Field studies have been performed in Lindon, Utah (February 2003) and Rubidoux, California (July 2003) to determine if the Rupprecht and Patashnick (R&P) Filter Dynamic Measurement System (FDMS) determines total fine particulate mass, including the semivolatile ammonium nitrate and organic material. Collocated measurements were made with the FDMS, a conventional tapered element oscillating microbalance (TEOM) monitor with a heated filter, an R&P differential TEOM monitor, the Brigham Young University (BYU) Real-Time Total Ambient Mass Sampler (RAMS), the BYU particle concentrator-organic sampling system (PC-BOSS), a PM2.5 Federal Reference Method (FRM), a PM2.5 speciation sampler, an R&P continuous nitrate monitor, and two Sunset continuous carbon monitors (one to measure quartz filter-retained particulate carbon and one to measure particulate semivolatile carbonaceous material lost from the particles on a filter during sampling). The RAMS and PC-BOSS samplers have been shown to determine fine particulate material, including both the semivolatile and the nonvolatile components. Linear regression analysis at the Lindon site between the FDMS (X) and the PC-BOSS (Y), and the FDMS (X) and the RAMS (Y), resulted in zero-intercept slopes of 1.01 ± 0.06 (r2 = 0.63) and 1.00 ± 0.01 (r2 = 0.69), respectively. At the Rubidoux sampling site, linear regression analysis between the PC-BOSS (X) and the FDMS (Y) gave a zero-intercept slope of 0.96 ± 0.02 (r2 = 0.90). Linear regression analysis between the FDMS (X) and the RAMS (Y) resulted in a zero-intercept slope of 0.99 ± 0.01 (r2 = 0.80). Measurements made at the two sites indicate that the FDMS and the R&P differential TEOM monitors do measure total fine particulate mass, including the semivolatile ammonium nitrate and organic material. Both the heated TEOM monitor and PM2.5 FRM did not measure the semivolatile material. The difference between the FDMS and a heated TEOM monitor was explained by the semivolatile ammonium nitrate and organic material measured by the various chemical composition monitors.