The determination of cyclophosphamide and its metabolites in blood plasma as stable trifluoroacetyl derivatives by electron capture chemical ionization gas chromatography/mass spectrometry

Abstract

A method is described for the determination of the antitumour drug cyclophosphamide and six stable metabolites in plasma of cancer patients, namely dechloroethyl-cyclophosphamide, 4-keto-cyclophosphamide, carboxy-phosphamide, alcophosphamide, nor-nitrogen mustard and the N-chloroethyl-1,3-oxazolidine-2-one, as methyl and/or trifluoroacetyl derivatives by single ion monitoring gas chromatography/mass spectrometry, mostly in the electron capture chemical ionization mode. The isolation of most metabolites was performed by solid-phase C-18 extraction in weakly acidic medium. The phosphoramide mustard isolated under these conditions decomposes readily to the nor-nitrogen mustard during derivatization. The original nor-nitrogen mustard and the chloroethyl-1,3-oxazolidine-2-one were isolated by liquid extraction with ethyl acetate in alkaline medium. Recoveries of 75-99% were measured using spiked blank plasma samples. Quantitation of metabolites in patient plasma samples was performed using two sets of calibration curves for the concentration ranges of 1-100 ng and 0.1-10 micrograms of metabolite per millilitre of original plasma.

Covalent binding of nitrogen mustards to the cysteine-34 residue in human serum albumin

“…Although we have not synthesized this particular adduct and therefore have no definitive proof for its identity, evidence for this structural entity has also been provided by others, e.g. in case of alkylation of haemoglobin (Thulin et al 1996) and metallothionein (Wei et al 1999) by cyclophosphamide, and also in case of (urinary) metabolites of cyclophosphamide (Momerency et al 1994;Joqueviel et al 1998). Tripeptide 2e could also be detected after Pronase digestion of albumin isolated from plasma obtained from patients treated with various doses of cyclophosphamide.…”

Estimation of the cancer risk to humans resulting from the presence of cyclophosphamide and ifosfamide in surface water

“…For both substances, the 4-hydroxy-oxazaphosphorine is the basic compound of cytotoxic specificity and carcinogenic selectivity (Momerency et al 1994b). The related mustards (phosphoramide mustard and isophosphoramide mustard) are the alkylating agents for both compounds (Saul et al 1979;Haas et al 1987;Goren 1991;Martino et al 1992;Boos et al 1992;Gilard et al 1993;Kümmerer 2008).…”

Liquid-liquid extraction procedure for trace determination of cyclophosphamide in human urine by high-performance liquid chromatography tandem mass spectrometry

“…In accordance with the results reported by Momerency et al 16 on the liquid-liquid extraction of CP, which gives higher yields than solid phase extraction using C 18 reversed phase columns, the liquid-liquid isolation technique was used. Since liquid extraction procedures are generally more dependent on pH than the solid-phase isolation methods, the experiments were performed at six different pH values (pH 4,5,6,7,8,10).…”

“…Moreover the on-line chromatographic analysis with mass selective detection allows the quantification of cyclophosphamide at lower ng/mL levels than the gas chromatographic methods. 16 The sensitive and specific procedure described in the present study seems to be the most appropriate one for the analyses of compounds of low volatility and thermal instability, and can be used to monitor occupational exposure to cyclophosphamide.…”