Component quantification in a sample by solid-phase microextraction is commonly performed by using a standard calibration with the SPME process. However, in some cases, it is necessary to determine precisely the absolute amount of analytes sorbed onto SPME fibers. Generally, it is estimated using external liquid calibration of the chromatograph. Due to the differences between SPME and liquid injections, this method can be inaccurate. In this paper, its validity was put to the test. First, the external liquid calibration was confronted with a multiple extraction approach previously described in the literature and called the ''depletion experiment.'' A lack of data correlation led to the development of another method to verify the external liquid calibration. It was based on an extraction of the fiber-sorbed analytes with the same solvent used for external liquid calibration. After checking that quantitative solvent-extraction was achieved, this enabled us to precisely determine the quantity of analytes present in the solvent and to quantify fiber-sorbed analytes. Statistical treatment of the data brought the conclusion that external liquid calibration, under the tested experimental conditions, was suitable to determine the absolute amount of fiber-sorbed analytes.