Investigation of a rapid infrared heating assisted mineralization of soybean matrices for trace element analysis

Multivariate optimization of the infrared radiation-assisted digestion of bivalve mollusk samples from Brazil for arsenic and trace metals determination using ICP OES

Bivalve mollusks are consumed worldwide and can provide an adequate intake of nutrients, but they have a high potential for toxic species accumulation. This study aims to evaluate an infrared radiation-assisted digestion method for mollusk sample analysis. A 23 full factorial design was used to evaluate reagent volume and heating time for sample decomposition. Limits of quantification (LOQ) were between 0.62 and 56 μg g-1, indicating suitability for trace elements determination in oyster, clam, mussel, and thick lucine samples. Under optimal conditions, the multi-elemental determination of As, Cd, Cu, Fe, and Zn was accomplished. Mussel, oyster, and clam samples showed the highest As content (≥ 23 μg g-1). Additionally, thick lucine samples have proved to be a potential Zn (95 ± 14 to 230 ± 23 μg g-1) and Fe (319 ± 7 to 1047 ± 90 μg g-1) source. For all samples, Cd concentration was below the LOQ.

Infrared assisted digestion used as a simple green sample preparation method for nutrient analysis of animal feed by microwave induced plasma atomic emission spectrometry

Based on green analytical chemistry principles it is important to evolve procedures that convert solid samples into solutions without using excessive reagent quantities, energy, temperature, and avoiding waste generation. To reach this aim, a simple infrared assisted digestion (IRAD) method for animal feed analysis was proposed. Infrared radiation (IR) with 2 mL of HNO₃ and 2 mL of H₂O₂ were assessed, presenting low dissolved organic carbon (DOC) and residual acidity (RA) in the final digest, being fully compatible with microwave induced plasma atomic emission spectrometry (MIP OES). Calcium, Cd, Cu, Fe, K, Mg, Na, P, Sr and Zn were determined in reference materials and in animal feeds. Limits of quantification were between 2.52 and 284 mg kg^-1 for Ca and P respectively. Recovery values ranged 80-120%, with relative standard deviations (RSD%) under 8%. The friendliness offered by the IRAD MIP OES method was evaluated by two green indexes. Concentrations in feedstuffs were compared with National Research Council (NRC) recommendations.

Enhanced Cadaverine Production by Engineered Escherichia coli Using Soybean Residue Hydrolysate (SRH) as a Sole Nitrogen Source

An economical source of nitrogen is one of the major limiting factors for sustainable cadaverine production. The utilization potential of soybean residue for enhanced cadaverine production by engineered Escherichia coli DFC1001 was investigated in this study. The SRH from soybean residue could get the protein extraction rate (PE) of 67.51% and the degree of protein hydrolysis (DH) of 22.49%. The protein molecular weights in SRH were mainly distributed in 565 Da (72.28%) and 1252 Da (17.11%). These proteins with small molecular weights and concentrated molecular weight distribution were favorable to be transformed by engineered E. coli DFC1001, and then SRH replaced completely yeast powder as an only nitrogen source for cadaverine production. The maximum cadaverine productivity was 0.52 g/L/h, achieved with a constant speed feeding strategy in the optimized SRH fermentation medium containing an initial total sugar concentration of 30 g/L and exogenous added minerals, which indicated that soybean residue could be a potential feedstock for economic cadaverine production.