The use of ortho-tolidine as a colorimetric test for gold

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) can serve as biochemical markers of various pathologies like liver disfunction and poisonings by nerve agents. Ellman’s assay is the standard spectrophotometric method to measure cholinesterase activity in clinical laboratories. The authors present a new colorimetric test to assess AChE and BChE activity in biological samples using chromogenic reagents, treated 3D-printed measuring pads and a smartphone camera as a signal detector. Multiwell pads treated with reagent substrates 2,6-dichlorophenolindophenyl acetate, indoxylacetate, ethoxyresorufin and methoxyresorufin were prepared and tested for AChE and BChE. In the experiments, 3D-printed pads containing indoxylacetate as a chromogenic substrate were optimal for analytical purposes. The best results were achieved using the red (R) channel, where the limit of detection was 4.05 µkat/mL for BChE and 4.38 µkat/mL for AChE using a 40 µL sample and a 60 min assay. The major advantage of this method is its overall simplicity, as samples are applied directly without any specific treatment or added reagents. The assay was also validated to the standard Ellman’s assay using human plasma samples. In conclusion, this smartphone camera-based colorimetric assay appears to have practical applicability and to be a suitable method for point-of-care testing because it does not require specific manipulation, additional education of staff or use of sophisticated analytical instruments.

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New Colorimetric Test for Rapid Diagnosis of Streptococcal Pharyngitis: A Warning

PEDIATRICS ◽

10.1542/peds.86.3.457 ◽

1990 ◽

Vol 86 (3) ◽

pp. 457-459

Author(s):

Michael A. Gerber ◽

Richard R. Facklam ◽

Martin F. Randolph ◽

Kathleen K. DeMeo

Keyword(s):

Drug Administration ◽

Diagnostic Tests ◽

Streptococcal Pharyngitis ◽

Rapid Diagnosis ◽

Group A Streptococci ◽

Pharmacologic Agent ◽

The Past ◽

Colorimetric Test ◽

Group A ◽

Rapid Tests

During the last few years there has been a dramatic proliferation of rapid tests for the diagnosis of group A β-hemolytic streptococcal pharyngitis.1 It is important for physicians to realize that the Food and Drug Administration does not approve these diagnostic tests as it would approve a pharmacologic agent, but simply permits a manufacturer to sell the test. Consequently, unacceptably inaccurate rapid tests for group A streptococci have been marketed in the past and could potentially appear again at anytime. In 1986, we studied a new enzyme fluorescence procedure (Strep-A-Fluor, Bio-Spec Inc, Dublin, CA) for the rapid diagnosis of group A β-hemolytic streptococcal pharyngitis.2

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Identification of Cat (Felis catus) Blood Splatter on Cotton Fabric After Periods of Drying Using Leucomalachite Green and Takayama Reagent

Journal of Basic Medical Veterinary ◽

10.20473/jbmv.v10i1.28593 ◽

2021 ◽

Vol 10 (1) ◽

pp. 15

Author(s):

Vanessa Ann Charles ◽

Tita Damayanti Lestari ◽

Djoko Legowo ◽

Ismudiono Ismudiono ◽

Nove Hidajati ◽

...

Keyword(s):

Cotton Fabric ◽

Confirmatory Test ◽

Chemical Methods ◽

Violent Crimes ◽

Green Is ◽

Food Dye ◽

Colorimetric Test ◽

Leucomalachite Green ◽

A Chain ◽

Imagej Software

Blood-stain or blood splatter analysis when used properly can assist in establishing a chain of events linked to violent crimes (Bevel and Gardner, 2008). The methods used in detecting blood splatters in the field are chemical methods. Leucomalachite green is a colorimetric test which is used to test the presence of blood (Castro and Coyle, 2008). Takayama reagent is a confirmatory test for blood (Strassman, 1922). The aim of this research is to detect the blood splatter on cotton fabric after it has been dried for 1 day, 3 days and 5 days using Leucomalachite green and Takayama reagent. Cotton fabric was specifically chosen for this experiment with 3 different periods of drying. The unstained cotton fabric was cut into squares, and a blood sample was splattered on each piece. The fabrics splattered with blood were then dried for 1 day, 3 days and 5 days. The blood splatter was then tested using Leucomalachite green and Takayama reagent, and the results were noted afterwards. For the control, red food dye was dried for 1 day then tested with Leucomalachite green and Takayama reagent. The image results of the Leucomalachite green test are analyzed using ImageJ software 1.8.0_112 where the red, green and blue pixels are converted to grayscale. The image results of the Takayama test are graded based on the number and pattern of crystal. In conclusion, Leucomalachite green and Takayama reagent are able to detect cat blood splatter on the cotton fabric. Leucomalachite green produced a higher intensity/ darker colour as a result of an older sample, and the lower intensity/ lighter colour as a result of a fresher sample of the Leucomalachite green test. Takayama reagent produced a densely packed pattern of crystals as a result of an older sample, and the loosely packed pattern of crystals as a result of a fresher sample of the Takayama test.

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A Colorimetric Test for Vitamin K 1

Science ◽

10.1126/science.94.2447.497-b ◽

1941 ◽

Vol 94 (2447) ◽

pp. 497-498

Author(s):

Filadelfo Irreverre ◽

M. X. Sullivan

Keyword(s):

Vitamin K ◽

Colorimetric Test

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Viscous Fingering of Miscible Liquids in Porous and Swellable Media for Rapid Diagnostic Tests

Bioengineering ◽

10.3390/bioengineering5040094 ◽

2018 ◽

Vol 5 (4) ◽

pp. 94

Author(s):

Holly Clingan ◽

Devon Rusk ◽

Kathryn Smith ◽

Antonio Garcia

Keyword(s):

Saliva Sample ◽

Fluid Motion ◽

Test Strip ◽

Viscous Fingering ◽

Test Method ◽

Colorimetric Test ◽

Significant Movement ◽

Miscible Liquids ◽

Korteweg Stresses ◽

Kinetics Of

In lateral flow and colorimetric test strip diagnostics, the effects of capillary action and diffusion on speed and sensitivity have been well studied. However, another form of fluid motion can be generated due to stresses and instabilities generated in pores when two miscible liquids with different densities and viscosities come into contact. This study explored how a swellable test pad can be deployed for measuring urea in saliva by partially prefilling the pad with a miscible solution of greater viscosity and density. The resultant Korteweg stresses and viscous fingering patterns were analyzed using solutions with added food color through video analysis and image processing. Image analysis was simplified using the saturation channel after converting RGB image sequences to HSB. The kinetics of liquid mixing agreed with capillary displacement results for miscible liquids undergoing movement from Korteweg stresses. After capillary filling, there was significant movement of liquid due to these fluidic effects, which led to mixing of the saliva sample with an enzyme test solution. Owing to the simplicity and speed of this test method, urea can be analyzed with an electronic nose over a useful range for detecting salivary urea concentration for rapid and early detection of dehydration.

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Fabrication of a Malaria-Ab ELISA Bioassay Platform with Utilization of Syringe-Based and 3D Printed Assay Automation

Micromachines ◽

10.3390/mi9100502 ◽

2018 ◽

Vol 9 (10) ◽

pp. 502 ◽

Cited By ~ 2

Author(s):

Christopher Lim ◽

Yangchung Lee ◽

Lawrence Kulinsky

Keyword(s):

Fused Deposition Modeling ◽

Color Change ◽

Colorimetric Assay ◽

Smart Phone ◽

Automated System ◽

Fused Deposition ◽

Colorimetric Test ◽

Qualitative Detection ◽

Deposition Modeling ◽

Automated Platform

We report on the fabrication of a syringe-based platform for automation of a colorimetric malaria-Ab assay. We assembled this platform from inexpensive disposable plastic syringes, plastic tubing, easily-obtainable servomotors, and an Arduino microcontroller chip, which allowed for system automation. The automated system can also be fabricated using stereolithography (SLA) to print elastomeric reservoirs (used instead of syringes), while platform framework, including rack and gears, can be printed with fused deposition modeling (FDM). We report on the optimization of FDM and SLA print parameters, as well as post-production processes. A malaria-Ab colorimetric test was successfully run on the automated platform, with most of the assay reagents dispensed from syringes. Wash solution was dispensed from an SLA-printed elastomeric reservoir to demonstrate the feasibility of both syringe and elastomeric reservoir-based approaches. We tested the platform using a commercially available malaria-Ab colorimetric assay originally designed for spectroscopic plate readers. Unaided visual inspection of the assay solution color change was sufficient for qualitative detection of positive and negative samples. A smart phone application can also be used for quantitative measurement of the assay color change.

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Desing of optical chemosensors for detection of cyanide ions in water environments

Yugra State University Bulletin ◽

10.17816/byusu20190182-87 ◽

2019 ◽

Vol 15 (1) ◽

pp. 82-87

Author(s):

Alexandra Alexandrovna Kudrevatykh ◽

Lyubov Stepanovna Klimenko ◽

Timofey Petrovich Martyanov

Keyword(s):

Aqueous Medium ◽

Absorption Spectra ◽

Stability Constants ◽

Molecular Interactions ◽

Color Change ◽

Cyanide Ion ◽

Colorimetric Test ◽

Optical Chemosensors ◽

Aqueous Mixture ◽

The Stability

Molecular interactions with various anions in the form of tetrabutylammonium salts in DMSO and DMSO-aqueous mixture were studied spectrophotometrically. It turned out that the solutions of 1-hydroxy-2-acylaminoanthraquinones in DMSO, originally yellow, became dark purple with the addition of cyanide, fluoride, phosphate, and acetate ions. The addition of other salts did not cause changes in the absorption spectra. When switching to aqueous DMSO, a contrasting color change in the solution was observed only with the addition of the cyanide ion. The stability constants of the complexes and the metrological characteristics of the processes were determined. On the basis of 1hydroxy-2-benzoylaminoanthraquinone, colorimetric test strips were made and tested for the detection of CN-ions in an aqueous medium.

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Analysis of the Phylogenic Relationship of Citrus Species by Colorimetric Test for Barks

Engei Gakkai zasshi ◽

10.2503/jjshs.12.15 ◽

1941 ◽

Vol 12 (1) ◽

pp. 15-23

Author(s):

Miyawo NAKAMURA ◽

Kenkichi NAKAYAMA

Keyword(s):

Citrus Species ◽

Colorimetric Test ◽

Phylogenic Relationship ◽

Relationship Of

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Evaluation of CARBA PAcE, a novel rapid test for detection of carbapenemase-producing Enterobacterales

Journal of Medical Microbiology ◽

10.1099/jmm.0.001290 ◽

2020 ◽

Author(s):

Janko Sattler ◽

Anne Brunke ◽

Axel Hamprecht

Keyword(s):

False Negative ◽

Rapid Test ◽

Content Type ◽

Columbia Blood Agar ◽

Fast Detection ◽

The Poor ◽

Colorimetric Test ◽

Mueller Hinton ◽

Mueller Hinton Agar ◽

Moderate Sensitivity

Introduction. Carbapenemase-producing Enterobacterales (CPE) are an increasing threat to global health. Fast detection is crucial for patient management and outbreak control. Hypothesis/Gap statement. Recently, a new commercial colorimetric test, CARBA PAcE, was released that has not yet been scientifically evaluated. Aim. Our goals were to evaluate the performance of CARBA PAcE using a large variety of different CPE. Methodology. CARBA PAcE was challenged with 107 molecularly characterized CPE and 53 non-CPE controls. Isolates were grown on Mueller-Hinton agar (MHA); in the case of a false-negative result, isolates were additionally inoculated on Columbia blood agar (CBA) and CARBA PAcE was repeated. The test was performed according to the manufacturer’s protocol. Results. CARBA PAcE showed an overall sensitivity and specificity of 72 % [confidence interval (CI) 62–80 %] and 91 % (CI 79–97 %), respectively, when isolates were grown on MHA. With growth on CBA, detection improved (especially of metallo-β-lactamases), resulting in an extrapolated sensitivity of 89 % (CI 81–94 %) for all carbapenemases and 96 % (CI 89–99 %) for the four major carbapenemases (NDM, OXA-48-like, KPC, VIM). Conclusion. CARBA PAcE is a simple and very rapid test for the detection of CPE which performs well for the major carbapenemases when isolates are grown on CBA. Laboratories should be aware of the limitations of this assay, such as moderate sensitivity when isolates are grown on more challenging agars such as MHA and the poor detection of some rare carbapenemases (e.g. IMI, OXA-58).

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Use of "EP"(Peroxidase) allele in soybean varietal characterization

Journal of Seed Science ◽

10.1590/2317-1545v36n4996 ◽

2014 ◽

Vol 36 (4) ◽

pp. 465-470

Author(s):

Bárbara Panoff Valário ◽

Cláudio Cavariani ◽

José de Barros França-Neto ◽

Elisa Serra Negra Vieira ◽

Juliana Pereira Bravo ◽

...

Keyword(s):

Plant Production ◽

Pcr Analysis ◽

Agarose Gel Electrophoresis ◽

Conventional Pcr ◽

Chain Reaction ◽

Pcr Assay ◽

Molecular Biology Technique ◽

Soybean Cultivars ◽

Colorimetric Test

The aim of this work was to evaluate the use of the molecular biology technique of PCR (Polimerase Chain Reaction) in the characterization of soybean cultivars. The study was performed at the Department of Plant Production, Faculty of Agricultural Sciences/ UNESP and Institute of Bioscience, Botucatu-SP. Fourteen commercial soybean cultivars were used, of which six were selected as positive reaction to peroxidase (BRS 320, BRS 284, BRS 232, BRS 7860RR, BRSMG 760SRR, BRS295RR), four as negative reaction (BRS 326, BRS 8160RR, BRSMG 800A (NutriSoy), BRS Valiosa RR) and four as double reaction (BRSGO 8060, BRS 270RR, FTS Campo Mourão and BRS 239). Thus, the results attained by the traditional biochemical colorimetric test for the 14 cultivars were compared with the conventional PCR assay. For PCR analysis, DNA was extracted from whole seeds and the primers were tested, and subsequently PCR and agarose gel electrophoresis were performed. The combination of primers prx9 + prx10 confirmed the use of the PCR reaction to characterize soybean cultivars considered doubtful by conventional colorimetric text.

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