Patent ID: 8017403

Claim:
A method for detecting the presence or amount of pyridoxal 5′-phosphate in a body fluid sample by tandem mass spectrometry, comprising: purifying said sample, wherein purifying comprises: (a) applying said sample to an extraction column under turbulent flow conditions whereby pyridoxal 5′-phosphate is reversibly retained by the extraction column, wherein said extraction column comprises particles with an average diameter of between about 35 μm and about 50 μm; (b) washing the extraction column under conditions whereby non-retained materials from the sample are washed from the column; (c) eluting retained pyridoxal 5′-phosphate from the extraction column; (d) applying the eluted pyridoxal 5′-phosphate from the extraction column to an analytical column under laminar flow conditions; and (e) eluting pyridoxal 5′-phosphate from the analytical column; (ii) generating a parent ion of said pyridoxal 5′-phosphate from said purified sample; (iii) generating one or more daughter ions of said parent ion; and (iv) detecting the presence or amount of one or more said ions generated in step (ii) or step (iii) or both, and relating the detected ions to the presence or amount of said pyridoxal 5′-phosphate in said body fluid sample.