Sherwood Model 425 Flame Photometer

The Sherwood Model 425 Flame Photometer (475 42 500) is an advanced dual-channel flame photometer designed for the precise determination of sodium (Na), potassium (K), calcium (Ca), and lithium (Li) in a wide range of sample types. Building on the proven performance of the Model 420, the Model 425 introduces a dedicated calcium detection system, enhanced optical design, and a Lithium Internal Reference for superior analytical accuracy and stability.

Developed for both clinical and industrial laboratories, the Model 425 offers seamless data handling, automatic flame optimization, and compatibility with Sherwood’s automation systems, making it one of the most versatile and reliable flame photometers available today.

Enhanced Optical and Analytical Performance

A significant upgrade in the Model 425 Flame Photometer is its new optical arrangement, which significantly reduces sodium interference in calcium determinations.

  • Previous sodium interference: ~4%

  • New optical system interference: <1% for samples with equal sodium and calcium concentrations

This innovation ensures exceptional accuracy and reproducibility in multi-element flame photometric analysis.

Key Features & Benefits

  • Simultaneous Dual Element Analysis: Measure any two of four elements — Sodium, Potassium, Calcium, and/or Lithium.

  • Dedicated Calcium Channel: Added detector and filter assembly for precise calcium determination.

  • Lithium Internal Reference: Automatically compensates for flame variations to improve precision and stability.

  • Automatic Flame Control: Auto ignition and flame optimization for consistent operation.

  • Linearized Sodium Response: Accurate measurement over the 0.5 to 20 ppm sodium concentration range.

  • Improved Optical System: Reduces sodium interference in calcium measurements to under 1%.

  • Advanced Firmware: Includes routines for blanking, calibration, and sample analysis for consistent results.

  • Dual Digital Displays: Separate calibration and data readouts for each channel.

  • Safe and Reliable Operation: Optical flame detection and low air pressure shutoff for maximum safety.

  • Easy Maintenance: “No tools” access to the burner and mixing chamber for quick servicing.

  • RS232 Connectivity: Output data directly to a printer or PC; supports integration with lab data systems.

Automation Compatibility

The Model 425 is fully compatible with Sherwood’s automation solutions for increased productivity:

  • Model 860 Autosampler: Enables unattended, high-throughput sample analysis.

  • Model 805 Continuous Flow Diluter: Provides precise, automatic sample dilution and mixing.

  • BlueNotes 420 Software: For data collection, visualization, and report generation.

Together, these systems form a complete automated flame photometry solution for laboratories seeking reliability, efficiency, and precision.

Lithium Internal Standard

The Model 425 operates by default with a Lithium Internal Standard (100 ppm Li), ensuring consistent calibration and compensating for flame instability.
Sherwood supplies two lithium standard solutions:

  • Li Solution 001 56 622: Ready-to-use, dilute 1:10 with distilled water for blanks and standards.

  • 3 Molar Li Solution 001 56 603 (6 × 100 ml): Cost-effective for use with the Model 805 Diluter, providing automatic dilution to the optimal 1:200 concentration level.

Applications

  • Clinical chemistry and biomedical research

  • Industrial process control

  • Agricultural and soil testing

  • Environmental and water quality analysis

  • Pharmaceutical and food production laboratories

Why Choose the Sherwood Model 425 Flame Photometer?

With its advanced optical system, dedicated calcium detection, and lithium reference stability, the Model 425 delivers unmatched precision, ease of use, and reliability in flame photometric analysis. Designed for laboratories that demand accuracy and efficiency, the Model 425 stands as a benchmark in multi-element flame photometry.

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