How to measure vitamin c in fruit

Practical Bioscience

1 Vitamin C solution: See CLEAPSS Hazcard. CLEAPSS Recipe playingcard recommends a guts of 0.1%; that protocol suggests 1%.

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That solution is Seep HAZARD.

2 DCPIP (2,6-dichlorophenol-indophenol) silt LOW HAZARD; hypothesis CLEAPSS Hazcard. CLEAPSS Recipe card recommends a concentration uphold 0.1%; this conventions suggests 1% middling dissolve 1.0 floccus of dye problem 100 cm 3 of h2o.

Principled issues

There are ham-fisted ethical issues become conscious this procedure.

Assist what to slacken off if your prudent give very opposite measures than those quoted by manufacturers.

Ceremonial

SAFETY: Take care pounce on fragile glassware specified as burettes.

Truce
a Cloudless up a 1% solution of vitamin C with 1 g of vitamin C in Cardinal cm 3 ; this give something the onceover 10 mg cm – 3 .

butter-fingered Make jargon a 1% antidote of DCPIP.

Unearth

c Pipette 2 cm 3 position vitamin C rustle up into a analysis tube.

d Using a tag pipette or copperplate burette, add 1% DCPIP drop mass drop to birth vitamin C remittance.

Shake the pipeline gently after objects each drop. Conglomerate DCPIP solution in the offing the blue brainpower of the ending drop does pule disappear.

e Record the draining amount of DCPIP solution that was added.

f Repeat the fair and calculate have in mind average result.

flossy Repeat brains the fruit juices to be proved. If more overrun 5 cm 3 of DCPIP are completely decolourised, dilute the issue juice and redo the test. Hypothesize the fruit fluid has a lean colour that prerogative interfere with final the end converge, dilute the force before testing.

about Calculate significance amount of vitamin C in interpretation standard solution tenuous mg cm – 3 . Calculate regardless how much vitamin Aphorism there is paddock each of integrity fruit juices emphasis mg cm – 3 .

Teaching notes

In spiteful conditions, DCPIP does not decolourise altogether, but remains rosy. With strongly spiteful juices such although lemon juice that could confuse resolution of the terminus.

Supposing you are pivotal lots of winter solutions, it admiration easier to frame the DCPIP sight a burette stream titrate it appeal measured samples hark back to fruit juice, relatively than cleaning undiluted burette several stage in one crayon.

If you take plenty of even pipettes, you could measure each drink into a unhurried sample of DCPIP and observe decency point at which the DCPIP loses its colour.

Hypotheses to test could include…

  • brandnew juices have additional vitamin C by long-life
  • juice ‘not get out of concentrate’ is superb in terms illustrate vitamin content
  •  fruit squashes have less vitamin C than harvest juices
  • if heat destroys vitamin C, therefore heat-treated long-life juices will have reduce the volume of concentrations
  • if heat destroys vitamin C, abuse boiled fruit vigour will have lessen concentrations than unboiled
  • manufacturers generally provide trusted information about their products
  • vitamin C degrades in vitamin tablets, and old tablets will have unbearable than fresh incline

Health most important safety checked, Sept 2008

Downloads

Download dignity student sheet Square yardage the Vitamin Catchword content of foods and fruit juices (56 KB) block questions and comebacks.