Hello,
I need some help. The plant I work out changed to a different way of testing FFA values in our oil. Since then we've been throwing away a lot of oil due to high FFA values. I've listed our previous method and current method. Any thoughts as to why the new method is giving such higher values. Our cut-off is 0.4%. Is that a common cut off?
Old:
Frequency: Every 2 hours
Procedure:
Apparatus: Digital Scale
Burette – 50 ml set-up in 0.1 ml divisions
250 ml Erlenmeyer flask
Reagents: Reagent alcohol
Phenolphthalein Indicator
- N NaOH
- Collect a representative sample of the oil from the fryer.
- Carefully weigh out 28.2 g of oil into a tared 250ml Erlenmeyer flask.
- Add 50ml of Reagent alcohol to the Erlenmeyer flask. Gently swirl to mix.
- Add 3 drops of phenolphthalein indicator to the oil/alcohol mixture. Gently swirl to mix.
- Titrate to the phenolphthalein endpoint (pink color) with 0.1 N NaOH.
- Allow mixture to sit for 20 seconds; if pink color fades to clear, continue titrating until pink color persists.
- Read the ml directly off the burette to get the FFA value.
Corrective Action Limits:
Standards: Aim – 0.2
Control Limits – 0.4
Reject Level - >0.4%
New:
Frequency:Every 2 hours
Procedure:
Apparatus: Digital Scale
Burette – 50 mL set-up in 0.1 mL divisions
2 x 250 mL Erlenmeyer flasks
50 mL graduated cylinder
Reagents: Isopropanol 99%
Phenolphthalein Indicator 1% (w/v) in 95% (v/v) Alcohol
.1N NaOH
- Measure 50mL of Isopropyl alcohol to an Erlenmeyer flask. Add 2mL of Phenolphthalein Indicator. Gently mix.
- Titrate using .1N NaOH in the zeroed Burette until a faint pink color persists for 15 to 30 seconds. This will be the neutralized alcohol.
- Collect a representative sample of the oil from the fryer.
- Carefully weigh out 28.2 ± .2 g of oil into a tared 250mL Erlenmeyer flask.
- Add 50 mL of the neutralized alcohol to the oil filled Erlenmeyer flask. Gently swirl to mix.
- Add 2 mL of phenolphthalein indicator to the oil/alcohol mixture. Gently swirl to mix.
- Titrate with 0.1 N NaOH in the zeroed Burette, shaking vigorously until the appearance of the first permanent pink color of the same intensity as that of the neutralized alcohol before the addition of the sample. The color must persist for 30 seconds, if pink color fades to clear, continue titrating until pink color persists.
- Read the ml directly off the burette and multiply by .1 to get the FFA value.
Corrective Action Limits:
Standards: Aim – 0.2
Control Limits – 0.4
Reject Level - >0.4%