Sample bottles must be rinsed three times with water from the Niskin bottle prior to filling. Vials are capped and re-assembled as soon as they are removed from the combustion furnace Caps and liners are covered and then dried overnight at 40☌. Caps and teflon cap liners are cleaned by a 4 hour soak in 10% hydrochloric acid, and then copiously rinsed with distilled water, followed by MilliQ water. Prior to sampling, 40 mL borosilicate glass vials are combusted for 4 hours at 450 ☌. Grease (whether mechanical grease from ship operations or sealing grease as employed for some gas sampling) should never be allowed to come in contact with the sample nipple. Every effort must be made not to touch the Niskin's nipple (the path of the water stream, from Niskin to sample bottle, must be kept very clean). Non-purgeable nitrogen compounds (which include organic and inorganic nitrogen species) are combusted and converted to NO, which when mixed with ozone chemiluminesces for detection by a photomultiplier.Ĭare must be taken to minimize contamination of the sample. Non-purgeable organic carbon (NPOC) compounds are combusted and converted to CO 2, which is detected by a nondispersive infrared detector (NDIR). The water is then injected onto a combustion column packed with platinum-coated alumina beads held at 680☌. An acidified seawater sample (< pH 3) is sparged with CO 2 free air to remove inorganic carbon.
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