Flame Photometry - Lab Report Example

Flame photometry Name Date Introduction Flame photometry is a method that is used to detect metals salts such as sodium, potassium, and calcium, detection occurs through the process of atomic emission. To detect these metals, solution containing them are prepared and aspirated on the flame. The flame will then evaporates the solution, atomizes the metal molecules and a valence electron of the metal is then excited to the upper level (Barringer, 1962). As electron returns to the ground, the light of every metal is emitted with characteristic wavelength. Analysis that is done to know the concentration of each metal is carried out by measuring the flame emission resulting from the solution that contains the element. Photometry equipment has optical filters; the filters are used to select the emitted wavelengths that are to be analyzed. In human body, potassium and sodium plays an important role. Their ions are power generators inside the body cells. All body nerves contain neutrons, in the body, nerves communicate by passing information from one part of the body to another, for example it performs tasks such as maintain body temperature and flexing body muscles (Gropper & Smith, 2013). An example is if a person wants to move, the brain will send a message to the legs muscles to move. Neurons transmit the message; they use ions in their communication, P and K is a source of ions in the body nerves. Another function is that sodium helps in maintaining blood pressure. When it is dissolved in blood, it attracts and hold water in blood, so it assist in maintain the right level of water in blood. Too much sodium causes high blood pressure so potassium is required to maintain sodium at the right level (Gropper & Smith, 2013). Sodium help in strengthening body bones, low intake of the mineral will result in weak bones, body developing cramps, and fatigue. Aims and objectives of the experiment The objective of this experiment is to measure the concentration of sodium and potassium that are contained in soy sauce solution that are provided. Another objective is creating a calibration curve from the results of both metals. Apparatus used 1. Flame photometer 2. Stock solutions of Na+ and K+, c = 1 mg/ml. 3. Six numbered 100 ml volumetric flasks. 4. Pipettes Flame photometer parts (Barringer, 1962) Flame source, this is a kind of a burner that produces flame that can be controlled, its form and temperature is controlled. Nebulizer and mixing chamber assists in moving solution to the flame at a steady rate. Optical system is made up of 3 parts namely convex mirror, lens, and filter. Convex mirror is meant to transmit light emitted from excited atoms and focus it on the lens (Sharma, 2000). The lens will then focus the radiated light on the slit. Mirror reflections will then go through the slit before reaching filters. The wavelength that is to be measured will then be isolated from any other emission. Lastly is the photo detector, it detects the light and measure the intensity of radiated emission. When the radiation struck the detector, the detector converts it to electrical signal; the produced electrical signal is equivalent to the light intensity. Procedure that was followed 1. A stock solution of 1000ppm (mg.l-1) was supplied and standard solution was prepared by diluting the stock. The standard solution was prepared in five different concentrations, that is 5, 10, 15, 20 ppm and unknown diluted. The solution was prepared using 100ml volumetric flasks. 2. When the food solutions was ready, we light the photometer flame with the help of the supervisor, the flame was stabilized and he gave us instructions on how to use it safely. 3. To clean and stabilize the unit, deionised water was first aspirated for around two minutes. Water was aspirated until it stabilized; the knob was set to read zero units as aspiration continued, aspiration was stopped immediately the knob read zero. 4. We started by aspirating the most concentrated food solution, as aspiration was going on we used the course and fine knobs to set the equipment reading to 100 units. After that we check again the zero reading by aspiring water and check again the 100 units whether it is still correct. 5. When the readings were correctly set we did not adjust any of the knobs while carrying out other readings. 6. Every standard solution was now aspirated one by one until the last solution, the units reading of each solution was recorded in a table, because of the burned memory effect; deionised water was aspirated between the solutions so as to clean the unit. 7. The third and sixth steps were repeated for all solutions, this was meant to improve the accuracy of the results. 8. After completing collection of data, we aspirate the unit for the last time using deionised was for a period of around two minutes and I shut off the equipment. 9. We cleaned up the area we were working at by disposing the solution on the sink. Results absorbance average Repeat2 Repeat1 k average Repeat2 Repeat1 Na concentration 0 0 0 0 0 0 0 0 0 57.5 60 55 55 63 63 63 63 5 127.5 125 130 130 147.5 140 155 130 10 200 200 200 200 187.5 180 195 170 15 252.5 255 250 250 240 240 240 200 20 7.2 7.2 7.2 7.2 35.2 35.2 35.2 35.2 unknown diluted (1/5000) Graph obtained from plotting sodium readings against concentration Photometry reading of the unknown solution is 35.2, hence from the graph the concentration of the unknown solution is Graph obtained from plotting potassium readings against concentration Photometry reading of the unknown solution is 7.2, hence from the graph the concentration of the unknown solution is Discussion The results show that as the concentration of the solution increases the photometry readings also increase. I repeated results reading more than once and the discrepancies between the figures were small, this shows that the results are almost accurate. I used average readings to plot the graph; this improves the accuracy of the readings. The concentration of the unknown potassium solution is 1.1 ppm while the concentration of unknown sodium solution is 2.1 ppm. When the metal solutions are aspirated into the equipment unit, the flame undergoes certain changes. The solvent that was used to dissolve the metal will then evaporate leaving the metal to burn on the flame (Ranganna & Ranganna, 1986). The salt will then get burned by the flame and it dissociate into atoms. When atoms absorb energy, they get excited and move to a high energy level. That level is not stable for atoms and they end up emitting energy in form of light radiation, when they emit the light they move back again to the lower energy level. The radiation light produce in the process is equivalent to the number of atoms that are excited. This means that the concentration of the solution is equivalent to the radiation of light produced by excited atoms. The equipment has a detector that can measure the intensity of radiated light, the intensity of the radiated light is equivalent to the radiated light, this is how the concentration of the solution is found (Ranganna & Ranganna, 1986). It has been found that different elements produce different light radiation when the atoms are in excited state. Though the experiment was carried out with precision, errors cannot miss out. One of the errors that affected the experiment was fluctuation of photometer. Photometer has a memory and when solution with metal passes through it remembers it. So before the next experiment is carried out, the unit should be first aspirated with deionised water to clean the unit and reset the memory back to its original state. The next source of error is impurities present in the concentration, though concentration was prepared to its best, impurities in the equipments might get into the solution (Ranganna & Ranganna, 1986). This impurities will influence the result because once the solvent evaporate they will remain with the metal. To minimize this error, use new apparatus and if the available apparatus have been used before clean them and it you ensure that there are no traces of impurities inside. Furthermore prepare solution in volumetric flasks should be covered to avoid impurities getting into it. Lastly, the error occurs due to poor flushing. After completing the first experiment, the unit was flushed with clean deionised water and the knob readings were set to zero. Due to poor flushing the photometer read around 0.2, the point two of the readings will affect the overall results of the experiment (Ranganna & Ranganna, 1986). To minimize this error flush the unit more than once with deionised water until it read zero, do not start using it when it not showing zero. Application of photometry The International Union of Pure and Applied Chemistry (IUPAC) have recommended the use of photometry in determining then amount of minerals such as sodium and potassium in food materials such as fruit juices and alcohol beverages (Sharma, 2000). In agriculture the presence of alkali and alkaline earth metals are important in cultivation. Photometry helps in determining whether these metals are found in the soil or not. To determine the kind of fertilizers that are suitable for certain types of soil, the soil will be first analyzed by photometry flame test (Sharma, 2000). Human body requires certain amount of potassium and sodium, too much of it and too little will cause certain problems such as high blood pressure and weakening of bones. To detect the amount in the body flame photometry method is used. The blood serum is diluted and aspirated into the flame. Conclusion The experiment was successful because we manage to achieve its objectives. We managed to measure the concentration of sodium and potassium contained in soy sauce solution. I also managed to create calibration and determine the amount of concentration of unknown solution. The solution of soy sauce was prepared and put in five different volumetric flasks. Photometry equipment was switched on and the solutions were aspirated into the unit one by one. The results from the readings were recorded in a table. When the solution was passed through the flame the solvent matter evaporated leaving the metals behind. The flame burned the metal into atomic state. The metals iron moved from lower energy level to higher energy level. In the high energy level they became unstable and they end up releasing light radiation, which is the light radiation that was measure to a certain the amount of metal concentration (Sharma, 2000). I encountered some errors while carrying out the experiment; the errors include the age of the apparatus, presence of impurities in the solution, and photometry fluctuation. This experiment method is important because it assist in determining the amount of metal substances in food materials such as juice and the amount of mineral substances such as potassium and sodium in the body. Recommendations Photometry should always be cleaned after use and after every experiment, deionised water should be flashed through the unit for more than 2 minutes, this will ensure that the unit becomes clean. Photometry has small holes and it can get blocked. The blockage can be managed by centrifuging after the experiment to ensure that no particles remain on the holes. References Coventry University. (2016). 223BMS Mini-projects (Forensic Food Analysis). Practical guide Gadag T. (2010) Engineering Chemistry, I. K. International Pvt Ltd Barringer, R. E. (1962). Flame photometric determination of sodium and potassium in beryllium metal. Oak Ridge, Tennessee, U.S. Atomic Energy Commission, Union Carbide Nuclear Company Sharma, B. K. (2000). Instrumental methods of chemical analysis (analytical chemistry). India, GOEL Publishing House Ranganna, S., & Ranganna, S. (1986). Handbook of analysis and quality control for fruit and vegetable products. New Delhi, Tata McGraw-Hill Mcclatchey, K. D. (2001). Clinical laboratory medicine. Philadelphia, Lippincott Wiliams & Wilkins Gropper, S. A. S., & Smith, J. L. (2013). Advanced nutrition and human metabolism. Belmont, CA, Wadsworth/Cengage Learning Read More

Apparatus used: 1. Flame photometer 2. Stock solutions of Na+ and K+, c = 1 mg/ml. 3. Six numbered 100 ml volumetric flasks. 4. Pipettes.A flame source is a kind of a burner that produces a flame that can be controlled, its form and temperature are controlled. Nebulizer and mixing chamber assists in moving the solution to the flame at a steady rate. The optical system is made up of 3 parts namely convex mirror, lens, and filter. A convex mirror is meant to transmit light emitted from excited atoms and focus it on the lens (Sharma, 2000).

The lens will then focus the radiated light on the slit. Mirror reflections will then go through the slit before reaching filters. The wavelength that is to be measured will then be isolated from any other emission. Lastly is the photodetector, which detects the light and measures the intensity of radiated emission. When the radiation struck the detector, the detector converts it to an electrical signal; the produced electrical signal is equivalent to the light intensity. A procedure that was followed:1.

A stock solution of 1000ppm (mg.l-1) was supplied and the standard solution was prepared by diluting the stock. The standard solution was prepared in five different concentrations, that is 5, 10, 15, 20 ppm, and unknown diluted. The solution was prepared using 100ml volumetric flasks. 2. When the food solutions were ready, we light the photometer flame with the help of the supervisor, the flame was stabilized and he gave us instructions on how to use it safely. 3. To clean and stabilize the unit, deionized water was first aspirated for around two minutes.

Water was aspirated until it stabilized; the knob was set to read zero units as aspiration continued, aspiration was stopped immediately the knob read zero. 4. We started by aspirating the most concentrated food solution, as aspiration was going on we used the coarse and fine knobs to set the equipment reading to 100 units. After that, we check again the zero reading by aspiring water and check again the 100 units whether it is still correct. 5. When the readings were correctly set we did not adjust any of the knobs while carrying out other readings. 6. Every standard solution was now aspirated one by one until the last solution, the units reading of each solution was recorded in a table, because of the burned memory effect; deionized water was aspirated between the solutions to clean the unit. 7. The third and sixth steps were repeated for all solutions, this was meant to improve the accuracy of the results. 8. After completing a collection of data, we aspirate the unit for the last time using deionized was for a period of around two minutes and I shut off the equipment. 9. We cleaned up the area we were working at by disposing of the solution on the sink.

The graph obtained from plotting sodium readings against concentration Photometry reading of the unknown solution is 35.2, hence from the graph, the concentration of the unknown solution is Graph obtained from plotting potassium readings against concentration Photometry reading of the unknown solution is 7.2, hence from the graph the concentration of the unknown solution is Discussion The results show that as the concentration of the solution increases the photometry readings also increase. I repeated the results reading more than once and the discrepancies between the figures were small, this shows that the results are almost accurate.

I used average readings to plot the graph; this improves the accuracy of the readings. The concentration of the unknown potassium solution is 1.1 ppm while the concentration of the unknown sodium solution is 2.1 ppm. When the metal solutions are aspirated into the equipment unit, the flame undergoes certain changes.

Read More