TM92-05 New Nitrogen-15/Nitrogen-14 Lab Codes

At present, there are only two lab codes in the National Water Quality Laboratory (NWQL) database for N-15/N-14 analyses, #1204 N-15/N-14 solid sample and #995 N-15/N-14 aqueous sample. These lab codes do not distinguish whether the ratio is based on NO3 or NH4. This not only omits important information in the database for future reference, but also causes a problem is a District requests both ratios and only one result can be entered. To solve this problem, we are going to invalidate lab code 995 and replace it with two lab codes-- #1717 N-15/N-14 aqueous based on NH4 and #1718 N-15/N-14 aqueous based on NO3. Likewise, we are going to invalidate lab code 1204 and replace it with two lab codes--#1719 N 15/N-14 solid based on NH4 and #1720 N-15/N-14 solid based on NO3.