Post-column detection of cadmium chelators by high-performance liquid chromatography using 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Analytical technologies in the biomedical and life sciences, 2020-03, Vol.1141, p.122025, Article 122025
• Main Authors: Chen, Chia-Shang, Ogawa, Shinya, Imura, Yuki, Suzuki, Michio, Yoshimura, Etsuro
• Format: Article
• Language: English
• Subjects: Animals; Aporphines - chemistry; Cadmium - chemistry; Cadmium chelator; Chelating Agents - analysis; Chelating Agents - chemistry; Chromatography, High Pressure Liquid - methods; Glutathione; High-performance liquid chromatography; Horses; Limit of Detection; Oxidative Stress
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2020.122025

•Simple method for detecting trace amounts of Cd chelators is presented.•Detection was based on the blue-shift in the UV–Vis spectrum of TPPS.•The method can be used to quantify thiol-free chelators. Cd(II) is toxic to many species, including humans, because it inactivates a number of enzymes and induces cytopathic effects in the liver, kidney, and skeletal tissues in humans. Metallothionein and glutathione (GSH) play a major role in the protection against Cd(II)-induced toxicity in mammalian cells. In this study, a relatively simple method for detecting trace amounts of Cd(II) chelators was developed by using 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (TPPS). The TPPS–Cd(II) complex was added to the elutions of high-performance liquid chromatography. The Cd(II) chelators separated by column chromatography were mixed with Cd(II)-bound TPPS (TPPS-Cd(II)). Cd(II) from TPPS-Cd(II) was chelated by the eluted Cd(II) chelators, resulting in the formation of free TPPS. The absorbance of TPPS shifted from 434 nm (TPPS–Cd(II)) to 414 nm (TPPS), and this characteristic shift was used to estimate the quantity and affinity of the Cd(II) chelators. This new method was compared with the bathocuproine disulfonate (BCS) method developed in our previous study. Instead of BCS-Cu(I), TPPS-Cd(II) was used as the colorimetric reagent. The experimental setup of the TPPS-based method is more general, and the preparation of the colorimetric solution is also much simpler than the BCS method. To verify the efficacy of this new method, we determined the actual Cd(II)-chelating ability of GSH in horse blood; the obtained concentration was in good agreement with the previously reported value.