title: A new method for quantitative determination of dimemorfan in human plasma using monolithic silica solid-phase extraction tips.
abstract: Dimemorfan was extracted from human plasma samples (100 μL) using MonoTip C(18) tips, which were packed with a C(18)-bonded monolithic silica gel attached to the inside of the tip. The samples, which contained dimemorfan and trimeprazine as an internal standard (IS), were mixed with 300 μL of distilled water and 50 μL of 1M glycine-sodium hydroxide buffer (pH 10). The mixture was extracted onto the C(18) phase of the tip by 20 sequential aspirating/dispensing cycles using a manual micropipettor. The analytes retained on the C(18) phase were then eluted with methanol by five sequential aspirating/dispensing cycles. The eluate was injected directly into a gas chromatograph and detected by a mass spectrometer with selected ion monitoring in positive electron ionization mode. An Equity-5 fused silica capillary column (30 m × 0.32 mm i.d., film thickness 0.25 μm) gave adequate separation of the dimemorfan, IS, and impurities. The recoveries of dimemorfan and the IS spiked into plasma were ≥83%. The regression equation for dimemorfan showed excellent linearity from 0.25 to 32.0 ng/100 μL of plasma, and the limit of detection was 0.125 ng/100 μL of plasma. The maximum intra-day and inter-day relative standard deviations were 13%, while accuracy ranged from 88% to 105%. Dimemorfan was stable for at least 12 h at 4°C, 4 weeks at -80°C, and three freeze-thaw cycles in plasma. This new method is expected to have application as a pretreatment for the rapid, simple, and quantitative determination of dimemorfan in plasma samples.
authors.affiliation: Department of Legal Medicine, Toho University School of Medicine, 5-21-16 Omorinishi, Ota-ku, Tokyo 143-8540, Japan. chika99@med.toho-u.ac.jp
authors.forename: Chika
authors.initials: C
authors.lastname: Hasegawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kumazawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Terada
authors.forename: Xiao-Pen
authors.initials: XP
authors.lastname: Lee
authors.forename: Keizo
authors.initials: K
authors.lastname: Sato
authors.forename: Seisaku
authors.initials: S
authors.lastname: Uchigasaki
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Kurosaki
mesh_terms: D000982:Antipruritics / Q000032:analysis; D000996:Antitussive Agents / Q000032:analysis; D006801:Humans; D009019:Morphinans / Q000032:analysis*; D010949:Plasma / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods*; D014291:Trimeprazine / Q000032:analysis*
chemical_list: D000982:Antipruritics; D000996:Antitussive Agents; D009019:Morphinans; C012621:dimemorfan; D014291:Trimeprazine