Quantitative measurement of 4-hydroxy tamoxifen in human plasma and mammary tumours by combined gas chromatography/negative chemical ionization mass spectrometry

Abstract

A highly sensitive and specific assay was developed for the quantitative measurement of 4-hydroxy tamoxifen (4-OH Tam) at the femtomole level in human plasma and mammary tumours. The drug and deuterated internal standard (4-OH Tam D4) were measured by gas chromatography/negative chemical ionization mass spectrometry with methane as the reactant gas. The two compounds of interest were isolated from the complex biological matrices using a solid-phase extraction procedure with Extrelut 1 columns. Soft operating conditions were required to convert 4-OH Tam to the fluorinated derivatives with pentafluorobenzyl chloride. The mass spectrometer was tuned to monitor the abundant and stable molecular ions at m/z 581 and 585 which were generated in the ion source by an electron capture process. This assay required only 0.5 ml of plasma or 0.5 g of mammary tissue, and the quantification limits of the method were 20 pg ml-1 for the body fluids or 100 pg g-1 for the tissue samples. The very low relative standard deviation and mean percentage error calculated during the different within-day or day-to-day repeatability assays have clearly demonstrated the ruggedness of the technique for routine analysis of 4-OH Tam.

Tamoxifen and its Main Metabolites Serum and Tissue Concentrations in Breast Cancer Women

“…The extraction from serum and tissue samples was performed according to the procedure of Langan-Fahey et al 7 and Girault et al, 8 respectively. One milliliter of serum was transferred to a polypropylene screw-cap tube containing 8 mL of a mixture of n-hexane/isoamyl alcohol (98/2) (v/v) and was extracted two times by mixing for 10 seconds, then centrifuged at 0°C for 10 minutes at 2000g.…”

Bioanalytical methods for determination of tamoxifen and its phase I metabolites: A review

“…Electron impact ionization (EI) is a widely used ionization method particularly for gases and volatile organic molecules. It was the preferred ionization technique in GC-MS analysis of tamoxifen metabolites [28,31,36,49,50,[73][74][75][76].…”

“…Lower limit of quantification levels of 100 pg g −1 tumor tissue and 20 pg mL −1 in plasma are reached using mass spectrometry as a detection technique [73].…”

Ultrasensitive Bioanalytical Assays for Cytotoxic Drugs: Focus on Locally Administered Anti-Cancer Agents

“…It was found that the cutaneous application of 4-OHT gel (0.5, 1 or 2 mg/day) to the skin of the breast produced high and consistent tumor concentrations of 4-OHT and much lower plasma levels. Thus far, there is only one, but a highly sensitive method to determine 4-OHT concentration in human plasma with a LLOQ of 0.02 ng/mL [41]. The drug and deuterated internal standard (4-OHT D4) were measured by GC/negative chemical ionization MS with methane as the reactant gas.…”