Urinalysis Lab Case

From analyzing the different urine samples containing glucose, albumin, an altered pH, and ketones, many observations were made. Through Benedict’s test, the Biuret test, the pH test and the odour test, many different characteristics were found. Ultimately, the unknown sample was found through these 4 tests.

It was notable that the urine sample containing Benedict’s solution and glucose turned to a brownish-red color when heated. Benedict’s solution is used to test for the presence of an aldehyde or ketone functional group (Gurien, 2008), in this test glucose was being searched for. The color change to a brick red color indicated a positive result. However, when Benedict’s solution was added to the control, no changes were evident. When Benedict’s reagent was tested on the unknown sample, no changes were prevalent, indicating that no aldehyde or ketone functional group was present in the sample.

In the second test, Biuret reagent was used to test for the presence of protein molecules in the urine sample, in this lab, the protein that was tested was albumin. When the indicator was added to the urine sample with albumin, the color of the solution turned purple. The color change to a violet color indicated that proteins had been detected (Gurien, 2008). On the other hand, when the Biuret reagent was added to the control, the sample turned clear. When the reagent was tested on the unknown sample, no changes were observed. This indicated that no proteins were present in the unknown sample.

In the third test, the pH of the altered sample and control sample was determined through a pH strip test. The control sample appeared to have a pH level of 4, while the altered sample had a pH level of 2. When the pH strip test was conducted on the unknown sample, a pH level of 2 was found. This result explains that the unknown sample must have had an altered pH level.

Lastly, the odour of the ketone sample and control sample was wafted and smelled. The smell of the sample containing ketones was similar to the smell of a nail polish remover solution. The tangy smell was a positive result for the presence of ketones. However, the control sample was odourless. In addition, the unknown sample was odourless, therefore no ketones were present in the sample.

Furthermore, the lab confirmed the reactions of Benedict’s and Biuret reagents found through previous research and experiments performed by scientists such as Ferdinand Rose and Stanlet Rossiter Benedict. Ferdinand Rose stated that the biuret reagent can be used to detect the presence of peptide bonds; the copper (II) ion is reduced to copper (I) which forms a complex with the nitrogen’s and carbon’s of the peptide bonds in an alkaline solution causing it to turn violet in the presence of proteins (Sastry, 2010). Stanlet Rossiter Benedict stated that Benedict’s reagent can be used to test for the presence of reducing sugars. The reagent consists of blue copper (II) ions which are reduced to copper (I) ions by the reducing sugar (Sastry, 2010).

This lab allowed one to apply their knowledge of the specialized tests to determine the characteristic of the unknown sample. By performing the lab, it was made clear that the unknown sample had a altered pH compared to the control. The glucose, ketone and protein tests conducted on the unknown sample appeared to be negative.

Although the results of the experiment were consistent with those of peers, a source of error could have been that during the ketone test, one may have not smelled the difference. One laboratory member did not smell the difference between the control and the sample containing ketones. This issue can result in uncertainty. A more precise way of identifying a sample as one that contains ketones should be used. Ketone strips just like the pH strips can be used the next time this lab is conducted so the investigator can be certain about the presence of ketones in the unknown sample. The ketone test strips (Figure 1.1) sold at local pharmacies are used for searching for ketones in urine samples and by using the strips, a quantitative result can be found. Another source of error could have been that one may have detected different proteins in the Biuret test. Since the Biuret test detects peptide bonds, any type of protein could have been detected. It does not necessarily mean that albumin had been detected. To fix this, an albumin testing kit could have been used to detect albumin and it’s concentration. By using an albumin testing kit (Figure 1.2), a quantitative result can be found.

Works Cited

Gurien, M. (2008, September 8). Benedict’s Reagent. OHIO: Biological Sciences at Ohio University. Retrieved May 11, 2013, from http://www.biosci.ohiou.edu/introbioslab/Bios170/170_2/benedict.htm

Gurien, M. (2008, September 8). Biuret Test. OHIO: Biological Sciences at Ohio University. Retrieved May 11, 2013, from http://www.biosci.ohiou.edu/introbioslab/Bios170/170_2/biuret.htm

Kidney Albumin Home Test Kit By Prima. (n.d.). Kidney (Albumin) Home Test Kit By Prima. Retrieved May 11, 2013, from http://www.mccabespharmacy.com/shop/health/health-tests/kidney-home-test-kit.html

ReliOn Ketone Test Strips – Walmart.com. (n.d.). Walmart.com: Save money. Live better.. Retrieved May 12, 2013, from http://www.walmart.com/ip/Reli-On-Ketone-Test-Strip/13037592

Sastry, P. (2010, March 8). History of Benedict’s Test and Biuret’s test. History of Benedict’s Test and Biuret’s test. Retrieved May 11, 2013, from http://www.docstoc.com/docs/28299534/Benedicts-Test-for-Reducing-Sugars