TABLE 1.

Electrophoretic mobilities and zeta potentials of Toxoplasma gondii oocysts and DG and GB surrogate microspheres in different water types

Water typeConductivity (μS/cm)aParticle typebpHcElectrophoretic mobility (μm/s/V/cm)dZeta potential (mV)e
Ultrapure4T. gondii6.7−3.42 (0.17)−43.74 (2.22)
DG5.5−1.08 (0.06)−13.85 (0.70)
Washed DG5.5−1.24 (0.08)−15.81 (0.92)
GB6.0−5.40 (0.39)−69.09 (4.95)
Freshwater130T. gondii7.0−1.26 (0.01)−16.16 (0.06)
DG7.0−0.38 (0.00)−4.90 (0.03)
Washed DG7.0−0.74 (0.01)−9.48 (0.11)
GB7.1−2.89 (0.21)−36.97 (2.63)
Freshwater + 5 mg/liter DOC154T. gondii6.7−1.48 (0.02)−19.02 (0.26)
Freshwater + 15 mg/liter DOC162T. gondii6.4−1.65 (0.05)−21.09 (0.67)
DG6.7−2.08 (0.06)−26.63 (0.81)
Washed DG6.7−1.67 (0.10)−21.35 (1.27)
GB6.8−4.11 (0.31)−52.62 (3.92)
Estuarine34,980T. gondii7.5−0.14 (0.16)−1.84 (2.03)
DG7.7−0.33 (0.18)−4.18 (2.29)
Washed DG7.7NAfNA
GB7.6−0.28 (0.11)−3.65 (1.41)
Seawater47,790T. gondii7.9−0.22 (0.07)−2.81 (0.83)
DG8.0−0.37 (0.10)−4.70 (1.24)
Washed DG8.0−0.21 (0.43)−2.66 (5.52)
GB7.8−0.26 (0.16)−3.36 (1.96)
  • a Conductivity of water solutions was measured after suspensions were prepared according to recipes provided in Materials and Methods.

  • b T. gondii, T. gondii oocysts; DG, Dragon Green surrogate microspheres; GB, Glacial Blue surrogate microspheres.

  • c The pH for each particle and water type was measured at the onset of the mobility experiments.

  • d Values represent the means of three replicates (standard error of the mean).

  • e Zeta potential was automatically converted from electrophoretic mobilities by the ZetaPALS instrument using the Smoluchowski equation (ζ = 4пημ/Ε, where ζ is zeta potential, η is viscosity of solution, μ is electrophoretic mobility, and Ε is dielectric constant of solution). Values represent the means of three replicates (standard error of the mean).

  • f NA, not assessed.