Sulfate Quantification via Barium Chloride

Agarose, BaCl₂ and trichloroacetic acid were purchased from Sigma-Aldrich. Glassware was rinsed several times in deionized H₂0 and then dried before preparing the reagents. A 0.5 % BaCl₂ + 0.01 % Agarose solution was prepared to a final volume of 50 ml using deionized H₂O and a stock solution of 0.1 % Agarose (dissolved by heating in deionized H₂O) and then stored at room temperature from 1 to 11 weeks prior to use. An 8 % trichloroacetic acid solution was prepared in 50 ml deionized H₂O. All reagents were stored away from light for up to 11 weeks. To prepare solutions with known sulfate levels, ranging from 0.05 to 2.0 mM, a stock 100 ml solution of 0.1 M K₂SO₄ (Sigma-Aldrich) was serially diluted in deionized H₂0. These standard solutions were used to generate a standard curve.