Search

Sudan dyes are strictly prohibited from being added to edible products as carcinogens and tetracycline hydrochloride (TC) remaining in animal-derived food may cause harm to the human body. Therefore, it is necessary to establish a high-sensitivity, simple and convenient method for the detection of Sudan dyes and TC in foods for safety purposes. In this work, multifunctional blue fluorescent carbon dots (B-CDs) were prepared by a one-step hydrothermal synthesis using glucose as the carbon source. The results show that the fluorescence intensity of B-CDs was significantly affected by the acidity of the solution and can be quenched by Sudan I, IV and TC through selective studies. Interestingly, the fluorescence quenching intensities of B-CDs have a good linear relationship with the concentration of Sudan I and IV at pH = 3–7. The wide range of pH is beneficial to broaden the application of B-CDs in a practical samples analysis. The method has been successfully applied to real food samples of tomato paste, palm oil and honey, and the detection limits are 26.3 nM, 54.2 nM and 31.1 nM for Sudan I, Sudan IV and TC, respectively. This method integrates Sudan dyes and TC into the same multifunctional B-CDs, which shows that the sensor has a great potential in food safety detection. [ABSTRACT FROM AUTHOR]

Abstract: A flow injection (FI) on-line preconcentration procedure for ultra-trace inorganic selenium was developed with detection by atomic fluorescence spectrometry. Selenium (IV) is co-precipitated with lanthanum hydroxide and collected on a PTFE beads packed column, the precipitate is afterwards dissolved with hydrochloric acid followed by hydride generation with reduction by tetrahydroborate. A thorough scrutiny was made for chemical variables and FI parameters. With a sampling volume of 3.4 ml, quantitative retention of selenium (IV) was obtained, along with an enrichment factor of 11 and a sampling frequency of 38 h−1. The detection limit, defined as 3 times the blank standard deviation (3σ), was 5 ng l−1. The precision was characterized by a RSD value of 1.2% (at the 0.5 μg l−1 level, n =11). The enrichment factor was further enhanced to 20 along with a detection limit of 3 ng l−1, with a sample loading volume of 6.8 ml. The procedure was validated with certified reference materials and biological samples. It was also applied to the speciation of inorganic selenium in surface waters. [Copyright &y& Elsevier]

A simple low-molecular-mass organic gelator based on salicylaldehyde acylhydrazone had been synthesized and carefully studied. This gelator could form a thermo-reversible supramolecular organogel in many solvents by self-assembling them into nanofibers. Notably, it could even solidify crude oil floating on seawater. Moreover, the gelator was triggered to form a yellow metallogel with blue-green fluorescence by adding Y3+. In addition, it could act as an efficient fluorescent probe for the selective sensing of Y3+ in the solution containing water. The detection limit of Y3+ was 1.039 μM. Furthermore, test strips containing this compound were prepared, successfully used for on-site monitoring of Y3+ in water. [Display omitted] • A simple gelator based on salicylaldehyde acylhydrazone has been developed. • The compound exhibits excellent gel properties, including solidifying crude oil. • The compound can act as a highly selective fluorescent probe for Y3+. • The test strip containing the compound can detect Y3+ in water. [ABSTRACT FROM AUTHOR]