Mercury analysis methods

Atomic absorption spectroscopy is more suited to samples where the number of metals is small, because it is essentially a single-element technique. The conventional air—acetylene flame is used for most metals however, elements that form refractory compounds, eg, Al, Si, V, etc, require the hotter nitrous oxide—acetylene flame. The use of a graphite furnace provides detection limits much lower than either of the flames. A cold-vapor-generation technique combined with atomic absorption is considered the most suitable method for mercury analysis (34). 

Ponce RA, BarteU SM, Kavanagh TJ, Woods JS, Griffith WC, Lee RC, Takaro TK, Faustman EM. 1998. Uncertainty analysis methods for comparing predictive models and biomarkers a case study of dietary methyl mercury exposure. Regulatory Toxicol Pharmacol 28 96-105. 

The methods for mercury analysis described earlier are based on continuous-flow technology and although this is easy to translate these procedures into an on-hne regine, several problems are associated with this. These are (a) presentation of a representative sample (b) conversion of all forms of mercury in the sample into the divalent form prior to reduction to mercury and (c) engineering the system to include sufficient robustness, control and flexibility. 

Mercury analysis by U.S. Environmental Protection Agency Method 1631... 

Procedures for the determination of 11 elements in coal—Sb, As, Br, Cd, Cs, Ga, Hg, Rb, Se, U, and Zn—by neutron activation analysis with radiochemical separation are summarized. Separation techniques include direct combustion, distillation, precipitation, ion exchange, and solvent extraction. The evaluation of the radiochemical neutron activation analysis for the determination of mercury in coal used by the Bureau of Mines in its mercury round-robin program is discussed. Neutron activation analysis has played an important role in recent programs to evaluate and test analysis methods and to develop standards for trace elements in coal carried out by the National Bureau of Standards and the Environmental Protection Agency. 

Volatility of the Elements and Sample Treatment. A prime consideration in developing an analysis method is the volatility of the element to be determined. Controlled combustion of the coal sample and collection of the volatile products is a good way to separate very volatile elements such as mercury and bromine. The few completely volatile elements are subsequently and easily purified. 

Mercury recovered in the ash probably represents mercury in the siliceous portion of the ash and mercury adsorbed onto the surface of the ash particles as the gas stream cools. Preliminary investigations showed that the coal analysis method does not account for all the mercury in the ash. This is a result of the significantly higher silicate concentration in the ash. In addition, the higher temperature ashes have a lower mercury concentration requiring a larger sample size for analysis. Because of these properties of the ash, the coal analysis method was modified to revolatilize the mercury quantitatively in the ash. 

Commission Decision 93/351/EEC of 19 May 1993 determining analysis methods, sampling plans and maximum limits for mercury in fishery products. Official Journal of the European Communities. No. L 144, pp. 23-24. 

Cold vapor atomic absorption spectrophotometric method is applicable only for the mercury analysis. The principle of this method is described below. 

Moretto, L.M., N.S. Bloom, P. Scopece, and P. Ugo. 2003. Application of ultra clean sampling and analysis methods for the speciation of mercury in the Venice lagoon (Italy). J. Phys. TV France 107 887-890. 

All bulk elemental analysis methods, such as NAA and FAAS, suffer from the serious disadvantage of lack of specificity in that the elements detected are not unique to FDR but also occur from occupational and environmental sources. Many surveys were carried out to determine background levels of lead, antimony, and barium on the hands of people not involved with firearms. Some surveys also included copper and mercury. Both general and occupational data were gathered and threshold levels established for each of the elements. The threshold level may be defined as the level above which the results may be significant and correlate to the discharge of a firearm. The best that could be stated was that the levels detected were consistent with the discharge of a firearm but could not be taken as conclusive proof of the presence of FDR. 

At the start of 1978 the particle analysis method183 replaced the flameless atomic absorption bulk elemental method184 as the firearm residue detection method in the NIFSL. Since then the particle analysis method has been substantially improved by the use of a sample concentration/cleanup procedure,185 the addition of a backscattered electron detector, and the development of an automated residue detection system.186 187 Despite these improvements the technique remains costly and labor intensive. Certain aspects of the system required further work, in particular, the particle classification scheme discharge particles from mercury fulminate-primed ammunition and discharge particles from new primer types (Sintox). 

Catalysts were characterised by two standard textural-analysis methods mercury porosimetry (AutoPore 9200, Micromeritics, USA) and physical adsorption of nitrogen (ASAP2010M, Micromeritics, USA). 

Chemical characterization total metal analysis has been performed using atomic adsorption spectroscopy (Varian Techtron analyzer). Metals were reported in % by weight (bulk) of total metal oxides in the support (W, Ni, Pt / Al-Si support). See Table 1. Physical method Surface, pore volume, and average pore diameter were measured using standard nitrogen adsorption and mercury porosimetry methods. See Table 1. 

These results confirm the suggestions of earlier workers (I, 2) that the mercury intrusion method can lead to structural deformation of solids during analysis. For silicas, there appears to be both an elastic deformation and an irreversible compression effect that contribute to the differences in... 

Horvat, M., Development of methods for low level mercury analysis and application on environmental biological samples. Dissertation (in Slovenian). University E. Kardelj , Ljubljana, Slovenia, 1989, pp. 1-164. 

The great advance for AFS in mercury analysis is associated with the CV atomization technique. The sample preparation procedures are the same as for CV-AAS. Most of the methods described below utilize the CV technique for liberation of mercury from the sample solution. Unless othenwise stated, the aeration gas was argon and the mercury fluorescence was measured directly at the outlet of the gas stream carrying the Hg(0) from the reaction vessel into the atmosphere (a "windowless cell"). 

Data collection. Two data sets are used to demonstrate the multiscale cluster analysis method and have been kindly provided by Dr. Roy Goodacre at Institute of Biological Sciences. University of Wales, Aberystwyth [64,65]. Ten microlitre aliquots of bacterial suspensions were evenly applied onto a sand-blasted aluminium plate. Prior to analysis the samples were oven-dried at 50°C for 30 min. Samples were run in triplicate. The FT-IR instrument used was the Bruker IFS28 FT-IR spectrometer (Bruker Spectro-spin, Banner Lane, Coventry, UK) equipped with an MCT (mercury-cadmium-telluride) detector cooled with liquid Ni. The aluminium plate was then loaded onto the motorised stage of a reflectance TLC accessory. The wave-... 

This review considers the literature of the past years (up to 1979) that treats the preconcentration of the priority pollution metals antimony, arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc. In some cases, a brief outline is given or some discussion of the method, but in most instances, the number of methods available precludes more than a mention of their specific application or special feature. For some elements such as mercury many methods of preconcentration are available, for others such as beryllium and thallium only a few are reported. Relatively few procedures actually detail the analysis of a sample containing several species both organic and inorganic, although this area is of major concern, because of large differences in the relative toxicity of the various species. 

Heyrovsky worked out the theory for the mercury electrode In polarography, an electrochemical analysis method which, after a few improvements, meant that ultra-traces could be analysed In heavy metals for instance. He was awarded the Nobel prize for his work In 1959. 

Crock, J. G. 1996. Mercury. In Methods of Soil Analysis. Part 3. Chemical Methods, ed. D. L. Sparks, 769-792. Soil Science Society of America Book Series 5. Madison, WI American Society of Agronomy-Sod Science Society of America. 

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