PRACTICUM 04 DETERMINATION OF Fe (IRON) CONTENT IN STOPS SPECTROPHOTOMETRICALLY Theoretical Foundation UV-Visible Spectrophotometry is a spectrophotometric method that is based on the absorption of light in the ultra violet (UV) and visible (Visible) regions of a compound. Compounds can be analyzed using this method if they have the ability to absorb in the UV or visible areas. Compounds that can absorb intensity in the UV region are called chromophores, whereas to carry out compound analysis in the visible light region, the compound must have color. UV-Vis spectrophotometry is a part of spectroscopic analysis techniques that uses near ultraviolet (190-380 nm) REM (electromagnetic radiation) and visible light sources. (380-780nm) using a spectrophotometer instrument. UV-Vis spectrophotometry involves quite large electronic energy in the molecules being analyzed, so UV-Vis spectrophotometry is more widely used for quantitative rather than qualitative analysis. The equipment used in spectrophotometry is called a spectrophotometer. Absorbance measurements using a UV spectrophotometer can be used for qualitative and quantitative analysis. The absorption wavelength is the difference in the size of the energy levels of the excited electron. Therefore, the absorption peak (λ) can be related to the types of bonds present in the species. The wavelength region for vacuum UV is 10-200 nm and near UV 200-380 nm. Iron is fourth in abundance in the earth's crust after oxygen, silicon and aluminum. In general, iron tends to form compounds in the form of Fe3+ compared to the form of Fe2+ and forms stable complexes with certain compounds. Iron analysis generally uses complexing agents such as selenite, color looks. batophenanthroline, 1,10-phenanthroline, molybdenum and diphenyl carbonate where the resulting complex can be detected using light spectrophotometry Tools and Materials 1. Tools - Erlenmeyer - Fillers - Measuring cup - Cuvette - Measuring flask - Measuring pipette - Drop pipette 2. Material - Aquades - Ammonium thiocyanate (NH4SCN) - FeCl3 - Concentrated HCl - Sangobion medicine Work Procedures 1. Preparation of standard solutions Iron (III) Chloride(FeCl3) - Weighed 0.001 grams Dissolve with concentrated HCl - Dilute to 100 mL with distilled water FeCl3 solution 10ppm - Pipette 5 mL, then put it in a measuring flask - Added ammonium thiocyanate solution - Dilute to 100 mL - Standard solution 5 ppm 2. Determination of Fe content using the Standard Addition Method Iron Sulfate Preparations - Weighed 0.1 gram - Dissolve with 2 mL concentrated HCl - Dilute with distilled water to a volume of 100 mL Iron sulfate solution - Pipette 5 mL - Put it in 2 different measuring flasks - Add 1 mL of standard solution to the first flask and no standard solution is added to the second flask - Added 3 mL of NH4SCN (ammonium thiocyanate) solution - Dilute with distilled water to the tera mark - The absorbance was measured at λ max ... nm