Determination of cyanide and thiocyanate in blood by gas chromatography and gas chromatography-mass spectrometry

Microextraction with smartphone detection of thiocyanate in saliva of tobacco smokers using paper-based analytical method

This study presents a novel, cost-effective approach involving spectrophotometric and smartphone paper-based (SPB) methods and a distinctive salting-out air-assisted dispersive microextraction procedure to quantify thiocyanate in saliva samples. The method relies on the inhibitory effect of thiocyanate on quinoneimine dye formation during the Emerson reaction with sodium hypochlorite. Spectrophotometry quantifies the extracted dye by monitoring quinoneimine color intensity reduction at 525 nm. In the SPB method, extracted dye is applied to a paper strip, a smartphone captures the colored paper, and an application analyzes red, green, and blue components. All analyte determination and extraction variables were explored. Both methods exhibit good linearity (10-100 μg/L) with a coefficient of determination of 0.9991 and a limit of detection of 7.5 μg/L for the spectrophotometric method, and a coefficient of determination of 0.9988 and a limit of detection of 8.8 μg/L for the SPB method. The calculated values for the enrichment factor and extraction recovery of the developed extraction methodology were 46% and 93%, respectively. The methods detect thiocyanate in saliva samples, producing results comparable to a validated method.

Spectral and theoretical analysis of derivatives of 1,2,3,3-tetramethyl-3H-indolium iodide (TMI), a highly selective derivatization reagent of cyanide, and their utility for the analysis of cyanide concentrations in beverages

We develop a specific derivatization gas chromatography-mass spectrometry (GC-MS) method for cyanide using 1,2,3,3-tetramethyl-3H-indium iodide as the derivatization reagent. The derivative compounds were synthesized and characterized using 1H nuclear magnetic resonance (NMR), 13C NMR, and Fourier transform infrared (FT-IR) spectroscopy. The high selectivity of this derivatization for cyanide is supported by calculations and activation energy comparisons. We applied this method to pure water, green tea, orange juice, coffee cafe au lait, and milk. Derivatization was performed by diluting 20 μL of sample solution with 0.1 M NaOH and adding 100 μL of saturated borax solution and 100 μL of 8 mM TMI solution, each drink was completed in 5 min at room temperature, and selected ion (m/z = 200) monitoring analysis was linear (R2 > 0.998) at 0.15 to 15 μM, with detection limits of 4-11 μM were shown. This method is expected to be widely used in forensic toxicology analysis and can be applied to beverages, which are forensically important field samples.

Quantification of 2-aminothiazoline-4-carboxylic acid as a reliable marker of cyanide exposure using chemical derivatization followed by liquid chromatography-tandem mass spectrometry

In this research, we have developed a novel and simple liquid chromatography coupled with electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for quantification of 2-aminothiazoline-4-carboxylic acid (ATCA), which is produced by the direct reaction of cyanide (CN) with endogenous cystine. In forensic science, detection of CN is important because CN is a poison that is often used for murder or suicide, in addition to being produced by the thermal decomposition of natural or synthetic materials. However, because CN disappears rapidly from body tissue, ATCA is thought to be a more reliable indicator of CN exposure. For the method reported herein, human blood samples (20 μL) were subjected to protein precipitation followed by derivatization with 4-bromoethyl-7-methoxycoumarin. Blood spiked with ATCA at concentrations ranging from 50 to 1500 ng/mL was used to prepare a calibration curve (lower limit of quantification; 50 ng/mL, lower limit of detection; 25 ng/mL). Our method uses chemical derivatization, so unlike previously reported methods, it does not require tedious pretreatment procedures, hydrophilic interaction liquid chromatography columns, or specialized equipment. In addition, our method allows for repeatable and accurate quantification of ATCA, with intra- and inter-assay coefficients of variation of below 5.0% and below 6.0%, respectively. We used the method to analyze ATCA in postmortem human blood samples, including samples from people who had intentionally ingested CN or were fire victims. Blood ATCA concentrations were higher among people who had ingested CN or were fire victims than among people in a control group (P < 0.0001). The data reported herein demonstrate that our LC/ESI-MS/MS method can be used to detect and quantify ATCA in postmortem blood samples and that CN exposure strongly affects ATCA concentration, providing a useful tool for detection of CN poisoning.

Determination of Cyanide in Blood for Forensic Toxicology Purposes-A Novel Nci Gc-Ms/Ms Technique

One of the recently evolving methods for cyanide determination in body fluids is GC-MS, following extractive alkylation with pentafluorobenzyl bromide or pentafluorobenzyl p-toluenesulfonate. The aim of this study was to improve previous GC methods by utilizing a triple quadrupole mass spectrometer, which could enhance selectivity and sensitivity allowing for the reliable confirmation of cyanide exposure in toxicological studies. Another purpose of this study was to facilitate a case investigation including a determination of cyanide in blood and to use the obtained data to confirm the ingestion of a substance, found together with a human corpse at the forensic scene. The blood samples were prepared following extractive alkylation with a phase transfer catalyst tetrabutylammonium sulfate and the PFB-Br derivatization agent. Optimal parameters for detection, including ionization type and multiple reaction monitoring (MRM) transitions had been investigated and then selected. The validation parameters for the above method were as follows-linear regression R2 = 0.9997 in the range of 0.1 µg/mL to 10 µg/mL; LOD = 24 ng/mL; LOQ = 80 ng/mL and an average recovery of extraction of 98%. Our study demonstrates the first attempt of cyanide determination in blood with gas chromatography-tandem mass spectrometry. The established method could be applied in forensic studies due to MS/MS confirmation of organic cyanide derivative and low matrix interferences owning to utilizing negative chemical ionization.

A fatal poisoning case of acetone cyanohydrin and citalopram

Acetone cyanohydrin (ACH) is a readily available source of cyanide and is widely used in basic and applied sciences. In toxicology, ACH is classified as extremely hazardous as it readily decomposes on contact with water, with the potential rapid release of highly toxic hydrogen cyanide (HCN). We report the case of a young woman found dead from the intentional ingestion of ACH and citalopram, an antidepressant of the selective serotonin reuptake inhibitor class. The autopsy findings included bright reddish-purple hypostasis and mild pulmonary edema. As ACH can decompose to acetone and HCN, we quantified the concentration of each compound and thiocyanate separately in various body fluids and organs and determined their whole-body distributions by using gas chromatography-mass spectrometry (GC-MS). We observed high concentrations of both acetone and cyanide in the blood (0.63 mg/mL and 17.99 mM, respectively) and gastric contents (9.76 mg/mL and 472.44 mM). The whole-body distributions of acetone and cyanide were similar (i.e., the concentration of each compound was the highest in the lung, followed by the heart, and then the liver). Our results suggest that not only the route of administration but also the dose taken could greatly affect the body distributions of cyanide in humans. In addition, as toxicological screening detected citalopram, which was not prescribed to the deceased, we performed a chiral analysis by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We determined that only (S)-citalopram was ingested antemortem; its concentration was 0.36 μg/mL, which is in the toxic range.

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.

A Screening Method for Cyanide in Blood by Dimethoxytriazinyl Derivatization-GC/MS

A simple screening analysis of cyanide in blood has been developed, using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM). DMTMM, a convenient reagent for dehydrocondensation, converted cyanide to 2-cyano-4,6-dimethoxy-1,3,5-triazine, the dimethoxytriazinyl derivative of cyanide. This reaction proceeded in whole blood samples after treatment with trichloroacetic acid, and in basic aqueous solution samples. Sufficient sensitivity was observed by the method using gas chromatography/mass spectrometry. Intra- and inter-day repeated analyses (0.05, 0.1, 0.25, 1 and 5 μg/mL, n = 5) were performed and the accuracy and precision were within 20% for the lower limit of quantification (LLOQ) and within 15% for other concentrations. LLOQs for the aqueous solution and blood were 0.05 and 0.1 μg/mL, respectively, which are suitable for detecting cyanide poisoning. The limits of detection (signal-to-noise ratio ≥ 3) for aqueous solution and blood were 0.01 and 0.05 μg/mL, respectively. Interference from 13 other anions was tested and no false positive response was obtained, even in the case of thiocyanate, nitrite and nitrate, which are known to yield cyanide by acid treatment of blood. This method is practical because it uses readily available reagents and equipment and is sensitive enough for the rapid screening of cyanide poisoning in forensic and clinical toxicology.

Identification of thiocyanates by Gas Chromatography - Mass Spectrometry in explosive residues used as a possible marker to indicate black powder usage

Black Powder (BP) is one of the most common improvised explosives, due to broad access in precursors and simple home-made preparation. Deflagration of black powder results in residues the chemical analysis of which presents limitations and has been performed with several techniques until today; nevertheless, Gas Chromatography-Mass Spectrometry (GC-MS) has never been used. In this study, a simple experimental protocol has been developed towards black powder residues identification, using GC-MS. The sample preparation does not require specialized equipment. Derivatization of thiocyanates coming from BP deflagration and identification of the relative derivative (PBF-SCN) was achieved by monitoring ions m/z 239, 181 and 161. This characteristic derivative was used as a marker to indicate BP usage. The protocol was optimized by investigating individually all experimental parameters and it was evaluated for false positives and negatives. Repeatability and limit of detection were calculated to be %RSD 7.67 and < 1 mg, respectively. No interference coming from other ingredients that might co-exist in BP residues was observed. This protocol may be applied directly and without previous preparation to evidence coming from cases of explosions, thus practically contributing in BP residues identification.

Development of an Analytical Protocol for Determination of Cyanide in Human Biological Samples Based on Application of Ion Chromatography with Pulsed Amperometric Detection

A simple and accurate ion chromatography (IC) method with pulsed amperometric detection (PAD) was proposed for the determination of cyanide ion in urine, sweat, and saliva samples. The sample pretreatment relies on alkaline digestion and application of Dionex OnGuard II H cartridge. Under the optimized conditions, the method showed good linearity in the range of 1-100 μg/L for urine, 5-100 μg/L for saliva, and 3-100 μg/L for sweat samples with determination coefficients (R) > 0.992. Low detection limits (LODs) in the range of 1.8 μg/L, 5.1 μg/L, and 5.8 μg/L for urine, saliva, and sweat samples, respectively, and good repeatability (CV < 3%, n = 3) were obtained. The proposed method has been successfully applied to the analysis of human biological samples.

Cyanides in the environment-analysis-problems and challenges

Cyanide toxicity and their environmental impact are well known. Nevertheless, they are still used in the mining, galvanic and chemical industries. As a result of industrial activities, cyanides are released in various forms to all elements of the environment. In a natural environment, cyanide exists as cyanogenic glycosides in plants seeds. Too much consumption can cause unpleasant side effects. However, environmental tobacco smoke (ETS) is the most common source of cyanide. Live organisms have the ability to convert cyanide into less toxic compounds excreted with physiological fluids. The aim of this paper is to review the current state of knowledge on the behaviour of cyanide in the environment and its impact on the health and human life.

Pentafluorobenzyl bromide-A versatile derivatization agent in chromatography and mass spectrometry: I. Analysis of inorganic anions and organophosphates

Pentafluorobenzyl bromide (PFB-Br) is a versatile derivatization agent. It is widely used in chromatography and mass spectrometry since several decades. The bromide atom is largely the single leaving group of PFB-Br. It is substituted by wide a spectrum of nucleophiles in aqueous and non-aqueous systems to form electrically neutral, in most organic solvents soluble, generally thermally stable, volatile, strongly electron-capturing and ultraviolet light-absorbing derivatives. Because of these greatly favoured physicochemical properties, PFB-Br emerged an ideal derivatization agent for highly sensitive analysis of endogenous and exogenous substances including various inorganic and organic anions by electron capture detection or after electron-capture negative-ion chemical ionization in GC-MS. The present article attempts an appraisal of the utility of PFB-Br in analytical chemistry. It reviews and discusses papers dealing with the use of PFB-Br as the derivatization reagent in the qualitative and quantitative analysis of endogenous and exogenous inorganic anions in various biological samples, notably plasma, urine and saliva. These analytes include nitrite, nitrate, cyanide and dialkyl organophosphates. Special emphasis is given to mass spectrometry-based approaches and stable-isotope dilution techniques.

LC-MS/MS analysis of 2-aminothiazoline-4-carboxylic acid as a forensic biomarker for cyanide poisoning

AIM

To demonstrate the potential of using 2-aminothiazoline-4-carboxylic acid (ATCA) as a novel biomarker/forensic biomarker for cyanide poisoning.

METHODS

A sensitive method was developed and employed for the identification and quantification of ATCA in biological samples, where the sample extraction and clean up were achieved by solid phase extraction (SPE). After optimization of SPE procedures, ATCA was analyzed by high performance liquid chromatography-tandem mass spectrometry. ATCA levels following the administration of different doses of potassium cyanide (KCN) to mice were measured and compared to endogenous ATCA levels in order to study the significance of using ATCA as a biomarker for cyanide poisoning.

RESULTS

A custom made analytical method was established for a new (mice) model when animals were exposed to increasing KCN doses. The application of this method provided important new information on ATCA as a potential cyanide biomarker. ATCA concentration in mice plasma samples were increased from 189 ± 28 ng/mL (n = 3) to 413 ± 66 ng/mL (n = 3) following a 10 mg/kg body weight dose of KCN introduced subcutaneously. The sensitivity of this analytical method proved to be a tool for measuring endogenous level of ATCA in mice organs as follows: 1.2 ± 0.1 μg/g for kidney samples, 1.6 ± 0.1 μg/g for brain samples, 1.8 ± 0.2 μg/g for lung samples, 2.9 ± 0.1 μg/g for heart samples, and 3.6 ± 0.9 μg/g for liver samples.

CONCLUSION

This finding suggests that ATCA has the potential to serve as a plasma biomarker / forensic biomarker for cyanide poisoning.

LC-MS/MS analysis of 2-aminothiazoline-4-carboxylic acid as a forensic biomarker for cyanide poisoning

AIM: To demonstrate the potential of using 2-aminothiazoline-4-carboxylic acid (ATCA) as a novel biomarker/forensic biomarker for cyanide poisoning.

METHODS: A sensitive method was developed and employed for the identification and quantification of ATCA in biological samples, where the sample extraction and clean up were achieved by solid phase extraction (SPE). After optimization of SPE procedures, ATCA was analyzed by high performance liquid chromatography-tandem mass spectrometry. ATCA levels following the administration of different doses of potassium cyanide (KCN) to mice were measured and compared to endogenous ATCA levels in order to study the significance of using ATCA as a biomarker for cyanide poisoning.

RESULTS: A custom made analytical method was established for a new (mice) model when animals were exposed to increasing KCN doses. The application of this method provided important new information on ATCA as a potential cyanide biomarker. ATCA concentration in mice plasma samples were increased from 189 ± 28 ng/mL (n = 3) to 413 ± 66 ng/mL (n = 3) following a 10 mg/kg body weight dose of KCN introduced subcutaneously. The sensitivity of this analytical method proved to be a tool for measuring endogenous level of ATCA in mice organs as follows: 1.2 ± 0.1 μg/g for kidney samples, 1.6 ± 0.1 μg/g for brain samples, 1.8 ± 0.2 μg/g for lung samples, 2.9 ± 0.1 μg/g for heart samples, and 3.6 ± 0.9 μg/g for liver samples.

CONCLUSION: This finding suggests that ATCA has the potential to serve as a plasma biomarker / forensic biomarker for cyanide poisoning.

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 µg L(-1), a linear range from 4 to 400 µg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.

New facile method to measure cyanide in blood

Cyanide, a well-known toxic substance that could be used as a weapon of mass destruction, is likely responsible for a substantial percentage of smoke inhalation deaths. The vitamin B(12) precursor cobinamide binds cyanide with high affinity, changing color and, correspondingly, its spectrophotometric spectrum in the ultraviolet/visible light range. Based on these spectral changes, we developed a new facile method to measure cyanide in blood using cobinamide. The limit of detection was 0.25 nmol, while the limit of quantitation was approximately 0.5 nmol. The method was reliable, requires minimal equipment, and correlated well with a previously established method. Moreover, we adapted it for rapid qualitative assessment of cyanide concentration, which could be used in the field to identify cyanide-poisoned subjects for immediate treatment.

Determination of iodide in urine using electrospray ionization tandem mass spectrometry

A rapid and sensitive electrospray ionization (ESI) tandem mass spectrometry (MS-MS) procedure was developed for the determination of iodide (I(-)). A gold (Au) and I(-) complex was formed immediately after the addition of the chelating agent NaAuCl(4) to I(-) solution, and was extracted with methyl isobutyl ketone. One to five microliters of the extract were injected directly into an ESI-MS-MS instrument. I(-) quantification was performed by selecting reaction monitoring of the product ion I(-) at m/z 127 derived from the precursor ion (197)AuI(2)(-) at m/z 451. I(-) concentration was measured in the quantification range from 10(-7) to 10(-5) M using 50 microL of solution within 10 min. Iodate was reduced to I(-) with ascorbic acid and determined. I(-) concentration in reference urine 2670a was measured after treatments.

Kinetic spectrophotometric method for trace determination of thiocyanate based on its inhibitory effect

A kinetic spectrophotometric method for the determination of thiocyanate, based on its inhibitory effect on silver(I) catalyzed substitution of cyanide ion, by phenylhydrazine in hexacyanoferrate(II) is described. Thiocyanate ions form strong complexes with silver(I) catalyst which is used as the basis for its determination at trace level. The progress of reaction was monitored, spectrophotometrically, at 488 nm (lambda(max) of [Fe(CN)(5)PhNHNH(2)](3-), complex) under the optimum reaction conditions at: 2.5x10(-3)M [Fe(CN)(6)](4-), 1.0x10(-3)M [PhNHNH(2)], 8.0x10(-7)M [Ag(+)], pH 2.8+/-0.02, ionic strength (mu) 0.02 M (KNO(3)) and temperature 30+/-0.1 degrees C. A linear relationship obtained between absorbance (measured at 488 nm at different times) and inhibitor concentration, under specified conditions, has been used for the determination of [thiocyanate] in the range of 0.8-8.0x10(-8)M with a detection limit of 2x10(-9)M. The standard deviation and percentage error have been calculated and reported with each datum. A most plausible mechanistic scheme has been proposed for the reaction. The values of equilibrium constants for complex formation between catalyst-inhibitor (K(CI)), catalyst-substrate (K(s)) and Michaelis-Menten constant (K(m)) have been computed from the kinetic data. The influence of possible interference by major cations and anions on the determination of thiocyanate and their limits has been investigated.

Determination of cyanide exposure by gas chromatography-mass spectrometry analysis of cyanide-exposed plasma proteins

Exposure to cyanide can occur in a variety of ways, including exposure to smoke from cigarettes or fires, accidental exposure during industrial processes, and exposure from the use of cyanide as a poison or chemical warfare agent. Confirmation of cyanide exposure is difficult because, in vivo, cyanide quickly breaks down by a number of pathways, including the formation of both free and protein-bound thiocyanate. A simple method was developed to confirm cyanide exposure by extraction of protein-bound thiocyanate moieties from cyanide-exposed plasma proteins. Thiocyanate was successfully extracted and subsequently derivatized with pentafluorobenzyl bromide for GC-MS analysis. Thiocyanate levels as low as 2.5 ng mL(-1) and cyanide exposure levels as low as 175 μg kg(-1) were detected. Samples analyzed from smokers and non-smokers using this method showed significantly different levels of protein-bound thiocyanate (p<0.01). These results demonstrate the potential of this method to positively confirm chronic cyanide exposure through the analysis of protein-bound cyanide in human plasma.

Determination of trace amounts of thiocyanate by a new kinetic procedure based on an induction period

A new, simple and sensitive kinetic spectrophotometric method with no need for removing of interfering substances is proposed for the determination of thiocyanate ion in biological and water samples. The procedure is based on the inhibiting effect of thiocyanate on the sodium periodate-potassium bromide-meta cresol purple (MCP) system in acidic media. The induction period of the reaction is proportional to the SCN- concentration. The decolorization of meta cresol purple by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. Under optimum conditions, thiocyanate can be determined in the range of 0.02-0.8 microg ml(-1) with a 3sigma detection limit of 5 ng ml(-1). The relative standard deviations for 10 replicate determinations of 0.060, 0.10 and 0.50 microg ml(-1) thiocyanate are 3.7, 2.4 and 1.0%, respectively. This method has been successfully used to the determination of thiocyanate content in smokers and non-smokers saliva and spiked water sample.