Aluminum Detection
People encounter Aluminum in their day-to-day lives in a very regular basis, for example in metal form these are used in aluminum foil, airplanes, and ever soda cans and in its many compound forms are used in antacids, fire extinguishers, antiperspirants, and food additives.
With all these sources for daily contact with Aluminum, the possible health effects of Aluminum have been studied and debated. Prolonged exposure andor intake of significant amounts of aluminum have been linked to respiratory problems, bone weakness and osteoporosis, and Alzheimers disease (Exley et al, 2001). The link between Alzheimers disease and the Aluminum found in antiperspirants especially have sparked much discussion as some studies have deemed the link inconclusive (Berkley Wellness Letter, 1993) while others say the evidence is strong (Perl, 1985 Shin, Lee Trojanowski, 1994). As these debates continue, standard procedures are required to test for the presence of Aluminum in both the subjects and the products that the subjects regularly use, to gain conclusive evidence and thus, viable conclusions.
Detecting Aluminum in antiperspirants. The main objective of this laboratory experiment is to test whether Aluminum is present in samples of a deodorant and an antiperspirant. In a study, for example, it may need to be determined whether Aluminum is truly the ingredient that causes the adverse effects, and the presence of Aluminum in products the subjects use need to be confirmed.
The process involves the extraction of what Aluminum ions (A3) may be present in the deodorant and the antiperspirant samples. The relevant reaction for the experiment (shown below) is the one that exists between the extracted ions with the aluminum reagent, in this case ammonium salt of aurintricarboxylic acid.
Al3 Aluminum reagent ( Al(OH)3
The product of the reaction is Al(OH)3, a gelatinous, cherry-red precipitate. Taking into consideration that basic pH conditions are carefully maintained during the testing process, this precipitate would not appear if the reaction does not occur. Of course, the reaction would not occur if there are no Al3 ions present thus, this is a simple, quantitative test for the presence of Aluminum. Since no Aluminum compounds as of yet are commonly used to inhibit body odor, and Aluminum chlorohydrate has long been used to inhibit perspiration it is reasonably to be expected that the antiperspirant would be positive for Aluminum content, while the deodorant would not.
Materials and Methods
Preparing the materials and samples. First, a boiling water bath was prepared in a clean, 400 mL beaker. Then, four test tubes were cleaned and dried, and prepared for labeling. The labeling of the four test tubes were as follows Test tubes number 1, 2, 3, and 4 were labeled Positive Control, Antiperspirant, Deodorant, and Blank, respectively.
With the materials thus prepared, the samples were prepared next. A pinch of Aluminum salt was placed inside Test tube 1 as the positive control. Next, a clean sheet of weighing paper was used to weigh 0.25 g of the antiperspirant, and the weighed sample was placed in Test tube 2. Then, another clean sheet of weighing paper was used weigh 0.25 g of the deodorant, and this new weighed sample was placed in Test tube 3. Nothing was placed inside Test tube 4, as this is the blank.
Extraction of Aluminum (Al3) ions. To each of the four tubes, 4 mL of distilled water was added and shortly after, 1mL of 6 M Hydrocholoric acid (HCl) was added to each tube as well. A stirring rod was then used to mix the contents of each tube thoroughly, while it was made sure that no contamination of the four samples occurred during stirring (such as using the same rod without cleaning it to stir all four tubes). All four tubes were then carefully placed inside the prepared boiling water bath and left for 5 minutes. The heat of the bath aids in the extraction of all Al3 ions that may be present in the samples.
Test for presence of Al3. Once the allotted 5 minutes was over, the tubes were then carefully removed from the bath and allowed to cool back to room temperature. The cooling process was closely monitored. It was then checked whether any solids were present inside any of the four tubes so these can be filtered with Whatman 1 filter paper and the filtrate collected in a clean test tube for further testing later.
Using a dropper, 2 drops of the Aluminum reagent were added to each of the four sample tubes and the solutions were mixed thoroughly. The color changes that were observed at this point were all noted. Next, under the fume hood, 6 M ammonium hydroxide (NH4OH) was added dropwise into each tube until a basic pH was reached, with the contents being mixed thoroughly after every addition of NH4OH. The pH was tested using red litmus paper, by stopping the addition of NH4OH once the litmus paper turned blue, which indicated basic pH.
Once basic pH was reached in all four of the sample tubes, the tubes were inspected for the presence of Al(OH)3 which was described as being a gelatinous, cherry-red precipitate that would be suspended in a clear solution. The test tubes were compared to each other and the results and observations were tabulated.
Results
Table 1. Results of the Aluminum Detection Experiment
Test Tube Test Tube LabelColor Change
After addition of Aluminum reagentColor Change
After addition of NH4OH1Positive ControlLight pinkPink2AntiperspirantCloudy whitePink3DeodorantYellowishClear4BlankLight pinkClear
The results of the experiment are tabulated in Table 1 above. It was documented that after the addition of the aluminum reagent, both the solutions inside the Positive Control and the Blank test tubes turned a light, pinkish color. On the other hand, the contents of the Antiperspirant test tube turned a cloudy white, while those inside the Deodorant test tube were a natural, light, yellowish color. Once NH4OH was added to the test tubes and basic pH was obtained in all four, however, it was observed that the respective contents of the Positive Control and Antiperspirant test tubes were pink, while the solutions inside the Deodorant and Blank test tubes were clear.
Discussion and Conclusions
It was observed that the contents of the four test tubes had differing reactions after the Aluminum reagent was added to them. At this stage, of course, the relevant reaction between the Aluminum ions and the reagent would not have taken effect yet since a basic pH was required for the reaction to occur.
Once the NH4OH drops were added to the solutions though, and all four test tubes were shown to have basic pH via the litmus papers these results indicate whether Aluminum is present in the samples or not. The Blank and the Positive Control test tubes serve as comparison points for the other two samples. The Blank, as expected, did not indicate any changes in color other than the colors of the added chemicals. The Positive Control is known beforehand to have Aluminum ions, from the Aluminum salt placed inside the test tube, so color changes similar to those observed in this test tube will indicate the presence of Aluminum ions. The solution inside the Positive Control tube was pink, and this was similar in appearance to the solution inside the Antiperspirant test tube. It is logical to infer then, that the Antiperspirant sample contained Aluminum. The final appearance of the Deodorant test tube was clear, similar to the Blank, so it is also logical to say that the Deodorant sample did not contain Aluminum.
The pink color of the solutions inside the Positive Control and Antiperspirant test tubes instead of the expected gelatinous, cherry-red precipitate can be attributed to either a contaminated or diluted Aluminum reagent, or minute amounts of Aluminum in the samples. Either reason would result in a small amount of the Al(OH)3 precipitate, and this red precipitate diluted in a clear solution after thorough mixing would account for the resulting pinkish color of the solutions as diluted red is pink. In future experiments, to make the results of the experiment more defined, and for the precipitate to be clearly seen, a few things can be done. First, the Aluminum reagent should be tested first, then larger amounts of the samples than were used in this experiment can be used (with the amounts of HCl and reagent also raised accordingly), and the solutions should be allowed to stand undisturbed for a reasonable amount of time for the precipitate to accumulate.
To conclude, though the quantitative results of the experiment were not as expected, it could still be logically inferred that the Antiperspirant contained Aluminum ions while the Deodorant did not. This was as expected since Aluminum chlorohydrate is commonly used to inhibit perspiration, and this would not normally be present in a plain deodorant.
Objective
A test for detecting the presence of Aluminum ions in regular substances people use in their day-to-day lives was performed successfully. Other than the skills involved in the preparation of the materials and samples and the execution of the steps of the methodology, both requiring strict adherence to laboratory protocol, skills in analysis and logic were also sharpened. The importance of including a Positive Control sample and a Blank or Negative Control sample in these types of tests was stressed as it was in the comparison to these samples that the presence or absence of Aluminum in the tested samples were confirmed. This type of test can be used in studies that aim to link the presence of Aluminum in everyday substances with specific diseases, to see if the affected subjects really do come in contact with enough amounts of Aluminum often enough for the cause-and-effect to be conclusive.
Also, once the Aluminum is conclusively linked to serious diseases like Alzheimers or breast cancer, and the presence of Aluminum becomes identified as significant health risk, a test like this can also be used to check if existing products still have Aluminum in them.
Categories:
0 comments:
Post a Comment