Patent ID: 7201878

Claim:
An aerosol-particle analyzer (APA) for measuring an analyte in particles in a gas comprising: (a) an analysis liquid chosen such that when the analysis liquid is mixed with the particles, an optical property of the analysis liquid varies according to the amount of the analyte in the particles; (b) an analysis-liquid-handling subsystem (ALHS) consisting of an analysis-liquid container (ALC) that holds the analysis liquid, a pump that is connected to the ALC and that controls the pressure of the analysis liquid in the ALC, a small hole in the ALC through which the analysis liquid can be expelled from the ALC by increasing the pressure in the ALC and can be drawn back into the receptacle by decreasing the pressure in the ALC, an electrode that is in contact with the analysis liquid in the ALC and that is used to control the electrical potential of the analysis liquid, and a shield electrode around the hole that is given a potential opposite that of the analysis liquid, that: (i) holds a charged volume of the analysis liquid at the hole in the ALC (CVALH) so that particles in a gas, especially particles that are charged opposite to the voltage of the CVALH, can collide with the CVALH and react with it so the optical property of the analysis liquid can be measured, and the amount of analyte can be determined, and (ii) ejects a small volume of the analysis liquid and thereby generates a new CVALH so that the next measurement can take place, (c) a charger that imparts a charge to airborne particles drawn through it; (d) a substantially gas-tight container, having a gas-tight connection to the ALHS such that the CVALH extends into the gas-tight container so that it is exposed to the gas and particles inside the gas-tight container, a gas-tight connection to the charger, through which gas and charged particles enter the gas-tight container where said gas-tight connection and charger are positioned such that the gas and particles pass near the CVALH, and a vacuum connection; (e) a vacuum pump connected to the vacuum connection of the gas-tight container that draws the gas and particle into the gas-tight container through the input and past the CVALH so that the particles can collide with the CVALH, and draws any the gas and particles that did not collide with the CVALH out through the vacuum connection; (f) a means to measure changes in the optical property of the CVALH so that the amount of analyte in the particles that combined with the CVALH can be determined from these measurements of the optical property; and (g) a collection vessel to collect and store the droplet ejected from the hole after the optical property of the CVALH has been measured.