Payne R B, Buckley B M, Rawson K M
Department of Chemical Pathology, St James's University Hospital, Leeds, UK.
Ann Clin Biochem. 1991 Jan;28 ( Pt 1):68-72. doi: 10.1177/000456329102800111.
There is controversy about whether protein interferes with ion measurements using ion-selective electrodes. We have investigated the effects of changes in the salt-bridge composition of five commercially available analysers with open, membrane-restricted or porous frit-restricted reference electrode junctions on measurements of an albumin solution prepared by gel filtration. When the manufacturers' salt bridges were used, instruments with open or membrane-restricted junctions showed apparent increases in the activity of ionized calcium, sodium and potassium in the presence of protein. When the hypertonic bridge solutions were replaced with 150 mmol/L potassium chloride this increase disappeared. The instrument with a porous frit-restricted junction showed no protein effect, but its response to changes in sample sodium chloride concentration in protein-free solution suggested that its junction was functionally equivalent to that formed with an isotonic sodium chloride bridge. Our results emphasize that liquid junction design and composition affect ion measurements in protein-containing solutions and suggest that the use of hypertonic bridge solutions for biological samples needs to be re-examined.
关于蛋白质是否会干扰使用离子选择电极进行的离子测量存在争议。我们研究了五种市售分析仪的盐桥组成变化的影响，这些分析仪具有开放、膜限制或多孔玻璃料限制的参比电极接头，对通过凝胶过滤制备的白蛋白溶液进行测量。当使用制造商的盐桥时，具有开放或膜限制接头的仪器在蛋白质存在下显示出离子钙、钠和钾的活性明显增加。当用150 mmol/L氯化钾替代高渗桥溶液时，这种增加消失。具有多孔玻璃料限制接头的仪器未显示出蛋白质效应，但其在无蛋白质溶液中对样品氯化钠浓度变化的响应表明，其接头在功能上等同于用等渗氯化钠桥形成的接头。我们的结果强调，液体接头的设计和组成会影响含蛋白质溶液中的离子测量，并表明需要重新审视将高渗桥溶液用于生物样品的情况。
