{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T19:37:16Z","timestamp":1771011436006,"version":"3.50.1"},"reference-count":30,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2015,3,26]],"date-time":"2015-03-26T00:00:00Z","timestamp":1427328000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000001","name":"U.S. National Science Foundation","doi-asserted-by":"crossref","award":["EAR-1052927"],"award-info":[{"award-number":["EAR-1052927"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Rapid Comm Mass Spectrometry"],"published-print":{"date-parts":[[2015,5,15]]},"abstract":"\n Rationale<\/jats:title>\n \n High\u2010precision hydrogen isotope ratio analysis of nitrogen\u2010bearing organic materials using high\u2010temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H\n 2<\/jats:sub>\n ) has been suspected as a possible cause of incomplete H\n 2<\/jats:sub>\n yield and hydrogen isotopic fractionation.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400\u00a0\u00b0C, have been compared using a selection of nitrogen\u2010bearing organic compounds, including caffeine. A focus of the experiments was to avoid or suppress hydrogen cyanide (HCN) formation and to reach quantitative H\n 2<\/jats:sub>\n yields. The technique also was optimized to provide acceptable sample throughput.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The classical HTC reaction of a number of selected compounds exhibited H\n 2<\/jats:sub>\n yields from 60 to 90 %. Yields close to 100 % were measured for the experiments with the chromium\u2010enhanced reactor. The\n \u03b4<\/jats:italic>\n 2<\/jats:sup>\n H values also were substantially different between the two types of experiments. For the majority of the compounds studied, a highly significant relationship was observed between the amount of missing H\n 2<\/jats:sub>\n and the number of nitrogen atoms in the molecules, suggesting the pyrolytic formation of HCN as a byproduct. A similar linear relationship was found between the amount of missing H\n 2<\/jats:sub>\n and the observed hydrogen isotopic result, reflecting isotopic fractionation.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n \n The classical HTC technique to produce H\n 2<\/jats:sub>\n from organic materials using high temperatures in the presence of glassy carbon is not suitable for nitrogen\u2010bearing compounds. Adding chromium to the reaction zone improves the yield to 100 % in most cases. The initial formation of HCN is accompanied by a strong hydrogen isotope effect, with the observed hydrogen isotope results on H\n 2<\/jats:sub>\n being substantially shifted to more negative\n \u03b4<\/jats:italic>\n 2<\/jats:sup>\n H values. The reaction can be understood as an initial disproportionation leading to H\n 2<\/jats:sub>\n and HCN with the HCN\u2010hydrogen systematically enriched in\n 2<\/jats:sup>\n H by more than 50 \u2030. In the reaction of HCN with chromium, H\n 2<\/jats:sub>\n and chromium\u2010containing solid residues are formed quantitatively. Copyright \u00a9 2015 John Wiley & Sons, Ltd.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1002\/rcm.7174","type":"journal-article","created":{"date-parts":[[2015,5,4]],"date-time":"2015-05-04T03:20:18Z","timestamp":1430709618000},"page":"878-884","source":"Crossref","is-referenced-by-count":31,"title":["Isotopic disproportionation during hydrogen isotopic analysis of nitrogen\u2010bearing organic compounds"],"prefix":"10.1002","volume":"29","author":[{"given":"Sreejesh","family":"Nair","sequence":"first","affiliation":[{"name":"Max\u2010Planck Institute for Biogeochemistry Jena Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heike","family":"Geilmann","sequence":"additional","affiliation":[{"name":"Max\u2010Planck Institute for Biogeochemistry Jena Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tyler B.","family":"Coplen","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey Reston Virginia USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haiping","family":"Qi","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey Reston Virginia USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Matthias","family":"Gehre","sequence":"additional","affiliation":[{"name":"UFZ Helmholtz Centre for Environmental Research Leipzig Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arndt","family":"Schimmelmann","sequence":"additional","affiliation":[{"name":"Indiana University Bloomington Indiana USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Willi A.","family":"Brand","sequence":"additional","affiliation":[{"name":"Max\u2010Planck Institute for Biogeochemistry Jena Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2015,3,26]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac00243a035"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac00284a058"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac9606766"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.1080\/10256019608036319"},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac60068a025"},{"key":"e_1_2_7_7_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac00009a014"},{"key":"e_1_2_7_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/0168-9622(88)90040-1"},{"key":"e_1_2_7_9_1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0231(19990715)13:13<1226::AID-RCM575>3.0.CO;2-9"},{"key":"e_1_2_7_10_1","doi-asserted-by":"publisher","DOI":"10.1021\/ac001447t"},{"key":"e_1_2_7_11_1","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1016\/0003-2670(95)00468-8","article-title":"On\u2010line determination of \u03b418O values of organic substances","volume":"319","author":"Werner R. 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