Development and single laboratory validation of a targeted liquid chromatography-triple quadrupole mass spectrometry-based method for the determination of insulin like growth factor-1 in different types of milk samples.

A simple and reliable targeted liquid chromatography-electrospray-tandem mass spectrometry (LC-MS/MS) method was developed and validated through the selection of two biomarker peptides for the identification and determination of bovine insulin like growth factor-1 (IGF-1) in milk samples. Two urea-based sample extraction procedures were tested. The validation results provided detection limits at the 1-5 ng IGF-1/mL level as a function of the milk matrix, precision ranged from 3 to 8% and the method accuracy in the different milk matrices was assured. Finally, IGF-1 was measured in milk samples obtained by treatment with eleven different technological processes: IGF-1 concentrations were spread over a wide range from 11.2 ± 0.3 ng/mL to 346 ± 8 ng/mL with a median of 57.0 ± 0.2 ng/mL. The highest amount of IGF-1 was found in fresh whole milk samples and no significant correlation was found between the total milk protein content and the IGF-1 concentration level.