Particle-size counter, solubility

The solubilities of A9-tetrahydrocannabinol were determined (7) by two methods 1) Beer s law plots were obtained by plotting the absorbance at one wavelength (225 nm) versus the amount of tetrahydrocannabinol added. The solubility of tetrahydrocannabinol was determined as that concentration at which deviation from Beer s law was observed 2) A modification of the procedure of Saad and Higuchi (11) for determining solubility by using a particle-size counter was also used ... 

This equipment has some limitations because the size range is hmited. In addition, the samples have to be suspended in an electrolyte solution, which can prove difficult if the sample is totally soluble in the solution. However, the Coulter Counter does provide both frequency and volume distributions against volumetric particle size. 

Figure 17.17 shows the results of a CCN closure study carried out during the 2003 Coastal Stratocumulus Imposed Perturbation Experiment (CSTRIPE), in which an aircraft-based CCN counter measured activation by marine boundary layer aerosols at 3 supersaturations. Observed CCN concentrations are compared to CCN concentrations predicted on the basis of the measured size distribution of the aerosol and assuming the aerosol was pure (NH4)2S04. Most of the data indicate that actual activation was less than that predicted. This result is consistent with the presence of insoluble or partially soluble material in the particles or externally mixed particles. Note the difference in concentration scales between the marine and continental airmasses this shows that the continental... 

For quite a while, the most useful method for determining particle distributions was that of electrical conductivity. The most widely used instrument is the Coulter Counter (named after the Inventors), although there are now other similar instruments on the market. It has largely been supplanted by the Laser-Diffractometer. Originally, the Coulter-Counter was designed to measure blood corpuscles which are 2-8 p in size. It has proven to be very suited to measure micron and submicron particles easily, accurately, and reproducibly. Consider a conductive solution consisting of water with a soluble salt, i.e.- 1% NaCl, and a... 

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