Cem Corporation

Robert N Revesz

James Edward Thomas

Michael J Collins

Wyatt P Hargett

An instrument and associated method are disclosed for the loss-on-drying determination of the volatile content of a wide variety of samples. The instrument includes a cavity in which a sample for which the volatile content is to be determined can be placed, a first source for introducing microwaves into the cavity that have frequencies substantially other than infrared frequencies, a second source for introducing radiant heat into the cavity at frequencies different from the frequencies introduced by the first source, an analytical balance for measuring the weight of a sample while the sample is in the cavity and on the balance, a temperature sensor capable of measuring and positioned to measure the temperature of a sample in the cavity and on the balance, and a processor in communication with the temperature sensor and each of the first and second sources for controlling the introduction of the frequencies of microwave and radiant energy into the cavity in response to the temperatures measured by the temperature sensor to control the sample temperature until the microwaves from the first source and the radiant heat from the second source dry the sample sufficiently for the processor to determine the volatile content of the sample based on the weight change of the sample on the balance.

Dual energy source loss-on-drying instrument

A method and associated apparatus are disclosed for microwave assisted content analysis. The method includes the steps of applying microwave radiation to a sample while concurrently rotating the sample while the microwave radiation is being applied and while concurrently weighing the sample and while measuring the temperature of the sample and controlling or moderating the microwaves applied to the sample based upon the measured temperature.

Microwave assisted content analyzer

A process for extracting extractable material from a base material in which it is present, while protecting against explosion of any solvent vapor in air includes heating by microwave radiation in a closed pressure-resistant and heat-resistant container, such base material, extractable material and organic extraction solvent, passing air near or into contact with the extraction container so that it will carry away from the container any escaping solvent vapor, and passing said air with the solvent vapor, if present, into contact with solvent detector which turns off a source of microwave radiation when the solvent vapor is present. Preferably the invented process will include passing the air, with any solvent vapor which may be present in it, to a flow detector, which will turn off the source of microwave radiation if flow ceases. The described processes may also include providing a rupture diaphragm to release extraction container contents at a pressure lower than that at which the container will fail, venting any contents exiting the container on to a collection container and venting vapor contents thereof to a solvent vapor detector. Also described are apparatuses for practicing the mentioned processes.

Apparatus for preventing explosions during microwave heated solvent

An explosion proof microwave heated solvent extraction apparatus or system for extracting organic materials includes a pressure resistant microwave transmissive extraction container, which is preferably of reinforced polyetherimide lined with fluoropolymer, in a microwave radiation heated chamber, with a device for controlling a microwave radiation generator, such as a magnetron, in response to the presence of any solvent vapor in a collection container for rupture diaphragm discharged material from an extraction container or in exhaust gas from the chamber. The presence of the solvent in the collection container or exhaust gas is preferably detected by a semiconductor gas sensor which decreases its electrical resistance in the presence of solvent vapors, thereby increasing its voltage and thus controlling operation of the magnetron, turning it off when solvent vapor (and a potentially explosive gas mixture) is present. Also described are other explosion prevention systems, including a fluoropolymer sheet covering a chamber ceiling and ceiling light, and a process for safely extracting organic materials, utilizing the described apparatus.

Explosion proof microwave heated solvent extraction apparatus

A highly preferred container for ashable material, which material is to be ashed by heat in an ashing furnace, while it is in such container, especially when such container is to be heated by microwave radiation onto microwave absorptive elements of the furnace, which thereby heat the container, is a heat resistant, walled container which is light weight, microwave transmissive, porous and air transmissive, which is of quartz microfibers that are held in desired walled container form, preferably in substantially flat cylindrical form. Such a container may be made by shaping a heat resistant, light weight, microwave transmissive and porous non-woven sheet of quartz microfibers to container form and heating and curing such sheet in such form, preferably after moistening it with water, whereby a form-retaining container results that can be successfully employed to hold ashable samples to be ashed for analysis during microwave powered ashings of such samples. The described containers may also be made by formation directly from the quartz microfibers, followed by sintering thereof to a form retaining article. Although pure quartz microfibers are preferred for the described containers they may contain or may be made of borosiliate glass, in which case their microwave transmission and high temperature stability can be decreased.

Heat resistant and light weight container for materials to be heated,

A container for an ashable material, to be ashed by heat in an ashing furnace, especially one heated by microwave radiation onto microwave absorptive elements thereof, comprises a heat resistant, walled container which is light weight, microwave transmissive and porous, and which is of quartz microfibers that are held in desired walled container form, preferably in substantially flat cylindrical form. Such a container is made by shaping a heat resistant, light weight, microwave transmissive and porous non-woven sheet of quartz microfibers to container form and heating and curing such sheet in such form, preferably after moistening it with water, whereby a form-retaining container results that can be successfully employed to hold ashable analytic samples during ashings thereof.

Growing community of inventors

Monroe, NC, United States of America

Robert N Revesz