Analytical Sciences最新文献

Detections of elements and molecules in coffee beans were carried out using single ICP-MS/MS coupled with a laser ablation sampling technique. For elemental analysis, laser-induced sample particles were introduced into the ICP, where the elements were ionized as M⁺ through the hard ionisation achieved in the high-temperature and atmospheric-pressure plasma (ICP). For molecular analysis, volatile organic compounds (VOCs) which were released from the solid material through laser-induced sample heating were introduced into collision/reaction cell (CRC), instead of the ICP ion source. The VOCs were ionised through ion reaction with ⁴⁰Ar⁺. After a 1-s laser ablation, isotopic signals of ²⁴Mg, ⁴³Ca, and ⁵⁹Co were observed at around 4 s, followed by protonated or molecular ions corresponding to butene, propanal, furan, butanone, pyridine, and methylfuran. In this study, the ionisation features of the VOCs released from milled coffee beans was investigated. The resulting VOCs were ionized either through ion reaction with ⁴⁰Ar⁺ or cationisation with three ions (⁷Li⁺, ²³Na⁺, and ¹⁰⁷Ag⁺). Among two ionisation approaches, cationisation with ¹⁰⁷Ag⁺ proved to be the most effective, yielding both the lowest fragmentation and the highest production efficiencies of cation adducts. These results clearly demonstrate that LA-ICP-MS/MS is now a rapid and versatile technique for detecting both elements and molecules in solid materials.

Glycerin is widely used in pharmaceuticals, cosmetics, and foods. In recent years, it has been mainly derived from plant-based materials, particularly palm oil. The most abundant polyphenol in palm oil is 3-O-caffeoylshikimic acid (CSA). Polyphenols reportedly react with oxygen to generate hydrogen peroxide (H₂O₂). In this study, we investigated the generation of H₂O₂ from CSA and palm-derived glycerin using the bis(2,4,6-trichlorophenyl)oxalate (TCPO) chemiluminescence method and electron spin resonance spectroscopy. H₂O₂ concentrations in the range of 10⁻⁴ to 10⁻⁶ mol/L were detected in commercial glycerin samples. In addition, the H₂O₂ concentrations in a commercial glycerin varied widely between batches, even among samples of glycerin produced by the same company. However, the concentrations were approximately 1/1000 of that permitted in disinfectants used in pharmaceuticals, indicating extremely low biological toxicity. Furthermore, the TCPO chemiluminescence method proved to be highly sensitive and precise, even in viscous glycerin samples, showing potential for application in quality control of glycerin formulations and related industrial products.

Ochratoxin A (OTA), a highly toxic mycotoxin, extensively contaminates a wide range of food commodities. Given increasing demands for sensitive and user-friendly detection platforms, we developed a colorimetric OTA biosensor leveraging copper-silver nanoclusters (Cu/Ag NCs), whose peroxidase-like activity is augmented via G/C-rich DNA hybridization. The system employs two tailored DNA strands: a template strand featuring a cytosine-rich domain for NC synthesis flanked by terminal recognition segments and an enhancer strand containing a guanine-rich signal amplification domain and a complementary linker. Upon OTA binding with the aptamer, the apt-template complex dissociates, facilitating template-enhancer hybridization to form G/C-rich double-stranded DNA. This structural transition substantially enhances the peroxidase-like activity of DNA-Cu/Ag NCs, accelerating the oxidation of 3,3',5,5'-tetramethylbenzidine by H₂O₂ while simultaneously amplifying the colorimetric signal. Quantitative OTA detection is accomplished by monitoring this dynamic color response. The biosensor demonstrates a semi-log linear detection range from 5.0 nM to 1.0 μM with a detection limit of 5.0 nM. Furthermore, the specific test has high selectivity for other common mycotoxins, and its applicability has been validated through real sample analysis, suggesting that the DNA-Cu/Ag NCs biosensor used for OTA detection holds promising practical applications in food samples.