Mass spectrometry method for measuring vitamin b6 in body fluid

A method for detecting the presence or amount of pyridoxal 5′-phosphate in a body fluid sample by tandem mass spectrometry, the method comprising:

• adding an internal standard to the body fluid sample;
• purifying the body fluid sample using turbulent flow liquid chromatography, high performance liquid chromatography, or both;
• ionizing pyridoxal 5′-phosphate and the internal standard in the body fluid sample to generate a parent ion of pyridoxal 5′-phosphate and a parent ion of the internal standard;
• generating one or more daughter ions of the parent ion of pyridoxal 5′-phosphate and one or more daughter ions of the parent ion of the internal standard;
• and
• detecting the presence or amount of the one or more daughter ions, and determining the presence or amount of pyridoxal 5′-phosphate in the body fluid sample from the presence or amount of the one or more daughter ions.