Total Organic Carbon Analyzer User Guide (from TOC_UG_20100429)
Manual Information
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Topic | See page… |
Introduction | 2 |
Apparatus, Reagents, & Materials | 3 |
Instrument Calibration/Verification | 9 |
Sample Preparation | 12 |
Sample Analysis | 17 |
Quality Assurance/Quality Control | 18 |
LIMS Integration | 19 |
Health, Safety, & Environment | 20 |
Maintenance & Troubleshooting | 21 |
Software Guide | 25 |
Introduction
Theory of Method
The Total Organic Carbon (TOC) instrument analyzes liquid samples by physically combusting the samples at 680°C for TOC or by chemically combusting the samples in 25% phosphoric acid for inorganic carbon (IC). The instrument measures the amount of carbon degraded to CO2 using nondispersive infrared gas analysis at 4.3 µm wavelength, calculated based on Lambert-Beer's law.
Total Carbon (TC)
To analyze for Total Carbon (TC) a sample is delivered to the TC combustion tube filled with platinum catalyst and heated to 680°C. Carrier gas (purified air or oxygen) , along with the CO2 generated by combustion, flows through the reaction vessel to the dehumidifier and scrubber, where it is cooled, dried, and purified. It then it passes into the nondispersive infrared detector, which generates an analog signal that is digitized and processed by the TOC Control software. The peak area is proportional to the concentration of total carbon in the sample.
Inorganic Carbon (IC)
During inorganic carbon analysis the liquid sample is introduced into the reaction vessel, which is half filled with 25% phosphoric acid. The sample is purged with carrier gas (high purity air) through the acid solution. The phosphoric acid reacts only with inorganic carbon components (CO32- and HCO3), transforming them to CO2. The CO2 is carried fromthe IC vessel through the dehumidifier and scrubber to the NDIR detector.
Total Organic Carbon
TOC concentration can be obtained by subtracting the IC concentration from the TC concentration.
Note: Before operating the TOC system every operator must get either additional training from a senior technician or carefully study all three manufacturer TOC/ASI/Software manuals.
Apparatus, Reagents, & Materials
Laboratory Apparatus
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Gas Generator
The Parker Balston (Whatman)78-40 TOC Gas Generator (Figure 1-7)converts compressed air into high purity carrier/combustion gas for the TOC analyzer with hydrocarbon levels < 0.1 ppm and CO2 level < 1 ppm.
The Gas Generator should be fed from the air compressor, not from an air tank, because of the high rate of air consumption. Incoming air should be relatively free of dust and water (typical air compressor produced air should meet these requirements).
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- Start: starts measurement
- Stop: stops the measurement after the current injection is complete
- Pause: pauses instrument operation after current injection is complete
- Halt: immediately interrupts measurement
- Continue: continues interrupted measurement sequence
- Peak Stop: stops current measurement