Colorimetric Determination of Salicylate in Urine - Lab Report Example

Colorimetric Determination of Salicylate in Urine Department Colorimetric Determination of Salicylate in Urine The aims of this laboratory practical are: i. Learn the steps followed in determination of salicylate in Urine ii. Determination of presence salicylate in urine. iii. Use iron III nitrate to determine concentration of salicylate in standard solutions and urine iv. Learn how to draw calibration curves Introduction Salicylate is a chemical compound that naturally occurs in most plants. They are mainly used by the plants to protect them against diseases and insects (PATERSON, et al., Strathclyde). Salicylates have varying effects on human beings depending on the quantity one has ingested. There are various foods that produce salicylate. These include tea, herbs, spices, food additives, some vegetables, most fruits, and flavour additives. Also, salicylates have been found in manufactured products such as industrial chemicals, medications, fragrances, some pesticides, and plastics (David, 2011). In plants, salicylate is used as a natural pesticide. In treatment, salicylate is used in the treatment of moderate to mild pain. The most commonly known salicylate is aspirin. Aspirin has been extracted from willow bark. Initially during its introduction, aspirin was considered to be very safe in treatment but in recent times, there have been numerous side effects that have been documented. These include such things as gastrointestinal effects, respiratory effects, hearing loss, faecal and urinary incontinence, salicylate induced hypoglycaemia, and toxicity of salicylate in breast milk (Cavanaugh & Bambenek, 1976). Despite of the known effects of the salicylates, there are numerous cases where salicylate is being used to treat various diseases. Moreover, there are numerous cases of poisoning that are prevalent in children, and adolescents. Considering the fact that a large number of people are consuming the drug either knowingly or unknowingly, determination of salicylate in the human body is paramount to facilitate proper prescription treatments. Colorimetric determination of salicylate in urine is one of the methods used in determination of salicylate in the human body. In this method, the presence of the compound is determined together with its concentration (Shaw, 2011). Methodology All the equipment for the practical was assembled. Picture (1) shows all the tools that were used Using a pipette, sodium salicylate was pipetted into five separate volumetric flasks with a capacity of 25.0 cm3. The pipetted volumes were 2.5 cm3 5.00 cm3, 7.50 cm3, 10.00 cm3, and 15.00 cm3. Picture (2) sodium salicylate solution in the flasks Using a pipette, 2.50 cm3 of iron III nitrate solution was added to the volumetric flask then made up to the mark using distilled water. Picture (5) added Iron (III) nitrate (6) added distilled water 15.00 cm3 of synthetic urine sample was then pipetted into another 25.00 cm3 volumetric flask and 2.50 cm3 of iron III added to the solution. The solution was then made up to the mark of the volumetric flask using distilled water. All the solutions were then stoppered, mixed thoroughly and then left to stand for five minutes. Picture (7, 8) mixing solutions and leave it for 5 minutes The concentration which gave the maximum absorbance value was found and then using the wavelength, the absorbance of each of the standard solution was determined together with the urine sample. Results and Discussion ABSORBANCE OF MOST CONCENTRATED STANDARD AT VARIOUS WAVELENGTHS WAVELENGTH (440)nm ABSORBANCE Distilled water as a reference 0.00 15.00 0.35 10.00 0.20 7.50 0.14 5.00 0.11 2.50 0.05 Urine sample 0.35 From the graph, the wavelength of a urine sample at an absorbance of 0.35 is 15 WAVELENGTH (520)nm ABSORBANCE 15.00 0.59 10.00 0.33 7.50 0.23 5.00 0.18 2.50 0.09 Urine sample 0.41 From the graph, the wavelength of a urine sample at an absorbance of 0.41 is 11.8 Concentration Calculation For V1 = 2.5 cm3 For V1 = 5.0 cm3 For V1= 7.5 cm3 For V1 = 10 cm3 For V1 = 15 cm3 STANDARDS AND URINE SAMPLE (cm3) CONCENTRATION (ppm) 15.00 60 10.00 40 7.50 30 5.00 20 2.50 10 Urine sample X Graph From the equation, the equation of the line is. This implies that the slope of the graph is 4 and the line has a y-intercept = 0. The Regression equation Rearranging the equation to make x the subject, Discussion Using beer lamberts law, concentration of salicylate can be easily determined (Shaw, 2011). The determination of the concentration of salicylate can be determined in ways. Ways using the beer lamberts law. If the molar absorptivity of a solution at a given wavelength is known, the concentration is calculated directly using the beer lamberts law. In this case, the molar absorptivity is not known, thus calculation of the concentration cannot be done directly. Thus to determine the concentration of the urine in the sample, a calibration curve is prepared. Determination of the concentration by the calibration curve does not rely on the molar absorptivity. Moreover, the dimensions of the cell containing the sample to be measured is not needed (Sood, 2006). Preparation of the calibration curve involves the determination of the absorbance at a wavelength that has a strongest absorption. This is done for a series of standard solutions including the unknown compound. Thus, a calibration curve is prepared by plotting a graph of absorbance of the solutions vs the concentrations of the solutions (Rashid, et al., 2006). Theoretically, the calibration curve is expected to be a straight. This is not the case with the experimental results. The resulting points are not on the straight line, and to make the straight line, a line of best fit is drawn among the points. The resultant non – straight line is attributed to the fact that the Beer lamberts law only holds for dilute solutions, but breaks down to solutions containing extremely high concentrations. Also, this may be due to the errors that may have been encountered while taking the measurements (Shaw, 2011). From the calibration curve, the line does not pass through the origin. Despite this, the line obeys beer lamberts law since it can be seen that absorbance is directly proportional to concentration i.e. as the concentration of a solution increase, the absorbance of the solution also increases (Shaw, 2011). Results show that the urine used in the experiment has a concentration of 4 ppm. The presence of salicylate in the urine at a concentration of 4 ppm indicates that the body from which the urine was extracted from has traces of salicylate. Conclusion The final results indicates that there is a concentration of 4ppm of salicylate in the urine sample. From these results, the amount of the salicylate urine in the body of can be easily determined and basing on the determination, a remedial measure taken. Thus it can be concluded that Colorimetric Determination of Salicylate in Urine is one among the most effective reliable techniques that can be utilized to analysis a urine sample to determine the concentration of salicylate. References Cavanaugh, M. A. & Bambenek, M. A., 1976. Colorimetric analysis for salicylate in urine: An experiment for nursing chemistry. Journal of Chemical Education, 55(7), p. 464. David, G., 2011. Analytical Chemistry. 1st ed. s.l.:Universities Press. PATERSON, J., RAJEEVSRIVASTAVA, BAXTER, G. & GRAHAM, A., Strathclyde. Salicylic Acid Content of Spices and Its Implications, Glasgow : University of. rashid, U., bhatti, H. N., hanif, M. & Ahmeed, R., 2006. Dtermination of Metabolite aspirin by colorimetric method in Human urine. Pakistan journal of Biological Sciences, 9(6), pp. 104-1008. Shaw, L. M., 2011. The Clinical Toxicology Laboratory: Contemporary Practice of Poisoning Evaluation. 1st ed. s.l.:Amer. Assoc. for Clinical Chemistry. Sood, 2006. Textbook of Medical Laboratory Technology. 1st ed. New Delhi: Jaypee Brothers Publishers. Read More