目的 筛查并确证不在饲料常规检测范围、完全未知的新型非法添加物异噻唑啉酮。 方法 样品经酸性乙腈提取后稀释，利用超高效液相色谱-四级杆-静电场轨道阱高分辨质谱仪测定。依据农业农村部第312号公告（2020年）规范性要求，对照采集的全扫描及二级扫描数据筛查并确证非目标物。 结果 确证饲料中非法添加异噻唑啉酮药物，并检测出药物质量分数为0.76%。 结论 本研究在饲料领域检出异噻唑啉酮工业杀菌剂非法添加的潜在风险，筛查与确证的思路和方法具有可推广性的借鉴意义。

Objectives The new illegal additive isothiazolinone, which is completely unknown and not within the scope of routine feed testing, was screened and confirmed. Methods The sample was diluted after extraction with acidic acetonitrile and determined with ultra-high performance liquid chromatography-quadrupole-electrostatic field orbitrap high resolution mass spectrometer (UPLC-Q-Exactive Orbitrap MS). Non-target substances were screened and confirmed by comparing the collected full-scan and second-level scan data according to the normative requirements of Announcement No. 312 (2020) of the Ministry of Agriculture and Rural Affairs. Results The illegal addition of isothiazolinone drugs was confirmed in feed, and detected the content of drug of 0.76%. Conclusions This study detected potential risks of the illegal addition of isothiazolinone industrial fungicide in the field of feed. The ideas and methods of screening and confirmation have reference significance to be promoted.