Atomic absorption spectrometry digestion

Raw foods were freeze-dried and analyzed for carbon isotopes using mass spectrometry. Cooked foods were prepared following historic recipes, then were freeze-dried prior to analysis. For the trace element analysis, foods (both raw and cooked) were wet ashed using nitric acid in Teflon lined pressure vessels and digested in a CEM Microwave oven. Analysis of Sr, Zn, Fe, Ca and Mg was performed using Atomic Absorption Spectrometry in the Department of Geology, University of Calgary. 

Zhang X, Cornelis R, De Kimpe J, and Mees L (1996) Arsenic speciation in serum of uraemic patients based on liquid chromatography with hydride generation atomic absorption spectrometry and on-line UV photo-oxidation digestion. Anal Chim Acta 319 177-185. 

Munoz O, Velez D, Montoro R (1999) Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) i- As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry. Analyst 124 601-607. 

Mercury was determined after suitable digestion by the cold vapour atomic absorption method [40]. Lead was determined after digestion by a stable isotope dilution technique [41-43]. Copper, lead, cadmium, nickel, and cobalt were determined by differential pulse polarography following concentration by Chelex 100 ion-exchange resin [44,45], and also by the Freon TF extraction technique [46]. Manganese was determined by flameless atomic absorption spectrometry (FAA). 

Neve et al. [547] digested the sample with nitric acid. After digestion the sample is reacted selectively with an aromatic o-diamine, and the reaction product is detected by flameless atomic absorption spectrometry after the addition of nickel (III) ions. The detection limit is 20mg/l, and both selenium (IV) and total selenium can be determined. There was no significant interference in a saline environment with three times the salinity of seawater. 

For example, the industrial preparation of mineral acids, such as sulfuric, hydrochloric and nitric, inevitably leads to them containing small concentrations of metals as impurities. If the acid is to be used purely as an acid in a simple reaction, the presence of small amounts of metals is probably unimportant. If, however, the acid is to be used to digest a sample for the determination of trace metals by atomic absorption spectrometry, then clearly the presence of metallic impurities in the acid may have a significant effect on the results. For this latter application, high-purity acids that are essentially metal-free are required. 

Jaffe, R., C.A. Fernandez, and J. Alvarado. 1992. Trace metal analyses in octocorals by microwave acid digestion and graphite furnace atomic-absorption spectrometry. Talanta 39 113-117. 

It is seen by examination of Table 1.11(b) that a wide variety of techniques have been employed including spectrophotometry (four determinants), combustion and wet digestion methods and inductively coupled plasma atomic emission spectrometry (three determinants each), atomic absorption spectrometry, potentiometric methods, molecular absorption spectrometry and gas chromatography (two determinants each), and flow-injection analysis and neutron activation analysis (one determinant each). Between them these techniques are capable of determining boron, halogens, total and particulate carbon, nitrogen, phosphorus, sulphur, silicon, selenium, arsenic antimony and bismuth in soils. 

Que-Hee and Boyle [70] analysed soils for total silicon using Parr bomb digestion with hydrofluoric-nitric-perchloric acid followed by inductively coupled plasma atomic absorption spectrometry. 

The acid digestion procedure described above for biological tissues. Crock and Lichte [135] recently described a similar procedure, involving hydrofluoric as well as nitric, perchloric and sulphuric acids, for dissolution of geological materials prior to arsenic and antimony determination by atomic absorption spectrometry. 

Once the sample is in solution in the acid and the digest made up to a standard volume the determination of metals is completed by standard procedures such as atomic absorption spectrometry or inductively coupled plasma optical emission spectrometry. 

Molybdenum may be identified at trace concentrations by flame atomic absorption spectrometry using nitrous oxide-acetylene flame. The metal is digested with nitric acid, diluted and analyzed. Aqueous solution of its compounds alternatively may be chelated with 8—hydroxyquinobne, extracted with methyl isobutyl ketone, and analyzed as above. The metal in solution may also be analyzed by ICP/AES at wavelengths 202.03 or 203.84 nm. Other instrumental techniques to measure molybdenum at trace concentrations include x-ray fluorescence, x-ray diffraction, neutron activation, and ICP-mass spectrometry, this last being most sensitive. 

Flame atomic absorption spectrometry can be used to determine trace levels of analyte in a wide range of sample types, with the proviso that the sample is first brought into solution. The methods described in Section 1.6 are all applicable to FAAS. Chemical interferences and ionization suppression cause the greatest problems, and steps must be taken to reduce these (e.g. the analysis of sea-water, refractory geological samples or metals). The analysis of oils and organic solvents is relatively easy since these samples actually provide fuel for the flame however, build-up of carbon in the burner slot must be avoided. Most biological samples can be analysed with ease provided that an appropriate digestion method is used which avoids analyte losses. 

P. Bermejo-Barrera, A. Moreda-Pineiro, O. Muniz-Navarro, A. M. J. Gomez-Fernandez and A. Bermejo-Barrera, Optimisation of a micro-wave-pseudo-digestion procedure by experimental designs for the determination of trace elements in seafood products by atomic absorption spectrometry, Spectrochim. Acta, Part B, 55(8), 2000, 1351-1371. 

N. Jalbani, T. G. Kazi, M. K. Jamali, M. B. Arain, H. I. Afridi, S. T. Sheerazi and R. Ansari, Application of fractional factorial design and Doehlert matrix in the optimisation of experimental variables associated with the ultrasonic-assisted acid digestion of chocolate samples for aluminium determination by atomic absorption spectrometry, J. AO AC Int., 90(6), 2007, 1682-1688. 

Mn(II) and Fe(II) were determined by differential pulse voltammetry (9, 30). The determinations were carried out within a few hours after sampling. Total dissolved and particulate Fe and Mn (after digestion of the particulate matter in a microwave digestion unit with HN03-HC1) were measured by flame or graphite furnace atomic absorption spectrometry. 

In the test method, the coal or coke to be analyzed is ashed under controlled conditions, digested by a mixture of aqua regia and hydrofluoric acid, and finally dissolved in 1% nitric acid. The concentration of individual trace elements is determined by either inductively coupled plasma-atomic emission spectrometry (ICPAES) or inductively coupled plasma-mass spectrometry (ICPMS). Selected elements that occur at concentrations below the detection limits of ICPAES can be analyzed quantitatively by graphite furnace atomic absorption spectrometry (GFAA). 

In an interlab oratory study involving 160 accredited hazardous materials laboratories reported by Kimbrough and Wakakuwa [28], each laboratory performed a mineral acid digestion on five soils spiked with arsenic, cadmium, molybdenum, selenium and thallium. Analysis of extracts was carried out by atomic emission spectrometry, inductively-coupled plasma mass spectrometry, flame atomic absorption spectrometry and hydride generation atomic absorption spectrometry. 

Nitric perchloric acid soluble cadmium has been determined in soils by an official method, which involves examination of the acid digest at 228.8 nm by atomic absorption spectrometry [48]. 

Chakraborty et al. [87] determined chromium in soils by microwave-assisted sample digestion followed by atomic absorption spectrometry without the use of a chemical modifier. 

Methods based on acid digestions of the soil with 7 M nitric acid [ 136] or sulfuric acid-nitric acid [137] have been described. Released mercury is absorbed in stannous chloride-sulfuric acid-hydroxylamine [ 136] or potassium permanganate-potassium persulfate-hydroxylamine-sodium chloride [137] prior to cold vapour atomic absorption spectrometry. 

Floyd and Sommers [142] evaluated a simple one-step digestion procedure for extracting total mercury from soils. The sample was digested with concentrated nitric acid and 4N potassium dichromate for four hours at 55 °C and the mercury in the extract determined by flameless atomic absorption spectrometry. The method can be applied to soils containing up to 20% organic matter. 

Standard official methods have been described for the determination of nitric-perchloric acid-soluble nickel [174] and acetic acid-extractable nickel [175] in soil. To determine nitric acid-perchloric acid-soluble nickel [174], the acid digest is dissolved in hydrochloric acid and the nickel is determined by atomic absorption spectrometry. To determine extractable nickel, the nickel is first extracted from the soil with 0.5 M acetic acid and the nickel is then converted to the ammonium pyrrolidine dithiocarbamate complex. Extraction of the complex with chloroform provides an extract for the determination of nickel by atomic absorption spectrometry. 

G. Tao, S. N. Willie, R. E. Sturgeon, Determination of total mercury in biological tissues by Bow injection cold vapour generation atomic absorption spectrometry following tetramethylammonium hydroxide digestion, Analyst, 123 (1998), 1215D1218. 

G. Schnitzer, A. Soubelet, C. Testu, C. Chafey, Comparison of open and closed focussed microwave digestions in view of total mercury determination by cold vapor atomic absorption spectrometry, Mikrochim. Acta, 119 (1995), 199-209. 

C. Cabrera, Y. Madrid, C. Camara, Determination of lead in wine, other beverages and fruit slurries by flow injection hydride generation atomic absorption spectrometry with on-line microwave digestion, J. Anal. Atom. Spectrom., 9 (1994), 1423-1426. 

K. J. Lamble, S. J. Hill, Arsenic speciation in biological samples by on-line high performance liquid chromatograph microwave digestion hydride generation atomic absorption spectrometry, Anal. Chim. Acta, 334 (1996), 261-270. 

M. Deaker, W. Maher, Determination of arsenic in arsenic compounds and marine biological tissues using low volume microwave digestion and electrothermal atomic absorption spectrometry, J. Anal. Atom. Spectrom., 14 (1999), 1193-1207. 

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