Changing the properties of samples after extraction from wet soil: a short review

Laboratory-dried specimens yield distorted information about the state of hydromorphic soil. Changes in the gas medium, humidity, temperature, aggregation capacity and illumination have an irreversible impact on the dried and powdered soil specimen. Properties of the dried hydromorphic soil can be altered significantly. Most altered are (1) the colour of the hydromorphic soils, (2) the рН value, and (3) the content of mobile trace metal (TM) compounds after drying the wet soil. Colour change (browning) of the hydromorphic soil is related to the oxidation of Fe(II). In a highly ferruginous soil, the browning is rapid and visible even to the naked eye. In the weakly ferruginous gley, the colour change is invisible to the naked eye, but instrumental field measurements reveal a slow and slight yellowing of the dried gley. In dried soils, laboratory рН values determined in soil suspension differ from the values determined in soil solution at the same time. The process of drying provokes a significant decrease in the content of mobile TM compounds, resulting in the illusion of less soil contamination than the real situation during hydromorphic soil humidification. When studying hydromorphic soils, it is desirable to accomplish the maximum possible field measurements. Laboratory analyses should only be carried out for specimens stored under dark conditions since they retain the initial humidity, temperature and gas composition.

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Anion and pH dependent molecular motion by a halogen bonding [2]rotaxane

Chemical Communications ◽

10.1039/c9cc04752b ◽

2019 ◽

Vol 55 (67) ◽

pp. 9975-9978 ◽

Cited By ~ 7

Author(s):

Harry A. Klein ◽

Heike Kuhn ◽

Paul D. Beer

Keyword(s):

Molecular Motion ◽

Anion Recognition ◽

Colour Change ◽

Halogen Bonding ◽

Chloride Anion ◽

Naked Eye ◽

Ph Dependent

A halogen bonding [2]rotaxane undergoes macrocycle translocation only upon both protonation and chloride anion recognition, resulting in a naked-eye detectable colour change.

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Comparison of Visual and Instrumental Assessment of Colour Differences on Finished Wooden Surfaces

Drvna industrija ◽

10.5552/drvind.2020.1954 ◽

2020 ◽

Vol 71 (2) ◽

pp. 201-207

Author(s):

Matjaž Pavlič ◽

Marko Petrič

Keyword(s):

Colour Change ◽

Visual Assessment ◽

Surface Finishing ◽

Colour Difference ◽

Naked Eye ◽

Instrumental Assessment ◽

A Value ◽

Starting Point ◽

Measurement Results ◽

Transparent Coating

Staining of wood with various substances and processes is an important part of surface finishing of wood. Colour differences as a result of staining and of exposure of coloured wood during its utilisation are usually evaluated by instrumental measurements. However, the measurement results can show something else compared to what our naked eye can see. Due to inhomogeneity of wood, this discrepancy can be even greater in the case of finished surfaces. The aim of our research was to evaluate distinctions between visual perception and numerically determined colour differences on differently finished wooden surfaces, to get information at which starting point the colour difference becomes visible, and to establish whether it is related to the nature of the surface. We established that the visual assessment is influenced by many factors and that there is a correlation between visual and instrumental assessments. The colour difference ΔE* of 0.5 should be considered as a value when it starts to become visible, and at the value of 2.0, observers already considered the colour difference as a different colour. It was stated that we have some tolerance in perceiving the colour change. This tolerance is more expressed in the case of transparent coating systems.

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A new hydrazone-based colorimetric chemosensor for naked-eye detection of copper ion in aqueous medium

Journal of Chemical Research ◽

10.1177/1747519819867799 ◽

2019 ◽

Vol 43 (9-10) ◽

pp. 426-430

Author(s):

Shao-Min Shi ◽

Qiao Li ◽

Sheng-Li Hu

Keyword(s):

Metal Ions ◽

Copper Ion ◽

Colour Change ◽

Selective Recognition ◽

X Ray Diffraction ◽

Binding Properties ◽

X Ray ◽

Naked Eye ◽

Colorimetric Chemosensor ◽

Naked Eye Detection

A new hydrazone-based colorimetric Cu2+ chemosensor is synthesized. Its structure was confirmed by single-crystal X-ray diffraction. Its binding properties towards various metal ions are examined through absorption spectroscopy. In aqueous THF solution, the chemosensor exhibits selective recognition towards Cu2+ over other metal ions with a colour change from colourless to pink. The complex formed between the chemosensor and Cu2+ ions forms a 2:1 stoichiometry with an association constant of 2.46 × 108M−2. The analytical detection limit for Cu2+ by the naked eye is as low as 10.0 μM.

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Lateral Flow Immunoassay for Naked Eye Detection of Mycobacterium tuberculosis

Journal of Sensors ◽

10.1155/2020/1365983 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Nazifah Ariffin ◽

Nor Azah Yusof ◽

Jaafar Abdullah ◽

Siti Fatimah Abd Rahman ◽

Nurul Hanun Ahmad Raston ◽

...

Keyword(s):

Developing Countries ◽

Mycobacterium Tuberculosis ◽

Point Of Care ◽

Colour Change ◽

Lateral Flow ◽

Lateral Flow Immunoassay ◽

Optical Signals ◽

Naked Eye ◽

User Friendly ◽

And Control

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. Detection and control of infectious diseases is a major problem, especially in developing countries. Lateral flow immunoassay (LFIA) has been introduced as a handheld immunoassay-based point-of-care platform for an automated detection of TB. The CFP10-ESAT6 antigen of M. tuberculosis was used as the target in early detection of TB using LFIA strip-based POC strategy. An interesting platform based on optical signals is implemented as a colour change in the detection area that is visible to the naked eye. The gold nanoparticles (AuNPs) were used as the colour probe for the detection of a target of interest. The high-resolution transmission electron microscopy (HRTEM) image and ultraviolet-visible spectrophotometer (UV-Vis) analysis confirmed that the synthesized AuNPs were appropriate for the immunoassay designed. The platform consists of AuNPs conjugated with specific antibodies (Ab) to capture the antigen of M. tuberculosis. Under the capillary effect, sandwich immunoreactions of AuNP-Ab-antigen were performed on the test pad of the immunostrip, which can be observed by the colour signal on the test line of the strip with a short assay time. Furthermore, the newly developed biosensor was utilized in CFP10-ESAT6 antigen detection in human sputum specimens with satisfactory results. The characteristic coloured bands enable visual detection (naked eye) of target analyte without instrumentation. This noninvasive diagnose system which is sputum-based detection could provide user-friendly and affordable diagnostic tests in developing countries.

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Synthesis and Chiral Recognition Properties of a Novel Colorimetric Chiral Sensor for Carboxylic Anions

Australian Journal of Chemistry ◽

10.1071/ch08009 ◽

2008 ◽

Vol 61 (4) ◽

pp. 310 ◽

Cited By ~ 9

Author(s):

Zhi-Hong Chen ◽

Yong-Bing He ◽

Chen-Guang Hu ◽

Xiao-Huan Huang ◽

Ling Hu

Keyword(s):

Mass Spectrometry ◽

1H Nmr ◽

1H Nmr Spectroscopy ◽

Chiral Recognition ◽

Colour Change ◽

Colorimetric Sensor ◽

Naked Eye ◽

Vis Spectroscopy ◽

Carboxylic Anions ◽

Stoichiometric Complex

Chiral colorimetric sensor 4 has been synthesized, and the structure characterized by IR and 1H NMR spectroscopy, mass spectrometry, and elemental analysis. The chiral recognition of the receptor was studied by 1H NMR and UV-vis spectroscopy. The results of non-linear curve fitting indicate that the receptor 4 and l- or d-mandelate and alanine anions form a 1:1 stoichiometric complex. The obvious colour change of receptor 4 can be observed by the naked eye when the enantiomers of mandelate and alanine anions are added, which demonstrates that receptor 4 may be used as the colorimetric sensor for the two carboxylic anions.

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Synthesis and properties of new N,N′-phenyltetrazole podand

Chemical Papers ◽

10.1515/chempap-2015-0209 ◽

2016 ◽

Vol 70 (3) ◽

Author(s):

Agnieszka Pazik ◽

Beata Kamińska ◽

Anna Skwierawska ◽

Sandra Nakonieczna ◽

Tadeusz Ossowski

Keyword(s):

Colour Change ◽

Electrochemical Methods ◽

Naked Eye ◽

Vis Spectroscopy ◽

Eye Colour

AbstractThe synthesis of a new chromogenic N,N′-phenyltetrazole receptor is reported here. The cationbinding properties of this receptor in solution were investigated by naked-eye colour change, electrochemical methods and UV-Vis spectroscopy in various solvents (CH

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Ratiometric Probe for Rapid Naked Eye Detection of Toxic Hydrazine: Real Time Application in Strip Test, Spray Test and Soil Analysis

10.21203/rs.3.rs-758105/v1 ◽

2021 ◽

Author(s):

Natarajan Vijay ◽

Sivan Velmathi

Keyword(s):

Real Time ◽

Soil Analysis ◽

Colour Change ◽

High Sensitivity ◽

Water Soluble ◽

Paper Strip ◽

Naked Eye ◽

Strip Test ◽

Ratiometric Probe ◽

Real Time Application

Abstract Striking colorimetric probe (CynH) for abrupt detection of hydrazine under complete aqueous solution was achieved. The water soluble probe was designed with electron “push-pull” strategy by coupling of 4-hydroxy benzaldehyde and 2, 3, 3-trimethylindolinine. The positively charged N-propylated indolinine make the probe completely soluble in water. The probe yields eye catching selective detection of hydrazine over other competing analytes with high sensitivity. Obvious colour change was observed from colourless to appearance of bright pink colour with hydrazine. It reacts quickly with hydrazine within 2 minutes and makes the probe an effective candidate for practical application. The real time application was demonstrated using paper strip to detect hydrazine vapour. This probe is superior to earlier reported probes because of its effective sensing of hydrazine displayed with various applications including real-time strip based sensing, spray test and soil analysis. In all the examinations, the probe yields distinct response with rapid naked eye colour change this overcomes the drawbacks of previous reports.

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Azulene–boronate esters: colorimetric indicators for fluoride in drinking water

Chemical Communications ◽

10.1039/c7cc07416f ◽

2017 ◽

Vol 53 (93) ◽

pp. 12580-12583 ◽

Cited By ~ 37

Author(s):

Carlos M. López-Alled ◽

Adrian Sanchez-Fernandez ◽

Karen J. Edler ◽

Adam C. Sedgwick ◽

Steven D. Bull ◽

...

Keyword(s):

Drinking Water ◽

Colour Change ◽

Boronate Esters ◽

Boronate Ester ◽

Naked Eye

Sensitive and selective fluoride indicators consisting of a boronate ester receptor motif, conjugated to an azulene reporter motif, are described. These exhibit a colour change visible to the naked eye when exposed to fluoride.

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Chirality sensing and size recognition of N-Boc-amino acids by cage-type dimeric lanthanide complexes: chirality detection of N-Boc-aspartate anions via luminescence colour change

Chemical Communications ◽

10.1039/c4cc10384j ◽

2015 ◽

Vol 51 (18) ◽

pp. 3808-3811 ◽

Cited By ~ 24

Author(s):

Hiroshi Ito ◽

Satoshi Shinoda

Keyword(s):

Amino Acids ◽

Lanthanide Complexes ◽

Colour Change ◽

Naked Eye ◽

Eu Complexes

A mixture of chiral luminescent macrotricyclic-cyclen-Tb–Eu complexes enabled naked-eye discrimination of N-Boc-d- and l-aspartates via luminescence colour change.

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