The purpose of this experiment is to find the amount of Fe in dietary tablets by UV-visible spectrophotometer. A Perkin-Elmer Lambda 6 UV-Visible spectrophotometer will be used for the unknown sample and the iron(II) standards.
Fe3+ in a dietary tablet is converted to Fe2+ and reacats with 1,10-phenathronile to form the tris(1,10-phenanthroline) iron (III) complex. Hydroquinone is used as the reducing agent ro reduce Fe3+ to Fe2+. The absorbance of the complex is measured using the UV-Visible spectrometry.
In atomic absorption atoms absorb part of the light from the source and the remainder of the light reaches the detectors. Atomic emission comes from atoms that are in a excited state because of the high thermal energy of the flame. Each element is measured by absorption or emission of ultraviolet or visible radiation by the gaseous atoms. Samples are vaporized between 2000 and 8000 K and the vapors are measured by absorption of characteristic wavelengths of radiation. The samples should be diluted to ppm to analyze major constituents.
Chemical equations that were used were the equation of the line y = mx + b which would be attained from a calibration curve. And Beer Lambert law: . Experimental Procedures
To prepare the standard iron solution weighed 0.0351 g of ferrous ammonium sulfate and added 1.25 mL of sulfuric acid. We added distilled water to make 500 mL. We dissolved 0.1005 g of 1,10-phenanthroline in a 100 mL volumetric flask. We then prepared 25 mL hydroquinone solution containing 0.2510 g of hydroquinone. In a 250 mL volumetric flask 6.2515 g of sodium citrate was used and distilled water was filled to the mark.
Five 100 mL volumetric flasks were filled with 1.00, 2.00, 5.00, 10.00, and 25.00 mL of standard Fe solution. To each flask sodium citrate was added until the solution reached a pH of...