Carbon Analysis (TC/TIC/TOC)

By Automated Combustion, Acidification and Coulometric Detection

Applications include: Pharmaceuticals, Sea water, Amines and hydrazines, Black liquors, Food, Soils and sediments, Geological materials, Sludges, Sulfur, Liquids containing particulates, Water and waste-water, Brines, Process Fluids, Corrosive Agents, Acids

Conforms to ASTM D 513

The CM250 Automated TC/TIC/TOC Carbon Analyzer is a complete analytical system capable of measuring total carbon, total organic carbon and total inorganic carbon in solid and liquid samples. Combining an automated high-temperature combustion furnace, an automated acidification module and a highly sensitive CO2 detector, the CM250 offers the flexibility to analyze most any sample type and concentration with a precision un-matched by other analytical techniques. (Meets the requirements of ASTM D 513). The CM250 system includes the following 3 components pictured above:

CM5014 CO2 Analyzer

-No user calibration-Wide, linear dynamic range

-Readability to 0.01 ug Carbon

-User selectable display units

-Floppy disk drive for archiving data

CM5240 Acidification Autosampler Module

-45 position carousel-Low dead volume reaction chamber

-Self cleaning-Selectable volume acid dispensing

-Pre-scrubber for removal of CO2 from carrier gas

-Post-scrubber for removal of interferents released during sample digestion

CM5200 Autosampler Furnace

-29 position carousel

-Two independent combustion zones controllable from ambient to 1100°C

-DIN and RS232 connectors for remote control operation

-Post-combustion scrubbers for removal of interfering gases

Instrument Capabilities

A major advantage of the CM250 Total Carbon Analyzer is the use of coulometric detection. Employing the principles of Faraday’s Law, the CM5014 CO2 Analyzer automatically measures the absolute mass amount of carbon dioxide resulting from the combustion or acidification of a sample.

No user-calibration is required and linear detection is available from less than 1 ug carbon to over 10,000ug carbon (or 5mg C/L to 50,000mg C/L for a typical 200ul sample combustion volume). Using this 100% efficient coulometric process, relative standard deviations of 0.2% or better are common for standard material. For smaller concentrations, an absolute deviation of approximately 1 ug C is typical.

Oxidation times vary with sample type and temperature although 5 to 7 minute analyses are typical.

Carbon Analysis Overview

Although our CM5014 CO2 Analyzer is sensitive to all carbon dioxide entering the coulometric reaction cell, the various carbon forms (TC, TOC and TIC) are distinguished by the manner in which the CO2 is formed – either combustion or acidification.

To better understand the full capabilities of the CM250 Carbon Analyzer, consider that total carbon (TC) is recognized as the sum of the inorganic (TIC) and organic (TOC) components. Thus, TC = TIC + TOC. By either direct measurement, sample pre-treatment, or difference techniques, all of these components can be measured with the CM150 on solid or liquid samples.

Specifically, total carbon can always be measured directly by the combustion of a sample while total inorganic carbon can always be measured directly by the acidification of a sample. However, the measurement of total organic carbon for most sample types requires either a pre-treatment step or the separate analyses of TC and TIC in order to obtain TOC by difference (TOC = TC – TIC).

For homogeneous liquids, the pre-treatment method is most commonly used. This step involves acidifying the sample and purging it of all TIC. The resulting solution is then analyzed by combustion to obtain the TOC result. On the other hand, liquids containing particulates and solids are most commonly analyzed by calculating the difference between separate TC and TIC analyses.

Principles of Operation

Total Carbon (TC)

The sample is initially weighed into a tin “boat” which is folded and placed into the 29 position sample carousel. Upon operation, the tin boat containing the sample is dropped from the sample carousel into the sample valve. The sample valve is purged and the sample boat is dropped into the combustion tube where it is combusted in a high-temperature oxygen rich atmosphere. In this environment, all of the carbon in the sample is rapidly oxidized to CO2. Interfering reaction products (including sulfur oxides, halide, water and nitrous oxides) are removed by the post-combustion scrubbers. The resulting CO2 is then swept into the CM5014 CO2 Analyzer where it is automatically measured using absolute coulometric titration.

Total Organic Carbon (TOC)

Although the direct TOC analysis of solids is occasionally performed using various sample pre-treatment methods, we generally recommend calculating TOC by difference, where TOC = TC – TIC.

Total Inorganic Carbon (TIC)

Samples are initially weighed into disposable Teflon® cups and loaded into a 45 position sample carousel. As the carousel rotates, each sample drops from the carousel into a small chamber where it is purged with a CO2-free carrier gas to eliminate atmospheric carbon dioxide. Once purged, the sample moves into the acidification chamber where it is oxidized. A second stream of CO2-free carrier gas transports the products of this reaction through a series of post-scrubbers (to remove potential interferences) and ultimately into the reaction cell of a CM5014 CO2 Analyzer where inorganic carbon evolved as CO2 is automatically measured using absolute coulometric titration.

Data Handling

Names, weights, volumes or areas of up to 50 samples can be entered to be used by the CM5014 in calculating the final result. Analytical progress is digitally displayed in user-selectable units. A detailed report is printed while each sample is running that includes the final result. Upon completion of a series of samples, a one page report will print, summarizing the analysis of all 50 samples. The results can also be stored to diskette for further data handling.

CM250 - TC/TOC/TIC Autoanalyzer

Includes: CM5014 CO2 Coulometer, CM5200 Autosampler Furnace, and CM5240 Automatic Acidification Module with tools and accessories for the analysis of solid or liquid samples. (P/N CM250-01 115V, 50/60Hz) (P/N CM250-02 230V, 50/60Hz)