Reliable field sampling and transfer of trace levels of ammonia is often necessary for environmental compliance and process monitoring and control. Corrosion and active surfaces will interact with ammonia samples to degrade sample quality and reliability. Typical materials used in ammonia sampling are: 304 stainless steel, 316 stainless steel, PTFE, PFA, and silicon coated stainless steel (SilcoNert 2000 or Dursan). Figure 1 compares ammonia interaction/response to common sampling materials.
Figure 1: Ammonia sampling reliability can be improved by using inert materials like PFA and SilcoNert 2000 (Sulfinert). Stainless steel adsorbs ammonia resulting in lost sample. Measured PTR-MS signals of ammonia (m17). 500sccm of 100ppb ammonia in nitrogen. All lines were 1.8m long not heated (30c).
Sample reliability can be improved by using inert materials like PFA and SilcoNert 2000 coated stainless steel. Material selection should account for environmental factors such as temperature, shock, abrasion or corrosion.
Sampling data courtesy of Ionimed Analytik.