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Validation of a liquid chromatography-tandem mass spectrometry method for simultaneous quantification of N,N-dimethylacetamide and N-monomethylacetamide in pediatric plasma |
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| Authors: | Sebastian P A Rosser Andrew J McLachlan Georg Hempel Jason Chung Peter J Shaw Steven J Keogh Christa E Nath |
| Institution: | 1. The Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, Australia;2. Sydney Pharmacy School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia;3. Institute for Pharmaceutical and Medicinal Chemistry and Clinical Pharmacy, University of Münster, Sydney, Germany;4. The Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, Australia
Department of Biochemistry, The Children's Hospital at Westmead, Sydney, Australia;5. The Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, Australia Cancer Centre for Children, The Children's Hospital at Westmead, Sydney, Australia;6. Cancer Centre for Children, The Children's Hospital at Westmead, Sydney, Australia;7. Department of Biochemistry, The Children's Hospital at Westmead, Sydney, Australia |
| Abstract: | N,N–dimethylacetamide is an excipient used in intravenous busulfan formulations, a drug used in hematopoietic stem cell transplantation conditioning. The aim of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for simultaneous quantification of N,N-dimethylacetamide, and its metabolite N-monomethylacetamide in plasma from children receiving busulfan. A 4 μl aliquot of patient plasma was extracted using 196 μl 50% methanol solution and quantified against calibrators prepared in the extraction solvent given negligible matrix effects across three concentrations. 9H2]-N,N-dimethylacetamide was used as an internal standard. Separation of N,N-dimethylacetamide and N-monomethylacetamide was achieved using a Kinetex EVO C18 stationary phase (100 mm × 2.1 mm × 2.6 μm) running an isocratic mobile phase of 30% methanol containing 0.1% formic acid at a flow of 0.2 ml/min over 3.0 min. The injection volume was 1 μl. Calibration curves for N,N-dimethylacetamide and N-monomethylacetamide were linear up to 1200 and 200 μg/L, respectively, with a lower limit of quantification 1 μg/L for both analytes. Calibrator accuracy and precision were within ± 10% of the test parameters across four concentration levels. Analytes were stable over 14 days at three different storage conditions. This method was successfully applied to measure N,N-dimethylacetamide and N-monomethylacetamide concentrations in a total of 1265 plasma samples from 77 children. |
| Keywords: | liquid chromatography-tandem mass spectrometry method validation N N-dimethylacetamide N-monomethylacetamide pharmacokinetics |