Abstract
Caffeine concentrations were measured in the urines of 11 361 athletes tested for
doping control in the Ghent doping control laboratory during the period 1993 - 2002.
Determination of these concentrations was done using an alkaline extraction with a
mixture of dichloromethane and methanol (9 : 1; v/v) followed by high performance
liquid chromatography and ultraviolet detection (HPLC-UV). The method was validated
according to ISO 17 025 standards (International Organisation for Standardisation).
Quantification was done by using a calibration curve in the range from 0 to 20 µg/ml.
The limit of quantification (LOQ) was 0.10 µg/ml. Most caffeine concentrations were
far below 12 µg/ml. Because the results were not normally distributed, transformation
of the data was done to evaluate the difference in detected concentrations in several
sports. This resulted in an overall average concentration of 1.22 µg/ml ± 2.45 µg/ml.
Comparison of those sports with more than 200 samples being analysed demonstrated
that caffeine concentrations in urine samples from bodybuilders are significantly
higher in comparison to urines taken in the other sports. Also, a significant difference
between caffeine concentrations found in cycling and concentrations found in other
sports, including athletics and some ball sports, was observed.
Key words
Sport - bodybuilding - cycling - doping analysis
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W. Van Thuyne
Doping Control Laboratory, Department of Clinical Chemistry, Microbiology and Immunology,
Ghent University
Technologiepark 30
9052 Zwijnaarde
Belgium
Telefon: + 3293313295
Fax: + 32 93 31 32 99
eMail: wim.vanthuyne@UGent.be
