Flame photometer for measurement of clinical samples

Flame photometer Sherwood - 410 - 420

  • Large accessible work area
  • The optical instantaneous flame detector
  • Air pressure detector

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Has been accepted worldwide as the standard manual Flame Photometer

410 model

The Model 410 can measure Sodium, Potassium, and Lithium, and with interchangeable filters, Calcium and Barium and is used in laboratories serving a very wide variety of industries. In the clinical field, the addition of a Lineariser module enables direct reading of Sodium as well as Potassium and Lithium values. It has all the safety features required in a modern flame photometer and helps the user with a convenient work area for the standards and samples. The operation of the instrument is straightforward with auto ignition and manual optimisation of the gas/air mixture. The measurement of clinical samples can be semi-automated with the use of the Model 805 Diluter which can take the serum, plasma and pre-diluted urine samples and apply 200:1 dilution. Model 410 has an analogue output for continuous monitoring of the single channel displayed. The standard output is 200 millivolts FSD this can be replaced with a 5-volt output to interface with "auto-analyser" systems.

420 model

The Model 420 has been developed from the Model 410 with the objective of improving the productivity and analytical performance of the laboratory when measuring Sodium and Potassium. The biggest improvement is dual channel operation allowing both Sodium and Potassium to be measured and displayed simultaneously. The Model 420 retains the heart of the Model 410 as described above but now adds a new auto flame optimisation and sophisticated software to achieve much-enhanced operation. The time taken to set up and calibrate the instrument is much reduced; this is achieved by the automatic ignition and optimisation of the flame conditions. The analytical performance is improved by the use of a Lithium Internal Standard signal which reduces any fluctuation in flame conditions and dilution errors. The readings on both channels are linear over the working range of Model 420. There are several monitoring and control functions included in the software driving the Model 420 thus measurements can only be made after blanking and calibration. The Model 420 can operate in Continuous or Peak mode. In Continuous mode, the Instrument displays the current value on each channel and through the analogue ports and an instantaneous reading can be printed at any time. In Peak mode, the Model 420 automatically detects a stable reading for transmission to a printer or computer and the display is frozen until the next sample is introduced.

Data output

The Model 420 readout is by two clear LED displays each of which can be continuously monitored via the analogue signal output which can be varied from 0.05 to 5.0 Volts. The readings can be transmitted via RS232 when requested by the operator.

With the optional printer, the date of analysis is printed at each calibration and the time is printed for each sample. QC and repeat samples are identified on the printout. Error codes and other diagnostic information is also printed out to aid the analyst.


Specially designed Air Compressors are available for both models including a Model 856 which includes a water-cooled trap for operations in humid atmospheres.

The Model 805 Continuous Flow Diluter is ideally suited to the Model 420 for Clinical analysis where the user simply offers the undiluted serum/urine sample to the inlet of the M805 and this is diluted and directly aspirated into the flame.

Automated analysis

A fully automated system can be realised using the Model 420, Model 820 Autosampler and the printer giving both analogue trace and printed output.

 Model 410Model 420
Large accessible work areaYesYes
Gas control/OptimisatonManualAutomatic
DisplaySingle channelDual channel
Result displayManual estimationAuto Peak
Result Held?NoYes
Internal StandardNoYes
RS232 (Printer/Computer Option)NoYes
Analogue Output VoltageFixedUser adjustable
Sample delayManualUser adjustable
User Help codesNoYes
QC and Repeat sample NumberingNoYes
Safety Features
Optical Instant Flame-On DetectorYesYes
Air Pressure DetectorYesYes
"Cool" ChimmeyYesYes
Full CE complianceYesYes & Yr2000
 LineariserBuilt in basic instrument
Sensitivity0.1ppm Na & K=100 unitsSame
Detection Limits
Na, K 20ppbNa, K 20ppb
SpecificityInterference less than 0.5%
Other elements at same concentration
Reproducibility1%<0.5% (peak mode)
GasPropane/Butane/Natural GasButane/Propane/LPG