Rapid amino acid quantitation with pre-column derivatization; ultra-performance reverse phase liquid chromatography and single quadrupole mass spectrometry

Background: We optimized a quantitative amino acid method with pre-column derivatization, norvaline (nva) internal standard and reverse phase ultra-performance liquid chromatography by replacing the ultraviolet detector with a single quadrupole mass spectrometer (MSnva)

Reference intervals for plasma sulfate and urinary sulfate excretion in pregnancy

Background: Sulfate is important for fetal growth and development. During pregnancy, the fetus relies on sulfate from the maternal circulation. We report reference intervals for maternal plasma sulfate levels and fractional excretion index (FEI) for sulfate in pregnancy, as well as sulfate levels in cord blood from term pregnancies

Plasma and urinary sulfate determination in a cohort with autism

Sulfate is important for mammalian development but is not routinely measured in clinical settings. The renal NaS1 sulfate transporter maintains circulating sulfate levels and is linked to renal sulfate wasting in mice. Some autistic individuals exhibit renal sulfate wasting, but the etiology is yet unknown. We measured plasma and urinary sulfate levels, calculated the fractional excretion index (FEI) of sulfate, and screened for two loss-of-function NaS1 sequence variants (R12X and N174S) in 23 autistic individuals. The FEI sulfate values ranged from 0.13 to 0.50. NaS1 variants were detected in 18 of the 23 individuals (11 heterozygous N174S, four homozygous N174S, two heterozygous R12X, and one individual carried both R12X and N174S). Those individuals with neither sequence variant had FEI sulfate ≤ 0.34, whereas FEI sulfate ≥ 0.35 was found in about 60 % (11 of 18) of individuals that had R12X and/or N174S. This study links renal sulfate wasting with loss-of-function NaS1 sequence variants in humans