A simple colorimetric device for rapid detection of Hg(2+) in water

A 'turn-on' fluorescent colorimetric device for Hg(2+) sensing was built using a dual light-emitting diode system. Fluorescence generated from a rhodamine derivative (RHD), an indicator for Hg(2+) sensing, was combined with a background red light, and the complex light was captured by a commercial charge coupled device camera or by the naked eye.     

A simple AuNPs-based colorimetric aptasensor for chlorpyrifos detection

In this work, a simple gold nanoparticles(Au NPs) based colorimetric biosensor was developed for chlorpyrifos(Chl) detection using an aptamer as the capture probe. The Chl-aptamer with low dissociation constant(Kd) of 58.59 ± 6.08 nmol/L was selected by ss DNA library immobilized systematic evolution of ligands by enrichment(SELEX). In the absence of Chl, the Chl-aptamer acted as the stabilizer for Au NPs in salt solution. In the presence of Chl, the highly specific Chl-aptamer bound with Chl ta...     

A simple naphthalene-based colorimetric sensor selective for acetate

A new naphthalene based receptor (L) has been designed and synthesized which shows a remarkable color change from colorless to pink on selective binding with acetate. The anion recognition property of the receptor via hydrogen bonding interactions is monitored by UV-vis, fluorescence, and ¹H NMR titrations. It is observed that in each case, the receptor shows a specific selectivity toward the acetate ion over other interfering anions. Thus, a significant bathochromic shift in UV-vis spectrum with a sharp pink color in ‘naked-eye’ makes the receptor suitable for the detection of the acetate ion.     

A simple colorimetric assay for muramic acid and lactic acid

The Barker and Summerson method of assaying lactic acid colorimetrically is modified to provide a simple and fast method of measuring lactic acid and other compounds such as muramic acid and glyceraldehyde that will release acetaldehyde on incubation in hot sulfuric acid. The assay can be done with open tubes and no more complicated equipment than a spectrophotometer. A further modification allows a relatively specific determination of formaldehyde.     

一种简单的化学传感体系对草酸根的比色识别

制备了一种基于2,7-萘二酚衍生物的双核锌配合物Zn2L,在水溶液中(HEPES 0．01 mol·dm-3,pH=7．4)Zn2L与指示剂邻苯二酚紫(PV)构筑成一种比色化学传感体系(CE)。该化学传感体系对草酸根具有良好的选择性识别作用,向CE溶液中加入草酸根引起溶液颜色由蓝色变为黄色。除丙二酸根对草酸根的识别具有轻微干扰外,其他二元酸离子包括邻苯二甲酸根,间苯二甲酸根,对苯二甲酸根,丁二酸根,戊二酸根,己二酸根对草酸根的识别无明显干扰。     

A simple thiourea based colorimetric sensor for cyanide anion

A simple and easily synthesized colorimetric anion sensor, based on a thiourea moiety as a binding subunit on a 1,2-cyclohexane backbone and a p-nitrophenyl group as a signaling unit, has been synthesized in a one step procedure. The selective sensing of anions, particularly cyanide, has been investigated in DMSO by UV-vis titration, ¹H NMR titration techniques and through ‘naked eye’ observation experiments.     

Lab-on-nanoparticle as a multidimensional device for colorimetric discrimination of proteins

Microchimica Acta - We report on a method for sensitive detection and discrimination of multiple proteins. The peroxidase-like activity of gold nanoparticles (AuNPs) is employed to...     

Salicylaldehyde-indole-2-acylhydrazone: a simple,colorimetric and absorption ratiometric chemosensor for acetate ion

A simple anion receptor (i.e. salicylaldehyde-indole-2-acylhydrazone) was synthesised and its recognition properties were investigated by naked-eye observation, UV–vis titration spectra, ¹H NMR spectroscopy and DFT calculations. The obtained results indicated that this receptor could realise the selective colorimetric sensing and absorption ratiometric response towards AcO^?  in CH₃CN–DMSO medium, by virtue of threefold intermolecular hydrogen bonding interactions formed with phenolic OH, indole NH and amide NH.     

A simple colorimetric method for the determination of ammonia in seawater

A method is proposed for the determination of trace amounts of ammonia in seawater. After calcium and magnesium have been chelated with CDTA, the blue colour obtained with hypochlorite and thymol-acetone is measured at 630 nm. The sensitivity is 1.3 ng NH₄⁺-N/cm².     

A micropillar-integrated smart microfluidic device for specific capture and sorting of cells

An integrated smart microfluidic device consisting of nickel micropillars, microvalves, and microchannels was developed for specific capture and sorting of cells. A regular hexagonal array of nickel micropillars was integrated on the bottom of a microchannel by standard photolithography, which can generate strong induced magnetic field gradients under an external magnetic field to efficiently trap superparamagnetic beads (SPMBs) in a flowing stream, forming a bed with sufficient magnetic beads as a capture zone. Fluids could be manipulated by programmed controlling the integrated air-pressure-actuated microvalves, based on which in situ bio-functionalization of SPMBs trapped in the capture zone was realized by covalent attachment of specific proteins directly to their surface on the integrated microfluidic device. In this case, only small volumes of protein solutions (62.5 nL in the capture zone; 375 nL in total volume needed to fill the device from inlet A to the intersection of outlet channels F and G) can meet the need for protein! The newly designed microfluidic device reduced greatly chemical and biological reagent consumption and simplified drastically tedious manual handling. Based on the specific interaction between wheat germ agglutinin (WGA) and N-acetylglucosamine on the cell membrane, A549 cancer cells were effectively captured and sorted on the microfluidic device. Capture efficiency ranged from 62 to 74%. The integrated microfluidic device provides a reliable technique for cell sorting.     

A simple device for determinations using Landolt reactions

Summary A device has been described which permits several Landolt reactions to be initiated simultaneously. All solutions remain at the same temperature, and mixing is rapid. This device improves the precision and the convenience of determinations using Landolt reactions.

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Zusammenfassung Eine Anordnung zur gleichzeitigen Ingangsetzung mehrerer Landolt-Reaktionen wurde beschrieben. Alle Lösungen werden bei gleicher Temperatur gehalten und rasch gemischt. Dadurch wird die Genauigkeit von Analysen mit Hilfe von Landolt-Reaktionen verbessert.

     

A simple colorimetric FIA method for the determination of pyrite oxidation rates

A method for the rapid determination of the oxidation rate of naturally occurring pyrite (FeS₂) samples is presented. The progress of the oxidation reaction was followed by measurement of the concentration of total dissolved iron using flow injection analysis. Iron was determined using UV-vis detection after reaction with the colorimetric reagent 5-sulfosalicylic acid in the presence of ammonia. The calibration function was linear between 5 and 150 mg L⁻¹, and the detection limit was 0.46 mg L⁻¹. The relative standard deviation was typically less than 1% (n = 10) and the measurement frequency was 60/h. The method was used to quantify the oxidation rate of 10 ground and cleaned pyrite samples (53 μm < x < 106 μm) from various international locations that were subjected to accelerate oxidation in acidic hydrogen peroxide. Results of these experiments showed that there was almost an order of magnitude of difference in oxidation rates of the pyrite samples.     

A simple method for the colorimetric and spectrophotometric determination of ferric iron in a large concentration range

Summary A method is described for the colorimetric or spectrophotometric determination of ferric iron based upon the measurement of the colour produced by hydrochloric acid. Concentrations within the range of 3 · 10^–5 M to 1.6 M may be determined by changeing the wave-lengthappropriately. Though the method is of lower sensitivity than other ones it offers the advantage of being simple and less time consuming. The errors amount to 4% in spectrophotometry and to 10% in colorimetry. If interfering ions are present the transmittance may be determined at two or more wave-lengths and results are obtained by appropriate calculation.

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Zusammenfassung Zur colorimetrischen oder spektralphotometrischen Bestimmung von dreiwertigem Eisen wird die Färbung mit Salzsäure verwendet. Es lä\t sich ein Konzentrationsbereich von etwa 3 · 10^–5 bis 1,6 m erfassen, wenn man zur Messung jeweils die geeignete Wellenlänge benutzt. Wenn das Verfahren auch weniger empfindlich als andere Methoden ist, so bietet es doch den Vorteil des geringen Zeitbedarfs und der einfachen DurchfÜhrung. Die Fehler betragen bis zu 4% (spektralphotometrisch) bzw. 10% (colorimetrisch). Störungen durch andere Ionen können durch Messung bei zwei oder mehreren Wellenlängen und entsprechende Berechnung umgangen werden.

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Contribution No. 120 from the Laboratory of Physical Chemistry, Faculty of Science, University of Zagreb.