Establishment and application of a new serum sodium candidate reference method

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• Serum sodium (Na) levels are critical clinical diagnostics.
• Accurate sodium quantification requires reliable laboratory methods.
• Evaluation of a novel inductively coupled plasma mass spectrometry (ICP-MS) method for serum sodium measurement.

Purpose of the Study:

• To assess the analytical performance of a new ICP-MS method for serum sodium quantification.
• To compare the ICP-MS method with existing sodium measurement techniques.
• To determine the suitability of the ICP-MS method as a reference method.

Main Methods:

• Serum samples were diluted and analyzed using ICP-MS with germanium (Ge) as an internal standard.
• Sodium calibration solutions were used with a standard addition method for quantification.
• Analytical performance, including precision and accuracy, was evaluated.

Main Results:

• The ICP-MS method demonstrated excellent linearity (r > 0.9999) and low coefficients of variation (<0.67%).
• Trueness was confirmed using a certified reference material (SRM 956d).
• Results showed high correlation (r = 0.9914) with the indirect ion-selective electrode (ISE) method, with a mean deviation of -0.15%.

Conclusions:

• The developed ICP-MS method is accurate, reliable, simple, and fast.
• This method is a strong candidate for a reference method in serum sodium standardization.
• It can aid in setting target values for routine laboratory measurements.