Determination of four arsenic species in soil by sequential extraction and high performance liquid chromatography with post-column hydride generation and inductively coupled plasma optical emission spectrometry detection

Abstract

Several procedures, involving various solvents and ultrasound, were evaluated for the extraction of four arsenic species, arsenite (As(III)), arsenate (As(V)), monomethylarsonate (MMA) and dimethylarsinate (DMA), from a silt loam soil to which species had been added at a concentration of 20 mg kg À1 . The best extraction was by a two-stage procedure: shaking for 24 h in the presence of 0.1 mol l À1 phosphoric acid followed by shaking for 24 h in 1.0 mol l À1 sodium hydroxide solution. The arsenic species in the extracts were separated by high performance ion-exchange liquid chromatography, derivatized to hydrides by reaction with tetrahydroborate(III) in a multi-mode sample introduction system (MSIS) and quantified by ICP-OES. Detection limits in solution ranged from 0.4 (As(III) and DMA) to 1 (MMA and As(V)) mgl À1, corresponding to 10 and 25 mgkg À1 in a 0.2 g soil sample and 5 ml of extractant. The most significant change over time was that As(III) was converted to As(V). When each species was added individually, arsenic was 100% recovered over a period of several months. When all four species were added together, the recovery was 89%. As the precipitation of humic acids was slow, the sodium hydroxide extract could be acidified and analyzed without loss of analyte species.

Sample Pre-treatment Methods for Organometallic Species Determination

“…The multi-elemental capability and compatibility with some LC mobile phases makes ICP-MS and ICP-OES the most attractive detectors for elemental speciation (Szpunar et al 2000, Montes-Bayon et al 2003, Al-Assaf et al 2009, Gettar et al 2000. In particular, ICP-MS offers excellent sensitivity, a wide linear dynamic range, the ability to be used for isotope dilution analyses, and offers high-speed analyses (Sutton and Caruso 1999).…”

Arsenic Speciation Analysis by Ion Chromatography - A Critical Review of Principles and Applications

“…Compared to other eluents, phosphate is a real buffer able to alter on column the pH of the injected sample to the eluent pH. As an AsV-analogue, it plays an indispensable role in displacing AsV from strong adsorbing sites and providing optimal recoveries in chromatography [130] or in extraction procedures [57]. Higher capacity anion exchangers (compare Table 5) required higher eluent pH and/or high phosphate concentrations to compete for arsenicals and elute AsV in a reasonable t R .…”

“…Just recently, a phosphate gradient (0-10 mmol/L, pH = 5.8) has been applied on a shorter (4.6 × 100), high capacity column (~150 μequiv. ), eluting AsV in 11 min [57].…”

“…Solvent extraction (SE) are now investigated with a high enrichment factor (115) [56], ultrasound assisted [57,58] and microwave assisted SE [59], solid phase micro-extraction [60][61][62][63][64].…”

Highly Sensitive SERS Detection of As3+ Ions in Aqueous Media using Glutathione Functionalized Silver Nanoparticles

“…7 Over the years, various analytical techniques for the detection of arsenic at the trace level have been developed, including atomic fluorescence spectrometry (AFS), 8À10 atomic absorption spectrometry (AAS), 11,12 inductively coupled plasma spectrometry (ICP) with optical emission detection 13À15 and high-performance liquid chromatography (HPLC) with optical spectrometry detection. 16,17 Although these methods can accurately measure arsenic in an environmental sample to microgram arsenic per liter concentrations, there is still a necessity for development of simple and rapid methods for field assays. 18 Surface-enhanced Raman scattering (SERS) technique, which can be used in conjunction with commercially available portable Raman systems, has emerged as a potentially promising solution due to its incomparable advantages.…”