Neutron activation analyzers require a nuclear reactor. MIT has done significant research and development work in monitoring mercury using neutron activation. Filters analyzed this way must be extracted with an acid solution prior to analysis. However, these quality control procedures will conform with those usually applied to monitoring of this type. Sampler precision is determined by statistically comparing the concentration results from the analysis of two discrete samples taken simultaneously at the same location.
Analytical precision is determined by the analysis of two separate aliquots of sample extract.
Statistical precision ranges by percentage can be expected to be larger for trace mercury measurement than for other measurements, because of the low expected absolute concentrations. Method accuracy for metals measurement is usually evaluated through the analysis of blind matrix spiked samples. The preparation of accurate reproducible spiked samples would be a challenge, again because of the low expected levels. The maintenance of the integrity and cleanliness of sample media would be a major part of a mercury monitoring QC program. All surfaces used to collect deposition samples for mercury must be kept scrupulously clean prior to exposure.