MEASUREMENT OF CHLORIDE CONCENTRATION IN BUTTER

Equipment Required:

1. pH/Ion Analyzer (recommended) or pH Meter with mV scale
2. detectION 3261 Chloride ISE.

Reagents:

Dilute HNO₃ (60ml) Concentrated HNO₃ diluted to 1 liter with distilled water) 1 mol/l Chloride Standard (58.443g NaCl in distilled water)

Sample Preparation:

1. Weigh out accurately, 10g butter (± 0.005g).
2. Place in beaker and make up to 100ml with dilute HNO₃
3. Heat mixture until butter melts (do not boil). Agitate or stir mixture to dissolve the chloride from the butter into the dilute HNO₃ avoid emulsifying the butter.
4. Allow to cool. The butter fat will set on top of the dilute HNO₃
5. Puncture the fat layer and remove liquid sample.

Standard Preparation:

Make up standards of 0.1 mol/l, 0.01 mol/l and 0.001 mol/l by dilution of the

1 mol/l standard in distilled water.

Add 1 part of each standard to 2 parts of dilute HNO₃

Method:

Immerse the electrodes in each of the standards, least concentrated first and most concentrated last, rinsing the electrodes with distilled water between standards.

Plot a graph on a semilog graph paper of mV response against standard concentration,                                        

Immerse the electrodes in the sample and plot sample concentration from the graph.

Using Ion Analyzer, this determination may be carried out directly in concentration units by use of the “Concentration” or “Activity” modes.

Calculations:

To calculate the actual chloride concentration of the weighed sample, multiply the sample concentration from the graph by the dilution factor, in this case x 10.