Field desorption mass spectrometric measurement of picomole amounts of leucine enkephalin in canine spinal cord tissue.

Leucine enkephalin is measured in canine spinal cord tissue in a structurally unambiguous manner. A rapid tissue procurement procedure minimizes enkephalin metabolism. High-performance liquid chromatography purification of brian neuropeptides is followed by field desorption mass spectrometric measurement of leucine enkephalin in spinal cord tissue extracts. Quantification is performed at the 70 ng (126 pmol) g-1 of wet weight tissue, or 70 parts per billion level. The higher homolog of leucine enkephalin, 2ala-leucine enkephalin, is utilized as internal standard. Straight-line statistics are obtained for a series of samples to which a peptide standard is added.