Demonstration experiments using universal indicators

Foster, Laurence S.; Gruntfest, I. J.

doi:10.1021/ed014p274

Cited by 55 publications

(40 citation statements)

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“…A universal pH indicator was prepared using methyl red, methyl orange, phenolphthalein, and bromothymol blue powders with a weight ratio of approximately 1:3:7:8. 25 Saturated solutions of Congo red, erythrosin B, alizarin yellow R, crystal violet, eriochrome black T, phenolphthalein, universal indicator, and bromophenol blue were prepared by adding 1.0 g of the indicator to a formulation composed of 70.0-g acetate buffer (0.1 mM, pH 5), 8.0-g ethylene glycol, 5.0-g triethylene glycol monobutyl ether, and 16.0-g glycerol. The sensor solutions were heated (~50°), sonicated for 5 hours, and then vacuum filtered twice using Whatman #1 filter paper.…”

Section: Methodsmentioning

confidence: 99%

Comparative chemometric analysis for classification of acids and bases via a colorimetric sensor array

Kangas

Burks

Atwater

et al. 2017

Journal of Chemometrics

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With the increasing availability of digital imaging devices, colorimetric sensor arrays are rapidly becoming a simple, yet effective tool for the identification and quantification of various analytes. Colorimetric arrays utilize colorimetric data from many colorimetric sensors, with the multidimensional nature of the resulting data necessitating the use of chemometric analysis. Herein, an 8 sensor colorimetric array was used to analyze select acid and basic samples (0.5 - 10 M) to determine which chemometric methods are best suited for classification quantification of analytes within clusters. PCA, HCA, and LDA were used to visualize the data set. All three methods showed well-separated clusters for each of the acid or base analytes and moderate separation between analyte concentrations, indicating that the sensor array can be used to identify and quantify samples. Furthermore, PCA could be used to determine which sensors showed the most effective analyte identification. LDA, KNN, and HQI were used for identification of analyte and concentration. HQI and KNN could be used to correctly identify the analytes in all cases, while LDA correctly identified 95 of 96 analytes correctly. Additional studies demonstrated that controlling for solvent and image effects was unnecessary for all chemometric methods utilized in this study.

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Section: Methodsmentioning

confidence: 99%

Comparative chemometric analysis for classification of acids and bases via a colorimetric sensor array

Kangas

Burks

Atwater

et al. 2017

Journal of Chemometrics

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“…Gay-Lussac (Szabadváry and 4 Oesper1964; Crosland 1978). Two types of pH paper are commonly used: litmus paper and universal (alkacid) paper (Foster and Gruntfest 1937).…”

Section: Most Common Methods For Ph Testingmentioning

confidence: 99%

pH and CO2 Sensing by Curcumin-Coloured Cellophane Test Strip

2015

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2 pH and CO 2 sensing by curcumin coloured cellophane test strip ABSTRACTCurcumin coloured cellophane test strip -fabricated without any synthetic material -is used to determine in situ the instantaneous pH changes in liquids and in the air. A low cost, portable sensor array for possible medical and food-industrial application is developed. Next to the pH detection, curcumin coloured test strip can be applied as CO 2 monitoring sensor, too. On-going processes and the structural changes are followed by UV-VIS spectrophotometer, ATR-FTIR and AFM.

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“…The mixed pH indicator consisted of 5 mg of thymol blue, 12.5 mg of methyl red, 50 mg of bromothymol blue, 100 mg of phenolphthalein, and 100 ml of ethanol, dissolved in 100 milliliter of water 32) . This mixed pH indicator exhibited several smooth color changes over a pH value range of pH 4.0-9.0, as shown in Fig.…”

Section: ・2 Preparation Of the Mixed Ph Indicatormentioning

confidence: 99%