YULIA RETNO PURWANINGSIH, 050710004 (2011) VALIDASI METODE SPEKTROFOTOMETRI UV � VIS UNTUK PENETAPAN KADAR BORAKS DALAM LONTONG. Skripsi thesis, UNIVERSITAS AIRLANGGA.

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Abstract

Borax, an illicit additive substance, was added in certain food product as a preservative. The UV-Vis spectrophotometry with curcumin as a reagent has been used for determination of borax in food. Curcumin is the most sensitive reagent for borax identification. The aim of this study was to verify whether UV-Vis spectrophotometry with curcumin as chelat ing agent fulfill valid ation criteria for determining borax in lontong . The optimum results were obtained when 1,0 ml solution of 0.125% curcumin and 1.0 ml of mi xed acetic acid glacial-sulfuric acid (1:1) were added. The absorbance of co mplex boro-curcumin was measured at 547 nm 50 minutes after the red color of complex solution obtained. The result shows that detection limit and quantitation limit were obtained 0.02487 ppm and 0.07535 ppm respectively, while coefficient of correlation (r) were 0.9690 ( r table was 0.959 for n = 5) with the linear regression y = 1.3127x – 0.0994 and Vxo = 15.53% (Vxo >5%). The recovery was 34.61 ± 0.54 % with coefficient of variation of 1.57%. Applicat ion of this method for determination borax in lontong of three samples which were taken from a traditional market in Surabaya showed that there was no borax detected. As c onclusion, this method was selective and valid for identification of borax in sample, but not eligible the quantitative validation criteria.

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