Monitor, Cyanid

The purpose of this chapter is to describe the analytical methods that are available for detecting and/or measuring and monitoring cyanide in environmental media and in biological samples. The intent is not to provide an exhaustive list of analytical methods that could be used to detect and quantify cyanide. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used to detect cyanide in environmental samples are the methods approved by federal organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that refine previously used methods to obtain lower detection limits, and/or to improve accuracy and precision. 

Sodium nitroprusside contains a nitroso (-NO) group, but is not an ester. It dilates venous and arterial beds equally. It is administered by infusion to achieve controlled hypotension under continuous close monitoring. Cyanide ions liberated from nitroprusside can be inactivated with sodium thiosulfate (Na2S203)(p.304). 

Linakis JG, Lacouture PG and Woolf A (1991). Monitoring cyanide and thiocyanate concentrations during infusion of sodium nitroprusside in children. Pediatr Cardiol, 12, 214-218. 

Abstract. Cyanides and hydrocyanic acid are one of the priority pollutants being most toxic. Therefore, it is very important to monitor cyanide concentration with specific and sensitive analytical methods. Some analytical methods for cyanide determination were presented in the last years spectrophotometer, potentiometer with silver cyanide electrode and titrimetric method. The paper presents original results concerning the spectrometric method and argentometric titration utilization for the measurement of cyanide concentration in some distilled alcoholic drinks from plums, grapes and apricots. The obtained cyanide concentrations vary between 0.0162 and 0.0970 mg/lOOmL, being under the imposed limits. 

There is often a need to monitor cyanide in air, water, solid waste, food, and other environmental samples. The cyanide present in these samples may include free (noncomplexed) cyanide such as hydrogen cyanide (or hydrocyanic acid in water solution), cyanogen (C2N2), cyanogen chloride, cyanide salts, or complexed cyanide such as metal-cyanide complexes of iron, nickel, copper, mercury, silver. Complexed cyanides are less toxic because they are less bioavail-able, but they may break down producing free cyanide, for example, as a result of the ultraviolet radiation in daylight. Analytical techniques for free... 

Detection. Many people can detect hydrogen cyanide by odor or taste sensation at the 1 ppm concentration in air, most at 5 ppm, but HCN does not have an offensive odor and a few people cannot smell it even at toxic levels. Anyone planning to work with hydrogen cyanide should be checked with a sniff test employing a known safe concentration. This test should be given periodically. Several chemical detection and warning methods can be employed. The most rehable are modem, electronic monitors based on electrolytes that react with hydrogen cyanide. 

EPR investigations are necessarily carried out in frozen solution at low temperature. Room temperature binding of thiols to FeMoco has been monitored by F NMR spectroscopy using /J-CF3C6H4S as the reporter ligand. These experiments revealed that the binding of thio-late is characterized by a dynamic equilibrium between the FeMoco and thiolate (159) and that cyanide and methyl isocyanide can bind to isolated FeMoco complexed with thiol (160). 

The Company and Spokane County Health Department Immediately contacted all well owners In the vicinity and tested the wells for cyanide contamination. The Company made bottled water available to the affected people on a temporary basis until a permanent uncontaminated supply could be obtained. A ground water monitoring program of selected wells was developed to verify the expected changes resulting from these remedial actions. Additional wells were Installed around the covered pile to support this monitoring program. 

Self-monitoring for cyanide must be conducted after cyanide treatment and before dilution with other streams. Alternatively, samples may be taken of the final effluent, if the plant limitations are adjusted based on the dilution ratio of the cyanide waste stream flow to the effluent flow. 

Dose- related increases in thiocyanate were observed, indicating that cyanide is liberated with the metabolism of acrylonitrile. In a study with human volunteers under controlled conditions, 2-cyanoethylmercapturic acid (CMA) was monitored in urine as an indication of exposure. On average, 22% of the absorbed acrylonitrile was metabolized to CMA however, considerable individual variability was observed. The CMA excretion ranged from 13% to 39% of the absorbed dose (Jakubowski et al. 1987). 

Falkner and Edmond [334] determined gold at femtomolar quantities in seawater by flow injection inductively coupled plasma quadrupole mass spectrometry. The technique involves preconcentration by anion exchange of gold as a cyanide complex, [AulCNjj], using 195Au radiotracer (ti/2 = 183 days) to monitor recoveries. Samples are then introduced by flow injection into an inductively coupled plasma quadrupole mass spectrometer for analysis. The method has a detection limit of 10 fM for 4 litres of seawater preconcentrated to 1 ml, and a relative precision of 15% at the 100 fM level. 

Except for the development of on-line systems for nutrients monitoring, the measurement of other inorganic non-metallic constituents is rather rare. Some commercial systems based on electrochemical sensing are proposed for the measurement of cyanide. A simple and rapid procedure for sulphide measurement in crude oil refinery wastewater has been developed [ 32 ]. Based on the de-convolution of the UV spectrum of a sample, this method has a detection limit of 0.5 mg L 1 and has been validated for crude oil refinery wastewater. 

BOX 1-1 WHOLE BLOOD LEVELS OF CYANIDE IN MONITORING AND NITROPRUSSIDE THERAPY STUDIES Leeser et al. (1990) ... 

The odor threshold, 0.58 ppm to 5.0 ppm (Amoore and Hautala 1983 Ruth 1986) is low compared with irritant or toxic concentrations. No acute exposures were located resulting in mild effects in humans. Three monitoring studies, involving no symptoms to mild symptoms during chronic occupational exposures of adult males, are relevant to development of AEGL-1 values. The symptoms and blood concentrations of cyanide in the monitoring study of Chandra et al. (1980) indicate that the workers may have been exposed at higher atmospheric concentrations than those reported. 

The 8-h no-effect mean geometric concentration of 1 ppm (with excursions up to 6 ppm) from the Leeser et al. (1990) study was used as the basis for time scaling the AEGL-1 values. This study was chosen because it was well conducted all workers had full medical examinations and routine blood tests, including measurements of blood cyanide and carboxyhemoglobin. Atmospheric HCN concentrations were monitored in the plant several times during the year. Because of the extrapolation from a long-term exposure, the... 

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