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    Model 420Cs

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    Product Overview

    The Model 420Cs is Sherwood’s newest addition to the Flame Photometer product line. Evolved from the well-established Model 420, the Model 420Cs provides a precision (%CV) ≤ 0.5, now achievable with all new Dual Channel models: i.e. the Model 420 & Model 425.

    Unique to the Model 420Cs is addition of a Caesium reference channel. This enables the analyst to work with Caesium or Lithium as an internal reference. The Model 420Cs’ additional internal reference option provides greater flexibility; operators have the ability to choose the internal reference element based on the sample matrix considerations or existing procedures developed for discontinued instrumentation such as the IL 943 Flame Photometer.

    A practical example where the Caesium option is beneficial is analysis of Lithium in clinical samples while still being able to benefit from the improved precision achieved by use of an internal reference.

    Measurement Range

    • Na Serum 110.0 to 170.0 mmol/l
    • Na Urine 0.0 to 199.9 mmol/l
    • K Serum 0.00 to 10.00 mmol/l
    • K Urine 0.0 to 200.0 mmol/l
    • Li Serum 0.00 to 3.00 mmol/l


    • Na Serum within ± 2 mmol/l
    • Na Urine within ± 4 mmol/l
    • K Serum within ± 0.2 mmol/l
    • K Urine within ± 2 mmol/l
    • Li Serum within ± 0.2 mmol/l


    • Na (140.0 mmol/l) ≤0.5% CV (with int Ref)
    • K (5.00 mmol/l) ≤0.5% CV (with int, Ref)
    • K (80.0 mmol/l) ≤0.5% CV (with int. Ref)
    • Li (1.50 mmol/l) ≤0.8% CV (with int. Ref)

    Dilution Factor

    • Na Serum/Urine 1/200 with de-ionised water
    • K Serum 1 in 200 with de-ionised water
    • K Urine 1 in 200 with de-ionised water
    • Li Serum 1 in 50 with de-ionised water

    The above is correct for use with Propane. Results obtained from 20 replicates of the same sample, aspirating sample for 20 seconds, then water for 10 seconds. To achieve the stated specification the flame must be alight for a minimum of 30 minutes, with diluent being aspirated. (For a brand new, newly installed unit, that stabilisation is highly likely to be greater than 30 minutes).


    • On board firmware with blanking, calibration and sample routines.
    • Simultaneous measurement of two out of three elements: Sodium, Potassium and/or Lithium.
    • Linearised Sodium response over the expected clinical Sodium concentration range (1 in 200 sample dilution).
    • Internal reference facility for improved precision.
    • Automatic flame ignition and optimisation.
    • Safety features including optical flame and low air pressure detection for fuel gas shut off.
    • Two digital displays for calibration and analysis data of each channel; analogue outputs for use with chart recorders and some on-line analysers.
    • A “no tools” maintenance approach allowing easy access to mixing chamber and burner assembly.
    • RS232 for data output to a serial printer.



    Items Included

    Model 420Cs 2-Channel Clinical Flame Photometer

    Atomiser Stainless Steel Complete

    Power Supply Unit Universal, IEC

    Tube, Drain

    Tube, Pvc Reinforced, 2 Metres

    Tube, Gas 6.3 Mm Id, 2 Metres

    Tube, Atomiser Inlet

    Solution; 140.0, 5.00 & 1.50 mmol/L Na, K & Li (100 Ml)

    Solution, 10000 PPMCaesium (100 Ml)

    Solution, 3 Molar Lithium (100 Ml)

    Wire, Atomiser Cleaning Pk3

    Lead, Instrument To Printer/PC

    Lead, Mains 2 Metres Black 10A IEC, Plain (No Plug)

    Operator Manual