Detection of prostaglandins in raw milk and the effect of processing technology on its stability.

This study established a solid-phase extraction-ultra-high-performance liquid chromatography-triple quadrupole tandem mass spectrometry method for the determination of naturally occurring prostaglandins (dinoprost) and their synthetic analogs (cloprostenol) in milk. The method was then validated to investigate the effects of 5 processing techniques (ultra-high-temperature sterilization, spray drying, pasteurization, skimming, and freezing) on the stability of added hormones in raw milk. The results showed that the limit of detection of this method was 0.04 to 0.12 ng/mL in the concentration range of 0 to 100 ng/mL, and the limit of quantitation was 0.11 to 0.37 ng/mL, with good linearity (R2 > 0.99). The processing results indicated that the recoveries after spray drying and ultra-high-temperature sterilization were both below 10%, which may be related to the properties of prostaglandins themselves. Furthermore, the effect of freezing on the residual rates of the 2 prostaglandins was almost negligible.