title: Assessment of tear concentrations on therapeutic drug monitoring. III. Determination of theophylline in tears by gas chromatography/mass spectrometry with electron ionization mode.
abstract: A simple and sensitive method for the quantitation of theophylline (TP) in tears and plasma developed using gas chromatography/electron-impact ionization/mass spectrometry. Tears were collected by non-invasive Schirmer method. Plasma was pipetted on a Schirmer tear test strip (cutting to 5 mm x 5 mm). Then, TP was converted directly into its pentafluorobenzoyl amide derivative without the need to perform any extraction from the biological fluid absorbed on Schiemer test paper and was quantified by gas chromatography-selected ion recordings with electron ionization mode. The concentrations in tears [C]t correlated very well with those of the free form in the plasma [Cf]p and those of the total form in the plasma [Cb+f]p. The ratios between TP concentrations in tears and plasma (free and total form) were as follows: [C]t/[Cb+f]p=0.53+/-0.20; [C]t/[Cf]p=1.21+/-0.19; [Cf]p/[Cb+f]p=0.44+/-0.14. The ratios of [C]t/[Cb+f]p, [C]t/[Cf]p and [Cf]p/[Cb+f]p were in good agreement with the previously published data.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nakajima
authors.forename: Shinji
authors.initials: S
authors.lastname: Sato
authors.forename: Susumu
authors.initials: S
authors.lastname: Yamato
authors.forename: Kenji
authors.initials: K
authors.lastname: Shimada
authors.forename: Shuji
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Akira
authors.initials: A
authors.lastname: Honda
authors.forename: Jiro
authors.initials: J
authors.lastname: Miyamoto
authors.forename: Harunobu
authors.initials: H
authors.lastname: Hirano
authors.forename: Mitsuyuki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyazaki