McGill University, Department of Natural Resource Science, Macdonald Campus, 21,111 Lakeshore Road, Ste-Anne-de Bellevue, Quebec, H9X 3V9, Canada.
McGill University, Department of Natural Resource Science, Macdonald Campus, 21,111 Lakeshore Road, Ste-Anne-de Bellevue, Quebec, H9X 3V9, Canada.
Talanta. 2020 Aug 15;216:120923. doi: 10.1016/j.talanta.2020.120923. Epub 2020 Mar 12.
Cyanotoxins are associated with harmful cyanobacterial blooms, but also exist in biological soil crusts and soils irrigated with cyanobacteria-contaminated water. To achieve an accurate analysis of cyanotoxins in soil, effective extraction, purification and determination methods are imperative. The most challenging aspect is extracting cyanotoxins from soil, due to their tendency to bind strongly to the soil matrix. We used a methanol-ammonium acetate solution to efficiently extract 17 cyanotoxins (microcystins, cylindrospermopsin, anatoxins, anabaenopeptins and cyanopeptolin) from soil. The extract was purified by on-line solid-phase extraction coupled with ultra-high-performance liquid chromatography tandem mass spectrometry. The optimized procedure involved two ultrasonication cycles of 15 min with 4 mL of methanol + 200 mM ammonium acetate, which recovered 60% to >90% of the added cyanotoxins from five soils with diverse organic matter, pH and texture. The method improved extraction by up to 10 times compared to a methanol/water solution. Linearity, accuracy and precision were validated on matrix-mixed soil with surrogate microcystin and cylindrospermopsin internal standards. Limits of detection were 0.001-0.3 ng g, depending on the cyanotoxins. The method was used to analyze cyanotoxins in 25 field-collected soils from Quebec, Canada. Out of the 25 soil samples, 11 soils had at least one cyanotoxin, and up to 8 different cyanotoxins were detected in one soil. The sum of all microcystins congeners was from 0.02 to 31 ng microcystins g soil. We also detected anabaenopeptin, the first reported occurrence of this cyanotoxin in soil.
蓝藻毒素与有害的蓝藻水华有关，但也存在于生物土壤结皮和被蓝藻污染的水灌溉的土壤中。为了实现对土壤中蓝藻毒素的准确分析，必须采用有效的提取、净化和测定方法。最具挑战性的方面是从土壤中提取蓝藻毒素，因为它们倾向于与土壤基质紧密结合。我们使用甲醇-乙酸铵溶液从土壤中高效提取 17 种蓝藻毒素（微囊藻毒素、节旋螺毒素、anatoxins、anabaenopeptins 和 cyanopeptolin）。提取物通过在线固相萃取与超高效液相色谱串联质谱法进行纯化。优化后的程序涉及两个 15 分钟的超声循环，使用 4 mL 甲醇+200 mM 乙酸铵，从五种具有不同有机质、pH 值和质地的土壤中回收了 60%至>90%的添加蓝藻毒素。与甲醇/水溶液相比，该方法的提取效率提高了 10 倍。在线性、准确性和精密度方面，采用基质混合土壤和替代微囊藻毒素和节旋螺毒素内标进行了验证。根据不同的蓝藻毒素，检测限为 0.001-0.3 ng g。该方法用于分析来自加拿大魁北克省的 25 个野外采集的土壤中的蓝藻毒素。在 25 个土壤样本中，有 11 个土壤至少含有一种蓝藻毒素，在一个土壤中检测到多达 8 种不同的蓝藻毒素。所有微囊藻毒素同系物的总和为 0.02 至 31 ng 微囊藻毒素 g 土壤。我们还检测到了 anabaenopeptin，这是该蓝藻毒素首次在土壤中被发现。
