PRACTICUM 02 DETERMINATION OF ACETOSAL TABLET CONTENTS USING THE UV SPECTROPHOTOMETRY METHOD BASIC THEORY Acetosal tablets are also called acetylsalicylic acid tablets or acidi acetylosalicylici compressi. Acetylsalicylic acid tablets contain C9H8O4 acetylsalicylic acid not less than 90.0% and not more than 110.0% of the amount stated on the label. Structure of acetylsalicylic acid: Acetyl salicylic acid, better known as acetosal or aspirin, is an antipyretic and antiinflammatory analgesic that is very widely used and is classified as an over-the-counter drug. Monohydroxy benzoic acid can exist as ortho, meta, and para isomers. Ortho isomers are salicylic acid and its derivatives, for example sodium salicylate, esters of the carboxyl group such as methyl salicylate and esters of the hydroxyl group such as acetosal. For example, para isomer derivatives are nipasol and nipagin, while meta isomers and their derivatives are almost not used in pharmaceuticals. Some derivative compounds of hydroxy benzoic acid: Benzoic acid is a fairly strong acid and can be used as a primary standard for standardizing strong bases with the indicator phenolphthaline. Acetosal has the appearance of a white crystal, generally like needles or arranged plates, or a white crystal powder; odorless or weak odor. Stable in dry air; in humid air it is gradually hydrolyzed into salicylic acid and acetic acid. Acetosal, which is salicylic acid whose hydroxy group has been esterified, easily dissolves in sodium hydroxide and hydrolyzes in excessive base on heating in a water bath. TOOLS AND MATERIALS Tool: - Mortar - Stamper - Drop pipette - Volume pipette - Funnel - Measuring flask - UV Vis Spectrophotometer - Cuvette Material: - Aspirin tablets contain 500 mg of acetosal - H2SO4 0.1 N - Ethanol - Aquadest WAYS OF WORKING a) Test the uniformity of tablet weight - Weigh 20 tablets one by one - Weigh 20 tablets at once - Calculate the average weight b) Preparation of Standard Solution: - Carefully weigh 100 mg of pure acetosal - Insert a 100 ml measuring flask - Add 5 ml of ethanol or to taste - Add 0.1 N H2SO4 to the mark c) Preparation of Sample Solution: - Grind 10 aspirin tablets - Carefully weigh 100 mg of aspirin - Insert a 100 ml measuring flask - Add enough ethanol until the aspirin dissolves - H2SO4 0.1 N up to mark limit d) Making a Standard Curve: - Take 1 ml of standard solution (do several variations in taking the volume of the standard solution to get different levels) - Insert a 100 ml measuring flask - Add 0.1 N H2SO4 to the mark - Scanning λ max - Measure the absorbance at λ max (227 nm) with a 0.1 H2SO4 blank - Obtained standard absorbance (Ab) - create a standard curve equation between concentration (x) and absorbance (y) e) Determination of levels: - Take 1 ml of solution - Insert a 100 ml measuring flask - Add 0.1 N H2SO4 to the mark - Measure the absorbance at λ max (227 nm) with a 0.1 H2SO4 blank - Obtained sample absorbance (As) Replication 2 times