Determination of cyanide in blood by electrospray ionization tandem mass spectrometry after direct injection of dicyanogold

Fluorescent probes for the detection of chemical warfare agents

Chemical warfare agents (CWAs) are toxic chemicals that have been intentionally developed for targeted and deadly use on humans. Although intended for military targets, the use of CWAs more often than not results in mass civilian casualties. To prevent further atrocities from occurring during conflicts, a global ban was implemented through the chemical weapons convention, with the aim of eliminating the development, stockpiling, and use of CWAs. Unfortunately, because of their relatively low cost, ease of manufacture and effectiveness on mass populations, CWAs still exist in today's world. CWAs have been used in several recent terrorist-related incidents and conflicts (e.g., Syria). Therefore, they continue to remain serious threats to public health and safety and to global peace and stability. Analytical methods that can accurately detect CWAs are essential to global security measures and for forensic analysis. Small molecule fluorescent probes have emerged as attractive chemical tools for CWA detection, due to their simplicity, ease of use, excellent selectivity and high sensitivity, as well as their ability to be translated into handheld devices. This includes the ability to non-invasively image CWA distribution within living systems (in vitro and in vivo) to permit in-depth evaluation of their biological interactions and allow potential identification of therapeutic countermeasures. In this review, we provide an overview of the various reported fluorescent probes that have been designed for the detection of CWAs. The mechanism for CWA detection, change in optical output and application for each fluorescent probe are described in detail. The limitations and challenges of currently developed fluorescent probes are discussed providing insight into the future development of this research area. We hope the information provided in this review will give readers a clear understanding of how to design a fluorescent probe for the detection of a specific CWA. We anticipate that this will advance our security systems and provide new tools for environmental and toxicology monitoring.

Diagnosis of lethal cyanide poisoning. Analysis by Anion-Exchange Chromatography with Pulsed Amperometric Detection

Cyanide is a poison widely used in cases of suicide or homicide. Although various methods to identify and quantify this substance are reported in the literature, they are mainly validated on biological fluids (e.g., blood and urine). In the present study, the Anion‐Exchange Liquid Chromatography with Pulsed Amperometric Detection (IC‐PAD) method was validated on blood and, for the first time, on gastric content, and organs (brain, lung, and liver). For each matrix, linearity, accuracy, precision, limit of detection (LOD), lower limit of quantification (LLOQ), matrix interferences, and carryover were assessed. The samples were extracted by steam distillation in acid environment for the following analysis by IC‐PAD. Furthermore, cyanide values found in two real poisoning cases are reported. For each investigated matrix, the analytical method satisfied all acceptance criteria for validation: it showed a good precision and accuracy, selectivity, and sensitivity with no carryover and matrix interference. The extraction by steam distillation in acid environment REDUCED the interference of the matrices and ALLOWED to perform the analysis with good precision and accuracy. In case #1, analysis showed a blood cyanide concentration of 0.99 μg/ml. In case #2, cyanide concentrations were 1.3 μg/g in brain, 0.8 μg/g in lung, 1.6 μg/g in liver, and 1.2 μg/g in gastric content. The cyanide concentrations found in the two reported cases have been suitable to cause death by poisoning.

A novel method for cyanide quantification in human whole blood using ion chromatography with amperometric detection and its application to cyanide intoxication cases

Cyanide is a highly toxic agent that has been frequently used for suicide in South Korea. It is also used in various industrial fields, such as metal plating, in which many accidental cyanide intoxications have occurred. To overcome the disadvantages of conventional cyanide analysis methods, a simple and fast method for the analysis of cyanide in whole blood using ion chromatography (IC) with amperometric detection was developed in this study. Whole blood samples were deproteinized, diluted, and analyzed using an IC-amperometric detection system. The limits of detection and quantitation were 0.1 and 0.2 mg/L, respectively. The method showed good linearity in the range of 0.2 to 50 mg/L with R²  > 0.99. The intra- and inter-assay precision and accuracy values were <10%. The established method was successfully applied to analyze whole blood samples from three cyanide intoxication cases.

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.

HCN emission by a Polydesmid Millipede Detected Remotely by Reactive Adsorption on Gold Nanoparticles Followed by Laser Desorption/Ionization Mass Spectrometry (LDI-MS)

Hydrocyanic acid (HCN) is a well-known defensive allomone in the chemical arsenal of millipedes in the order Polydesmida. The presence of HCN in the headspace vapor of adult Xystocheir dissecta (Wood, 1867), a common millipede from the San Francisco Bay Area, was traced by laser desorption/ionization-mass spectrometry (LDI-MS). To accomplish this, the headspace vapor surrounding caged, live millipedes was allowed to diffuse passively over gold-nanoparticle (AuNP) deposits placed at various distances from the emitting source. The stainless steel plates with AuNP deposits were removed and irradiated by a 355-nm laser. The gaseous ions generated in this way were detected by time-of-flight mass spectrometry. The intensity of the mass spectrometric peak detected at m/z 249 for the Au(CN)₂^- complex anion was compared to that of the residual Au^- signal (m/z 197). Using this procedure, HCN vapors produced by the live millipedes could be detected up to 50 cm away from the source. Furthermore, the addition of H₂O₂, as an internal oxygen source for the gold cyanidation reaction that takes place in the AuNP deposits, significantly increased the detection sensitivity. Using the modified H₂O₂ addition procedure, HCN could now be detected at 80 cm from the source. Moreover, we found a decreasing intensity ratio of the Au(CN)₂^-/Au^- signals as the distance from the emitting source increased, following an exponential-decay distribution as predicted by Fick's law of diffusion. Graphical abstract.

Gold Nanoparticles (AuNPs) as Reactive Matrix for Detection of Trace Levels of HCN in Air by Laser Desorption/Ionization Mass Spectrometry (LDI-MS)

Under direct laser desorption/ionization mass spectrometric conditions, the irradiation of target spots made of gold nanoparticle residues generates a series of peaks at m/z 197, 394, 591… representing Au_n^- ions (n = 1-3). In contrast, spectra recorded from gold nanoparticles directly mixed with an alkali cyanide exhibited an additional peak at m/z 249, indicating an abundant generation of gaseous [Au(CN)₂]^- ions upon irradiation. The relative intensity of the m/z 249 peak surged when the amount of cyanide in the mixture was increased. Most remarkably, a peak at m/z 249 was observed even from neat AuNPs upon irradiation, if a nearby spot, which was not irradiated, happened to bear a cyanide sample. We postulated that traces of HCN emanating from the headspace of aqueous cyanide solution during the sample-plate preparation is sufficient to convert gold to AuCN, which is subsequently detected as [Au(CN)₂]^-. Further experiments demonstrated that the relative intensity of the m/z 249 peak diminishes exponentially as the AuNP spot becomes more distant from the putative HCN source. Eventually, the method was developed as an efficient procedure to detect HCN or alkali cyanides. Using KCN, the detection limits were determined to be below 10 pg of CN^- per spot. The method also demonstrated that, upon crushing, the seeds or roots of certain fruits and vegetables such as apple, peach, radish, and cassava, but not carrot, release HCN in amounts detectable by this method. Graphical Abstract.

Zeolite-like Metal-Organic Framework (MOF) Encaged Pt(II)-Porphyrin for Anion-Selective Sensing

The selectivity and sensitivity of sensors are of great interest to the materials chemistry community, and a lot of effort is now devoted to improving these characteristics. More specifically, the selective sensing of anions is one of the largest challenges impeding the sensing-research area due to their similar physical and chemical behaviors. In this work, platinum-metalated porphyrin (Pt(II)TMPyP) was successfully encapsulated in a rho-type zeolite-like metal-organic framework (rho-ZMOF) and applied for anion-selective sensing. The sensing activity and selectivity of the MOF-encaged Pt(II)TMPyP for various anions in aqueous and methanolic media were compared to that of the free (nonencapsulated) Pt(II)TMPyP. While the photoinduced triplet-state electron transfer of Pt(II)TMPyP showed a very low detection limit for anions with no selectivity, the Pt(II)TMPyP encapsulated in the rho-ZMOF framework possessed a unique chemical structure to overcome such limitations. This new approach has the potential for use in other complex sensing applications, including biosensors, which require ion selectivity.

A novel method for determination of inorganic oxyanions by electrospray ionization mass spectrometry using dehydration reactions

Novel methods for the determination of inorganic oxyanions by electrospray (ES) ionization mass spectrometry have been developed using dehydration reactions between oxyanions and carboxylic acids at the ES interface. Twelve oxyanions (VO3 (-) , CrO4 (2-) , MoO4 (2-) , WO4 (2-) , BO3 (3-) , SiO3 (2-) , SiO4 (4-) , AsO4 (4-) , AsO2 (-) , SeO4 (2-) , SeO3 (2-) and NO2 (-) ), out of 16 tested, reacted with at least one of four aminopolycarboxylic acids, i.e. iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid and triethylenetetramine-N,N,N',N″,N'″,N'″-hexaacetic acid, at the ES interface to produce the dehydration products that gave intense mass ion responses, sufficient for trace analysis. As examples, trace determinations of Cr(VI) and silica in water samples were achieved after online ion exchange chromatography, where the dehydration product of CrO4 (2-) and NTA (m/z 290) and that of SiO4 (4-) and IDA (m/z 192) were measured. The limits of detection of the respective methods were 17 nM (0.83 ng Cr/ml) for Cr(VI) and 0.17 μM (4.8 ng Si/mL) for SiO4 (4-) .

Cyanide toxicokinetics: the behavior of cyanide, thiocyanate and 2-amino-2-thiazoline-4-carboxylic acid in multiple animal models

Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN(-)) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250-300 g), (ii) rabbits (3.5-4.2 kg) and (iii) swine (47-54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and eliminated. Thiocyanate concentrations rose more slowly as cyanide was enzymatically converted to SCN(-). Concentrations of ATCA did not rise significantly above the baseline in the rat model, but rose quickly in rabbits (up to a 40-fold increase) and swine (up to a 3-fold increase) and then fell rapidly, generally following the relative behavior of cyanide. Rats were administered cyanide subcutaneously and the apparent half-life (t1/2) was determined to be 1,510 min. Rabbits were administered cyanide intravenously and the t1/2 was determined to be 177 min. Swine were administered cyanide intravenously and the t1/2 was determined to be 26.9 min. The SCN(-) t1/2 in rats was 3,010 min, but was not calculated in rabbits and swine because SCN(-) concentrations did not reach a maximum. The t1/2 of ATCA was 40.7 and 13.9 min in rabbits and swine, respectively, while it could not be determined in rats with confidence. The current study suggests that cyanide exposure may be verified shortly after exposure by determining significantly elevated cyanide and SCN(-) in each animal model and ATCA may be used when the ATCA detoxification pathway is significant.

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.

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.

Selective detection of iodide and cyanide anions using gold-nanoparticle-based fluorescent probes

We developed two simple, rapid, and cost-effective fluorescent nanosensors, both featuring bovine serum albumin labeled with fluorescein isothiocyanate (FITC))-capped gold nanoparticles (FITC-BSA-Au NPs), for the selective sensing of cyanide (CN(-)) and iodine (I(-)) ions in high-salinity solutions and edible salt samples. During the preparation of FITC-BSA-Au NP probes, when AuNPs were introduced to the mixture containing FITC and BSA, the unconjugated FITC and FITC-labeled BSA (FITC-BSA) adsorbed to the particles' surfaces. These probes operated on a basic principle that I(-) and CN(-) deposited on the surfaces of the Au NPs or the etching of Au NPs induced the release of FITC molecules or FITC-BSA into the solution, and thus restored the florescence of FITC. We employed FITC-BSA to protect the Au NPs from significant aggregation in high-salinity solutions. In the presence of masking agents such as S(2)O(8)(2-)/Pb(2+), FITC-BSA-Au NPs facilitated the selective detection of CN(-) (by at least 150-fold in comparison with other anions). We also demonstrated that the FITC-BSA-Au NPs in the presence of H(2)O(2) could selectively detect I(-) down to 50 nM. Taking advantages of their high stability and selectivity, we employed our FITC-BSA-Au NP-based probes for the detection of CN(-) and I(-) in water samples (pond water, tap water, and seawater) and detection of I(-) in edible salt samples, respectively. This simple, rapid, and cost-effective sensing system appears to demonstrate immense practical potential for the detection of anions in real samples.