“Do it yourself” reference materials for δ 13C determinations by isotope ratio mass spectrometry

Abstract

A method is described to prepare inexpensive organic reference materials for routine stable isotope work. The method blends isotope-enriched and isotope-depleted materials to match closely international measurement standards. Examples are presented showing how (13)C-enriched and (13)C-depleted glucose were blended to match the isotopic compositions of the international carbon isotope standards, NBS 19 and L-SVEC. Preparation of the blended standards was straightforward, and the prepared solutions proved easy to dispense into tin capsules and easy to combust in a conventional isotope analysis system. The blended materials allow a laboratory to perform a two-point calibration for isotopic composition on a daily basis, with the use of an international reference material recommended for routine quality assurance. The blending method can be applied widely to make isotope standards for other elements and compounds.

Guidance for characterization of in‐house reference materials for light element stable isotope analysis

“…This can be both time‐consuming and difficult to apply. Producing solutions of simple single chemicals is one approach to ensuring homogeneity 23 . Those solutions could also be freeze‐dried in sufficiently small droplets if a solid form is required 9 …”

“…Producing solutions of simple single chemicals is one approach to ensuring homogeneity. 23 Those solutions could also be freeze-dried in sufficiently small droplets if a solid form is required. 9 For more complex matrices such as biological tissues or soil, material preparation can become laborious.…”

“…e.g. 19,23 Other sources of information include publications that describe the preparation and characterization of RMs from commercial RM producers, e.g. 10,12,[24][25][26] or RMs from other parties.…”

Biofilm-specific uptake does not explain differences in whole-stream DOC tracer uptake between a forest and an agricultural stream

“…We passed DOC and 13 C-DOC samples through pre-combusted Whatman GF/F filters (Whatman, Inc., Florham Park, NJ, U.S.A. 195%). The mixed standards were prepared from 13 C-labeled urea and urea with a natural isotope abundance by isotope blending (Carter and Fry 2013). The precision of enriched samples was \ 20%.…”

A stable isotope ratio approach to investigate the origins of illicit methylamphetamine in Queensland, Australia

“…When considering links between MA from multiple seizures, 20 comparisons of δ 13 C / δ 15 N compositions were also found to highlight different grouping patterns 21 compared to conventional profiling techniques [13]. 22 Early research demonstrated that batches of MA, manufactured by reductive amination of 1-23 phenylpropan-2-one (aka phenylacetone or P2P), using identical reagents and equipment had 24 markedly different δ 15 N compositions [14]. Further, systematic research into the preparation of 25 MDMA by reductive amination found significant isotopic variation with changing reaction 26 conditions; δ 2 H values were most affected by imine stir time; δ 13 C values were most affected by 27 the overall efficiency (completeness) of the reaction; δ 15 N values were most affected by an excess 28 of methylamine [15].…”