System for monitoring the progress of a chemical reaction in a microwave-assisted heating system

• US 6,034,361 A
• Filed: 04/28/1999
• Issued: 03/07/2000
• Est. Priority Date: 04/28/1999
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Hudak, George J.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): PWU, JEFFREY C
• Application Number:
  US09/300,492
• Time in Patent Office: 314 Days
• Field of Search: 219/702, 219/687, 219/696, 219/693, 219/750, 422/21
• US Class Current: 219/702
• CPC Class Codes: B01J 19/126 Microwaves
• CPC Class Codes: H05B 6/806 for laboratory use

Abstract

A system for monitoring the progress of a chemical reaction in a microwave-assisted preparation of a sample, having a microwave energy source, a waveguide coupled to the microwave energy source and having a waveguide cavity, and a resistive load coupled to the waveguide, wherein the sample that is to be subject to microwave-assisted heating is situated in a reaction vessel. The reaction vessel is located in the path of the forward microwave radiation between the microwave energy source and the resistive load. An energy monitoring device is interposed between the reaction vessel and the resistive load so as to monitor the energy not absorbed by the reaction vessel. The energy absorbed by the sample may be calculated in accordance with the level of energy measured by the energy monitoring device to provide a value that indicates the status of the chemical reaction. Alternatively, the reaction vessel may be located in the path of the forward microwave radiation between the microwave energy source and a terminal end of the waveguide. An isolator provided in the form of a circulator coupled to the resistive load is located in the path of the forward microwave radiation between the microwave energy source and the reaction vessel so as to allow the forward energy to proceed to the sample, and to divert reverse energy to the resistive load. The energy absorbed by the sample may be calculated in accordance with the difference in the levels of energy respectively measured by forward energy and reverse energy monitoring devices.

Claims

1. A system for monitoring the progress of a chemical reaction in a microwave-assisted preparation of a sample, comprising:

a microwave energy source for radiating a known level of microwave energy;

a waveguide having a waveguide cavity and a predetermined geometry, the waveguide being coupled to the microwave energy source for receiving said radiated microwave energy;

a reaction vessel for containing the sample; and

a resistive load coupled to the waveguide;

wherein the waveguide geometry is constructed to position the reaction vessel in the path of the forward microwave radiation between the microwave energy source and the resistive load; and

an energy monitoring device interposed between the reaction vessel and the resistive load so as to monitor the energy directed to the resistive load;

whereby the energy absorbed by the sample may be calculated in accordance with the level of energy measured by the energy monitoring device to provide a value that indicates the status of the chemical reaction.

2. A system for monitoring the progress of a chemical reaction in a microwave-assisted preparation of a sample, comprising:

a microwave energy source for radiating a known level of microwave energy;

a waveguide having a waveguide cavity and a predetermined geometry, the waveguide being coupled to the microwave energy source for receiving said radiated microwave energy;

a reaction vessel for containing the sample;

a container subassembly located in the waveguide cavity for receiving the reaction vessel and for locating the reaction vessel within the waveguide cavity at a predetermined position in the path of the forward microwave radiation between the microwave energy source and a terminal end of the waveguide;

an isolator provided in the form of a circulator coupled to the resistive load located at a predetermined position in the path of the forward microwave radiation between the microwave energy source and the reaction vessel so as to allow the forward energy generated by the energy source to proceed to the sample, and divert reverse energy to the resistive load; and

means for monitoring forward energy and reverse energy levels in the waveguide;

wherein the energy absorbed by the sample may be calculated in accordance with the difference in the levels of energy respectively measured by the forward energy and reverse energy monitoring devices to provide a value that indicates the status of the chemical reaction.