Separation,speciation and quantification of both chromium(Ⅵ)and chromium(Ⅲ)in tanned leather samples:a comparative study and validation of analytical methods

In the present work,a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented.For the analysis by ion chromatography-inductively coupled plasma-mass spectrometry,two different columns were tested,as well as different mobile phases and different pH of the samples.The optimized analytical method permitted the separation of Cr(Ⅲ)and Cr(Ⅵ)using 75 mmol/L NH_(4)NO_(3)pH 3 as chromatographic eluent.The method was validated and applied to real samples,allowing the determination of both species simultaneously,even when there is a huge difference of concentration between Cr(Ⅲ)and Cr(Ⅵ).Limit of detection and limit of quantification for Cr(Ⅲ)were found to be 0.016 and 0.054μg/L(0.3 and 1.1μg/kg),respectively,and for Cr(Ⅵ)0.13 and 0.43μg/L(7 and 22μg/kg),respectively.Possible species interconversions were monitored through the use of chromium isotopic standards,which confirmed that the optimized methodology preserves chromium speciation during extraction and analysis.Fourier-transform ion cyclotron resonance-mass spectrometry permitted the structure elucidation of the complex formed during ethylenediaminetetraacetic acid extraction.

Quantitative extraction of chromium Ⅵ and Ⅲ from tanned leather: a comparative study of pretreatment methods

In this study,seven pretreatment methods for chromium speciation in tanned leather were evaluated:acidic miner‑alization,ethylenediaminetetraacetic acid(EDTA)extraction,diethylenetriaminepentaacetic acid(DTPA)extraction,alkaline extraction(NH 4 OH),ammonium nitrate extraction(NH 4 NO 3),water extraction,and phosphate buffer extrac‑tion.Acidic mineralization permitted the decomposition of the organic matter and ensured the complete digestion of leathers,giving access to the total content of chromium in each sample using inductively coupled plasma‑atomic emission spectrometry(ICP‑AES).From all the extractant media tested,EDTA proved to be the most efficient,allowing the extraction of Cr(VI)and Cr(III)as a Cr(III)‑EDTA complex,quantitatively.Method validation is presented for EDTA extraction and direct mineralization.For the EDTA extraction,method detection limit(MDL)and method quantifica‑tion limit(MQL)for total Cr in leather were 3.4 ppb and 11.2 ppb(µg of total Cr per L of extraction solution),respec‑tively.Due to the lack of leather certified reference materials(CRMs)for Cr(VI),accuracy was evaluated by spiking leather samples with a Cr(VI)solution.The spike recovery of EDTA microwave assisted extraction ranged from 91.0 to 108.6%.Interday precision was also evaluated and all variation coefficients were below 5%,for both mineralization and EDTA extraction.This article provides an efficient procedure to extract quantitatively chromium from leather,while maintaining the speciation,which can be further followed by ion chromatography‑inductively coupled plasma‑mass spectrometry(IC‑ICP‑MS).

Valorization of sustainable vegetable oil deodorizer distillate as a novel fatliquor

The deodorizer distillate(DD)is a byproduct of vegetable oil processing industry and is rich in functional bioactive components.This study aimed to employ phosphorylation modification for DD to produce a new sustainable fatliquor.The bioactive ingredients in DD,namely fatty acids,sterols,and tocopherols,were determined by using HPLC and GLC.The results revealed that the DD sample contained a high percentage of unsaturated fatty acids(72.3%)and high levels ofγandδ-tocopherols(54.8%and 31.60%,respectively).Mechanical parameters(tensile strength,elongation at break,and tear strength)of leather were improved after being treated with the prepared fatliquor emulsion.Eventually,SEM showed that the texture of the fatliquored leather had been remarkably enhanced.Moreover,the fatliquored leather possessed effective antibacterial effect against the specified+ve,-ve bacteria,and Candida albicans microorganisms.The strength,fullness,soft handle,and elasticity of leather were all improved,and the grain of leather was protected from becoming loose after drying.

Advancing collagen-based biomaterials for oral and craniofacial tissue regeneration

The oral and craniofacial region consists of various types of hard and soft tissues with the intricate organization.With the high prevalence of tissue defects in this specific region,it is highly desirable to enhance tissue regeneration through the development and use of engineered biomaterials.Collagen,the major component of tissue extracellular matrix,has come into the limelight in regenerative medicine.Although collagen has been widely used as an essential component in biomaterial engineering owing to its low immunogenicity,high biocompatibility,and convenient extraction procedures,there is a limited number of reviews on this specific clinic sector.The need for mechanical enhancement and functional engineering drives intensive efforts in collagen-based biomaterials concentrating on therapeutical outcomes and clinical translation in oral and craniofacial tissue regeneration.Herein,we highlighted the status quo of the design and applications of collagen-based biomaterials in oral and craniofacial tissue reconstruction.The discussion expanded on the inspiration from the leather tanning process on modifications of collagen-based biomaterials and the prospects of multi-tissue reconstruction in this particular dynamic microenvironment.The existing findings will lay a new foundation for the optimization of current collagen-based biomaterials for rebuilding oral and craniofacial tissues in the future.

Collagen-based materials in reproductive medicine and engineered reproductive tissues

Collagen,the main component of mammal skin,has been traditionally used in leather manufacturing for thousands of years due to its diverse physicochemical properties.Collagen is the most abundant protein in mammals and the main component of the extracellular matrix(ECM).The properties of collagen also make it an ideal building block for the engineering of materials for a range of biomedical applications.Reproductive medicine,especially human fertility preservation strategies and reproductive organ regeneration,has attracted significant attention in recent years as it is key in resolving the growing social concern over aging populations worldwide.Collagen-based biomaterials such as collagen hydrogels,decellularized ECM(dECM),and bioengineering techniques including collagen-based 3D bio-printing have facilitated the engineering of reproductive tissues.This review summarizes the recent progress in apply-ing collagen-based biomaterials in reproductive.Furthermore,we discuss the prospects of collagen-based materials for engineering artificial reproductive tissues,hormone replacement therapy,and reproductive organ reconstruction,aiming to inspire new thoughts and advancements in engineered reproductive tissues research.