Atomic absorption spectrometry sodium

A medium throughput approach to evaluating sodium channel activity is the measurement of sodium flux across cell membranes [103]. In these experiments, a tracer that permeates the channel and is easily quantifiable is used to analyze sodium influx. Traditionally, radioactive tracers such as 22Na+ or [14C]guanidinium have been used. Alternatively, Li+ can be used as a tracer and analyzed by atomic absorption spectrometry. Sodium flux assays can be used to test approximately 105 compounds per year. They offer a robust readout of channel activity, but lack voltage control and temporal resolution. To examine sodium channel blockade by measuring sodium flux,... 

For the deterrnination of trace amounts of bismuth, atomic absorption spectrometry is probably the most sensitive method. A procedure involving the generation of bismuthine by the use of sodium borohydride followed by flameless atomic absorption spectrometry has been described (6). The sensitivity of this method is given as 10 pg/0.0044M, where M is an absorbance unit the precision is 6.7% for 25 pg of bismuth. The low neutron cross section of bismuth virtually rules out any deterrnination of bismuth based on neutron absorption or neutron activation. 

Spencer and Sachs [29] determined particulate aluminium in seawater by atomic absorption spectrometry. The suspended matter was collected from seawater (at least 2 litres) on a 0.45 tm membrane filter, the filter was ashed, and the residue was heated to fumes with 2 ml concentrated hydrofluoric acid and one drop of concentrated sulfuric acid. This residue was dissolved in 2 ml 2 M hydrochloric acid and the solution was diluted to give an aluminium concentration in the range 5-50 pg/1. Atomic absorption determination was carried out with a nitrous oxide acetylene flame. The effects of calcium, iron, sodium, and sulfate alone and in combination on the aluminium absorption were studied. 

Sturgeon et al. [59] have described a hydride generation atomic absorption spectrometry method for the determination of antimony in seawater. The method uses formation of stibene using sodium borohydride. Stibine gas was trapped on the surface of a pyrolytic graphite coated tube at 250 °C and antimony determined by atomic absorption spectrometry. An absolute detection limit of 0.2 ng was obtained and a concentration detection limit of 0.04 pg/1 obtained for 5 ml sample volumes. 

Soo [96] determined picogram amounts of bismuth in seawater by flameless atomic absorption spectrometry with hydride generation. The bismuth is reduced in solution by sodium borohydride to bismuthine, stripped with helium gas, and collected in situ in a modified carbon rod atomiser. The collected bismuth is subsequently atomised by increasing the atomiser temperature and detected by an atomic absorption spectrophotometer. The absolute detection limit is 3pg of bismuth. The precision of the method is 2.2% for 150 pg and 6.7% for 25 pg of bismuth. Concentrations of bismuth found in the Pacific Ocean ranged from < 0.003-0.085 (dissolved) and 0.13-0.2 ng/1 (total). 

The collection behaviour of chromium species was examined as follows. Seawater (400 ml) spiked with 10-8 M Crm, CrVI, and Crm organic complexes labelled with 51Cr was adjusted to the desired pH by hydrochloric acid or sodium hydroxide. An appropriate amount of hydrated iron (III) or bismuth oxide was added the oxide precipitates were prepared separately and washed thoroughly with distilled water before use [200]. After about 24 h, the samples were filtered on 0.4 pm nucleopore filters. The separated precipitates were dissolved with hydrochloric acid, and the solutions thus obtained were used for /-activity measurements. In the examination of solvent extraction, chromium was measured by using 51Cr, while iron and bismuth were measured by electrothermal atomic absorption spectrometry. The decomposition of organic complexes and other procedures were also examined by electrothermal atomic absorption spectrometry. 

A Cis column loaded with sodium diethyldithiocarbamate has been used to extract copper and cadmium from seawater. Detection limits for analysis by graphite furnace atomic absorption spectrometry were 0.024 pg/1 and 0.004 xg/l, respectively [283]. 

Trace amounts of molybdenum were concentrated from acidified seawater on a strongly basic anion exchange resin (Bio-Rad AG1 X-8 in the chloride form) by treating the water with sodium azide. Molybdenum (VI) complexes with azide were stripped from the resin by elution with ammonium chlo-ride/ammonium hydroxide solution (2 M/2 M). Relative standard deviations of better than 8% at levels of 10 xg per litre were attained for seawater using graphite furnace atomic absorption spectrometry. 

Carr [562] has studied the effects of salinity on the determination of strontium in seawater by atomic absorption spectrometry using an air-acetylene flame. Using solutions containing 7.5 mg/1 strontium and between 5 and 14% sodium chloride, he demonstrated a decrease in absorption with increasing sodium chloride concentration. To overcome this effect a standard additions procedure is recommended. 

Yamamoto et al. [33] have studied the differential determination of heavy metals according to their oxidation states by flameless atomic absorption spectrometry combined with solvent extraction with ammonium pyrrolidinedithio-carbamate or sodium diethyldithio-carbamate. 

Phytic acid solutions were prepared by titrating sodium phytate (Sigma Chemical Company) with HCl the concentration was determined by analyzing for inorganic phosphate after wet ashing with HoSOu-HNOo (3 2) for 45 minutes. The concentration of CaCl stock solutions was measured by atomic absorption spectrometry. 

The determination of arsenic by atomic absorption spectrometry with thermal atomization and with hydride generation using sodium borohydride has been described by Thompson and Thomerson [117] and it was evident that this method could be modified for the analysis of soil. 

Mannheim, Germany). The slices were kept refrigerated in 5 mM sodium azide. Demineralization was done in 0.5 M EDTA, pH 7.4, at 4°C, while the release of calcium was measured by atomic absorption spectrometry. Mean collagen mass of fhe experimenfal slices was 3.33 0.36 mg or 11.1 1.2 nmol. 

Lei et al. reported a method for the indirect determination of trace amounts of procaine in human serum by atomic absorption spectrophotometry [54], The sample was mixed with HCIO4, heated at 85°C for 30 minutes, diluted to a known volume with water, and centrifuged. 1 mL of the supernatant solution was buffered with 0.1 M sodium acetate-acetic acid to pH 3.86, and mixed with 0.2 M Zn(SCN)j reagent to a final concentration of 0.1 M. After dilution to 50 mL with water, the solution was shaken for 1 minute with 10 mL of 1,2-dichloroethane, whereupon the zinc extracted into the organic phase was determined by air-acetylene flame atomic absorption spectrometry for the indirect determination of procaine. The detection limit was found to be 0.1 pg/g, with a recovery of 89-98% and a coefficient of variation (n = 10) equal to 3.2%. 

The most useful chemical species in the analysis of arsenic is the volatile hydride, namely arsine (AsH3, bp -55°C). Analytical methods based on the formation of volatile arsines are generally referred to as hydride, or arsine, generation techniques. Arsenite is readily reduced to arsine, which is easily separated from complex sample matrices before its detection, usually by atomic absorption spectrometry (33). A solution of sodium borohydride is the most commonly used reductant. Because arsenate does not form a hydride directly, arsenite can be analyzed selectively in its presence (34). Specific analysis of As(III) in the presence of As(V) can also be effected by selective extraction methods (35). 

Inorganic As(III) and As(V) were determined by atomic absorption spectrometry using the hydride technique. Total inorganic arsenic, As(III) + As(V), was measured after a prereduction reaction of As(V) to As(III) in acidic solution containing potassium iodide and ascorbic acid. For the selective hydride formation of As(III), samples were maintained at pH 5.0 during the hydride reaction (with 3% NaBH4, 1% NaOH) with a citrate-sodium hydroxide buffer solution (31). As(V) was determined by difference between total As and As(III). The detection limit of As(III) and As(V) was 0.1 nM. The selectivity of this method was checked by additions of As(III) and As(V) to lake water 95-100% recovery of As(III) and As(V) was found (32). 

The determination of arsenic by atomic absorption spectrometry with thermal atomisation and with hydride generation using sodium borohydride has been described by Thompson and Thomerson [29], and it was evident that this method couldbe modified for the analysis of soil. Thompson and Thoresby [30] have described a method for the determination of arsenic in soil by hydride generation and atomic absorption spectrophotometry using electrothermal atomisation. Soils are decomposed by leaching with a mixture of nitric and sulfuric acids or fusion with pyrosulfate. The resultant acidic sample solution is made to react with sodium borohydride, and the liberated arsenic hydride is swept into an electrically heated tube mounted on the optical axis of a simple, lab oratory-constructed absorption apparatus. 

The recommended procedure for the determination of arsenic and antimony involves the addition of 1 g of potassium iodide and 1 g of ascorbic acid to a sample of 20 ml of concentrated hydrochloric acid. This solution should be kept at room temperature for at least five hours before initiation of the programmed MH 5-1 hydride generation system, i.e., before addition of ice-cold 10% sodium borohydride and 5% sodium hydroxide. In the hydride generation technique the evolved metal hydrides are decomposed in a heated quartz cell prior to determination by atomic absorption spectrometry. The hydride method offers improved sensitivity and lower detection limits compared to graphite furnace atomic absorption spectrometry. However, the most important advantage of hydride-generating techniques is the prevention of matrix interference, which is usually very important in the 200 nm area. 

Smith and Lloyd [82] determined chromium(VI) in soil by a method based on complexation with sodium diethyldithiocarbamate in pH 4 buffered medium followed by extraction of the complex with methylisobutylketone and analysis of the extract by atomic absorption spectrometry (Evans R, City Analyst, Dundee, UK, private communication) [86]. Using this method, levels of chromium(V) of between 90 and 176 mg/1 were found in pastureland on which numerous cattle fatalities had occurred. 

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. 

An official standard method has been published for the determination of 1 M ammonium nitrate-extractable sodium in soils. The sodium content of the extract was determined by atomic absorption spectrometry [214],... 

Maher [6] has described a method for the determination of down to O.Olmg/kg of organoarsenic compounds in marine sediments. In this procedure, the organoarsenic compounds are separated from an extract of the sediment by ion exchange chromatography, and the isolated organoarsenic compounds are reduced to arsines with sodium borohydride and collected in a cold trap. Controlled evaporation of the arsine fractions and detection by atomic absorption spectrometry completes the analysis. 

Kagaya, S., Y. Kuroda, Y. Serikawa, and K. Hasegawa. 2004. Rapid determination of total mercury in treated waste water by cold vapor atomic absorption spectrometry in alkaline medium with sodium hypochlorite solution. Talanta 64 554-557. 

International Standard Organization. 1993. Water quality. Determination of sodium and potassium. Part 2 Determination of potassium by atomic absorption spectrometry. ISO 9964-2. International Organization for Standardization, Case Postale 56, CH-1211, Geneva 20 Switzerland. 

Small et al. [6] used this technique to determine ammonion ion in rain. Kadowaki [35] applied ion chromatography for the determination of sodium, potassium, ammonium, calcium and magnesium in rainwater samples. The method was compared to atomic absorption spectrometry and found to be less influenced by interferences. 

Yamamoto [44] separated organoarsenic compounds from seawater by column chromatography. The oiganoarsenic compounds were reduced to arsine with sodium borohydride and analysed by atomic absorption spectrometry... 

S. Rapsomanikis, O. X. F. Donard, J. H. Weber, Speciation of lead and methyllead ions in water by chromatography/atomic absorption spectrometry after ethylation with sodium tetraethyl borate, Anal. Chem., 58 (1986), 35-37. 

A 250 mL sample of each solution from the polyethylene bottle was filtered through a Millipore filter (0.45 urn pore size). The concentrations of chloride, nitrate and sulfate ions in the filtrate were determined by ion chromatography using a YEW IC 100 of Yokogawa Hokushin Electric Co. Ltd. The concentrations of sodium and potassium were determined by flame emission spectrometry and concentrations of calcium and magnesium by atomic absorption spectrometry using a Hitachi 170-50 Atomic Absorption Spectrophotometer. An aliquot of each filtrate was used for the determination of Sr by ICP emission spectrometry after adding nitric acid (0.1 N), detailed analytical conditions of which are reported elsewhere (3). 

---