Determination of mercury in concentrated mineral acids by electrothermal atomic absorption spectrometry using gold amalgamation

Abstract

A method for the determination of trace amounts of mercury in concentrated hydrochloric, sulphuric and phosphoric acids by atomic absorption spectrometry at the p.p.b. level has been developed. After reduction of inorganic mercury compounds to mercury vapour, the vapour is transported by an inert gas from the solution and trapped on the gold coated wall of a graphite cuvette. In the second step of the determination, the absorbance signal from the atomisation of mercury released from the amalgam is measured. Peak height and area are both proportional to the mercury level between 5 and 100 p.p.b. with an RSD of up to 15%. Solutions of NaBH4 or Sn" were used as reducing agents.

On-line sample pre-treatment systems interfaced to electrothermal atomic absorption spectrometry†

“…However, interest in improving knowledge on the biochemical cycle and environmental behavior of such elements led to the development of new separation/preconcentration procedures capable of detecting trace amounts (sub-ng l 21 level) of the elements and their species in samples of different nature. Improved sensitivity has been obtained when volatile materials or compounds, such as gas chromatography (GC) effluents, 60,61 mercury vapor [61][62][63][64][65][66][67][68][69][70][71] or hydrides, [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86] have been introduced directly, on-line, into a pre-heated GF or trapped in situ and subsequently atomized. 13,21 These compounds are transferred into the furnace either via the internal gas line of the instrument or through an interface, directly introduced into the sampling port of the tube.…”

“…However, in situ trapping on more durable coatings, such as Zr or Ir, appears to have solved the problem, because repeated application of such coatings does not seem necessary during the lifetime of the graphite tube. There are many reports on mercury vapor absorption on gold-, [64][65][66] platinum-, 67,68 palladium- 69 or iridium-coated 63,70,71 graphite tubes and absorption of hydrides on carbide-forming elements (Zr, Nb, Ta and W) [72][73][74][75] or noble metals (Pt, Pd, Ir or Pd/Ir). [73][74][75][76][77][78][79][80][81][82][83][84][85][86] On-line matrix separation/digestion followed by ETAAS detection ETAAS has very low detection limits for many elements in aqueous solutions, but it is very sensitive to matrix interferences even with sophisticated background correction and chemical modification.…”

Total Mercury Determination in Biological and Environmental Standard Samples by Gold Amalgamation Followed by Cold Vapor Atomic Absorption Spectrometry

“…One of the most widely used techniques for the determination of mercury is the cold vapor generation method followed by atomic absorption spectrometry (9)(10)(11). Either stannous or borohydride compounds are used to reduce the mercury compounds to elemental mercury (Hg 0 ), followed by sweeping the free mercury atoms into an absorption cell and subsequent detection by appropriate mercury line.…”

Performance of the transverse heated filter atomizer for the atomic absorption determination of mercury

“…Dithizone (Dz, diphenylthiocarbazone) forms very stable, uncharged chelates of mercury, 13,14 which can be extracted into any organic solvent that is less polar than water, even from diluted strong acids. 15 In addition, Halasz et al 9 reported that mercury dithizonate is thermally more stable in a graphite furnace than any other mercury compound.…”