Laboratori de Bromatologia i Toxicologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, València, Spain.
Talanta. 2009 Nov 15;80(1):294-306. doi: 10.1016/j.talanta.2009.06.062. Epub 2009 Jul 4.
Beta-casomorphins (b-CMs) are bioactive peptides derived from casein with opioid agonist effects similar to morphine. The use of electrospray (ESI) with quadrupole ion-trap mass spectrometry (QIT-MS) for these compounds in two matrices, cheese and milk, was examined. It was compared to a liquid chromatography (LC) coupled to mass spectrometry (LC-MS), and a "soft" ionisation technique, NanoMate, with selected ion monitoring (SIM), which are unreliable for the determination of trace casomorphins in derived milk products. b-CM mass fragmentation pathways were done for the four most common b-CMs: beta-casomorphin (1-5) bovine (b-CM-5), beta-casomorphin (1-7) bovine (b-CM-7), [D-Ala2, D-Pro4,Tyr5]-beta-casomorphin (1-5) amide (b-CM-10) and beta-casomorphin (1-5) amide [D-Ala2,Hyp4,Tyr5] (b-CM-11). The major product ions obtained in QIT-MS were used to construct fragmentation pathways for b-CMs. The different collision energies using automated nanoelectrospray ion source NanoMate and conventional LC in QIT-MS were studied. Calibration data for b-CMs, using spiked milk or cheese samples (10 g or 10 mL), were: NanoMate/MS (25-1000 microg/L), r(2)=0.998; NanoMate/MS(2) (5-1000 microg/L), r(2)=0.9992; NanoMate/MS(3) (2.5-1000 microg/L), r(2)=0.9998. Reproducibility data (% RSD, N=5) for NanoMate/MS(n) mode ranged between 2.0 at 500 microg/L and 7.0 at 10 microg/L.
β-酪啡肽（β-CMs）是源自酪蛋白的生物活性肽，具有与吗啡相似的阿片样激动作用。本文采用电喷雾（ESI）与四极杆离子阱质谱（QIT-MS）联用，对奶酪和牛奶两种基质中的这些化合物进行了研究。并与液相色谱（LC）-质谱（LC-MS）联用和“软”电离技术 NanoMate 与选择离子监测（SIM）进行了比较，后两种方法在痕量酪啡肽的测定中不可靠，特别是在衍生乳制品中。本文对四种最常见的β-CMs 进行了β-CM 质量碎裂途径研究：β-酪啡肽（1-5）牛（b-CM-5）、β-酪啡肽（1-7）牛（b-CM-7）、[D-Ala2，D-Pro4，Tyr5]-β-酪啡肽（1-5）酰胺（b-CM-10）和β-酪啡肽（1-5）酰胺[D-Ala2，Hyp4，Tyr5]（b-CM-11）。在 QIT-MS 中，主要得到的产物离子用于构建β-CMs 的碎裂途径。研究了使用自动纳升电喷雾源 NanoMate 和常规 LC 在 QIT-MS 中不同的碰撞能量。使用加标牛奶或奶酪样品（10 g 或 10 mL）进行β-CMs 的校准数据为：NanoMate/MS（25-1000 μg/L），r（2）=0.998；NanoMate/MS（2）（5-1000 μg/L），r（2）=0.9992；NanoMate/MS（3）（2.5-1000 μg/L），r（2）=0.9998。NanoMate/MS（n）模式的重复性数据（%RSD，N=5）在 500 μg/L 时为 2.0，在 10 μg/L 时为 7.0。
