Organic solvent-free reversed-phase ion-pairing liquid chromatography coupled to atomic fluorescence spectrometry for organoarsenic species determination in several matrices

Determination of Adenylate Nucleotides in Amphipod Gammarus fossarum by Ion-Pair Reverse Phase Liquid Chromatography: Possibilities of Positive Pressure Micro-Solid Phase Extraction

Adenine nucleotides—adenosine monophosphate, diphosphate, and triphosphate—are of utmost importance to all living organisms, where they play a critical role in the energy metabolism and are tied to allosteric regulation in various regulatory enzymes. Adenylate energy charge represents the precise relationship between the concentrations of adenosine monophosphate, diphosphate, and triphosphate and indicates the amount of metabolic energy available to an organism. The experimental conditions of adenylate extraction in freshwater amphipod Gammarus fossarum are reported here for the first time and are crucial for the qualitative and quantitative determination of adenylate nucleotides using efficient and sensitive ion-pair reverse phase LC. It was shown that amphipod calcified exoskeleton impeded the neutralization of homogenate. The highest adenylate yield was obtained by homogenization in perchloric acid and subsequent addition of potassium hydroxide and phosphate buffer to achieve a pH around 11. This method enables separation and accurate detection of adenylates. Our study provides new insight into the complexity of adenylate extraction and quantification that is crucial for the application of adenylate energy charge as a confident physiological measure of environmental stress and as a health index of G. fossarum.

Selective solid-phase extraction of four phenylarsonic compounds from feeds, edible chicken and pork with tailoring imprinted polymer

The novel molecularly imprinted microspheres for four phenylarsonic compounds have been firstly prepared with the reversible addition-fragmentation chain transfer polymerization in a suspension system. The resulting polymeric microspheres were characterized by infrared spectrum, scanning electron microscope and differential scanning calorimetry. With serial adsorption experiments, the polymeric microspheres showed highly specific molecular recognition, fast mass transfer rate and robust adsorption of the substrates. Then, the imprinted polymer was used as the solid-phase extraction adsorbent to extract the phenylarsonic compounds from the feeds, edible chicken and pork. The cartridge was washed with 2 mL ethyl acetate and eluted with 3 mL of methanol- acetic acid (90:10, v/v). The recoveries of the molecularly imprinted solid-phase extraction (MISPE) column ranged from 83.4% to 95.1%. This work provided a versatile approach for the specific extraction of the organoarsenic compounds from complicated matrices and exhibited a bright future for the application of MISPE column.

Mineral Composition of Dry Dog Foods: Impact on Nutrition and Potential Toxicity

Detailed mineral profile of a selection of commercially available complete dry dog foods was determined using ICP-MS (Se, Cu, Mn, Zn, and nonessential trace elements), flame photometry (Na and K) and atomic and molecular spectrophotometry (Ca, P, Mg, and Fe). The contribution of ingredients to the mineral composition was correlated to the food market segment. Results showed an oversupply of essential elements due to the energy density effect on feed intake. Additives contributed from 40.8 to 55.1% to the total trace elements contents. With the exception of Se, all trace elements were supplied above the nutritional requirements of adult dogs. Legal limits of Cu, Se, and Zn were surpassed. The content of nonessential trace elements included values in the range of nanograms to micrograms per kg, without surpassing safe upper limits. This work brings awareness to the need to find supplementation strategies that ensure nutritional adequacy and avoid waste.

Speciation analysis of organoarsenic compounds in livestock feed by microwave-assisted extraction and high performance liquid chromatography coupled to atomic fluorescence spectrometry

The development of a new method to determine the presence of the organoarsenic additives p-arsanilic acid (ASA), roxarsone (ROX) and nitarsone (NIT) in livestock feeds by high performance liquid chromatography coupled to ultraviolet oxidation hydride generation atomic fluorescence spectrometry (HPLC-UV/HG-AFS) after microwave assisted extraction (MAE) was proposed. Chromatographic separation was achieved on a C18 column with 2% acetic acid/methanol (96:4, v/v) as the mobile phase. The limits of detection (LODs) were 0.13, 0.09 and 0.08mgL^-1, and the limits of quantification (LOQs) were 0.44, 0.30 and 0.28mgL^-1. The relative standard deviations (RSDs) for ASA, ROX and NIT determined from five measurements of the mixed calibration standard were 3.3, 5.3, and 5.4%, respectively. MAE extraction of phenylated arsenic compounds using 1.5M H₃PO₄ at 120°C for 45min allowed for maximum recoveries (%) of total arsenic (As) and organoarsenic species, with no degradation of these compounds. The extraction of total As was approximately 97%, and the As species recoveries were between 95.2 and 97.0%. The results of the analysis were validated using mass balance by comparing the sum of extracted As with the total concentration of As in the corresponding samples. The method was successfully applied to determine the presence of these compounds in feed samples. ASA was the only As species detected in chicken feed samples, with a concentration between 0.72 and 12.91mgkg^-1.

Arsenic accumulation and speciation in rice grown in arsanilic acid-elevated paddy soil

P-arsanilic acid (AsA) is a emerging but less concerned contaminant used in animal feeding operations, for it can be degraded to more toxic metabolites after being excreted by animals. Rice is the staple food in many parts of the world, and also more efficient in accumulating arsenic (As) compared to other cereals. However, the uptake and transformation of AsA by rice is unclear. This study aimed to evaluate the potential risk of using AsA as a feed additive and using the AsA contaminated animal manure as a fertilizer. Five rice cultivars were grown in soil containing 100mg AsA/kg soil, after harvest, As species and their concentrations in different tissues were determined. Total As concentration of the hybrid rice cultivar was more than conventional rice cultivars for whole rice plant. For rice organs, the highest As concentration was found in roots. AsA could be absorbed by rice, partly degraded and converted to arsenite, monomethylarsonic acid, dimethylarsinic acid, arsenate. The number of As species and their concentrations in each cultivar were related to their genotypes. The soil containing 100mg AsA/kg or more is unsuitable for growing rice. The use of AsA and the disposal of animal manure requires detailed attention.

A comparative evaluation of different ionic liquids for arsenic species separation and determination in wine varietals by liquid chromatography - hydride generation atomic fluorescence spectrometry

The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00μg As L(-1). The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties.

Organoarsenicals in poultry litter: detection, fate, and toxicity

Arsenic contamination in groundwater has endangered the health and safety of millions of people around the world. One less studied mechanism for arsenic introduction into the environment is the use of organoarsenicals in animal feed. Four organoarsenicals are commonly employed as feed additives: arsanilic acid, carbarsone, nitarsone, and roxarsone. Organoarsenicals are composed of a phenylarsonic acid molecule with substituted functional groups. This review documents the use of organoarsenicals in the poultry industry, reports analytical methods available for quantifying organic arsenic, discusses the fate and transport of organoarsenicals in environmental systems, and identifies toxicological concerns associated with these chemicals. In reviewing the literature on organoarsenicals, several research needs were highlighted: advanced analytical instrumentation that allows for identification and quantification of organoarsenical degradation products; a greater research emphasis on arsanilic acid, carbarsone, and nitarsone; identification of degradation pathways, products, and kinetics; and testing/development of agricultural wastewater and solid treatment technologies for organoarsenical-laden waste.