The quantitative determination of intact proteins in biological samples by LC with high-resolution MS detection can be a useful alternative to ligand-binding assays or LC-MS-based quantification of a surrogate peptide after protein digestion. The 22-kDa biopharmaceutical protein somatropin (recombinant human growth hormone) was quantified down to 10 ng/mL (0.45 nM) in 75 μL of rat plasma by the combination of an immunocapture step using an anti-somatropin antibody and LC-MS on a quadrupole-time of flight instrument. Accuracy and precision of the method as well as its selectivity and sensitivity did not depend on the width of the mass extraction window nor on whether only one or a summation of multiple charge states of the protein analyte were used as the detection response. Quantification based on deconvoluted mass spectra showed equally acceptable method performance but with a less favorable lower limit of quantification of 30 ng/mL. Concentrations in plasma after dosing of somatropin to rats correlated well for the deconvolution approach and the quantification based on the summation of the response of the four most intense charge states (14+ to 17+) of somatropin.

中文翻译：

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通过液相色谱-高分辨率质谱分析生物样品中完整的蛋白质定量：大鼠血浆中的生长激素。

用高分辨率MS检测通过LC定量测定生物样品中完整蛋白的方法，可以替代配体结合测定或蛋白质消化后基于LC-MS的替代肽定量。通过使用抗生长激素抗体和LC-MS的免疫捕获步骤的组合，在75μL大鼠血浆中将22 kDa生物制药蛋白生长激素（重组人生长激素）定量至10 ng / mL（0.45 nM）。四极飞行时间仪。该方法的准确性和精密度以及其选择性和灵敏度既不取决于质量提取窗口的宽度，也不取决于蛋白质分析物的仅一种电荷状态还是多种电荷状态的总和用作检测响应。基于解卷积质谱的定量显示了同样可接受的方法性能，但定量下限为30 ng / mL，效果较差。向大鼠给药生长激素后，血浆中的浓度与去卷积方法和基于生长激素的四个最强电荷态（14+至17+）的响应之和的定量相关性很好。