A disposable blood cyanide sensor

Coumarin Linked Cyanine Dye for the Selective Detection of Cyanide Ion in Environmental Water Sample

A benzoxazole-coumarin-based probe BOC, was synthesized and validated for its anion sensing ability and found to be effective in recognizing cyanide ions. Upon addition of cyanide, a spontaneous color change was observed that was visible to the naked eye. The sensitization process takes place with nucleophilic addition, and the cyanide ion added to the probe disrupts the intra molecular charge transfer transition (ICT) between the donor and acceptor units, causing the pink colored probe to become yellow. Ultraviolet and fluorescence methods were applied to measure the detection limits of probes with added cyanide ions, which were found to be 3.47 µM and 2.48 nM. The stoichiometry of the probe with the cyanide ion was determined by the Job's method, NMR titration, and mass spectrometry and was found to be in a 1:1 ratio. The results obtained from the visual and UV-visible spectral studies are justified by theoretical calculations. The cyanide-loaded probe induced visual changes, which enabled the development of a test strip for field application, and the prepared strip can be used to detect the ppm level of cyanide in water samples. The developed probe, BOC, can be used to detect cyanide ions in various water samples.

A Coumarin-Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide

In this study, we synthesized a coumarin-hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol-1·cm-1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN-). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN-) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN-). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN- over the concentration range of 1-9 μM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 μM. Using UV-Vis spectrophotometry, the linear detection range for CN- was found to be 1-27 μM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 μM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN- by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively.

Cyanine-based Fluorescent Probe for Cyanide Ion Detection

Cyanine-based probe-possessing indolium iodide and indole unit were synthesized in two-step with easy available raw material: a potential probe for the cyanide ion detection. The detecting ability of the probe was investigated and confirmed by a visual and instrumental approach. A noticeable color change from orange to colorless obtained only for cyanide ions and other added ions does not impart any changes visually and through UV and Fluorescence technique. To confirm the mechanism of sensing 1H-NMR recorded. From the result, the peak belonging to N-methyl displayed an upfield shift from 4.01 δ ppm to 2.74 δ ppm due to the disappearance of indolium iodide ion and the olefin protons peaks were shifted from 7.19 to 6.17 and 8.70 to 7.20 δ ppm confirms the nucleophilic addition of cyanide ion to the probe. Test kit from filter paper prepared for the real-time monitoring cyanide ion. The prepared strip is effective in detecting cyanide ion with a visual color change.

Determination of nitric oxide using light-emitting diode-based colorimeter with tubular porous polypropylene membrane cuvette

On the basis of the Griess-Saltzman (GS) reaction, an optical device for nitric oxide (NO) detection in exhaled breath and atmosphere was developed by employing the light-emitting diode (LED, 560 nm) as the light source, light-to-voltage converter (LVC) as the detector, and porous polypropylene membrane tube (PPMT) as the cuvette. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection and color reaction; two ends of the PPMT were connected with the LED and LVC to detect the change of light transmissivity in the wavelength range of 530 to 590 nm mainly. A gas absorber filled with GS reagents was installed prior to another absorber filled with KMnO₄ solution to eliminate the interference of coexisting NO₂. Under the optimized experimental conditions, the device achieved a limit of detection (3σ/k) of 4.4 ppbv for NO detection. The linearity range of this device was divided into two segments, i.e., 25 to 100 ppbv and 50 to 1000 ppbv, with both coefficients of determination > 0.99. The relative standard deviation was 2.7% (n = 9, c = 100 ppbv), and the analytical time was 5.5 min per detection. The minimum detectable quantity was decreased to 1.18 ng, which was ~ 100 times lower than the original GS method (115 ng). The present device was applied for determination of NO in exhaled breath, vehicle exhaust, and air. In addition to satisfactory spiking recoveries (i.e., 103% and 107%), the analytical results of the present device were in agreement with the results obtained by the standard method. These results assured the practicality of the developed device for NO detection in real environmental samples.

A new chemosensor for cyanide in blood based on the Pd complex of 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol

A new indirect chemosensor for the detection of cyanide in blood is developed. 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol, a yellow dye, forms a blue-coloured complex with palladium ions. The yellow colour of this complex is regained upon reaction with cyanide ions. The complex shows high selectivity for the detection of cyanide over 16 other anions. The system was applied to two different methods for the detection of cyanide in human whole blood. As a quantitative absorbance method, blood samples were mixed with acid, and the resulting vaporised hydrogen cyanide was absorbed in an alkaline solution containing the complex in a Conway cell. The resulting absorbance response of the solution at 450 nm is linear over the range 4-40 μM (R2 = 1.000), and the limit of detection is 0.6 μM. Furthermore, the complex-soaked paper is applicable as a test strip for cyanide detection. When a test strip is used with 0.5 mL of blood, the limit of detection is 15 μM. The detection limits of these two methods are below the toxic blood cyanide concentration (19 μM). Therefore, both methods allow the quantification and screening of cyanide in blood samples. Furthermore, the test strip is low cost and enables on-site analysis.

Origami paper analytical assay based on metal complex sensor for rapid determination of blood cyanide concentration in fire survivors

Cyanide-based blood poisoning can seriously damage fire victims and cause death if not detected quickly. Previous conventional methods require laboratory equipment, which are expensive and increase the duration of the analysis. Here, a simple origami based microfluidic device was introduced for point of need detection of blood cyanide concentration in people involved in fire. The device is made of four layers of paper. Each layer was in the size of 1 × 1 cm folded on each other. In this work, the blood sample was acidified by trichloroacetic acid to separate cyanide from methaemoglobin in the form of HCN gas. The produced gas released into borate buffer to recover free cyanide ions which interacted with the Pt complex ([Pt(p-MeC₆H₄)₂(phen)]) used as a receptor in this study. Optimized conditions were applied to have a suitable interaction causing the color of the receptor to change from yellow to colorless. The color changes were recorded by a smartphone, and the sensor response was calculated by the routine image analysis software. The assay was capable of determining cyanide ions at different concentrations in the range of 1.0 to 100.0 µmol L⁻¹. The detection limit of these determination was equal to 0.4 µmol L⁻¹. The assay responses were not affected by the interfering species. As a practical analysis, the proposed sensor was applied to determine cyanide ions in the blood sample of 20 studied fire survivors and 10 controls with high accuracy.

Assembling PVP-Au NPs as portable chip for sensitive detection of cyanide with surface-enhanced Raman spectroscopy

Cyanide (C≡N) can lead to blood, cardiovascular system, and nervous system disorders owing to the acute and chronic toxicity; thus, aiming at the group or individual poisoning incidents, it is necessary to develop the sensitive and credible method for rapid on-site detection of poisons cyanide. Surface-enhanced Raman spectroscopy (SERS) with the advantages of providing fingerprint information of target molecules and single-molecules sensitivity has been widely used in on-site analysis; however, the SERS measurements always suffer from the problem of the stability of substrates. Here, the polyvinylpyrrolidone (PVP)-stabilized Au NPs (PVP-Au NPs) have been assembled through the simple, convenient evaporation-induced strategy with the large-scale hotspots substrates. The presence of PVP can not only facilitate the assembly of Au NPs but also prevent the corrosion of CN^- towards the Au NPs with the formation of [Au (CN)₂]^-1, providing high stable and reproducible SERS signals. Moreover, the PVP-Au NPs have been assembled on the Si wafer to fabricate the portable SERS chip for rapid on-site detection of CN^- with an RSD of 5.8% and limitation of 100 ppb. Furthermore, by coupling a portable Raman spectrometer, the SERS spectra of CN^- spiked into different specimens to simulate the poison samples have been collected and analyzed on SERS chips with the recovery of 89-103% and RSD not higher than 11.3%. Consequently, the fabricated SERS chip with assembled PVP-Au NPs can provide sensitive and credible detection for CN^- in different specimens, and then would satisfy the rapid on-site evaluation of CN^- in poisoning incidents with the portable Raman spectrometer. Graphical Abstract.

Highly sensitive and straightforward methods for the detection of cyanide using profluorescent glutathionylcobalamin

The extreme toxicity of cyanide and its continued use in various industries have raised concerns over environmental contamination and, therefore, considerable attention has given to develop facile and sensitive methods of cyanide detection. In this study, we developed highly sensitive and straightforward methods of cyanide detection using eosin-labeled glutathionylcobalamin (E-GSCbl) containing fluorescent eosin-labeled glutathione (E-GSH) as the upper axial ligand to the cobalt. E-GSH fluorescence was strongly quenched in E-GSCbl. The E-GSH ligand of E-GSCbl was replaced specifically by cyanide, showing recovery of the E-GSH fluorescence. This profluorescent property of E-GSCbl enabled detection of cyanide in aqueous solutions, yielding a lower detection limit of 10 nM (0.26 μg L^-1). Moreover E-GSH exhibited strong luminescence under UV-light that was quenched in E-GSCbl, and this allowed naked-eye detection of cyanide at concentrations as low as 100 nM. This study demonstrates that profluorescent E-GSCbl is a highly sensitive cyanide chemosensor that can detect nanomolar concentrations of cyanide.

Attenuation Coefficients of Tubular Conduits for Liquid Phase Absorbance Measurement: Shot Noise Limited Optimum Path Length

We trace the history of liquid core waveguides (LCWs, also called liquid core optical fibers) and the role Teflon AF (TAF) has played in their development. We show that, in any shot noise limited situation, the optimum signal-to-noise ratio (S/N) occurs at a path length of 1/α_a{ln[1 + 2(α_a/α_b)]}, approximately 2/α_b under most conditions, α_a and α_b being the light attenuation coefficient due to the analyte and the background, respectively. The analysis shows that LCW length should be selected depending on the applicable α_b value. An overly long LCW may exhibit a lower signal-to-noise ratio. Water-filled TAF-clad fused-silica (FS) tubes show the lowest attenuation across the wavelength range. Nevertheless, except at λ ≥ 600 nm, the observed α_b values far exceed those reported for pure water: it appears that both impurities in the water and waveguide losses are involved. In examining the attenuation in various water-filled tubes, we find that the transmission of air-surrounded FS tubes is second only to TAF-clad FS tubes and is better than that of TAF tubes or externally mirrored FS tubes. Surprisingly, except for a window centered at ∼250 nm, light transmission in a water-filled poly(tetrafluoroethylene) (PTFE) tube is worse than in poly(ether ether ketone) (PEEK) tubing. Light transmission in PTFE tubes improves with increasing wall thickness.

An easy to make chemoreceptor for the selective ratiometric fluorescent detection of cyanide in aqueous solution and in food materials

A ratiometric fluorescent receptor selectively detects cyanide in aqueous solution and food materials via deprotonation of a phenolic hydroxyl group.

Rationally designed molecules for resurgence of cyanide mitigated cytochrome c oxidase activity

Cytochrome c oxidase (CcOX) containing binuclear heme a₃-Cu B centre (BNC) mechanises the process of electron transfer in the last phase of cellular respiration. The molecular modelling based structural analysis of CcOX - heme a₃-Cu B complex was performed and the disturbance to this complex under cyanide poisoning conditions was investigated. Taking into consideration the results of molecular docking studies, new chemical entities were developed for clipping cyanide from the enzyme and restoring its normal function. It was found that the molecules obtained by combining syringaldehyde, oxindole and chrysin moieties bearing propyl/butyl spacing groups occupy the BNC region and effectively remove cyanide bound to the enzyme. The binding constant of compound 2 with CN^- was 2.3 × 10⁵ M^-1 and its ED₅₀ for restoring the cyanide bound CcOX activity in 10 min was 16 µM. The compound interacted with CN^- over the pH range 5-10. The comparison of the loss of enzymatic activity in the presence of CN^- and resumption of enzymatic activity by compound 2 mediated removal of CN^- indicated the efficacy of the compound as antidote of cyanide.

Online High Temporal Resolution Measurement of Atmospheric Sulfate and Sulfur Trioxide with a Light Emitting Diode and Liquid Core Waveguide-Based Sensor

High temporal resolution components analysis is still a great challenge for the frontier of atmospheric aerosol research. Here, an online high time resolution method for monitoring soluble sulfate and sulfur trioxide in atmospheric aerosols was developed by integrating a membrane-based parallel plate denuder, a particle collector, and a liquid waveguide capillary cell into a flow injection analysis system. The BaCl₂ solution (containing HCl, glycerin, and ethanol) was enabled to quantitatively transform sulfate into a well-distributed BaSO₄ solution for turbidimetric detection. The time resolution for monitoring the soluble sulfate and sulfur trioxide was 15 h^-1. The limits of detection were 86 and 7.3 μg L^-1 ( S/ N = 3) with a 20 and 200 μL SO₄^2- solution injection, respectively. Both the interday and intraday precision values (relative standard deviation) were less than 6.0%. The analytical results of the certificated reference materials (GBW(E)08026 and GNM-M07117-2013) were identical to the certified values (no significant difference at a 95% confidence level). The validity and practicability of the developed device were also evaluated during a firecracker day and a routine day, obviously revealing the continuous variance in atmospheric sulfate and sulfur trioxide in both interday and intraday studies.

High Time-Resolution Optical Sensor for Monitoring Atmospheric Nitrogen Dioxide

High time-resolution monitoring of nitrogen dioxide (NO₂) is of great importance for studying the formation mechanism of aerosols and improving air quality. Based on the Griess-Saltzman (GS) reaction, a portable NO₂ optical sensor was developed by employing a porous polypropylene membrane tube (PPMT) integrated gas permeation collector and detector. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection. Its two ends were respectively fixed with a yellowish-green light-emitting diode and a photodiode for optic signal reception. NO₂ was automatically introduced through the collector by two air pumps cooperating with a homemade gas injector. Under the optimized conditions, the device presented good performance for monitoring NO₂, such as a limit of detection of 5.1 ppbv (parts per billion by volume), an intraday precision of 4.1% (RSD, relative standard deviation, n = 11, c = 100 ppbv), an interday precision of 5.7% (RSD, n = 2-3 per day for 5 days, c = 100 ppbv), an analysis time of 4.0 min, and a linearity range extended to 700 ppbv. The developed device was successfully applied to analyzing outdoor air with a comparable precision to that of the standard method of China. The high time-resolution characteristic that includes sampling 15 times per hour and a good stability for 10 days of urban air analysis had also been evaluated.

Two benzoyl coumarin amide fluorescence chemosensors for cyanide anions

Two new benzoyl coumarin amide derivatives with ortho hydroxyl benzoyl as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions in acetonitrile have also been examined. The influence of electron donating diethylamino group in coumarin ring and hydroxyl in benzoyl group on recognition properties was explored. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectral change and high sensitivity. The import of diethylamine group increases smartly the absorption ability and fluorescence intensity of the compound, which allows the recognition for cyanide anions can be observed by naked eyes. The in situ hydrogen nuclear magnetic resonance spectra combining photophysical properties change and job's plot data confirm that Michael addition between the chemosensors and cyanide anions occurs. Molecular conjugation is interrupted, which leads to fluorescence quenching. At the same time, there is a certain extent hydrogen bond reaction between cyanide and hydroxyl group in the compounds, which is beneficial to the recognition.

Structure–reactivity correlation in selective colorimetric detection of cyanide in solid, organic and aqueous phases using quinone based chemodosimeters

The five new colorimetric chemodosimeters sense cyanide selectively and sensitively in aqueous and organic media via a nucleophilic addition mechanism exhibiting quantitative structure–reactivity correlation.

A direct and rapid method to determine cyanide in urine by capillary electrophoresis

Cyanides are poisonous chemicals that widely exist in nature and industrial processes as well as accidental fires. Rapid and accurate determination of cyanide exposure would facilitate forensic investigation, medical diagnosis, and chronic cyanide monitoring. Here, a rapid and direct method was developed for the determination of cyanide ions in urinary samples. This technique was based on an integrated capillary electrophoresis system coupled with laser-induced fluorescence (LIF) detection. Cyanide ions were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) and a primary amine (glycine) for LIF detection. Three separate reagents, NDA, glycine, and cyanide sample, were mixed online, which secured uniform conditions between samples for cyanide derivatization and reduced the risk of precipitation formation of mixtures. Conditions were optimized; the derivatization was completed in 2-4min, and the separation was observed in 25s. The limit of detection (LOD) was 4.0nM at 3-fold signal-to-noise ratio for standard cyanide in buffer. The cyanide levels in urine samples from smokers and non-smokers were determined by using the method of standard addition, which demonstrated significant difference of cyanide levels in urinary samples from the two groups of people. The developed method was rapid and accurate, and is anticipated to be applicable to cyanide detection in waste water with appropriate modification.

Comment on "Rapid visual detection of blood cyanide" by C. Männel-Croisé and F. Zelder, Analytical Methods, 2012, 4, 2632

Cyanide poisoning from Inhaled HCN is all too common in victims of smoke inhalation in fires. While the toxic effects arise primarily from its inhibitory effects on cytochrome c oxidase, the majority of the cyanide binds to methemoglobin (metHb) in the blood. It can be considered as the detoxification mechanism: one of the antidotes used earlier was nitrite which primarily works by converting hemoglobin to metHb (normally present to the extent of ~1% of the total hemoglobin). Vitamin B12 (hydroxocobalamin) and related analogs have long been known to have high affinity for cyanide and has been used as antidotes - the binding of cyanide to many compounds in this general family also results in a significant change in color that can be used for analytical purposes. Männel Croisé and Zelder (Anal. Methods, 2012, 4, 2632) have advocated direct addition of a related compound to blood samples and isolating the colored measurand on a solid phase extraction cartridge. While they demonstrated attractive rapid measurement of cyanide in spiked blood samples, we believe that this is not a practically usable procedure regardless of the exact chromogenic reagent used. Cyanide bound to metHb dissociates too slowly for a 1 min reaction to work as suggested - we believe for reasons unknown (eg., metHb levels in their blood samples unusually low), cyanide added to their blood samples did not (have time to) bind to metHb and these samples may not resemble real situations where significant amount of the cyanide will be bound to metHb.

Benzoquinone–imidazole hybrids as selective colorimetric sensors for cyanide in aqueous, solid and gas phases

One of the five new receptors developed, which works via the formation of H-bonds, exhibited a striking visible colour change selectively with cyanide ion in solid, aqueous and gas phases.

A catalytic chemodosimetric approach for detection of nanomolar cyanide ions in water, blood serum and live cell imaging

The nano-molar detection of cyanide in live cell imaging and blood serum has been achieved through cyanide catalysed fluorescence enhancement with a TON between 70 and 360.

Ultra-sensitive determination of cyanide in surface water by gas chromatography-tandem mass spectrometry after derivatization with 2-(dimethylamino)ethanethiol

A gas chromatography-tandem mass spectrometric (GC-MS/MS) method has been established for the determination of cyanide in surface water. This method is based on the derivatization of cyanide with 2-(dimethylamino)ethanethiol in surface water. The following optimum reaction conditions were established: reagent dosage, 0.7 g L(-1) of 2-(dimethylamino)ethanethiol; pH 6; reaction carried out for 20 min at 60°C. The organic derivative was extracted with 3 mL of ethyl acetate, and then measured by using GC-MS/MS. Under the established conditions, the detection and quantification limits were 0.02 μg L(-1) and 0.07 μg L(-1) in 10-mL of surface water, respectively. The calibration curve had a linear relationship relationship with y=0.7140x+0.1997 and r(2)=0.9963 (for a working range of 0.07-10 μg L(-1)) and the accuracy was in a range of 98-102%; the precision of the assay was less than 7% in surface water. The common ions Cl(-), F(-), Br(-), NO3(-), SO4(2-), PO4(3-), K(+), Na(+), NH4(+), Ca(2+), Mg(2+), Ba(2+), Mn(4+), Mn(2+), Fe(3+), Fe(2+) and sea water did not interfere in cyanide detection, even when present in 1000-fold excess over the species. Cyanide was detected in a concentration range of 0.07-0.11 μg L(-1) in 6 of 10 surface water samples.

Light-emitting diodes for analytical chemistry

Light-emitting diodes (LEDs) are playing increasingly important roles in analytical chemistry, from the final analysis stage to photoreactors for analyte conversion to actual fabrication of and incorporation in microdevices for analytical use. The extremely fast turn-on/off rates of LEDs have made possible simple approaches to fluorescence lifetime measurement. Although they are increasingly being used as detectors, their wavelength selectivity as detectors has rarely been exploited. From their first proposed use for absorbance measurement in 1970, LEDs have been used in analytical chemistry in too many ways to make a comprehensive review possible. Hence, we critically review here the more recent literature on their use in optical detection and measurement systems. Cloudy as our crystal ball may be, we express our views on the future applications of LEDs in analytical chemistry: The horizon will certainly become wider as LEDs in the deep UV with sufficient intensity become available.

Development of a fluorescence-based sensor for rapid diagnosis of cyanide exposure

Although commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes in areas such as mining, electroplating, and synthetic fiber production. The "heavy" use of cyanide in these industries, along with its necessary transportation, increases the possibility of human exposure. Because the onset of cyanide toxicity is fast, a rapid, sensitive, and accurate method for the diagnosis of cyanide exposure is necessary. Therefore, a field sensor for the diagnosis of cyanide exposure was developed based on the reaction of naphthalene dialdehyde, taurine, and cyanide, yielding a fluorescent β-isoindole. An integrated cyanide capture "apparatus", consisting of sample and cyanide capture chambers, allowed rapid separation of cyanide from blood samples. Rabbit whole blood was added to the sample chamber, acidified, and the HCN gas evolved was actively transferred through a stainless steel channel to the capture chamber containing a basic solution of naphthalene dialdehyde (NDA) and taurine. The overall analysis time (including the addition of the sample) was <3 min, the linear range was 3.13-200 μM, and the limit of detection was 0.78 μM. None of the potential interferents investigated (NaHS, NH4OH, NaSCN, and human serum albumin) produced a signal that could be interpreted as a false positive or a false negative for cyanide exposure. Most importantly, the sensor was 100% accurate in diagnosing cyanide poisoning for acutely exposed rabbits.