van Ingen H E, Huijgen H J, Kok W T, Sanders G T
Academic Medical Centre, Dept. of Clinical Chemistry, Amsterdam, The Netherlands.
Clin Chem. 1994 Jan;40(1):52-5.
We performed an analytical evaluation of a commercially available instrument for determining ionized magnesium through use of a neutral carrier, liquid-membrane-based ion-selective electrode. Reproducibility (CV 2-4%), linearity (0.30-2.50 mmol/L), lower limit of detection (0.30 mmol/L), and absence of interference from Ca2+ indicate adequate performance for measuring ionized magnesium in plasma or serum samples in the normal to high-concentration range. Sodium in excess of 150 mmol/L caused a negative bias, which can be explained by ionic strength-induced changes in activity coefficients. The use of heparin as an anticoagulant must be restricted to concentrations < 15 units/mL because of the binding of magnesium to heparin. The mean +/- SD concentration of ionized magnesium and its fraction of total magnesium in 76 healthy volunteers were 0.56 +/- 0.05 mmol/L and 0.65 +/- 0.04, respectively.
我们使用基于中性载体、液膜的离子选择性电极对一种市售的用于测定离子化镁的仪器进行了分析评估。该仪器的重现性（变异系数为2%-4%）、线性范围（0.30-2.50 mmol/L）、检测下限（0.30 mmol/L）以及不受Ca2+干扰，表明其在正常至高浓度范围内测定血浆或血清样本中离子化镁时性能良好。超过150 mmol/L的钠会导致负偏差，这可以通过离子强度引起的活度系数变化来解释。由于镁会与肝素结合，因此肝素作为抗凝剂的使用浓度必须限制在<15单位/mL。76名健康志愿者的离子化镁平均浓度±标准差及其占总镁的比例分别为0.56±0.05 mmol/L和0.65±0.04。
