Headspace sorptive solid phase microextraction (HS-SPME) combined with a spectrophotometry system: A simple glass devise for extraction and simultaneous determination of cyanide and thiocyanate in environmental and biological samples

Miniaturized dual-wavelength β-correction spectrophotometric probe for sensitive detection of cyanide in water via formation of cyano dithizone adduct

Cyanide toxicity in water significantly threatens public health and the environment. To address this, a miniaturized simple, low-cost, selective and sensitive direct dual wave β-correction spectrophotometric probe has been established for cyanide detection in water. The dual-wavelength β-correction spectrophotometry enhances the selectivity and sensitivity of the probe in the presence of interfering species. The assay relies a highly selective nucleophilic addition of cyanide ions to dithizone (H2Dz) as chromogenic reagent in aqueous media of pH 6.8-7.2, forming a red-colored cyano H2Dz adduct. The electronic spectrum of the formed adduct displays a sharp absorption peak at λmax = 480 nm, enabling precise colorimetric detection. The molar absorptivity and Sandell's sensitivity index for the cyano H2Dz adduct with and without β-correction spectrophotometry were 5.62 × 103, and 1.79 × 103 L mol-1 cm-1, and 0.002 and 0.0033 µg cm-2, respectively. Beer's law and Ringbom's plots are valid in the range 0.01-5.0 and 0.06-2.0 µg mL-1 CN- concentration, respectively. The limits of detection (LOD) and quantification (LOQ) improved from 1.03 × 10-1 and 3.13 × 10-1 μg/mL using ordinary spectrophotometry to 2.8 × 10-2 and 8.7 × 10-2 μg mL-1 employing β-correction spectrophotometry. The probe offers rapid response, good anti-interference ability, reproducibility, and cost-effectiveness. The probe was successfully applied for detection of trace levels of cyanide ions in water with good repeatability. It has been also validated in water samples with good recoveries (99.2 ± 5.02 %). The experimental Student t test (texp = 1.2-1.5) was lower than the critical (texp = 2.78) at 95 % probability (n = 5). The stoichiometry and mechanism of formation of the cyano adduct were assigned and addressed.

Qualitative and quantitative nondestructive determination of cyanide in water and distilled spirits by Raman integrating sphere

Cyanide often forms as a byproduct during the fermentation process of distilled spirits, and excessive amounts can cause damage to health. Cyanide poisoning is also common in alcoholic beverages and water. Therefore, the cyanide content measurement in water and distilled spirits is essential. Here, a Raman integrating sphere technique for the in situ detection of cyanide has been established, and a lower limit of detection of 1.56 mg L-1 in water and ethanol was achieved, owing to the efficient collection of Raman signals and the efficient use of laser power. The Raman peak of cyanide is located at 2080 cm-1. The detection range was from 1.56 to 25 mg L-1 cyanide in water, ethanol, and liquor with high linearity (R2 = 0.9986, 0.9986, and 0.9908) and precision (%RSD = 5.53%, 6.92%, and 14.12%). This instrument provides an alternative method for detecting cyanide, which can not only be used for accurate qualitative and quantitative detection of cyanide but also for food safety detection and physical evidence analysis of cyanide in beverage poisoning. Key to our method is that it offers advantages such as no need for sample pretreatment, simplicity and speed of operation, non-destructive analysis, minimal sample consumption (only 3 milliliters are required for a single measurement), and the ability to preserve the analyzed sample as evidence.

An innovative fluorescent probe for the detection of cyanide - enhanced sensitivity by controlling its electrostatic potential and suitable for applications such as cell imaging and food analysis

As cyanide is a huge hazard to the environment and human health, the study of the method of detecting low concentrations of cyanide is of great significance. In general, materials with strong positive electrostatic properties can use electrostatic attraction to enrich anions in the water near the materials, then realize rapid detection of low concentration anions by fluorescent probes. In this paper, fluorescent probes PI-S, PI-I and PI-N with cyanide-specific recognition and different charges were synthesized to study the relationship between the charge effect of probes and the sensing sensitivity. Through the zeta potential test and the calculation of the surface electrostatic potential, the positive electricity of PI-S, PI-I and PI-N gradually increased, the ΔG < 0 of the adsorption process gradually decreased, CN- could be aggregated to the vicinity of probes. As a result, the detection limit of the probe was gradually reduced from 1.07 × 10-6 to 5.03 × 10-8 M, the sensitivity was significantly enhanced. Therefore, this is expected to be a new strategy to improve the sensitivity of anion probes by increasing the positive electricity of molecules. In addition, PI-N has good anti-interference ability, short response time and certain application value in cell imaging and identification of endogenous cyanide in food.

Simultaneous determination of cyanide and thiocyanate in milk by GC-MS/MS using cetyltrimethylammonium bromide as both phase transfer catalyst and protein precipitant

A method was developed for simultaneous determination of cyanide and thiocyanate in milk by gas chromatography-tandem quadrupole mass spectrometry (GC-MS/MS). Cyanide and thiocyanate were derivatized with pentafluorobenzyl bromide (PFBBr) as PFB-CN and PFB-SCN, respectively. Cetyltrimethylammonium bromide (CTAB) was employed both as a phase transfer catalyst and a protein precipitant in the sample pretreatment, which facilitates the separation of the organic and aqueous phases, and greatly simplifies the pretreatment procedures to achieve simultaneous and rapid determination of cyanide and thiocyanate. Under the optimized conditions, the limits of detection (LODs) of cyanide and thiocyanate in milk were 0.006 mg/kg and 0.015 mg/kg, and the spiked recoveries ranged from 90.1% to 98.2% and from 91.8% to 98.9% with relative standard deviations (RSDs) less than 18.9% and 15.2%, respectively. The proposed method was validated as a simple, fast and highly sensitive method for the determination of cyanide and thiocyanate in milk.

Aqueous Two-Phase System–Ion Chromatography for Determination of Thiocyanate in Raw Milk

Thiocyanate could effectively inhibit bacteria in milk and extend the shelf life of milk. However, excessive addition will lead to health risks. Therefore, the determination of thiocyanate in raw milk has received a lot of attention, but the determination could be interfered with by other components in raw milk and the pre-treatment of raw milk is complex. In this study, a new pretreatment method combined with ion chromatography (IC) for rapid and sensitive determination of thiocyanate is proposed. An acetonitrile/(NH4)2SO4 aqueous two-phase system (ATPS) was developed for the separation and enrichment of thiocyanate in raw milk. Response surface methodology was performed to optimize the extraction conditions and an efficient pretreatment were obtained using ATPS composed of 42% acetonitrile (w/w) and 16% (NH4)2SO4 (w/w), with the pH 4.7, and the recovery of thiocyanate reached 107.24 ± 0.5%, and the enrichment ratio was 10.74 ± 0.03. IC was used to establish a thiocyanate enrichment method. The linear range was from 0.05 to 15 mg/L and R2 = 0.998, the limit of detection (LOD) was 0.2 μg/L, the limit of quantification (LQD) was 0.6 μg/L. Hence, it is feasible to combine ATPS with IC for the enrichment and determination of thiocyanate in raw milk.

Boron fluoride regulated “naked eye” and ratiometric fluorescent detection of CN− as a test strip and its bioimaging

Cyanide ions (CN⁻) are widely used in chemical and industrial processes, but not only can they cause environmental pollution, what is worse is that when a small amount of cyanide enters the human body, in the less severe cases, they pose health risks, and in the more severe cases, they can lead to death.

Mg-Al-CO3 layered double hydroxide reinforced polymer inclusion membrane as an extractant phase for thin-film microextraction of cyanide from environmental water samples

In this paper, a flexible and efficient nano-reinforced polymer inclusion membrane (PIM) was fabricated and used for cyanide (CN^-) extraction from water samples. Aliquat 336 (a liquid anion exchanger) was embedded in poly(vinyl chloride) (PVC) support as the extractant. Mg-Al-CO₃ layered double hydroxide (LDH) with high surface area and anion exchange ability was applied to promote the extraction efficiency of PIM. A PIM comprising 56% PVC, 40% Aliquat 336, and 4% Mg-Al-CO₃ LDH showed the best extraction efficiency. A single beam ultraviolet-visible spectrophotometer was used for the detection of cyanide. Surface morphology of the PIM was studied by field emission scanning electron microscopy. The experimental parameters influencing the extraction process were investigated and optimized. The intra- and inter-day relative standard deviations at two different concentrations were in the range of 2.8-7.6%. The dynamic range of the method was in the range of 5-500 μg L^-1, and the detection limit was 1.4 μg L^-1. The LDH reinforced PIM showed proper characteristics for the extraction of cyanide from real water and wastewater samples with recoveries between 82 and 115%.

Application of ion chromatography with pulsed amperometric detection for the determination of trace cyanide in biological samples, including breast milk

Cyanide (CN) is the biomarker of exposure to the components of tobacco smoke, although its presence in biological samples is also due to the consumption of products containing cyanogenic glycosides. In this work, we determine the concentration of the free cyanide in urine, saliva and breast milk matrices, using ion chromatography with pulsed amperometric detection (IC-PAD). IC-PAD is an emerging method, with only few documented applications in urine and saliva, and the presented determination in breast milk is its first published report for any method. The biological samples, which were obtained from women staying in a maternity ward, showed cyanide concentrations spanning 1.82-98.47 μg L^-1. Under the optimized chromatographic conditions, the IC-PAD system exhibited satisfactory repeatability (R < 3%, n = 3) and good linearity in the range of 1-100 μg L^-1. Thus, it proved to be an effective tool for monitoring trace cyanide concentration in a series of human body fluid matrices, including breast milk. This last matrix is especially important due to the possible effect on infant health related to the mothers' smoking habits.

Miniaturized sample preparation methods for saliva analysis

Saliva, as the first body fluid encountering with the exogenous materials, has good correlation with blood and plays an important role in bioanalysis. However, saliva has not been studied as much as the other biological fluids mainly due to restricted access to its large volumes. In recent years, there is a growing interest for saliva analysis owing to the emergence of miniaturized sample preparation methods. The purpose of this paper is to review all microextraction methods and their principles of operation. In the following, we examine the methods used to analyze saliva up to now and discuss the potential of the other microextraction methods for saliva analysis to encourage research groups for more focus on this important subject area.

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.