Quantification of Kryptofix 2.2.2 in 2-[(18)F]FDG and other radiopharmaceuticals by LC/MS/MS.

A high-performance liquid chromatography-tandem mass spectrometric method (LC/MS/MS) was developed and validated for the quantitative analysis of Kryptofix (K-222) in the radiopharmaceuticals of 2-deoxy-2-[(18)F] fluoro-D-glucose (2-[(18)F]FDG) and 3-(3-((3-fluoropropyl)thio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine (FPTZTP). With an internal standard, the limit of quantitation for K-222 was 1.0 ng/ml. This is so far the most sensitive method for the quantification of K-222. Excellent linearity (RSQ = 0.9997) was obtained over the range of 1.0-100 ng/ml. Good precision and accuracy were also observed. The method is amenable to the validation of radiosynthetic methods.