Simple dilute-and-shoot method for urinary vanillylmandelic acid and homovanillic acid by liquid chromatography tandem mass spectrometry.

Background: Neuroblastomas are pediatric tumors characterized by overproduction of catecholamines. The catecholamine metabolites, vanillylmandelic acid (VMA) and homovanillic acid (HVA), are used in clinical evaluation of neuroblastoma. Tandem mass spectrometry (LC-MS/MS) is an effective analytical method for measurement of VMA and HVA in urine.

Practical LC-MS/MS Method for 5-Hydroxyindoleacetic Acid in Urine.

Background: Serotonin, an endogenous biogenic amine found in enterochromaffin cells of the gastrointestinal tract, is produced in excess by carcinoid tumors. The primary urinary metabolite of serotonin, 5-hydroxyindoleacetic acid (5-HIAA), is used in the diagnosis and management of carcinoid disease. This study describes the development and validation of a dilute-and-shoot LC-MS/MS method for the measurement of 5-HIAA in urine.

A rapid HPLC method used to establish pediatric reference intervals for vitamins A and E.

Background: Serum concentrations of the fat-soluble vitamins A (retinol) and E (tocopherol) are measured to assess deficiency and, in the case of vitamin A, toxicity. We modified our existing HPLC method for analyzing vitamins A and E by using a high throughput analytical column and small diameter tubing to reduce analysis time. The modified HPLC method was used to establish pediatric reference intervals for these vitamins.