Yingying Li,Haoliang Zhao,Weijun Yang,Yong Gao,Liming Wang
Trace cobalt ion in the zinc sulfate electrolyte is the most difficult to be removed among all metallic impurities and has the most detrimental effect on zinc electrowinning. In this study, poly(p-hydroxystyrene) resin was first prepared from polystyrene, and then 1-nitroso-2-naphthol was grafted onto poly(p-hydroxystyrene) resin through -O- group by a series of reactions to obtain the 1-nitroso-2-naphthol-grafted-poly(p-hydroxystyrene) resin. Finally, the grafted resin was supported on SiO2. The supported resin could removal trace cobalt ions with good selectivity and reusability in the zinc sulfate leachate, which can meet the requirements of the industrial electrolytic zinc process.
Urinary 5-hydroxyindole-3-acetic acid (5-HIAA) is a marker for diagnosis of patients with carcinoid tumors. In clinical practice, a simple colorimetric assay has widely been utilized for urinary 5-HIAA via its reaction with 1-nitroso-2-naphthol (NNa) in nitrous acid medium. However, this colorimetric assay has been criticized for lack of specificity. Herein, we proposed a novel SERS-based method for selective detection of urinary 5-HIAA by the use of a modified nitrosonaphthol reaction, in which hydrochloric acid is substituted for nitric acid to control the reaction conditions. This slight modification is crucial to be able to detect the cationic products in the acidic reaction mixture, because the chloride-aggregated Ag colloids not only create enormous hot spots for SERS enhancement, but also improve the chemical stability of nanostructured Ag substrates in acidic environment. Under optimized conditions, the present method can detect 5-HIAA within 12 min at concentrations as low as 1.2 ng/mL, which is 1000 times lower than that of conventional colorimetric method . And more importantly, the present method exhibits specific response toward 5-HIAA against other metabolites with similar structures in the urine. The relative standard deviation (RSD) of the present method is less than 5%, suggesting the acceptable reproducibility. The recoveries ranging from 89.6% to 106.3% were obtained for spiked human urine samples with RSD of 3.7–4.9%. Furthermore, several healthy person’s urine samples were also analyzed using the present method, and experimental results are in compliance with the levels recorded in a healthy population. On the basis of these results we can conclude that the present SERS-based method can provide a valuable alternative to conventional colorimetric assay for clinical diagnosis, evaluating prognosis, and monitoring of treatment in carcinoid tumors.
Kai Wu,Wenlong Wang,Shubing Yang,Xu Zhang,Peizeng Yang,Yuefei Ji,Jing Chen,Junhe Lu
As global warming intensifies freeze-thaw cycles, the understanding of environmental chemistry processes in ice and their potential impact on global water quality becomes increasingly important. This study investigated the transformation of 1-naphthol in the presence of nitrite (NO 2 - ) under slightly acidic conditions in ice, focusing on the formation of nitro-naphthol. Results demonstrated that increasing NO 2 - concentration enhanced the conversion of 1-naphthol and the formation of nitrated products. This transformation of 1-naphthol was attributed to the freeze-concentration effect, which led to the accumulation of H + , NO 2 - , and 1-naphthol in the liquid-like grain boundary layer amid ice crystals. In this brine, NO 2 - underwent protonation to form reactive nitrous acid (HNO 2 ) and nitrosonium ions (NO + ), which facilitated the nitration, nitrosation, and oxidative coupling reactions, respectively. The pH was shown to influence nitro products formation by altering the HNO 2 to NO + ratio. Toxicity assessment revealed increased toxicity of the NO 2 - /1-naphthol solution after freezing treatment, likely due to the formation of nitrated products, whereas natural organic matter (NOM) reduced this toxicity by suppressing the generation of nitrated products. The findings of this study advance the understanding of NO 2 - chemistry and the behavior of hydroxylated polycyclic aromatic hydrocarbons in cold environments.
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