Assays - Amoxicillin

Determination of Amoxicillin in human serum and plasma by high-performance liquid chromatography and on-line postcolumn derivatization

Author: H.J. Mascher, C. Kikuta
Publisher: J. Chromatogr. A, 812 (1998), 221-226

A highly selective and fast HPLC method was developed for the determination of amixicillin in human serum and plasma. After protein precipitation with perchloric acid, an aliquot of the supernatant was neutralized by mixing it with sodium acetate solution and injected into a C18 HPLC column. Detection was done by a fluorescence detector after on-line postcolumn derivatisation with fluorescamine. The practical limit of quantification was 0.1 µg/ml using 0.3 ml of plasma. Linearity was given in the tested range of 0.1 to 15 µg/ml plasma. Inter-day precision (relative standard deviation) over 7 days for 0.42 µg/ml was ± 7.27 %; for 4.54 µg/ml, ± 5.24 % and for 13.18 µg/ml, ± 5.25 %. Stability over 50 days in serum and plasma occurs at -70°C but not at -20°C (-25 to -35 % reduction). This method was used for thousands of human serum and plasma samples.

Determination of Amoxicillin [Amoxycillin] in plasma by high-performance liquid chromatography with fluorescence detection after online oxidation

Author: H.J. Mascher, C. Kikuta
Publisher: H. Mascher und C. Kikuta, J. Chromatogr. 506 (1990) 417-421

A simplified high-performance liquid chromatographic method for the determination of amoxicillin in plasma is described. Specific and sensitive fluorescence detection was achieved by on-line post-column electrochemical oxidation, using an electrochemical detector. Owing to the high specificity of the detection system, deproteinized plasma samples could be injected directly without prior treatment. This method permits a very fast and reproducible determination of amoxicillin in plasma on a routine basis at levels, down to 50 ng/ml. The absolute detection limit is about 10 pg injected.