We developed a novel analytical method to measure the D‐ and L‐isomers of aspartic acid ( AA ) in the eye lens of beluga whales ( Delphinapterus leucas ) for age determination. The method was based on hydrolysis of the eye lens under acidic conditions followed by direct injection onto a Chirobiotic T (25 cm × 4.6 ID , 5 μm particle size) high performance liquid chromatography analytical column and detection by tandem mass spec...