Folic acid (FA) is an ingredient that must be added to infant milk powder to avoid potential defects. Rapid, sensitive and reliable detection methods are needed to determined FA addition levels. Thus, this study established a microsphere immunochromatographic test strip for time-resolved luminescence detection (TRLM-ICTS) based on carboxyl-functionalized time-resolved luminescent microspheres (Eu-TRLMs) prepared by a one-step method as fluorescent markers for the immediate quantitative detection of FA in milk powder. Eu-TRLMs prepared by the one-step method showed good dispersion, high stability and strong fluorescence intensity, which is improving the sensitivity of TRLM-ICTS. In the performance evaluation of TRLM-ICTS, the detection limit was 0.487 ng mL⁻¹, the recovery rate was 97.3–105 %, and the actual sample detection results were in line with those of UPLC-MS/MS. TRLM-ICTS has the advantages of rapid, high sensitivity and strong specificity and could as a practical quantitative detection method for the detection of FA in milk powder.

叶酸 (FA) 是一种必须添加到婴儿奶粉中以避免潜在缺陷的成分。需要快速、灵敏和可靠的检测方法来确定 FA 添加水平。因此，本研究以一步法制备的羧基功能化时间分辨发光微球（Eu-TRLMs）为荧光标记，建立了用于时间分辨发光检测的微球免疫层析试纸条（TRLM-ICTS），用于即时定量检测。奶粉中 FA 的检测 一步法制备的Eu-TRLMs分散性好、稳定性高、荧光强度强，提高了TRLM-ICTS的灵敏度。在TRLM-ICTS的性能评估中，检出限为0.487 ng mL ^-1,回收率为97.3~105%,实际样品检测结果与UPLC-MS/MS一致。TRLM-ICTS具有快速、灵敏度高、特异性强等优点，可作为一种实用的奶粉中FA的定量检测方法。