To determine the caffeine intent in tea bag, we can use UP spectroscopic method with single-beam UP or double-beam I-JP. Spectrophotometer is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometer deals with visible light, near-ultraviolet, and near-infrared, but does not cover time-resolved spectroscopic techniques. Spectrophotometer involves the use of a spectrophotometer. A spectrophotometer is a photometer that can measure intensity as a function of the light source avalanche.
Important features of spectrophotometers are spectral bandwidth and linear range of absorption or reflectance measurement. Caffeine is a chemical found in coffee, tea, cola, mate, and other products. Caffeine is most commonly used to improve mental alertness, but it has many other uses. Caffeine is used by mouth or rectally in combination with painkillers (such as aspirin and acetaminophen) and a chemical called reexamine for treating migraine-headaches. It is also used with painkillers for simple headaches and preventing and treating headaches after epidural anesthesia.
Caffeine works by automating the central nervous system (CNN), heart, muscles, and the centers that control blood pressure. Caffeine can raise blood pressure, but might not have this effect in people who use it all the time. Caffeine can also act like a “water pill” that increases urine flow. But again, it may not have this effect in people who use caffeine regularly. Also, drinking caffeine during moderate exercise is not likely to cause dehydration. Objectives To determine the caffeine content in tea bag sample by UP spectroscopic method. Standard Preparation 1 . All apparatus that used in the Standard Preparation should be dried.
Rinse the glassware with Acetone for 2-3 times thoroughly and dry under compressed air 2. Accurately weigh 18 – 21 MGM caffeine into a 10-ml volumetric flask. 3. Dissolve it with chloroform and dilute to the mark. Transfer the whole content into a 50-ml beaker. Proceed to step 3 immediately. 4 Dilute 2. 50 ml of the above solution to 50. 0 ml with chloroform (Stock standard solution). 5. Accurately transfer 1. 0, 2. 0, 3. 0, 4. 0 and 5. 0 ml of the stock standard solution to five 25-ml volumetric flasks, dilute with chloroform to the mark. Sample Preparation 1. Record the net weight of the tea bag as labeled in the package. Accurately weigh about 1 g of tea leaves from the tea bag. 3. Place the tea leaves into a 250-ml beaker, add 150 ml freshly boiled distilled water and place a watch glass on the top of the beaker. Stir the content occasionally for 3 minutes. 4. Cool the beaker to room temperature with an ice-bath and filter the whole content into a 250-ml separating funnel. Rinse the beaker thoroughly with denizen water, filter and combine with the previous filtrate. 5. Extract the tea sample extract with two 15-ml, and then two 1 0-ml chloroform successively. Collect the chloroform layers with a 250-ml conical flask. 6.
Add an appropriate amount of anhydrous sodium sulfate into the conical flask. If the anhydrous sodium sulfate clumps after gently shaking, it indicates that water is present in the chloroform extract. Add more anhydrous sodium sulfate until no more clumping and a clear chloroform layer is observed. 7. Filter the mixture to a 100-ml volumetric flask (dried). Rinse the conical flask thoroughly with chloroform, filter into the same 100-ml volumetric flask and dilute to the mark with chloroform. 8. Further dilute 2. 0 ml of the above solution to 25. 0 ml with chloroform (using dried glassware). Spectroscopic Determination
Perform a UP spectrum scan both for the middle concentration of the standard solution and the sample solution from 400 NM to 200 NM. Measure the absorbency at 276. 5 NM for the above working standard solutions and sample solution with chloroform as the blank. If the absorbency of the sample solution is greater than the absorbency of the highest standard concentration solution, further dilute the sample solution. Tea bag sample information: Brand name: AH4053124341 Product name: 25 Net weight of the tea bag: g Place of origin: China Weight of tea leaves from the tea bag: 0. Eggs Expiry date: 28/10/2014 Instrument information:
Brand name: SHIMMIED Corporation/ Perking Elmer Model no: (Single-beam) Venin-1240 (Double-beam) Lambda 37040 Mass of caffeine: 20. OMG Standard result: Concentration(MGM/ml) Absorbency at 276. NM Standard 1 0. 00406 MGM/ml 0. 176 Standard 2 0. 00812 MGM/ml 0. 316 Standard 3 0. 01218 move 0. 468 Standard 4 0. 01624 MGM/ml 0. 622 Standard 5 0. 02030 move 0. 777 Sample result: Sample 1 unknown 0. 620 R-0. 9998 RAW=O. 9996 Discussions Data Treatment: Mass of caffeine used= 20. OMG 20. OMG of caffeine dissolved into ml by chloroform. 20. OMG / ml = 2. MGM/ml 2. Ml is diluted to ml by chloroform. [ 2. MGM/ml (2. 5) ] / ml = 0. MGM/ml
For SST. L Mil is diluted to ml by chloroform. 0. 1015 / 25 = 0. Magma,’ml SST. 2 ml is diluted to ml by chloroform. [0. 1015 (2) ] / 25 = 0. Magma/ml SST. 3 ml is diluted to ml by chloroform. [0. 1015 / 25 = 0. Magma/ml SST. 4 ml is diluted to ml by chloroform. [0. 1015 / 25 = 0. Magma/ml SST. 5 Ml is diluted to ml by chloroform. [0. 1015 / 25 = 0. Magma/ml The sample’s absorbency is 0. 620, according to the standard calibration curve the sample’s concentration is 0. Magma/ml. For the concentration of caffeine in ml solution from ml dilution: 0. 0161 9(25) / 2 = 0. MGM/ml The amount of caffeine in solution: . 024 (100) = 20. MGM Since 20. MGM of caffeine is come from 0. Eggs, thus in one tea bag there is 20. MGM of caffeine. (20. MGM per tea bag) According the spectra of the standard and sample, the concentration of sample is higher than standard’s as it had a higher point at maximum absorption peak. Since with higher concentration, there will be more caffeine particle thus having a higher concentration. The spectra show the tea have a close purity with the standard caffeine as they have very similar absorption spectrum. Errors: 1. Not all caffeine can be collected in the water as some may still in the tea leaves. 2.
Some caffeine in the tea leave may lose as not all can fully diffuse into the chloroform. 3. Each batch of tea may not gave the same concentration of caffeine. 4. Some caffeine may stay in the instrument wall. 5. Caffeine will vaporized along time after dissolved in the chloroform. Improvement: 1. Longer cool down time can fully dissolve in water 2. Repeat the procedure in separators funnel. Because it can fully diffuse caffeine to chloroform. 3. Immediately go through the experiment after caffeine dissolved. 4. Each time cleaning the instrument wall by using chloroform. 5. More tea leaves from different batch should be tested.