Comparative study of extraction methods of silver species from faeces of animals fed with silver-based nanomaterials

Abstract

Extractions methods based on ultrapure water, tetramethylammonium hydroxide (TMAH), and tetrasodium pyrophosphate (TSPP) were applied to faeces collected from two in vivo experiments of pigs and chickens fed with a silver-based nanomaterial to study the fate and speciation of silver. For TMAH extraction, cysteine and CaCl2 were used to evaluate their stabilization effect on the silver forms. The analytical techniques single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS), hydrodynamic chromatography hyphenated to ICP-MS (HDC-ICP-MS) and asymmetric flow field flow fractionation coupled to ICP-MS (AF4-ICP-MS) were applied to the simultaneous detection of particulate and dissolved silver. Results have shown that water extraction was a suitable option to assess the environmental release of silver, with percentages of 3 and 9% for faeces of pigs and chickens, respectively. The use of TMAH extraction combined with SP-ICP-MS analysis was useful to characterize Ag-containing particles (less than 1%). Both stabilizers, cysteine and CaCl2, have a similar effect on silver nanoparticle preservation for chicken faeces, whereas cysteine-Triton was better for pig samples. In any case, silver extraction efficiency with TMAH was low (39–42%) for both types of faeces due to a matrix effect. TSPP followed by ICP-MS enabled the fractionation of the silver in the faeces, with silver sulphide (41%) and ionic silver (62%) being the most abundant fractions. Graphical Abstract

The potential of a multi-method platform centred on ICP-MS to provide new insights into the size-resolved quantification of TiO2 particles in food

“…The separation program (Table 2) consisted of a focusing step (7 minutes, crossflow 1.5 mL min −1 ), transition time (0.1 min) and the elution step (3 min power decay from 1.5 to 0.1, and then 40 min constant at 0.1 mL min −1 ). Similar flow profiles with crossflow reductions after the focus step have been reported, 46–49 including applications for TiO 2 nanoparticles in food. 27 Additional washing step time (10 min, 0 mL min −1 crossflow) was added at the end of the program.…”

Nanosilver-based materials as feed additives: Evaluation of their transformations along in vitro gastrointestinal digestion in pigs and chickens by using an ICP-MS based analytical platform

“…The low bioaccessibility of the silver from the additive is reflected in its low retention in animal tissues, as it has been confirmed by i n vivo experiments [ 42 ]. Under such conditions, most of the ingested silver is excreted through the faeces [ 43 ], and the use of slurries and manure as amendments in agriculture should consider the potential mobilization of silver species in the environment.…”

Atomic spectrometry update: review of advances in elemental speciation

“…Before analysis though a sample preparation step is usually needed and Jiménez et al have evaluated three solvents, HPW, TMAH (25%) and 10 mmol per L Na 4 P 2 O 7 (TSPP) for the extraction of Ag species in faeces collected pigs and chickens fed with a Ag-based nanomaterial. 135 For the TMAH extraction, cysteine and CaCl 2 were used to evaluate their stabilisation effect on the Ag forms, i.e. the prevention of the formation of particulates from any Ag + present.…”