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SCA-130-308



                                                                ■ Results
            ■Kit for high-salt samples                          The duplicate determination of the salt
            The TOC-L series features a kit for high-salt       solutions yielded the following results:
            samples, which significantly increases the
            instrument’s availability. The kit consists of a              Sample             NPOC      RSD
            combustion tube of a special geometry and a                                     [mg/kg]    [%]
            unique catalyst mixture.                             Sodium nitrate (>99,9%)      22,8      4,7
                                                                 Sodium nitrate (>99,9%)      24,0      6,8
                                                                 Sodium nitrate (>99,9%)      <10        ‐
                                                                                              (9,0)
                                                                 Sodium nitrate (>99,9%)      10,2      5,4


                                                                  10
                                                                  9
                                                                 Signal[mV]  6 3


                                                                  0
                                                                  -1
                                                                   0         5         10        15         20
                                                                                      Zeit[min]
                                                                      Fig. Example peaks: Sodium nitrate





            In this application, sample acidification is
            carried out with sulfuric acid which is used to
            modify the sample matrix. Due to the higher
            melting point of NaSO 4 (888 °C) compared to
            801 °C of NaCl the lifetime of the combustion
            tube is longer.

            ■ Interferences
            The  combustion  of  nitrogen  compounds  can
            lead  to  the  formation  of  nitrous  oxide  gas.   ■ Recommended Analyzer / Configuration
            Nitrous oxide exhibits absorption bands in the      TOC-L CPH
            same IR detection range as CO 2 and can,            ASI-L
            therefore,  be misinterpreted for CO 2. In          High-Salt-Kit
            addition, nitrous oxide can cause tailing and       B-Type-Scrubber
            can affect the peak symmetry.

            A B-type scrubber  is used to  eliminate
            possible interference by nitrous oxide. Due to
            the high solubility of N 2O in water, the gas is
            dissolved in the B-type scrubber and will not
            reach the detector.
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