Delloyd's Lab-Tech Chemistry

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Determination of Sodium by Flame Emission

Equipment:
Flame Photometer, Aspirator pump, Fuel gas.
Dri-block heater, Bottle-top dispensette.

Sample:

Suace sample ;(0.20g)
A = Teriyaki sauce (dilution= 1:10)
B = Soy sauce (dilution= 1:25)
C = Worcestershire sauce (dilution= 1:5)

Apparatus:
Boiling tubes, volumetric flasks 50ml, grad pipettes 1, 2, 5ml.

Chemicals:
Glycerol: HOCH2CH(OH)CH2OH, FW = 92.09.
Sodium chloride (pure), NaCl, FW = 58.44
Potassium chloride (pure), KCl, FW = 74.56
Calcium carbonate, CaCO3, FW = 100.09
Aluminium nitrate, Al(NO3)3.9H2O, FW = 375.14
Methanol, CH3OH, FW = 32.04
Hydrochloric acid dilute.

Solutions preparation:

1. 1000 ppm Na standard. Dissolve 2.542g of dried pure (analar) NaCl in 1 liter deionised water.
2. 1000 ppm K standard. Dissolve1.90g of dried pure (analar) KCl in 1 liter deionised water.
3. 1000 ppm Ca standard. Weigh out 2.4973g of analar CaCO3, dissolve in about 25mls 0.1M HCl in a beaker, then quantitatively transfer and make up to 1 liter in a volumetric flask.
4. 3% Aluminium nitrate: Dissolve 60g of the salt 2 liters water.
5. Methanol. Use ordinary grade. Add 10mls into volumetric flasks containing standards.
6. Glycerol. Use ordinary grade. Add 10mls into volumetric flasks containing standards

Analytical notes:

Predigest 0.2g soy sauce in 5 mls conc nitric acid for 1 hr. then heat digest for 1 1/2 hrs. on dri block. Install baffle-chamber between aspirator diaphragm pump and instrument (if necessary).

1. Range for measurements is 1ppm – 5ppm
2. Provide 100 ppm Na and K standards from the 1000 ppm prepared solutions. Dilute 100mls to 1 liter deionised water or 10mls to 100ml vol.
3. Need to check flow rate directly from burner:
Tube = 1 meter long = 2.25cm radius
Flow rate / meter = 13.64secs.
Volume of tube = 1.59 liters
Flow rate = 7.0liters / min.

4. Values for Na content in some analysed samples:
Baby food = 240mg / 100ml.
Bitters concentrate = 3.2mg / 100ml
Soy sauce (low sodium) = 130mg / 5ml (7696mg / 286ml)

Operation of Instrument:

Follow User’s Guide: obtain help and advice from Demonstrator or Technician



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