The pendant drop tensiometry is a preferred primary method for measuring interfacial tension (IFT) or surface tension. In a typical experimental setup, Gravitational pull opposes an interfacial tension forces to cause a liquid drop to develop into a pendant-like shape. The process comprises quantitatively modifying a theoretical profile generated through calculating the Young–Laplace capillarity formula to such an experimental pendant drop analysis and information by performing digital image analysis. However, specific parameters of this method lead to uncertainty in the obtained value of IFT. The present work aims to determine the role of factors such as evaporation of the hanging drop and its changing volume in interfacial tension, which is acting as major source of error in determining IFT of distilled water. This study details the measurement process and evaluation of standard errors with interfacial tension readings of distilled water by using pendant drop method with three calibrated needles of diameters, 0.9 mm (20 G), 1.27 mm (18 G) and 1.65 (16 G) mm. The needle’s diameter influenced the evaporation rate and the value of IFT. Also, it is essential to consider these factors for further evaluating measurement uncertainties when determining the IFT of biological fluids. In addition, the present study makes an effort to determine the measurement error associated with drop volume and evaporation rate of drop in study. The distilled water used in the measurement had an absolute Interfacial tension of 72 mN/m, and the enlarged measurement errors were predicted to be in the range of 0.4–0.6%. It is critical to consider these associated measurement errors when determining the IFT of liquids for metrological application such as establishing primary standards for measurement pertaining to biological fluids.

悬滴张力测定法是测量界面张力 (IFT) 或表面张力的首选主要方法。在典型的实验装置中，重力与界面张力相反，导致液滴发展成悬垂状。该过程包括通过执行数字图像分析将通过计算杨-拉普拉斯毛细管公式生成的理论轮廓定量修改为这样的实验悬滴分析和信息。然而，该方法的具体参数导致获得的IFT值存在不确定性。目前的工作旨在确定诸如悬滴蒸发及其体积变化等因素在界面张力中的作用，这是确定蒸馏水 IFT 的主要误差来源。本研究详细介绍了使用悬滴法使用直径为 0.9 mm (20 G)、1.27 mm (18 G) 和 1.65 (16 G) mm 的三种校准针测量蒸馏水界面张力读数的标准误差的测量过程和评估。针的直径影响蒸发速率和IFT 值。此外，在确定生物液体的 IFT 时，必须考虑这些因素以进一步评估测量不确定性。此外，本研究还努力确定与研究中液滴体积和液滴蒸发速率相关的测量误差。测量中使用的蒸馏水的绝对界面张力为72 mN/m，预计放大的测量误差在0.4-0.6%范围内。在确定计量​​应用（例如建立生物液体测量的主要标准）的液体 IFT 时，考虑这些相关的测量误差至关重要。