Isotope data of key pollutants are needed for source apportionment analysis in natural ecosystems. Isotope data for cadmium (Cd), a rare and dispersed but toxic element, are very limited mainly due to its low contents in the natural environment. In this study, for samples with low Cd content but high organic matter content, a dry ashing pre-treatment method was proposed to effectively enrich Cd to meet the requirements of its isotope analysis (Cd content > 20 ng). This method was applied to soils, sediments, biological tissues, and coal, with a maximum digestion weight of 1.67 g or more. With the assistance of quartz microfiber filter membranes during dry ashing, good Cd recovery (91.6–108.0%) and significant removal of organic matter were achieved. Mass bias was corrected by combining the silver external standard (Ag-doping) method with the sample-standard-bracketing (SSB) method, and Cd isotope measurements were performed under wet plasma conditions (with an accuracy of 0.060‰). Cd isotopic compositions obtained by the dry ashing method were compared with those obtained by the high-pressure bomb digestion method, and the differences ranged from −0.056 to 0.076‰, indicating that the dry ashing with wrapped membranes method did not cause any fractionation of Cd during the sample pre-treatment process. Meanwhile, the tolerance of tin (Sn) and zinc (Zn) elements provided a significant advantage under wet plasma conditions over dry plasma conditions without reducing the tolerance of molybdenum (Mo) and zirconium (Zr). The method developed in this study should enhance the application of Cd isotopes in investigating Cd cycling in primary ecosystems and organisms.
Bo Zhang,Yang Liu,Shengnan Li,Ruonan Li,Yunhui Zhang,Hua Zhao
Wild mushroom poisoning is an emerging global food safety issue, especially in subtropical regions like southwestern China, where incidents are geographically clustered. Current detection methods are often time-consuming and overlook region-specific toxins. We developed a rapid, sensitive, and accurate method for the simultaneous detection of ten characteristic mushroom toxins prevalent in Guizhou, China. The method combines graphite multi-walled carbon nanotubes (G-MWCNTs) for sample preparation with Orbitrap high-resolution mass spectrometry (HRMS). Wild mushroom samples were extracted via ultrasonic-assisted methanol–water extraction, purified using G-MWCNTs, and separated on a Hypersil GOLD C18 column (100 mm × 2.1 mm, 1.9 μm). Gradient elution was performed with 0.1% formic acid + 0.01% ammonia and acetonitrile; quantification used the external standard method. The method achieved LODs of 0.005–0.2 mg/kg and LOQs of 0.015–0.6 mg/kg, with RSDs below 18.11% and excellent linearity (R2= 0.9936–0.9989). Among 45 wild mushroom samples, toxin levels ranged from 0.032 to 445.10 mg/kg, with a detection rate of 22.22%, suggesting notable poisoning risk. This method reduces pretreatment time while ensuring high analytical performance, offering a reliable tool for rapid toxin screening and supporting regional surveillance of wild mushroom poisoning.
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