Analysis of Steroids in Mixtures Using the Kinetics of Blue Tetrazolium Reduction

Guttman, David E.

doi:10.1002/jps.2600550910

Cited by 19 publications

(6 citation statements)

References 4 publications

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“…Singh and Verma reported a single absorbance peak at 780 nm using Prussian blue, while this study found two peaks, one at 300 nm and the other at 670 nm . Multiple studies report a peak at 525 nm for blue tetrazolium; however, our results show a peak at 510 nm. , The reason for both discrepancies is the difference in the solvent system . The blue tetrazolium method has the lowest LoD at 97 ng/mL.…”

Section: Results and Discussioncontrasting

confidence: 78%

“…Blue tetrazolium in conjunction with tetramethylammonium hydroxide yields a magenta solution. In this study, we used methanol as a primary solvent, while previous studies used either ethanol or dichloromethane. , The use of methanol decreased the reaction time (approximately 25% faster than ethanol) with no changes in sensitivity. Figure D,H shows that the peak absorption increases with respect to increasing concentrations of cortisol.…”

Section: Results and Discussionmentioning

confidence: 99%

“…18 Later on, reagents that used blue tetrazolium provided an even greater steroid assay, which lowered the reaction time to 10 min compared to the 90 min of Porter−Silber. 19,20 Singh and Verma recently reported another method using cortisol's reduction properties to form Prussian blue from iron(III) and hexacyanoferrate(III), which is comparable to past formulations in terms of sensitivity, precision, and speed. 21 monitoring and detection in sweat and saliva with disposable biosensors, colorimetric analysis has become a prime candidate for such tasks that use simple and easy analytical analysis.…”

Section: ■ Introductionmentioning

confidence: 92%

“…The Porter–Silber reagent has been improved upon throughout the years, which results in faster reaction rates and a more robust color. − Concurrent with the Porter–Silber reagent, Clark developed another corticosteroid specific reagent, which consists of dilute sulfuric acid and diphenylamine . Later on, reagents that used blue tetrazolium provided an even greater steroid assay, which lowered the reaction time to 10 min compared to the 90 min of Porter–Silber. , Singh and Verma recently reported another method using cortisol’s reduction properties to form Prussian blue from iron(III) and hexacyanoferrate(III), which is comparable to past formulations in terms of sensitivity, precision, and speed . With the rise of competitive protein binding immunoassay techniques, colorimetric reactions have been largely made obsolete, with little research published since the 1970s.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Colorimetric Analyses to Determine Cortisol in Human Sweat

Pearlmutter

Tiangco

et al. 2020

ACS Omega

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Colorimetric analysis, which relies on a chemical reaction to facilitate a change in visible color, is a great strategy for detecting cortisol, which is necessary to diagnose and manage the wide variety of diseases related to the hormone, because it is simple in design, inexpensive, and reliable as a standard cortisol analysis technique. In this study, four different colorimetric cortisol analyses that use various chromogens, which include sulfuric acid, Porter–Silber reagent, Prussian blue, and blue tetrazolium, are studied. Modifications to the classic Porter–Silber method are made by increasing the carbon content of the alcohol and adding gold nanoparticles, which result in a twofold increase in reaction rate and a slight decrease in the limit of detection (LoD). After a comparison of the reaction rate, LoD, dynamic range, characteristic peaks, and color stability of all methods, blue tetrazolium demonstrates a low LoD (97 ng/mL), broad dynamic range (0.05–2 μg/mL), and quick reaction rate (color development as fast as 10 min), which are well within the requirements for human biofluids. Cortisol in artificial saliva and sweat and in human sweat was determined while confirming that no excipients or other biomarkers interfered with the reactions. Twenty-one human sweat samples were tested using blue tetrazolium and revealed a significant difference between male and female apocrine cortisol concentrations and showed a highly significant difference between apocrine and eccrine cortisol concentrations. Colorimetric methods of cortisol can compete with existing electrochemical sensors because of their similar accuracy and detection range in certain wearable biosensor applications. The simplicity of colorimetric methods advances potential applications in skin-interfaced bio-electronics and point-of-care devices.

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Section: Results and Discussioncontrasting

confidence: 78%

Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Comparison of Colorimetric Analyses to Determine Cortisol in Human Sweat

Pearlmutter

Tiangco

et al. 2020

ACS Omega

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“…Certain kinetic aspects of the blue tetrazolium reaction were reported, e.g., the corticosteroid reaction is first order (17). Significant variations in the reaction rates of corticosteroids of closely related structures also were noted (1,9,14,15,18,19).…”

mentioning

confidence: 98%