The measured results of particle number concentration of 88,000 and 220,000 particles/mL (200 and 500 ng/L) were 81,507 ± 162.56 and 175,929 ±1921 particles/mL and the biases were −7.38 ± 0.18% and −20.03 ±0.87% respectively. The measured result of 220,000 particles/mL AuNPs was deviated from calibration curve obviously.