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Determining Properties

The laboratory analytical capabilities are focused on measuring the physical properties of metal colloids. The single most important property of a colloid is the particle surface area which determines how well a colloid will interact with its environment. The greater the surface area, the greater the interaction. Particle surface area relates directly to the effectiveness of the colloid in human physiology. For a given concentration of particles (expressed in parts-per-million or ppm) the particle surface area is inversely proportional to the particle size. The smaller the particle, the larger the particle surface area.

To calculate the particle surface area, the following properties must first be determined:

Total Concentration (ppm) = total concentration measures both the particles and ions present in the sample.

Ionic Concentration (ppm) = ionic concentration is measured by first removing the particles from the sample using ultra-centrifugation.

An ultracentrifuge capable of producing up to 602,000 G-forces is used to separate the particles from the ions in the sample colloid. For more details on this equipment see: Beckman L8-80M

Total and ionic concentrations are measured using Atomic Emission Spectroscopy (AES). The instrument used to make this measurement vaporizes the sample in a plasma operating at 10,000 degrees Centigrade and then measures the spectral emission lines generated by the atoms in the sample. An Inductively Coupled Plasma (ICP) produces the temperatures required to vaporize the sample. The instrument is called an ICP-AES and is manufactured by Varian. For more details on this state-of-the-art scientific instrument see: Varian Vista-MPX

Particle Concentration (ppm) = particle concentration is calculated by subtracting ionic ppm from total ppm.

Particle Size Distribution = Dynamic light scattering is employed to produce a plot and a table showing how the particle sizes are distributed across a size range from 0.3 nm to 10,000 nm. For each peak in the distribution a percentage of total volume is calculated to indicate what percentage of the total particle volume is attributed to the particles of that specific size.

The instrument used to make the particle size distribution measurements is the Nano ZS made by Malvern Instruments of the U. K. For more details on this instrument see: Malvern Zetasizer Nano ZS

Particle Surface Area Calculation - Using the particle concentration (ppm) and particle size volume percentage for each size peak in the distribution, the particle surface area can be calculated for each volume peak. The total surface area is the sum of the areas calculated for each volume size peak in the distribution and is expressed as square centimeters. The Colloid Surface Area table can be used to convert the concentration (ppm) for a given size particle into the surface area value.