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Issue 10, 2010
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Characterization and evaluation of two-dimensional microfluidic chip-HPLC coupled to tandem mass spectrometry for quantitative analysis of 7-aminoflunitrazepam in human urine

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Abstract

Microfluidic chip-based high-performance-liquid-chromatography coupled to mass spectrometry (chip-HPLC-MS) has been widely used in proteomic research due to its enhanced sensitivity. We employed a chip-HPLC-MS system for determining small molecules such as drug metabolites in biological fluids. This chip-HPLC-MS system integrates a microfluidic switch, a 2-dimensional column design including an enrichment column (160 nL) for sample pre-concentration and an analytical column for chromatographic separation, as well as a nanospray emitter on a single polyimide chip. In this study, a relatively large sample volume (500 nL) was injected into the enrichment column for pre-concentration and an additional 4 μL of the initial mobile phase was applied to remove un-retained components from the sample matrix prior to chromatographic separation. The 2-dimensional column design provides the advantages of online sample concentration and reducing matrix influence on MS detection. 7-Aminoflunitrazepam (7-aminoFM2), a major metabolite of flunitrazepam (FM2), was determined in urine samples using the integrated chip-HPLC-MS system. The linear range was 0.1–10 ng mL−1 and the method detection limit (signal-to-noise ratio of 3) was 0.05 ng mL−1 for 7-aminoFM2. After consecutive liquid–liquid extraction (LLE) and solid-phase extraction (SPE), the chip-HPLC-MS exhibited high correlation between 7-aminoFM2 spiked Milli-Q water and 7-aminoFM2 spiked urine samples. This system also showed good precision (n = 5) and recovery for spiked urine samples at the levels of 0.1, 1.0, and 10 ng mL−1. Intra-day and inter-day precision were 2.0–7.1% and 4.3–6.0%, respectively. Clinical urine samples were also analyzed by this chip-HPLC-MS system and acceptable relative differences (−1.3 to −13.0%) compared with the results using a GC-MC method were determined. Due to its high sensitivity and ease of operation, the chip-HPLC-MS system can be utilized for the determination of small molecules such as drug metabolites and neurotransmitters in biological fluids for clinical diagnosis.

Graphical abstract: Characterization and evaluation of two-dimensional microfluidic chip-HPLC coupled to tandem mass spectrometry for quantitative analysis of 7-aminoflunitrazepam in human urine

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Publication details

The article was received on 27 May 2010, accepted on 24 Jul 2010 and first published on 02 Sep 2010


Article type: Paper
DOI: 10.1039/C0AN00355G
Analyst, 2010,135, 2737-2742

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    Characterization and evaluation of two-dimensional microfluidic chip-HPLC coupled to tandem mass spectrometry for quantitative analysis of 7-aminoflunitrazepam in human urine

    H. Bai, S. Lin, S. Chan and M. Fuh, Analyst, 2010, 135, 2737
    DOI: 10.1039/C0AN00355G

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