A revision in hydrogen isotopic composition of USGS42 and USGS43 human-hair stable isotopic reference materials for forensic science.

摘要: The hydrogen isotopic composition (δ(2)HVSMOW-SLAP) of USGS42 and USGS43 human hair stable reference materials, normalized to the VSMOW (Vienna-Standard Mean Ocean Water)-SLAP (Standard Light Antarctic Precipitation) scale, was originally determined with a high temperature conversion technique using an elemental analyzer (TC/EA) glassy carbon tube filling analysis by isotope-ratio mass spectrometer (IRMS). However, TC/EA IRMS method can produce inaccurate δ(2)HVSMOW-SLAP results when analyzing nitrogen-bearing organic substances owing formation cyanide (HCN), leading non-quantitative sample into molecular (H2) for analysis. A single-oven, chromium-filled, (Cr-EA) coupled substantially improves measurement quality reliability hydrogen- material because hot chromium scavenges all reactive elements except hydrogen. materials have been analyzed Cr-EA method, values their non-exchangeable fractions revised: [Formula: see text] where mUr=0.001=‰. On average, these revised are 5.7mUr more positive than those previously measured. It is critical that readers pay attention in publications as they may need adjust previous ensure on same isotope-delta scale.