Methodological investigations on DOC determinations by the HTCO method.

SKOOG, ANNELIE; THOMAS, DAVID; LARA, RUBÉN JOSÉ; RICHTER, K. W.

MARINE CHEMISTRY

Elsevier

Lugar: Amsterdam; Año: 1997 p. 39 - 44

0304-4203

&amp;amp;amp;amp;amp;lt;!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:DE; mso-fareast-language:DE;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} /* List Definitions */ @list l0 {mso-list-id:694115011; mso-list-type:hybrid; mso-list-template-ids:1179174070 67567631 67567641 67567643 67567631 67567641 67567643 67567631 67567641 67567643;} @list l0:level1 {mso-level-tab-stop:36.0pt; mso-level-number-position:left; text-indent:-18.0pt;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} --&amp;amp;amp;amp;amp;gt; <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Results are presented on the function and use of the catalyst in the commonly employed high-temperature catalytic oxidation (HTCO) method for determination of organic carbon concentrations. The instrument used was a Shimadzu TOC 5000 analyzer with a 0.5% platinum-coated aluminum oxide catalyst. Some basic considerations on gas flow rates and volumes of the catalyst kiln, together with experiments using carrier gas with and without oxygen, led to the conclusion that O2 is unlikely as the source of reacted oxygen in the HTCO oxidation of organic carbon. Results from injections of 14C-labelled organic material showed that no residual carbon remains on the catalyst surface after a large number of injections. This indicates that the oxidation of organic carbon to gaseous compounds is complete and the catalyst is not a source of carry over signal between injections. The blank signal from injection of water probably originates from carbonaceous compounds contained in the catalyst particles. A series of salt water injections (salinity 34.4) showed that > 2500 injections can be made without deterioration of catalyst performance.