Direct Titration of Sulfates

Abstract

suggested a direct titration method for sulfates with the use of tetrahydroxyquinone as an ized to the acid side of the phenolphthalein end point. Phosphate was found to be an interfering ion.It was the aim of this investigation to extend the sulfate range, which was found possible, and to find a diluent that could be used in place of ethyl or denatured alcohol, because of the difficulty of obtaining either the ethyl or the denatured alcohol in many plants, owing to certain government restrictions. Isopropyl alcohol was found to answer this purpose. Elimination of the phosphate ion is desirable and it was found that this ion could be eliminated up to 60 p. p. m. by changing the pH value of the titrating solution to about 4.0. ExperimentalThe indicator used throughout this study was manufactured in the Betz laboratory and considerable quantities of this material have been supplied to the field.Detailed directions are given below for a determination of sulfate by direct titration using THQ as the indicator.Materials and Reagents. Standard barium chloride solution, the strength varying from 1 cc. = 1 mg. of SOi to 1 cc. = 50 mg. of SOi, standardized gravimetrically. An indicator composed of disodium tetrahydroxyquinone ground with dried potassium chloride in a 1 to 300 ratio, and passing a 100-mesh screen.Ethyl alcohol or alcohol denatured by formula No. 30 or No. 3-A, or isopropyl alcohol. Phenolphthalein indicator and bromocresol green indicator (if phosphates are present). Sodium chloride crystals, c. p.

Determination of Sulfate by Conductometric Titration: An Undergraduate Laboratory Experiment

“…Unfortunately, a difficulty arises in finding a suitable way of detecting the end point of the titration. Numerous indicators have been tried, with varying success, including Alizarin Red S, Tetradroxyquinone, Thorin, and dimethylsulfonazo III. − Problems encountered include the necessity of including an organic solvent, such as methanol, to dissolve the indicator, the necessity of prior removal of interfering substances, cost, sensitivity, and toxicity. Other indicators exhibit similar limitations.…”

The application of the metal organic framework for ion removal in seawater

“…Seawater was centrifuged to separate any impurities before further analysis, then subjected to Mohr's method titration to quantify the anion Cl À . The anion sulfate was obtained using a direct titration with the indicator of THQ [28]. The analysis of cation Na + , K + , Mg 2+ , and Ca 2+ was carried on using atomic absorption spectroscopy (Shimadzu AA 6200) at wavelength 589.5 nm, 766.5 nm, 285.2 nm, and 422.7 nm, respectively.…”

Microdetermination of Sulfate Obtained from Combustion of Organic Compounds

“…Recent studies (6,(8)(9)(10)(11)18) on the use of tetrahydroxyquinone as an indicator in the direct titration of the sulfate ion led the authors to study its use in a micromethod for the direct titration of sulfur as sulfate, following burning of the sulfur-containing compound in oxygen in the regular manner. Sheen and Kahler (10) used 0.025 N barium chloride, but this is too high a concentration for microwork.…”