Sulfur dioxide (SO2) is used as a universal additive to wine due to its excellent antioxidative, antimicrobic, and anti-brown characteristics and also because it is the product of natural fermentation of grapes. The concentration of SO2 in wine is strictly regulated since SO2 at high concentrations can damage tissues, organs, and various systems of human beings. In this study, an atomic fluorescence spectrometer (AFS) was used for the determination of SO2 by measuring its molecular fluorescence signal excited by a zinc hollow cathode lamp (Zn HCL, 213.8 nm) under simple and mild conditions without igniting the atomizer. The instrumental settings were first optimized by detecting gaseous SO2 prepared in advance. Under the optimal conditions, the instrumental limit of detection (LOD) for SO2 was found to be 0.17 μg, and the relative standard deviation (RSD) of 200 μg SO2 was 1.3%. The method was developed for determining the total SO2 in wine samples extracted by sodium hydroxide and generated in the form using sulfuric acid. The LOD of 0.79 μg mL−1 for this method was achieved for the total SO2 analysis of wine samples with a 5.2% RSD at a concentration level of 30 μg mL−1. The advantages of this method are simplicity, high throughput, less interference, relatively low cost, and less chemical consumption.
Xiaozhi Wang,Weijun Zhao,Lingfeng Li,Xiangyang Wang,Peng Li,Yu Wang,Jikui Luo
Sulfites (sulfur dioxide) and inorganic sulfites are types of food additives and preservatives, widely used in the production of food and herbal medicines (HMs). However, the overingestion of sulfites and its associates are harmful to human health and may cause medical complications. Various methods and instruments have been developed for measuring sulfites in foods and HMs, but they typically suffer from many issues, such as high detection limitation, inaccurate and non-reliable results, time and labor-intensive sample preparation, and high cost. Herein, we present a fast, sensitive, and quantitative method to determine sulfites in HMs using field asymmetric-wave ion mobility spectrometry (FAIMS) coupled with a headspace bubbling method. The headspace air bubbling method is effective and efficient at generating stable sulfur dioxide (SO2) in the gas phase for FAIMS analysis. It allows sulfites with a concentration down to 1 mg kg−1 to be easily detected by this new method in 20 min, much shorter than with current technologies. The limits of detection (LOD) and limits of quantification (LOQ) are 1 mg kg−1 and 3 mg kg−1 in HMs, respectively. The new method is of great significance to ensure medical safety and for HM production quality control.
Kexin Pan,Liyuan Chen,Guangjun Tian,Juyue Zhou,Suying Xu,Leyu Wang
Development of fluorescent probes with high sensitivity and specificity is always desirable, yet, challenging. Conventionally, improving the responses of probes relied on optimizing the reactivities of recognition sites, either by increasing the binding affinity or reaction rates. Herein, we found the sensitivity and response kinetics could be improved by changing the aggregation behaviors of probes. As a proof-of-concept, benzothiazole derivatives with different side chain lengths were prepared and the enhanced responses toward sulfur dioxide (SO 2 ) were observed for the probe with longer side chain. We demonstrated that the long side chain facilitates formation of tightly aggregates, which possessed higher positive charges and susceptible recognition sites as compared with probes possessing short side chains, resulting in better sensitivity and faster responses. In addition, we also demonstrated the generality of such design protocols with probes displaying aggregation induced emission (AIE) properties. Thus, the proposed side chain engineering strategy provides new paradigm for probe design.
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