injected) has been achieved and the dansyl derivatization method has been applied to the determination of oestradiol in spiked serum.
