A field deployable method for a rapid screening analysis of inorganic arsenic in seaweed

Abstract

Inorganic arsenic (iAs) in 13 store-bought edible seaweed samples and 34 dried kelp (Laminaria digitata) samples was determined by a newly developed, field-deployable method (FDM) with the aid of a field test kit for arsenic in water. Results from the FDM were compared to results from speciation analysis achieved by using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The FDM consisted of a simple extraction method using diluted HNO3 to quantitatively extract iAs without decomposing the organoarsenicals to iAs followed by the selective volatilisation of iAs as arsine (AsH3) and subsequent chemo-trapping on a filter paper soaked in mercury bromide (HgBr2) solution. Method optimization with a sub-set of samples showed 80–94% iAs recovery with the FDM with no matrix effect from organo-arsenic species in the form of dimethylarsinic acid (DMA) on the iAs concentration. The method displayed good reproducibility with an average error of ±19% and validation by HPLC-ICP-MS showed that the results from the FDM were comparable (slope = 1.03, R2 = 0.70) to those from speciation analysis with no bias. The FDM can be conducted within an hour and the observed limit of quantification was around 0.05 mg kg−1 (dry weight). This method is well suited for on-site monitoring of iAs in seaweed before it is harvested and can thus be recommended for use as a screening method for iAs in seaweed. Graphical abstractScreening seaweed for their inorganic arsenic concentration within one hour without bias has been made possible in the field by using a field deployable arsenic kit. Its accuracy and precision was compared to HPLC-ICPMS. Electronic supplementary materialThe online version of this article (doi:10.1007/s00604-017-2151-1) contains supplementary material, which is available to authorized users.

Arsenic Species in Seaweeds Commercially Available in the United States

“…The tAs concentrations in the seaweeds (Figure 1) varied greatly, ranging from 3000 to 105 000 ng/g; 86 400−104 700 (hijiki). In general, as observed in previous studies, 29,30,32,33,36 brown seaweeds had higher arsenic than red and green algae. Exceptions were the two lavers (red algae), which contained more arsenic than some brown algae, i.e., arame (A1 and A2) and wakame (W10 and W12).…”

Tracing the natural and anthropogenic influence on the trace elemental chemistry of estuarine macroalgae and the implications for human consumption

“…For As and As speciation determination two macroalgal species were selected for analysis, Fv as it spans the length of the estuary, and LD, as this is the species that can be harvested. Analysis was carried out using methods described by Bralatei et al (2017). Total As was measured after microwave-assisted digestion by ICP-MS. Speciation used high performance liquid chromatography (HPLC) coupled to ICP-MS. Rhenium-Os isotope analysis utilised isotope-dilution negative ion mass spectrometry (Racionero-Gómez et al, 2017).…”

Comparison of on-site field measured inorganic arsenic in rice with laboratory measurements using a field deployable method: Method validation

“…After minutes the iAs concentration in the sample extract was determined using the colour change of the detector strip (Palintest, U.K.) by comparing it to a calibrated chart. Alternatively, the concentration of sample solution was determined using the arsenator photometer (Palintest, U.K.) as described by Bralatei et al (2017Bralatei et al ( , 2015. One analyses was complete within around one hour.…”

“…In view of this challenge, Bralatei et al (2015) modified a commercial arsenic field kit designed to measure iAs in water into a field deployable method (FDM) to allow determination of iAs in rice on-site. The method developed by Bralatei et al (2015) employs the Gutzeit reaction in which the sample containing As(III) and/or As(V) reacts with sodium borohydride under acidic conditions and converts both species of iAs to arsine gas (AsH3) (Equation 1) (Bralatei et al, 2017(Bralatei et al, , 2015Hung et al, 2004).…”