![]() ![]() Some other authors have reported the determination of Cr(VI) in leather samples based on its extraction with a phosphate buffer, NaOH or through a sequential extractions scheme. Both methods rely on the complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) for UV–Vis detection and offer a limit of quantification (LOQ) of 3 mg/kg for Cr(VI). The analysis of the extract is performed via colorimetric or chromatographic analysis. Ĭoncerning hexavalent chromium determination, the International Organization for Standardization (ISO) 17075 standard describes a procedure for the selective extraction of Cr(VI) in tanned leather using a phosphate buffer: K 2HPO 4♳H 2O at pH 8.0. The European Union regulates hexavalent chromium’s content to 3 mg/kg in leather goods coming into direct contact with skin, while the leather standard by Oeko-Tex® limits total chromium content to 2 mg/kg for leather products intended for babies. Additionally, in direct contact with the skin, chrome-tanned leather products may elicit allergic contact dermatitis. ![]() Trivalent chromium (Cr(III)) is not considered as toxic but it can be unintentionally oxidized into hexavalent chromium (Cr(VI)), a known mutagenic and carcinogenic, as a consequence of different factors. ) make chrome tanning the most widespread technique. The multiple advantages of this process (fast tanning reaction, it confers high hydrothermal stability, it allows the retention of colorants, etc. Chrome tanning uses trivalent chromium salts as tanning agents. Among the different tanning methods, chrome tanning is the most common technique and accounts for around 90% of global leather production. ![]() Tanning is the process of transforming raw hide into leather. Fourier-transform ion cyclotron resonance-mass spectrometry permitted the structure elucidation of the complex formed during ethylenediaminetetraacetic acid extraction. 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. Limit of detection and limit of quantification for Cr(III) were found to be 0.016 and 0.054 \(\upmu\)g/L (0.3 and 1.1 \(\upmu\)g/kg), respectively, and for Cr(VI) 0.13 and 0.43 \(\upmu\)g/L (7 and 22 \(\upmu\)g/kg), respectively. 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). The optimized analytical method permitted the separation of Cr(III) and Cr(VI) using 75 mmol/L NH 4NO 3 pH 3 as chromatographic eluent. 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. In the present work, a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |