Page 33 - Application Handbook - TOC
P. 33

SCA-130-303



            The system is calibrated using the automatic        ■Result
            dilution function in the range of 0.5 mg/L to 10
            mg/L.                                               The duplicate determination of sulfuric acid
                                                                yielded the following results:




                                                                                     NPOC           RSD
                                                                    Sample
                                                                                     [mg/l]          [%]
                                                               Sulfuric acid
                                                               (98%)                <10 (4,6)         -
                                                               Sulfuric acid        <10 (5,4)         -
                                                               (98%)


                       Fig. Multi-point calibration             The sulfuric acid fulfilled the required purity
                          with dilution function                criteria of TOC < 10 mg/L.

            ■ Kit for high-salt samples                         The use of suitable gas washers (scrubbers)
            For the determination, a TOC-L CPH equipped         enables reproducible TOC  measurements in
            with a kit for high salt loads was used. The kit    concentrated sulfuric acid.
            consists of a special catalyst tube, a special
            mixture of various catalyst beads and a
            ceramics grid, which replaces the platinum
            net.

            Sample acidification when using the high-salt
            kit, is  carried out with  sulfuric acid. Sulfuric
            acid is used to modify the sample matrix.
            While NaCl has a melting point of 801 °C, the
            melting point of NaSO 4 is higher (881 °C).
            This has a positive effect on the lifetime of the
            combustion tube.

            For this reason, sulfuric acid is  measured
            directly    using     the    high-salt    kit.      ■ Recommended analyzer / Configuration
                                                                TOC-L  CPH
                                                                OCT-L
                                                                High-Salt-Kit
                                                                B-Type-Scrubber with diluted hydrochloric
                                                                acid with wire net.
                                                                Mist-Scrubber
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