Model 425

Product Overview

The Model 425 Flame Photometer (475 42 500) expands upon capability of the Model 420 Flame Photometer with addition of a detector and filter assembly specific for Calcium determination.  It also offers a “301 mode” feature which allows connection to a few of the more popular continuous flow systems.

The Model 425 defaults to measurement with Lithium Internal Reference. This should be added to the blank, calibration standards and samples such that they all contain the same concentration of Lithium; i.e. ~ 100 ppm.  The Model 425 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; 6x 100 ml) which when diluted 1:200 will give the optimum Lithium internal reference level. This is cheaper than using the 001 56 622 and is designed to be used with the Model 805 Dilutor where it is simultaneously diluted and mixed to the correct dilution for blank, calibrators and samples.

The Model 425 Flame Photometer has RS232 output for printer or computer connection and is compatible with our Model 860 Autosampler for unattended sample analysis. The Model 425 may be used with the Model 805 Continuous Flow Dilutor, again in-conjunction with or without the Model 860 Autosampler and with or without BlueNotes 420 software

A new optical arrangement implemented in 2018 gives improvement for the hitherto known issue of Sodium interference with Calcium determinations.  Previously reported interference was around the 4% mark and interference in newly manufactured units is now reduced to be less than 1% for samples containing equal concentrations of both Sodium and Calcium.

• On board firmware with blanking, calibration and sample routines.
• Simultaneous measurement of two of four elements: Sodium, Potassium, Calcium and/or Lithium.
• Linearised Sodium response over the Sodium concentration range 0.5 to 20 ppm
• Internal Reference facility (Lithium) 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 print

Lithium Internal Standard

The Model 425 defaults to measurement with Lithium Internal Standard. This should be set to 100 ppm Li and is added to the blank, calibration standards and samples.

The Model 425 is supplied with Li solution 00156622. 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 (00156603; 6x 100 ml) which when diluted 1:200 will give the optimum Lithium internal standard. This is cheaper than using the 00156622 and is designed to be used with the Model 805 Diluter where it is simultaneously diluted and mixed at the correct dilution to the standards and samples.