Determination of Calcium in Analgesic Tablets Using Atomic Absorption Spectrophotometry Michael N. Ouigleyl Mellon Hall, Duquesne University, Pittsburgh, PA 15282 Many articles have been published in this Journal describing experiments for the determination of various analgesics in proprietary brands of pharmaceutical tablets (1-19). Although a number of articles describing the use of atomic absorption spectrophotometry have also been published in this Journal (2040), a marriage between the two t o ~ i c has s not been r e ~ o r t e dhere. This is not too surorisi i g because most explriment designers would prefer focus attention on the determination of active inmedients. which are usually organic in nature. In fact, analgesic tablets can be analyzed just a s easily for the inactive, inorganic ingredients, which are often found in greater than trace amounts (>I%).The procedure presented below allows one to determine the amount of calcium contained in calcium carbonate coated analgesic tablets and follows the recommendations of orevious6 reported methods (41).
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tb
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Experimental Caution: Use care in the preparation of the lanthanum reagent. Ahighly exothermic reaction results from the addition of the acid to the lanthanum oxide.
5%( w / u j Lanthanum Solution. Weigh o u t approximately 59 g of lanthanum oxide, and transfer i t to a l-L beaker. Add 50 mL of deionized water. Slowlv add 250 mL of concentrated hydrochloric acid solution and allow to cool. Finally add suff~cientwater to make a ~ ~ r o x i m a t e1 lv Use calcium
Working Standard Solutions. From the stock standard solution repare a set of working standard solutions (1-10 mg/L Ca ) by serial dilution. If using 50.0-mL volumetric flasks, add 2.0 mL of 5%lanthanum solution to each flask before diluting to the mark.2
E
SolutionA. Grind one or two coated tablets, such a s Bnfferin (Bristol-Myers Squibb), into a fine powder using a mortar and pestle. Accurately weigh out approximately 200 me of the oowdered tablet into a beaker. and add 20 mL 0f;oncent;ated hydrochloric acid solution. Quantitativelv transfer this solution to a 100.0-mL volumetric flask; and dilute to the mark with deionized water,
'Current address: Bradfield Hall, Cornell University, Ithaca, NY 14853.
2~anthan~m acts as a re easlng agenl. prevenmg tne mtrod~cton of nvo a! le calc L m pyropnospnale lnlo me flame Allernawe lecnn qLes nvo.ve lne adott on of elnyleneolam nelelraacet c ac d (EDTA) to the solutions or use of a higher-temperature nitrous oxidelacetyleneflame.
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Journal of Chemical Education
Use a n atomic absorption spectrophotometer with a n air1 acetylcnc flame to analyze the ~ a "working standard solutions and the tcit solution(s,. Set the wavelength to 422.7 nm and the slit wldth to 0.7 nm. iLJsinc a I'erkin-El-mer 1100 instrument, we obtained a linear calibration curve for the ranee 1m d L to 10 me& Ca2+).P r e ~ a r ae calibration curve from th'data acq&ed fo; analysis of the workine standard solutions. and find the concentration of Ca2+present in the test solition(s) by interpolation. Keeping in mind that two dilutions (10-fold and 20-fold1 were made on the ongmal solut~on,calculate the percentage calc~umpresent in the tablet uslng the follmvmgequatlon.
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%Ca in tablet =
(10)(2O](Xmgc~'+IL) (0.1000 L) - mg of tablet powder
From a large number of determinations, we find that Bufferin tablets contain a n average 12.02% calcium.
Solutions
500-mglL ca2+Stock Standard Solution. carbonate as the primary standard.
Solution B. Pass solution Athrough a cone of coarse filter paper, and then dilute 5.0 mLofthe filtrate to 100.0 m1, with deionized water. Test Solution. Dilute 5.0 mL of solution B and 10.0 mL of 5% lanthanum solution to 50.0 mL with deionized water.
Literature Cited 1. Yamelle, M. K: West, K. J. J Chem. Educ. 1989, 66. 601 2. Street. K W.Jx J Chem. Edue. 1988.65. 1127. 3. Brown', R. D.J. Chem. Educ. 1985,62;811. 4. Beaver, R. W.; Bunch, J.E.; Jones, L A J. Chem. Edur 1983,60,1WO 5. Haddad. P: Hutehins, S.:TUfi M. J. Chem Educ. 1989.60. 166. 6. Kage3.R. A.:Fanvell,S.0.J. Chem. E d l v 1983.60, 163. 7. Martin. N. H. J. Chem. E d w . 1981.58.8I8. , 8. Byrd,J.E. J. Chem Educ. 1979,56,809. 9. Fiigen, R. A.; Plude, J.L.;Seitr. W . R. J Cham. E d u . 1979.66.658. 10. Cormieg R. A,:Hudson. W B.; Siege], J. A. J. Chem. Educ. 1979.56,180. 11. Chasar. D. W ;n t h , G. B. J. Chem. Edue. 1974.51.487. 12. Madsen, B. C. J Chem. Educ. 1973,60,852. 13. Marsh,D. G.:Jacobs,D. L.;Veening. H. J Chem. Edue. 1973,50,626. 14. Broun, D. B.;Riedman. L. 8.J Chem Educ 1973,50,214. 15. Paul&, J. W J Cham Educ. 1973,50,134. 16. Neman, R. L. J Chem.Educ. 1972.49.834. 17. Lieu, V T. J Chem Educ. 1971.48.478. 18. Shen. S. Y,Gi1man.A. J. J. Chem. Educ. 1965.42.540, 19. Proctor, J. S.; Robe*, J.E. J. C b m . E d w . 1961,38,471. 20. Williamson, M.A.J. Chem. Educ 1989,66,261. 21. Sangsils, S.; Labinaz, G.; Poland, J. 8.:van Loon, G. W J. Chem Educ 1880, 66, ,c,
""A.
22. Choi, S.; Larrabee, J.A. J. Chpm.Educ. 1989.66.864, Z.Bye, R. J. Chem. Edue. 1987,64,188. 24. Co1eman.M. F M. J. Cham. E d u . 1985,62,261. 25. Me3ucci.R. C. J Cham.Edue. 1983.60.238, 26. Lehman, T. A,: Everett, W W J. Cham. Educ. 1982.59.797, 27. Hoaluna, L. C.; Recihardt, P. B.:Stohberg, R. J. J. Chem. E d w . 1981,JS. 580. 28. Pinnell, R. P:Zanella,A.W. J. Chem. Educ. 1981.58. M4. 29. Andenon, J. L.; Gmhs, J.;Flick, D.J. Chem. Edue. 1980,57,521. 30. Ho8lung.J.W.:Snell,N.B.: Sturnan, B. T. J Chem Educ. 1977.54. 123. 31. Paschal, D. C. J. Chem.Educ. 1876.53. 165. 32. Pomeroy, R. K: Drikitia. N.; Koga, Y. J. Cham. Educ 1975.52, 544. 33. Stock, M. G.; Litt1e.D. J.;Donovan, R.J. J Chem. Educ 1974, 51, 51. 34. Stemporzewslu,S. E.:Butler,R.A.:Barry, E.F. J. Chem. E d u . 1974,51,332. 35. Thistlewaite, P J.; l h a s e , M. J Chem. Edue. 1974.51.687, 36. Hur1but.J. A: Gilbert, L. K: Buddington, B. N.; Rees,T F. J. C h ~ mEdue. . 1974.51, 734. 37. Lieu, V T:Cannon, A,; Huddleston, W E. J Chem. Edue. 1974.51.752, . 8.:Lethbridge, J.W J Chem. Edue. 1973.50,793. 33. Davles. M 39. Bast, J.C. J. Chem. Edue. 1973,50,396. 40. Argeuer,R. J.;Mite, C. E. J. Cham. Educ. 1912,49,27. 41. Dallymple, B. A: Kenner, C. T J Pharm. Sc&.1969,58,604.
