Carbon analyzer with improved catalyst

Details Carbon analyzer with improved catalyst Carbon analyzer with improved catalyst

1999-04-27

2002-04-23

Warden, Jill (Department: 1743)

Chemical apparatus and process disinfecting, deodorizing, preser

Analyzer, structured indicator, or manipulative laboratory...

Means for analyzing liquid or solid sample

C422S068100, C422S078000, C436S145000, C436S146000, C436S159000

Reexamination Certificate

active

06375900

ABSTRACT:

BACKGROUND OF THE INVENTION
Carbon analyzers are used in a variety of industries to provide analytical information relating to carbon concentration in a given specimen. Such industries include the chemical, pharmaceutical, food, and beverage industries. Carbon analyzers are also frequently used in the analysis of drinking water, groundwater, wastewater and soils in order to test for contaminants and to ensure compliance with governmental regulations.
There are generally two types of carbon present in a given specimen, organic carbon such as complex hydrocarbons or pesticides and inorganic carbon such as carbonate and bicarbonate. The organic carbon and inorganic carbon comprise the total carbon of a specimen. Thus, if total organic carbon is the quantity of interest it can be obtained by subtracting the inorganic carbon value from the total carbon value. EPA Method 9060, published September 1986, provides further reference relating to total organic carbon measurement.
Carbon analyzers themselves generally fall into one of two categories depending upon the manner in which they convert the specimen, through oxidation, into water and carbon dioxide. The first type is known as wet chemical oxidation analyzers. Wet chemical oxidation analyzers oxidize a specimen by subjecting it to a chemical environment such as persulfate while bombarding the specimen with ultraviolet radiation. An example of such an analyzer is the Phoenix 8000™ analyzer available from Tekmar-Dohrmann, of Cincinnati, Ohio. The second type is known as combustion analyzers. These analyzers subject the specimen to an elevated temperature, sometimes as high as about 1000 degrees Celsius to oxidize the specimen. An example of this type of analyzer is the model DC-190™ Combustion TOC Analyzer also available from Tekmar-Dohrmann. For either type of analyzer, the net result is theoretically complete oxidation of the specimen.
Different analyzers and methodologies lend themselves better to different applications. Combustion analyzers are generally able to more effectively oxidize high molecular weight specimens. One limitation of combustion analyzers, however, had been the effects of matrices such as salt water upon the combustion chamber itself. At such high temperatures, sodium chloride has a devitrifying effect on quartz glassware, as well as other undesirable effects. One solution for such matrices as well as most other matrices has been to provide a e catalyst in the combustion chamber which lowers the activation temperature of the specimen thus providing better oxidation at lower temperatures. For example, when the specimen is exposed to platinum (Pt) on alumina (Al
2
O
3
) as a catalyst, the temperature can be reduced to about 670 degrees Celsius. This lower temperature operation ameliorates some of the difficulties with matrices such as salt water.
As lab automation and technology in general have progressed, there is an increasing need to provide accurate and repeatable carbon analysis more rapidly thus reducing cycle time and increasing throughput.
SUMMARY OF THE INVENTION
A combustion carbon analyzer includes a combustion chamber having a platinum on titania (TiO
2
) catalyst. A method of oxidizing a carbon-containing specimen is also provided which includes exposing the specimen to a catalyst comprising platinum on titania. A method of conditioning the catalyst to remove carbon is also provided.
Embodiments of the invention provide quicker analyses thus reducing cycle time and increasing throughput. Further, catalysts of embodiments of the invention resist trapping specimen and cracking better than previous catalysts.


REFERENCES:
patent: 4355056 (1982-10-01), Dalla Betta et al.
patent: 4619902 (1986-10-01), Bernard
patent: 5106754 (1992-04-01), Steele et al.
patent: 5271900 (1993-12-01), Morita
patent: 5425919 (1995-06-01), Inoue et al.
patent: 5501801 (1996-03-01), Zhang et al.
patent: 5620610 (1997-04-01), Ishii et al.
patent: 5820823 (1998-10-01), Godec et al.
“Measuring Carbon in Salty Waters”, Methods & Application Notes, Copyright 1999, Tekmar Dohrman, TOC-010, Rev. Oct. 1995, pp. 1-2.
“The History of Laboratory TOC Analyzers”, Shimadzu Products, pp. 1-2., printed from www site http://www.ssi.shimadzu.com/products/4_total_organic_carbon/tochis.html, on Apr. 16, 1999.
“Total Organic carbon”, Method 9060, Sep. 1986, pp. 1-5.

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