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    Model 420

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    Product Overview

    The Model 420C Flame Photometer was developed from the Single Channel Model 410 Flame Photometer, with the objective of improving productivity and analytical performance, when measuring Sodium and Potassium. It is available for order against two part numbers:

    • The 420C (475 42 000) is delivered as standard with a mixed calibration concentrate containing 140.0, 5.00 and 1.50 mmol/l of Na, K and Li.
    • The M420 Industrial (475 42 100) is delivered as standard with individual 1000ppm calibration concentrates for Na, K and Li.

    Dual Channel operation, allows both Sodium and Potassium to be calibrated, measured and displayed simultaneously. The Model 420 Flame Photometer retains many of the Model 410’s attributes: ease of use, ease of maintenance and stable flame design and is enhanced with auto flame optimisation, internal standard referencing and on-board firmware to achieve significant improvement in sample throughput and precision. The time taken to set up and calibrate the instrument is much reduced; achieved by automatic ignition and optimisation of the flame conditions. The analytical performance is improved using a Lithium Internal Reference signal which compensates for fluctuation in flame conditions. The internal reference feature (Reference Mode) can be turned off if required. Readings on both channels are linear over the working range of the Model 420 Flame Photometer. There are several monitoring and control functions included in the firmware; thus, measurements can only be made after blanking and calibration.

    The Model 420 Flame Photometer can operate in Continuous or Peak mode. In Continuous mode the instrument displays the current value on each channel and through the analogue ports. An instantaneous reading can be printed at any time. In Peak mode the Model 420 Flame Photometer automatically detects a stable reading, following sample introduction, for transfer to a printer or computer and the display is frozen until the next sample is introduced.

    The Model 420 Flame Photometer has RS232 output for printer or computer connection and is compatible for standalone use with Sherwood’s Model 860 Autosampler; providing unattended sample analysis. The system may be used with the Model 805 Continuous Flow Diluter, again in-conjunction with or without the Model 860 Autosampler.

    420 Industrial (475 42 100)

    RANGE Displayed

    • Na 0.00 – 9.99; 10.0 – 199.9
    • K 0.00 – 9.99; 10.0 – 199.9
    • Li 0.00 – 9.99; 10.0 – 199.9

    SENSITIVITY

    • Minimum Detection level =3 x noise
    • Na 20 ppb
    • K 20 ppb
    • Li 50 ppb

    SAMPLE CONCENTRATION entering aspiration

    • Na 0.5- 20 ppm
    • K 0.5- 20 ppm
    • Li 0 – 20 ppm

    Minimum Concentration to display 100 units

    • Na 0.5 ppm
    • K 0.5 ppm
    • Li 0.5 ppm

    SPECIFICITY

    • Na, K & Li Interference is 0.5% value of element under analysis.

    REPRODUCIBILITY (K=10ppm 20 aliquots from single sample)

    • With Li Reference in operation < 0.5% CV
    • Without < 1.0% CV

    LINEARITY (To be tested without Li Internal Standard)

    • For Na, K & Li with appropriate solution concentration, within the limits shown under Sample Concentrations (above), set at 100 will read 48-52 at midpoint ( Nominal 50).

    SPEED OF ANALYSIS

    • Variable (sample every 15-60 seconds) at user option

    DIMENSIONS

    • 510mm x 390mm x 345mm 9.5 Kg Net
    • 730mm x 450mm x 450mm 16.5 Kg Packed

    MINIMUM SAMPLE REQUIREMENT

    • 1.5ml (Diluted sample)

    420C (475 42 000)

    SODIUM MEASUREMENT

    Sodium is highly prone to self-absorbance in the flame above a concentration of 10 ppm. Linearising
    software has been incorporated in the Model 420. At the normal clinical level of sodium 140mmol/l even
    diluted by 1:200 exceeds this concentration.
    (NB. 140 mmol/l x 22.98 A.W.(Na). =3217.2 ppm x 1/200 = approx. 16 ppm).

    LITHIUM INTERNAL Reference

    The Model 420 defaults to measurement with Lithium Internal Reference
    The Model 420 is supplied with Li solution 001 56 622. This should be diluted 1:10 with distilled water
    and the resulting solution used as the blank and to dilute the calibration standard and samples.
    Sherwood Scientific can supply a 3 Molar solution of Li (001 56 603; 6 x 100ml), which when diluted 1:200
    will give the optimum Lithium internal standard. This is more cost effective than using the 001 56 622 and is designed to be used with the Model 805 Diluter where it is simultaneously diluted and mixed at the correct dilution with calibration standards and samples.

    RANGE Displayed

    • Na 0.00 – 9.99; 10.0 – 199.9
    • K 0.00 – 9.99; 10.0 – 199.9
    • Li 0.00 – 9.99; 10.0 – 199.9

    SAMPLE CONCENTRATION entering aspiration

    Element PPM mg/l meq/l
    Na 0.5 – 20 0.5 – 20 0.022 – 0.87
    K 0.5 – 20 0.5 – 20 0.013 – 0.5
    Li 0.0 – 20 0.00 – 20 0.00 – 2.9

    SPECIFICITY

    • Na, K & Li Interference is < 0.5% value of element under analysis
    • K 0.00 – 9.99; 10.0 – 199.9
    • Li 0.00 – 9.99; 10.0 – 199.9

    SENSITIVITY

    (i) Minimum Detection level =3 x noise
    Element PPM mg/l meq/l
    Na 0.02 0.02 0.0009
    K 0.02 0.02 0.0005
    Li 0.05 0.05 0.007

    LINEARITY (To be tested without Li Internal Standard)

    • Na The 00156100 Standard diluted 1:200 set at 140 will read 68 – 72 at midpoint (Nominal 70).
    • K The 00156100 Standard diluted 1:200 set at 5.0 will read 2.40 – 2.60. (Nominal 2.50).

    (ii) Minimum Concentration to give 100 units on display
    Element PPM mg/l meq/l
    Na 0.05 0.05 0.0022
    K 0.05 0.05 0.0013
    Li 0.05 0.05 0.072

    DIMENSIONS

    • 730mm x 450mm x 450mm 16.5 Kg Packed
    • 510mm x 390mm x 345mm 9.5 Kg Nett

    REPRODUCIBILITY (20 aliquots from single 10ppm Potassium solution)

    • With Li Reference in operation < 0.5% CV
    • Without <1.0% CV

    SPEED OF ANALYSIS

    • Variable (sample every 15-60 seconds) at user option

    ASPIRATION RATE

    • 3-6 ml/min

    SPEED OF ANALYSIS

    • Variable (sample every 15-60 seconds) at user option

    MINIMUM SAMPLE REQUIREMENT

    • 1.5ml (Diluted sample)