IA and EE on Vitamin C quantification
1. Ammonium Oxalate, prepared by dissolving 0.08g ammonium oxalate in 100ml pH 5 buffer
2. Vit C (0.001M ), prepared by dissolving 0.018g of Vit C in 100ml ammonium oxalate solution
3. Perform 2 fold dilution on 0.001M Vit C.
4. Add 1 ml Vit C into a quartz cuvette and 2ml of ammonium oxalate ( as a stabiliser )
5. Leave for 10 mins
6. Prepare a blank with 1ml water and 2 ml ammonium oxalate
7. Set up UV spectrophotometer at 266nm and quantify.
Result shown below
* Oxalate solution used as stabiliser and pH around 5 as both affect the stability of Vitamin C
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IA and EE on Glucose Quantification
1. 1% glucose std was prepared ( 1g in 100ml )
2. Perform 2 fold serial dilution ( 1%, 0.5%, 0.25%, 0.125% )
3. Add 2 ml of 1% glucose + 2 ml of DNS (3,5 dinitrosalicylic acid) into a 50ml test tube.
4. Repeat step 1 to 3 for different glucose concentration
5. Place all tubes in boiling water bath for 5 mins for colour formation. ( red brown)
6. Transfer 1 ml of solution from tube to cuvette and added 2ml of water to dilute it
7. Set visible spectrophotometer at 487nm.
8. Prepare a blank containing 1ml DNS + 2ml water.
9. Measure absorbance at 487nm
10. Plot std calibration curve
11. Beer's Law works only for diluted solution.
12. Recommended range for glucose ( 1% to 0.01%)
13.Expt will not work if too little glucose is used
13.Expt will not work if too little glucose is used
Video,Glucose Quantification using DNS with visible spec
Click HERE on glucose quantification and preparation of DNS solution.
* Resulting Glucose/DNS solution must be diluted with water as Beer's Law only applies for diluted solution.
*Experimental Kit can be purchased for EE and IA work.
* Glucose solution range must be around 1% to 0.1% for colour determination.
* All item can be purchased from Carolina Biologicals or Kemtecscience
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IA and EE on Iron Quantification
Preparation
1. 0.01M iron(II), prepared by dissolving 3.92g of Fe(SO4)2(NH4)2.6H2O in 2M HCI to 1liter.
2. Perform 2 fold serial dilution.
4. Add 1 ml of iron (II) std to cuvette
5. Add 0.5ml 5% trisodium citrate/buffer to cuvette( use pH <6)
6. Add 0.5ml 10% hydroxyammonium chloride (reducing agent to reduced all iron (III ). Ignore this step if you think iron (II) is not oxidised.
7. Add 1ml 0.01M phenanthroline for colour formation.
8. Leave for 24 hours for iron (II) phenanthroline complex to form ( orange red )
9. Set visible spectrophotometer at 508nm
10.Prepare a blank ( 1 ml water, 0.5ml trisodium citrate, 0.5ml hydroxyammonium chloride, 1ml phenanthroline )
10.Prepare a blank ( 1 ml water, 0.5ml trisodium citrate, 0.5ml hydroxyammonium chloride, 1ml phenanthroline )
10. Measured absorbance for iron(II) std in cuvette shown above
Result on iron quantification
2 fold dilution from 0.0001M was done, absorbance was measured after 24 hours.
Std Calibration curve for iron(II) standard at 508nm.
Std Calibration curve for iron(II) standard at 508nm.
Click HERE, sample EE on iron quantification with visible spec
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IA and EE on Quantification for starch iodine solution
Starch with iodine solution forms blue black colouration.
1. Prepare 0.01% starch solution ( 0.01g in 100ml )
2. Perform a 2 fold dilution ( 0.01, 0.005, 0.00250, 0.00125, 0.000625%)
3. Add 1ml 0.01% starch to cuvette
3. Add 50ul 1% iodine solution ( adjust volume accordingly to obtain appropriate blue black)
4. Set visible spec at 567nm
5. Prepare a blank ( 1ml water + 50ul iodine )
6. Measure absorbance for iodine starch solution and plot std calibration curve.
Hints and tips
- Starch iodine must be diluted with water as Beer's Law, works for diluted solution.
- Starch solution decomposes over time (Prepare fresh)
- Volume of 1% Iodine must be adjusted accordingly so a blue black is formed.
Video, Starch Iodine quantification using Visible Spec
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EE and IA on DNA Quantification
1. Prepare 5% DNA by adding 5ul of lambda DNA (stock 0.1mg) to 100ul TE ( DNA buffer ) into microcentrifuge
2. Perform 2 fold dilution. ( 5, 2.5, 1.25, 0.625, 0.3125%)
3. Add 100ul DNA solution into a quartz cuvette
4. Set UV spectrophotometer at 260nm
5. Prepare blank ( 100ul TE buffer )
6. Measure absorbance at 260 and plot DNA std calibration curve at 260nm
DNA std calibration curve at 260nm.
DNA and TE buffer can be purchased from Carolina
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Suggested IA and EE that can be done by IB Bio/IB Chem
For Vitamin C,
DNA and TE buffer can be purchased from Carolina
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Suggested IA and EE that can be done by IB Bio/IB Chem
For Vitamin C,
- EE on the effect of UV radiation (A,B,C ) on the decomposition of Vitamin C quantified using UV spectrophotometer.
- EE/IA on effect of heat, temperature, pH, presence of transition metal ions on the decomposition of Vit C measured using UV spectrophotometer/iodine titration method
- EE/IA on how changing pH, temperature, inhibitors, ionic salt conc affect the amylase activity measured using visible spectrophotometer. ( by either monitoring the decrease in absorbance of starch/iodine solution over time or by measuring the absorbance of starch/iodine solution after a period of time using the std calibration curve)
- EE/IA on how temperature affect the amount of iron content in spinach, seaweed, brocolli measured using visible spec
- EE on the relationship between different part of plants with the amount of iron content measured using visible spec
- EE on how temperature affect the stability of DNA double strand ( breaking of hydrogen bond ) measured using UV spec
- EE on how different extraction techniques, using SDS, Proteinase K, Protease, Phenol Chloroform affect the amount of DNA/purity of DNA measured using UV spec
- EE/IA on how changing pH, temperature, inhibitors, ionic salt conc affect the rate of digestion of amylase on starch/iodine solution measured using visible spec ( by either monitoring the decrease in absorbance of starch/iodine over time or by measuring the absorbance of starch/iodine over a period of time using std calibration curve)
Most importantly we must establish a sound methodology and a reliable way to quantify.
.......................................................................................................................................................Kinetics is appropriate for Complete Design for IB Chem IA.
Research Question for kinetics must have the 4 criteria to score a complete
- IV and DV
- Well defined
- Measureable
- Focus
How changing conc of HCI affect the pressure change due to release of hydrogen gas measured using a pressure sensor in a reaction bet hydrocloric acid and magnesium ribbon (Complete)
How changing conc of thiosulphate affect the rate of sulfur formation in a reaction bet sodium thiosulphate and hydrochloric acid (Partial)
How will changing concentration of thiosulphate affect the rate of disappearance of cross X due to formation of sulphur in a reaction between sodium thiosulphate and hydrochloric acid (Complete)
Using ICT Vernier Lab Pro for Quantification.
How changing conc of thiosulphate affect the change in light intensity due to formation of sulphur measured using a light sensor in a reaction bet sodium thiosulphate and hydrochloric acid (Complete)
How changing conc of potassium iodide affect the change in absorbance/ transmittance due to formation of blue black colouration measured using a visible spec in an iodine clock reaction ( potassium iodide with H2O2)(Complete)
Iodine Clock reaction is a very good experiment for Chem IA
Reagent used are H2O2, KI, S2O3, starch, and stop watch or visible spectrophotometer
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Visible Spectrophotometer for IA experiment in Chem/Biology
Below is a sample of my Video tutorial on using Visible spectrophtometer for quantification.
- Need to calibrate
- prepare standard calibration curve
- prepare a serial dilution
Research Question
How changing salt conc affect amylase activity in its hydrolysis of stach into simple sugar measured using visible spectrophotometer by monitoring its blueblack colouration over time.
Research Question
How changing temperature affect the activity of invertase enzyme measured using visible spectrophotometer by monitoring its blueblack colouration change over time.
Rate of reaction or enzyme activity can be measured using Pressure or pH sensor
Vernier sensors for IA experiments
IA which involves the released of any gases, hydrogen, oxygen, carbon dioxide or any change in pressure, Pressure Sensor is used while any change in pH a pH sensor can be used.
Hydrogen Peroxide with catalase can be measured using an oxygen /pressure sensor
Digestion of fat/milk with lipase can be measured using pH sensor.
Research Question
How changing conc of hydrochloric acid affect the pressure change due to released of hydrogen gas in a reaction bet magnesium ribbon and hydrochloric acid measured using pressure sensor?
Research Question
How changing albumin conc affect the rate of diffusion of water into a Visking Tubing containing albumin solution measured using a pressure sensor.
How changing temperature of pancreatic lipase with bile affect the rate of digestion of milk into glycerol and fatty acids measured using a pH sensor?
