A key component of the Readiness Verification Plan (RVP) prepared by the NADP Quality Assurance Advisory Group (QAAG) was to implement  an AMoN  comparison study between ICAL (Illinois State Water Survey) and WCAL (Wisconsin State Laboratory of Hygiene). The study incorporated collocated (ICAL and WCAL) passive ammonia samplers following the NADP-dedicated sampling and analysis protocols.

As specified in the RVP, Radiello® passive ammonia samplers were prepared at ICAL and WCAL and sent to 11 AMoN sites. Each AMoN site received 3 samplers from both WCAL and ICAL consisting of replicate samplers (“A” and “B”) and an un-deployed travel blank. Samplers were deployed following standard AMoN protocols and shipped back to their respective laboratories. All Radiello® cores from the samplers and the travel blanks were extracted and analyzed for ammonium. Measurements of ammonium (mg/L) were converted to ammonia air concentration (µg/m³) based on sampler deployment time, extract volume, and published Radiello® core sampling rates.

A wide range of site concentrations were included in the study, with the average ammonia results ranging from 0.29 µg/m³ at WA99 to 14.8 µg/m³ at UT01. The analysis results produced by both labs were nearly identical. 

A and B replicate averages were compared between each lab resulting in a median percent difference of -6.1% with respect to I-CAL. In comparison, ICAL triplicates for 2016 had a median RSD of 4.3%. The median WCAL field replicate (A and B) RPD was 1.9%.  

Median travel blank concentrations were very similar for I-CAL and W-CAL with median RPD of -4.1% with respect to ICAL.  Travel blanks from ICAL ranged from 0.06 to 0.22 µg/m³ while WCAL travel blanks ranged from 0.07 to 0.23 µg/m³. These are all well below the flagging criteria of 0.399 µg/m³. The median travel blank concentration for both ICAL and WCAL data sets was 0.12 µg/m³. This is just slightly higher than the ICAL median travel blank concentration from 2016 of 0.094 µg/m³.

Overall, there was exceptional agreement between ICAL and WCAL results indicating supplies and procedures were equivalent.

Another RVP requirement involved an assessment of the AMoN supplies/facilities. This was assessed in association with the collocated study by analyzing quality control blanks from the preparation/extraction period including: cores, sonicator water, sampler jars, assembled samplers, preparation room, preparation hood and extraction hood. Although lab construction was not complete and the primary ammonia hoods were not in place at the time, the majority of the quality control samples met the RVP goals.