Polarographic determination of cyanide as nickelcyano complex in blood plasma after selective extraction in a methylene blue impregnated polyethylene column

A method for the determination of cyanide in blood plasma by differential pulse polarography (DPP) is described without a drastic acidification of the sample. Cyanide was determined as tetracyanonickelate(II)-anion complex after a microwave-acid assisted cleanup and a selective complex extraction in a polyethylene methylene blue (PE-MB) impregnated column. The cyano complex was eluted from the column with water/acetonitrile and determined by pulse-polarography at –380 mV (Ag/AgCl). The linear range of calibration was obtained from 1.2 to 9.6 μg of cyanide with r = 0.99 and RSD = 9% of 1.2 μg of cyanide. A detection limit of 40 μg L^–1 was calculated and the recoveries of cyanide from spiked samples were about 80%. This method was compared with the classical pyridine-pyrazolone method. Received: 3 September 1997 / Revised: 21 January 1998 / Accepted: 24 January 1998     

Preconcentration and Spectrophotometric Determination of Chromium (VI) and Total Chromium in Drinking Water by the Sorption of Chromium Diphenylcarbazone with Surfactant Coated Alumina

Abstract

A simple and inexpensive method for determining chromium (VI) in drinking water by spectrophotometry after preconcentration with sodium dodecyl sulphate (SDS) coated alumina column is described. Chromium(VI) is reacted with diphenylcarbazide (DPC) and the Cr-DPC complex is quantitatively adsorbed onto a SDS coated alumina column from 800 ml of sample solution. The complex is then eluted with a 8 ml mixture of methanol, acetone and hydrochloric acid and determined by spectrophotometry. Total chromium can be determined after oxidation of chromium (III) to chromium (VI) by KMnO₄. The relative standard deviation (10 replicate analyses) at the 10 μg l^?1 of chromium (VI) and 10 μg l^?1 of total chromium were 3.5% and 3.4% and corresponding limits of detection (based on 3 σ) were 0.040 μg l^?1 and 0.033 μg l^?1, respectively.     

Indirect Determination of Cyanide by Atomic Absorption Spectrometry

Abstract

Two methods for determination of cyanide by atomic absorption spectrometry (AAS) are developed. Both methods are based on the formation of an ion association compound between a metal complex, (Ag(CN)₂ ^? or Cu(CN)₃ ^2-), and a quaternary ammonium ion (benzyldimethylhexadecylammonium ion). The ion association compound is extracted into isomethylbutylketone (IBMK) and the metal is determined by AAS directly in extract. The method based on the formation of silver cyanide complex provides a reproducibility of 2.5%, a recovery of 99% and a detection limit of 1.7 μg/L while the method based on the formation of copper complex gives a reproducibility of 6%, a recovery of 93% and a detection limit of 0.6 μg/L. Several foreign ions were studied: the method based on the formation of Ag(CN)₂ ^? presents minor interferences.     

Polarographic determination of cyanide as contaminant in pralidoxime mesylate formulations

A method for the polarographic determination of cyanide as contaminant in pralidoxime mesylate (PM) formulations was developed. The volatile cyanide formed in the formulations was stabilized as tetracyanonickelate (TCN) anion complex after reaction with ammoniacal Ni(II) solution. The stable TCN anion complex (K(stb)=10(31)) was determined by anodic stripping voltammetry at the hanging mercury drop electrode (HMDE). The polarographic signal was proportional to the cyanide concentration and the high concentration of PM did not interfere. The linear range of calibration was from 1.2 to 16 mug cyanide with r=0.998. The RSD was 1.3% (n=5) for 2.4 mug cyanide and a detection limit of 0.8 mug cyanide was calculated. The proposed method is adequate as a quality control of PM formulations.     

New methods for the detection of cyanide based on displacement of the glutathione ligand of glutathionylcobalamin by cyanide

Glutathionylcobalamin (GSCbl) is a vitamin B₁₂ derivative that contains glutathione as the upper axial ligand to cobalt via a Co–S bond. In the present study, we discovered that cyanide reacted with GSCbl, generating cyanocobalamin (CNCbl) and reduced glutathione (GSH) via dicyanocobalamin (diCNCbl) intermediate. This reaction was induced specifically by the nucleophilic attack of cyanide anion displacing the glutathione ligand of GSCbl. Based on the reaction of GSCbl with cyanide, we developed new methods for the detection of cyanide. The reaction intermediate, violet-coloured diCNCbl, could be applied for naked eye detection of cyanide and the detection limit was estimated to be as low as 520 μg L^?1 (20 μM) at pH = 10.0. The reaction product, CNCbl, could be applied for a spectrophotometric quantitative determination of cyanide with a detection limit of 26 μg L^?1 (1.0 μM) at pH = 9.0 and a linear range of 26–520 μg L^?1 (1.0–50 μM). In addition, the other reaction product, GSH, could be applied for a fluorometric quantitative determination of cyanide with a detection limit of 31 μg L^?1 (1.2 μM) at pH = 9.0 and a linear range of 31–520 μg L^?1 (1.2–20 μM). These new GSCbl-based methods are simple, highly specific and sensitive with great applicability for the detection of cyanide in biological and non-biological samples.     

Determination of cyanides in electroplating solutions as Ni(CN)42– and analysis by capillary electrophoresis

A CE method was developed for the determination of total (free and weakly bound) cyanide in electroplating solutions based on the use of a cationic surfactant (TTAB) and complexation with Ni(II)-NH₃ solutions to Ni(CN)₄ ^2–. Both direct complexation and cyanide distillation combined with complexation were tested. Under optimized conditions, this method is time-saving compared to standard methods. Total cyanide determined by CE had detection limits (with respect to the initial sample concentration) of 0.5 μg/mL for direct complexation and 50 ng/mL for distillation combined with complexation. Total cyanide and cyanide not amenable by chlorination (CNAC) were determined in real samples from spent electroplating baths.     

Column Preconcentration of Palladium Using Phenanthrenequinonedioxime Supported on Naphthalene by Atomic Absorption Spectroscopy

Abstract

A solid chelating compound, phenanthrenequinonedioxime(PQDO) supported on naphthalene provides a rapid and economical means of preconcentration of palladium from the aqueous samples. Palladium forms a complex with PQDO supported on naphthalene in the column at pH 1.2～2.7. The metal complex and naphthalene are dissolved out from the column with 5 ml of dimethylformamide-nitric acid (100+4) and the absorbance is measured atomic absorption spectrometer at 244.7 nm. A calibration curve is linear over the concentration range 1～24 μg of palladium in 5 ml of the final solution. The sensitivity for 1% absorption is 0.126 μg/ml (0.153 μg/ml for the direct AAS method from the aqueous medium). The method has been used for the determination of palladium in various synthetic samples and can be safely applied to the environmental samples too.     

The determination of gold by anodic stripping voltammetry

A method is described for the routine determination of gold as its chloride or cyanide complex by anodic stripping voltammetry at a glassy carbon electrode coupled to a microprocessor-controlled voltammeter. The preferred supporting electrolyte is 0.1 M HCl/0.32 M HNO₃, with plating at ?200 mV or ?1200 mV (vs. Ag/AgCl). The stripping peak potentials range from 830 to 1150 mV (vs. Ag/AgCl) depending on concentration and plating time. Precision (percent relative standard deviation) is better than 5 % for a range of concentrations between 5 μg l^?1 and 1000 μg l^?1. The detection limit is about 5 μg l^?1 for a 5-min plating period. Interferences from Cu, Hg, Ag and other electroactive species are overcome by preliminary extraction with diethyl ether.     

A Fluorimetric Method for the Determination of Cyanide with Fluorescein and Iodine∗

Abstract

A rapid, simple and sensitive fluorimetric method has been developed for the determination of cyanide with fluorescein as fluorogenic reagent (λ_ex = 494 nm, λ_em = 514 nm) at pH 6.0–7.0. A linear calibration curve was obtained in the range 0.004–2.0 μg CN^?/25 ml. The detection limit is 0.004 μg CN^-/25 ml. The method was successfully applied to the determination of cyanide in waste water.

     

Rapid liquid chromatographic determination of residual penicillin G in milk

A simple and rapid high-performance liquid chromatographic (HPLC) method for determination of residual penicillin G (benzylpenicillin, PCG) in milk was developed. The sample preparation was performed by stirring with ethanol and reacting with 5 M 1,2,4-triazole-mercury (II) chloride solution at 65?°C for 10 min followed by an ultra centrifugation step. The HPLC separation was carried out using a Mightysil^® RP-4GP column, a mobile phase of acetonitrile and 0.1 M phosphate buffer (pH 6.5) (35:65, v/v) and a photo-diode array detector. The average recoveries from spiked PCG (0.004, 0.01, 0.05 and 0.1 μg/mL) were above 86% with coefficients of variation between 1.2 and 4.5%. The limit of detection was 0.004 μg/mL. This value corresponds to the maximum residue limit (MRL) in milk (0.004 μg/mL, EU and Japan). The total time required for the analysis of one sample was below 40 min.     

Simultaneous determinationof cyanide and thiocyanate by the pyridine/barbituric acid method after diffusion through a microporous membrane

A flow-injection system for the simultaneous determinationof cyanide and thiocyanate is described. A microporous tubular PTFE membrane module with an outer casing was constructed and included inthe system. Cyanide and thiocyanate diffuse thourgh the membrane wall from the phosphoric acid donor stream to a phosphate or carbonate buffer acceptor stream. Percentage transference of cyanide and thiocyanate were 68% and 59%, respectively, at pH 6.0. At pH 8.1, the percentage transference of cyanide was only 19%. The transferred cyanide and thiocyanate are determined by a pyridine/barbituric acid method. Thiocyanate reacts slowly with chloramine-T at pH 8.1, so that cyanide can be determined without interference from thiocyanate. Total cyanide and thiocyanate are determined at pH 6.0. The detection limits (S/N = 3) are 0.3 μM cyanide and 0.2 μM thiocyanate at pH 6.0, and 5 μM cyanide at pH 8.1. A mechanism for the transference thourgh the membrane is discussed. Bromine interferes with the determination of cyanide and thiocyanate at both pH 6.0 and 8.1. Hexacyanoferrate(II) and hexacyanoferrate(III) interfere at pH 8.1, but not at pH 6.0. Cyanate, oxaloacetate, oxalate, tartrate, albumin, globulin and lysozyme do not interfere.     

Development of a Simple and Inexpensive Optical Absorption One‐Shot Sensor Membrane for Detection and Determination of Cyanide Ions in Water Samples

A new one‐shot optical cyanide ion sensor is proposed for determination of cyanide ions. The sensor was constructed by immobilizing crystal violet (CV) on triacetylcellulose membrane. The sensing mechanism involves reaction between cyanide ions and the immobilized CV at pH = 5.4, which results in a decrease in absorbance of the membrane at 600 nm. The sensor shows sufficient repeatability, reproducibility, operational lifetime of 3 weeks, and a response of less then 10 min under the optimum conditions and response time of 8 min. Cyanide can be determined in the concentration range of 50.0‐800 μg mL^‐1 with a detection limit of 5.0 μg mL^‐1. Most ions do not interfere with the determination of cyanide ions. The proposed sensor was successfully applied to the determination of cyanide in spiked water samples.     

Modified analcime loaded with zincon as a useful material for the separation and preconcentration of trace palladium and its determination by third-derivative spectrophotometry

This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5 to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO) and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996. Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d ³ A/dλ³ (peak-to-peak signal between λ₂ = 625 and λ₁ = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d ³ A/dλ³) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in various synthetic and water samples. The text was submitted by the authors in English.     

固相萃取-高效液相色谱法对血液中唑吡坦及其两种羧酸代谢物的同时测定

建立了固相萃取-高效液相色谱分析血液中唑吡坦、6-羧酸唑吡坦及苯基-4-羧酸唑吡坦的方法。采用Waters Oasis HLB 3 mL固相萃取小柱萃取,以乙腈-2.5 mmol/L醋酸铵水溶液为流动相,梯度洗脱,经ZORBAX Eclipse XDB-C18色谱柱(4.6 mm×250 mm,5μm)分离,二极管阵列检测器(DAD)检测,检测波长为250 nm,外标法定量。比较了不同洗脱溶剂、溶液pH值对回收率的影响。在优化条件下,唑吡坦、6-羧酸唑吡坦及苯基-4-羧酸唑吡坦的线性范围分别为40~2000μg/L(r=0.9999)、20~2000μg/L(r=0.9998)和40~2 000μg/L(r=0.9998),检出限为1.2~3.3μg/L。添加16、160、360μg/L 3个水平的混合标准溶液,3种化合物的回收率为86%~106%,相对标准偏差均小于8%。结果表明,该方法具有操作简便、回收率高、精密度好和灵敏度高等特点,适于血液中唑吡坦及其2个羧酸代谢物的分析,可为相关案件提供方法及技术支持。     

高效液相色谱串联质谱法测定牛奶中的高氯酸盐

建立了高效液相色谱-串联质谱测定牛奶中高氯酸盐的方法.样品经1%乙酸-乙腈(体积比1:4)混合溶液提取,于6 000 r/min离心20 min后,经0.2μ m的尼龙滤膜、On-GuardⅡRP柱、On-GuardⅡAg柱和On-GuardⅡBa柱净化,最大反相性能色谱柱C12(Synergi 4u MAX-RP 8...     

Determination of cyanide and thiocyanate by a spectrophotometric flow-injection method

A rapid spectrophotometric flow-injection method is described for the determination of cyanide and thiocyanate. The method involves a two-step procedure in which the total concentration of both species is first determined (using sodium isonicotinate/sodium barbiturate reagents), after which the cyanide is complexed with nickel(II) and thiocyanate is quantified separately; the cyanide concentration is calculated by difference. Various parameters such as pH, temperature and nickel concentration were optimized. The method is applied to synthetic sample solutions and the results are compared with those obtained by the ASTM distillation method. The limits of detection for cyanide and thiocyanate are 0.05 and 0.08 μg ml^?1, respectively, with a sample throughput rate of 10 h^?1.     

The impact of nitrogen fertilizers on degradation and leaching of chlorotoluron in soil

Abstract

This study presents the developed and applied methods for the determination of carbendazim in environmental samples originating from several field studies.

For water samples sample pretreatment consisted of a solid phase extraction (SPE) on cartridges packed with 200 mg SDB-1. In case of solid samples the performance of microwave assisted solvent extraction (MASE) and classical ultrasonic extraction with acetone-ethyl acetate were studied. The latter technique was selected because of the reduced time of manual operations. Instrumental analysis of extracts of water samples was performed on-line with coupled column reversed phase liquid chromatography (LC/LC) and UV detection (280 nm) allowing to assay carbendazim to a level of at least 0.1 μg/l. Improved column life time was obtained by performing the favorable LC separation of carbendazim at high pH on newly developed 5 μm Extend-pH bidentate C18 material.

The combination of a short column packed with 5 μm Inertsil ODS-5 and a mobile phase at low pH material was most adequate as the regards the robust and fast processing of extracts of solid samples and allowed in most cases the screening of carbendazim in soils and sediments to a level of 10μg/kg.

The developed procedures yield overall recoveries for carbendazim of 101, 80 and 71 % in water (levels, 0.1—1.2 μg/l: n=12), soil (levels, 10 and 100 μg/kg; n=22) and sediments (levels, 10 and 100 μg/kg; n=11), respectively, with a repeatability and reproducibility below 7 % for all method/matrix combinations. Soil samples with aged residues (level, 100 μg/kg; n=10) provided an overall recovery of 71% and no significant decrease of carbendazim was observed during nine weeks of storage in the refrigerator.     

Determination of soluble cyanide in soil samples by differential pulse polarography

Soluble cyanide can be determined ins oil samples by differential pulse polarography. Interference from sulphide is avoided by treating the alkali-stabilized sample solutions with lead carbonate prior to distillation of cyanide from the soil extract. Less than 10 μg l^?1 cyanide can be determined accurately, depending on teh weight of sample taken and the final collection volume. For a 100-g soil sample, the detection limit is 5 ng g^?1, which is similar to the limit of a standard spectrophotometric method. Relative standard deviations are 1–3%.     

液相色谱-质谱法对饮用水中六价铬的测定

建立了液相色谱分离、电喷雾质谱测定饮用水中六价铬的方法.水样经微孔滤膜过滤后直接进样,以乙腈-1.5 mmol/L四丁基氢氧化铵水溶液为流动相,Xterra~(TM) MS C_(18)色谱柱分离六价铬,使用单四极杆质谱,选择离子模式检测,监测离子为m/z 118、117、101、85,其中117为定量离子.Cr(Ⅵ)的线性范围为1.0 ～100.0 μg/L,方法定量下限为1 μg/L.在空白水样中分别添加1.0、2.0、10.0 μg/L的六价铬,测得平均回收率(n=5)依次为91%、94%、97%,相对标准偏差分别为12.2%、7.4%、3.5%.测定了42个饮用水样品,其中17批检出六价铬,检出量为1.2 ～15.4 μg/L.     

Spectrophotometric determination of total cyanide in waste waters in a flow-injection system with gas-diffusion separation and preconcentration

An automated flow-injection system with gas diffusion separation and preconcentration and spectrophotometric detection is described for the determination of total cyanide in waste waters. An unstable red intermediate product of the reaction of cyanide with isonicotinic acid and 3-methyl-1-phenyl-2-pyrazolin-5-one is used instead of the conventional blue final product to improve the efficiency. A novel combination of a gas-diffusion separator with the sampling valve enables efficient on-line separation, preconcentration and sampling of cyanide. The sampling frequency is 40 h^?1 and the detection limit is 0.006 μg ml^?1 (3σ) when a 2-ml sample is taken and a preconcentration factor of 3.5 is achieved. The relative standard deviation is 1.4% (n = 22) at the 0.5 μg ml^?1 level. Results obtained with the proposed method are in good agreement with the standard manual spectrophotometric method. Interference studies show that in the presence of 1,10-phenanthroline, most potential interferents present in appreciable amounts do not interfere, but the interference from cobalt is not overcome in this system.