Soy Sample Potassium and Sodium Concentration - Assignment Example

ANALYSIS OF NA AND K IN SOY SAUCE Name Course Tutor University Department Aim This experiment seeks to determine soy sample potassium and sodium concentration by comparing its absorbance to the corresponding absorbance of potassium and sodium standards. Background Theory Food composition databases are used by the health professional and dietitian to assess patients' status and their dietary intakes. Additionally, they can be used to assess whether foods and other products have adequate dietary levels to identify correlations between health and diets. Sodium and potassium are essential nutrients required for the normal functioning of the body. Sodium is responsible for maintaining osmotic pressure of the extracellular fluid. Potassium regulates osmotic pressure inside the cell and activating glycolytic and respiratory enzymes. Nevertheless, excessive consumption of sodium is linked high blood pressure, which increases the risk of hypertension and other related diseases. WHO has recommended at least 3510 mg per day of potassium and less than 2000 mg intake of sodium per day (WHO 2012). However, most of the processed and packaged foods do not meet the required guidelines. Several analytical techniques can be used to quantify the amount of sodium and potassium present in a product, mainly flame photometry. Flame photometry is a branch of atomic spectroscopy that is used to determine of metal salts such as Na and K. Flame photometry is used for both qualitative and quantitative analysis of such elements because they are readily excited higher energy levels at relatively low flame temperatures (Grove 2013). The solutions containing metal ions are aspirated into the flame, where the metal is atomized and sublimated, and a valence electron is excited to a higher energy level. When the electron returns to its ground state, a characteristic wavelength is emitted that is used for qualitative analysis. A flame photometer has optical filters that select particular emission wavelength monitored for the analyte species. Comparing emission intensities of the sample with that of the standards helps in calculating the concentration of the unknown sample. The color wavelength distinguishes a particular element while the color intensity tells us the amount of that element that is present. The flame in the flame photometer provides energy of excitation to atoms when metals are introduced into the flame (Skoog et al. 2014). A sample is introduced into the flame at a constant rate, and the optic filters select color detected in the photometer. In this experiment, potassium and sodium were analyzed using flame emission photometry. Materials and Methods Materials required: Conical flasks, Beakers, Pipettes, Measuring cylinders, Standard flasks, magnetic stirrer, glass rod, Deionized water, Hydrochloric acid (HCl): 0.5% HCl (V/V), Sodium chloride (NaCl), and Potassium chloride (KCl). Apparatus: Flame photometer and Electrical balance. Preparation of Standard Solution 0.635 grams of an analytical reagent quality sodium chloride (NaCl) was weighed and transferred to a 250 ml volumetric flask through a funnel. Then, distilled water was added to the reagent and stirred using a magnetic stirrer. When the crystals were completely dissolved, distilled water was added up to the solution up to 250 ml mark. The standard stock solution prepared contained 1000ppm/ 1000 ppm of sodium and potassium. From the 1000 ppm stock standard solution, 5, 10, 15, and 20 ppm standard solution in the 100ml volumetric flask were prepared through serial dilution according to the table below. Simultaneously, 0.477 grams of an analytical reagent quality of potassium chloride (KCl) was weighed and transferred into another 250 ml volumetric flask through a funnel. The process of serial dilution was repeated. Flask number 1 2 3 4 Vol. of Na/K standard solution in 100ml flask 0.5 1 1.5 2 Conc. Of solution obtained in ppm 5 10 15 20 Sample Preparation The test sample was given in a flask. The sample was then diluted 5000 times to fit in the standard range. Procedure 15 minutes were allowed for instrument warm up to ensure optimum performance. During this period deionized-distilled water was aspirated to clean out the sample tube and aspirator. Distilled water was used as a blank solution and aspirated to calibrate the instrument to read out zero. The sensitivity control was set using the highest concentration of sodium till the galvanometer read 100. The emission intensity of the remaining standard solutions was also measured according to the table 2 below. Then, water was run through the instrument again and the emission intensity of the soy sauce was also measured; however, the sample was diluted 5000 times to ensure that the signal obtained was in the standards range. For accuracy, the standards and the sample were measured in duplicate. Water was run through the instrument and sodium was replaced with potassium filter. The procedure of reading the standards and the sample was repeated. Emissions were noted for all standard solutions as well as the sample. The average emission measurement was calculated, and calibration curves for both sodium and potassium were plotted to determine the concentration of Na and K in the soy sauce sample. Results Table: 2 Emission for Na+ and K+ with respective concentration and unknown sample Absorbance Repeat2 Repeat1 K Repeat2 Repeat1 Na Concentration 0 0 0 0 0 0 0 60 55 55 63 63 63 5 125 130 130 140 155 130 10 200 200 200 180 195 170 15 255 250 250 240 240 200 20 7.2 7.2 7.2 35.2 35.2 35.2 Unknown diluted (1/5000) Table 3: Average Emission for Na+ and K+ with respective concentration and unknown sample Absorbance Concentration Na K 0 0 0 5 63 56.67 10 141.67 128.33 15 181.67 200 20 226.67 251.67 sample (1/5000) 35.2 7.2 The quantitative determination of sodium and potassium in the sample were performed using the method of calibration curve. The calibration curves were defined based on five points. The concentration of potassium and sodium ranged between 0 and 20 ppm. Figure 1: Flame Photometry analysis of sodium The concentration values of the unknown solution were determined using the equation y = 11.987x. The Na absorbance of (1/5000) dilution sample = 35.2 According to the calibration curve equation conc of (1/5000) dilution sample Y=Mx + C Y = 35.2 35.2 = 11.987* x. X = 35.2/11.987 X = 2.9365 ppm 1/5000 sample = 2.9365 ppm Sample concentration = 2.9365 * 5000 The concentration of Na in the sample = 14682.6 ppm Figure 2: Flame Photometry analysis of Potassium The concentration values of the unknown solution were determined using the equation y = 12.8x. The Na absorbance of (1/5000) dilution sample = 7.2 According to the calibration curve equation conc of (1/5000) dilution sample Y=mx + c Y = 7.2 7.2 = 12.8* x. X = 7.2/12.8 X = 0.5625 ppm 1/5000 sample = 0.5625 ppm Sample concentration = 0.5625 * 5000 The concentration of Na in the sample = 2812.5 ppm Discussion The standard solution of both potassium and sodium were aspirated to the flame photometry to calibrate and establish consistency reading in sample measurement. Hence, the calibration graph was linear and an indication that it could adequately help in the determination of samples. The concentration of both potassium and sodium in the soy sauce sample was compared against the standard solution of sodium and potassium. Figure 1 graph was plotted on the Y-axis Table (Intensity of emission of sodium) verses X-axis (concentration of sodium in ppm). Figure 2 graph was plotted on the Y-axis Table (Intensity of emission of potassium) verses X-axis (concentration of potassium in ppm). According to the experiment results, the unknown sample has sodium concentration of 14682.6 ppm and potassium concentration of 2812.6 ppm. The recommended daily dietary intake of potassium for an adult is 4,700 mg/day. In this experiment, the soy sauce sample has a concentration of 2812.6 mg, which is lower than the required amount of 4,700 mg. On the other, hand the recommended daily amount of sodium concentration is 2000 mg/day. The unknown sample has 14, 682 mg, which exceed the required amount of sodium concentration in the body. Soy sauce is a processed product and food processing is associated with an increase in sodium content apart from sodium chloride, but also, these additives may contain minerals in their formulation added during processing to achieve the product desired characteristics such as modifying texture, flavor, and prolonging shell-life (Aburto et al. 2013). In this case, the concentration of sodium in soy sauce exceed the required amount by more than six times, and it is risky for our health. Excess sodium intake is harmful because it leads to increased blood pressure, and in some cases, it results in the build-up of fluid in people with congestive heart failure, cirrhosis or kidney disease. On the other hand, the amount of potassium in soy sauce does not meet the required dietary intake which is 3700 mg per day. Sherman and Mehta (2009), suggest that companies should consider additives on the dietary potassium to ensure that the products meet the required amount. Low potassium intake is associated with hyperkalemia, which is a significant cause of increased mortality in chronic disease patients. For this reason, they should seek long-term alternative by including potassium contents on the foods on the nutritional label so that people can know the amount they take. Both sodium and potassium calibration curves appears linear with (r2 = 9802) and (r2 = 0.9967) respectively. A good calibration curve should have an R-squared value greater than 0.97; therefore our curves were within the required range. The results of emission intensity fluctuated at times, but the sources of error mainly revolve around the photometer. Emission intensity fluctuation in the photometer reading was an area of concern. However, to minimize its effect, each solution was allowed to flush the instrument for about 10 seconds before taking the readings. However, the apparatus may not have been properly and adequately cleaned in the past, and some residue may be present inside the capillary tube. Finally, the photometer was calibrated zero using distilled water before running the sample and standards; however, there was a photometer reading an indication that 10 seconds may not be sufficient flushing time. Conclusion According to the results of the experiment, the determination of sodium and potassium in samples by flame photometry was attained after a simple dilution with distilled water. The analyzed sodium content in the sample was found to be higher than the required amount while the potassium content did not meet the required guidelines. To cut down the sodium content and increase the potassium in the diets of the population, manufacturers need to reformulate their products. Also, regulation agencies need to implement strict regulations and monitoring, as well as increase awareness among the public to contain hypertension and other related disorders (WHO 2012). Future studies should analyze other mineral contents in the food products to determine whether they meet the dietary guidelines. Also, other methods of sample preparation should be used to ensure that all the potassium and sodium is extracted from the matrix for analysis. References Aburto, NJ, Ziolkovska, A, Hooper, L, Elliott, P, Cappuccio, FP, & Meerpohl, JJ 2013, 'Effect of lower sodium intake on health: systematic review and meta-analyses', British Medical Journal, vol.346, pp.1326. Grove, E.L 2013, Applied Atomic Spectroscopy, Springer Science & Business Media, New York. Sherman, A R, Mehta, O 2009, 'Potassium in food additives: something else to consider', Journal of Renal Nutrition vol.19, no. 6, pp. 441-442. Skoog, DA, West, DM, Holler, FJ, & Crouch, SR 2014, Fundamentals of Analytical Chemistry, (9th ed.) Cengage Learning World Health Organisation 2012, Guideline: Sodium Intake for Adults and Children. viewed 13 April 2016, Read More