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Measurement of 5‐fluoro‐2′‐deoxyuridine serum levels by gas chromatography chemical ionization mass spectrometry
Author(s) -
Gelijkens C. F.,
De Leenheer A. P.,
Sandra P.
Publication year - 1980
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200071125
Subject(s) - chemistry , deoxyuridine , reagent , chromatography , gas chromatography , mass spectrometry , chemical ionization , detection limit , selected ion monitoring , derivatization , gas chromatography–mass spectrometry , analytical chemistry (journal) , ionization , ion , organic chemistry , biochemistry , dna
Abstract Serum levels of 5‐fluoro‐2′‐deoxyuridine in cancer treated patients were measured by gas chromatography mass spectrometry under chemical ionization conditions; 1‐(2‐deoxy‐β‐D‐lyxofuranosyl)‐5‐fluorouracil (3′‐ epi ‐5‐fluoro‐2′‐deoxyuridine) was used as an internal standard. The drug and internal standard were quantitatively isolated from the serum sample by a mini‐column anion exchange method and the extract permethylated using potassium‐ tert ‐butoxide in dimethylsulphoxide and methyl iodidie. The derivatized nucleosides were then re‐extracted from the reaction mixture and analysed on a glass capillary column coated with Superox‐4. The column was coupled directly to the chemical ionization source of the mass spectrometer; NH 3 was used as the reagent gas. The gas chromatographic effluent was monitored at m/z 289, the [MH] + ion of the N,O ‐permethyl derivatives of 5‐fluoro‐2′‐deoxyuridine and the internal standard. Recovery of 5‐fluoro‐2′‐deoxyuridine from serum in the 0–1 μg ml −1 concentration range averaged 93 ± 2% (SD); a linear detector response was observed up to 50 ng 5‐fluoro‐2′‐deoxyuridine ml −1 . At the 10 ng ml −1 level, a within‐run assay precision of 10% (CV) ( n = 5) was found, while a detection limit of about 1 ng 5‐fluoro‐2′‐deoxyuridine ml −1 of serum was attained. The method was applied to the measurement of disappearance curves of 5‐fluoro‐2′‐deoxyuridine in the serum of treated patients.