Isotopic enrichment in the pre- and post-dose urine samples, the dose given and the local tap water was measured using isotope ratio mass spectrometry (Hydra 20-20; SerCon) at St John's Research Institute, Bangalore, India.
Gross NH4+ mineralization was measured using laboratory isotopic pool dilution, and microbial community composition was evaluated using microbial membrane lipids.
When measured using the isotopic approach, RH increased by 60%, from 1.26 ± 0.29 μmol m− 2 s− 1 in the low, to 2.06 ± 0.55 μmol m− 2 s− 1 in the high nitrogen treatment.
To investigate the cytosolic NADPH metabolism of P. chrysogenum, the oxPPP flux was measured using the isotopic non-stationary gluconate tracer method.
All patients initially received four cycles of carboplatin AUC 7 (AUC=area under the curve, calculated using the Calvert formula (Calvert et al, 1989) where the glomerular filtration rate (GFR) was measured using an isotopic method).
Carbon and nitrogen isotopic compositions were measured using a NA2500 continuous flow-isotope ratio mass spectrometer, Conflo III and Delta Plus (Thermo Fisher Scientific, Waltham, MA, USA) and are reported in the conventional δ13C and δ15N notation relative to Vienna Pee Dee Belemnite and atmospheric nitrogen, respectively.
Sulfur isotopic compositions were measured using a Sira 10 dual inlet stable isotope ratio mass spectrometer (VG Isogas, Cheshire, UK).
Isotopic enrichment in protein-bound amino acids was measured using gas chromatography-combustion-isotope ratio mass spectrometry (Finigan-MAT, Bremen Germany) [29].
Graphitization yield and isotopic fractionation were measured using a PDZ Europa ANCA-GSL elemental analyzer interfaced to a PDZ Europa 20−20 isotope ratio mass spectrometer (Sercon Ltd., Cheshire, UK).
Lead is separated using Biorad AG-1X8 anionic resin and its isotopic composition is measured using a Neptune plus Multi-collector ICP-MS.
