An automated sequential sampling system for particulate acid aerosols: description, characterization, and field sampling results.

An automated sequential sampling system for the measurement of particulate acid aerosols was developed in order to allow the routine collection of daily samples with only once-per-week site visits. The system's design, operation, and associated quality assurance (QA), quality control (QC), and data validation procedures are described. Results from a multi-year field application of this system in the Buffalo, Albany, and New York City metropolitan areas are reported, as well as from external audits and interlab analytical intercomparisons. It is found that the system successfully collected 94% of all possible samples in these three cities between May 1988 and December 1989. Weekly QA field blanks and positive control filters indicate that these data were collected with negligible acid contamination or neutralization. Peak aerosol acidity levels at these sites were found to be highest during the summer months, with peak 24-hr average levels in the 300-400 nmol/m3 range. It is concluded that this system represents a more convenient means of collecting extended daily records of valid particulate acid aerosol concentrations than has been possible in the past.