Sherwood Model 410 Flame photometer, determination of Sodium and Potassium

The Sherwood Model 410 Flame photometer directly measures Alkali and Alkaline Earth metals:

Sodium (Na),  in use
Potassium (K),  in use
Lithium (Li),  not in use
by means of a low temperature flame using propane, butane or Natural gas. The measurement data displayed directly on the Model 410 Flame Photometer in mmol/L or in mg/L, depending from the unit setup.

Element switch


Flame control window


ON / OFF Switch

Self-adjusting level trap

Aspiration inlet

Method F-025F - The Determination of Sodium and Potassium

This method involves the dilution of sample with deionised water followed by filtration (if necessary) and finally aspiration directly into a Sherwood Flame photometer.

Equipment Required:

1. Sherwood Flame photometer

2. Filtration apparatus

3.Volumetric glassware

Reagents:

1. 1000 ppm (1g/L) sodium and potassium standards
2. Diluted Standards

2.Deionised water

Method:

  1. Prepare by dilution of the stock standards (1g/L) 100, 50, 25, 10,5 and 1 ppm Na+ and 25, 10, 5, 1 and 0,5 ppm K mix-standards. Deionised water is the blank solution.
  2. Take pure water sample or dilution (ad to 1 mL of water sample9mL deionised water).
  3. If necessary filter the sample /or dilution through an ash less filter paper (eg. Whatman 540) into a litre volumetric flask. Ensure that the solid particles retained by the paper are washed thoroughly and washings directed into the same 1 litre flask. Dilute to the mark with deionised water, stopper the flask and mix by inversion.
  4. Set up the flame photometer as outlined in its instruction manual for sodium.
  5. Set blank to zero with deionized water.
  6. Aspirate the standards and record their stable readings.
  7. Plot a graph of meter reading against standard concentration.
  8. Aspirate the sample solution into the flame photometer.
  9. Record the meter reading and from the graph read off its sodium concentration.
  10. Adjust the filter position to select the potassium filter and repeat stages 5 to 9 for potassium.

Note that if the Na and K concentrations in the water sample are outside the range of standards the sample should be diluted accordingly.

Calculation:

Multiply the concentration of Na and K obtained from the graph by the dilution factor, ie. x 100, to express the result in ppm or mg/l of Na or K in the original fruit juice.

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Fotómetro de llama M410

El estándar de fotometría de llama delmercado

Medidadirecta Na, K, Li, Ca, Ba pormedio de llama de bajatemperaturautilizandopropano, butano o gas natural. La medidapuedeser semi automáticautilizando el diluidor 805 con factoresdedilución de 200:1 para Na y K y 50:1 para Litio.

Esnecesaria la utilización de uncompresor de airelibre de acitecomo el modelo 851 y un regulador de gas (el reguladorsecundarioestáincorporadoen el M410.

  • Sensibilidad: Na<0,5ppm, K<0,5ppm, Li<2ppm, Ca<5ppm y Ba<200ppm Concentraciónmínima para dar 100 unidadesen el display
  • Reproducibilidad: <2%
  • Límite de detección:< 20ppb para Na y K
  • Salida de datos: analógica. RS232 opcional