Question 11

Serial dilution techniques can be used to estimate the concentration of suspended microplastic particles in environmental water samples.

An environmental scientist collects a 50 cm³ water sample estimated to contain 4.0 × 10⁵ microplastic particles.

6% of the 50 cm³ sample is transferred to a beaker and made up to 30 cm³ with distilled water.
An additional five-fold dilution of this mixture is carried out, producing a final 30 cm³ solution.
0.5 cm³ of this final 30 cm³ solution is passed through a membrane filter.

Each microplastic particle retained on the membrane filter is assumed to be detected and counted under a fluorescence microscope.

Estimate the number of microplastic particles the scientist would expect to observe on the membrane filter.

Serial dilution techniques can be used to estimate the concentration of suspended microplastic particles in environmental water samples.

An environmental scientist collects a 50 cm³ water sample estimated to contain 4.0 × 10⁵ microplastic particles.

6% of the 50 cm³ sample is transferred to a beaker and made up to 30 cm³ with distilled water.
An additional five-fold dilution of this mixture is carried out, producing a final 30 cm³ solution.
0.5 cm³ of this final 30 cm³ solution is passed through a membrane filter.

Each microplastic particle retained on the membrane filter is assumed to be detected and counted under a fluorescence microscope.

Estimate the number of microplastic particles the scientist would expect to observe on the membrane filter.

Practical skills assessed in the practical endorsement