Delipidated Human Serum for IVD Assay Development — Complete Guide

Delipidated human serum is one of the most misunderstood reagents in IVD assay development. Many labs order it without fully understanding what lipid removal actually does to serum composition — and how that affects their assay. This guide covers everything you need to know before reaching for a delipidated lot.

What Is Delipidated Human Serum?

Delipidated human serum is processed human serum from which lipoproteins and lipids have been selectively removed. The most common method is lipoprotein precipitation — treating the serum with a precipitating agent that causes lipoproteins (LDL, VLDL, chylomicron remnants) to aggregate and sediment, which are then removed by centrifugation. The resulting serum is optically clear with significantly reduced lipid content.

The key point: delipidation is selective. Unlike activated charcoal treatment, standard lipoprotein precipitation does not remove hormones, steroids or most proteins. IgG, albumin and most growth factors remain intact — which is exactly what you want when you need a lipid-free matrix without disturbing the rest of the serum composition.

Why You Need Lipid-Free Serum Matrix

Lipemia — elevated lipid content in a serum sample — is one of the three most common sources of preanalytical interference in clinical chemistry, alongside haemolysis and icterus. It causes errors through several distinct mechanisms:

• Light scattering: Triglyceride-rich particles (chylomicrons, VLDL) scatter light across the entire UV/Vis spectrum. In photometric assays this looks like increased absorbance — which the instrument interprets as more analyte.
• Surface binding: Lipid particles adsorb non-specifically to antibody-coated surfaces in immunoassays, reducing effective binding capacity and increasing background noise.
• Volume displacement: The lipid volume displacement effect causes pseudohyponatremia in ISE-based sodium assays — a well-documented clinical interference.
• Electrode interference: In direct ISE assays, lipid layers can transiently block electrode surfaces.

How to Use Delipidated Serum in a CLSI EP7 Lipemia Study

The standard CLSI EP7 approach for lipemia interference characterisation uses a dose-response design: you create a series of serum samples with increasing triglyceride concentrations and measure your analyte at each level. Delipidated serum serves as the zero-lipid baseline matrix.

1. Start with delipidated serum — your "zero lipid" matrix. Confirm it is optically clear and contains your analyte of interest at a clinically relevant concentration.
2. Prepare a lipid stock — typically Intralipid 20% (intravenous lipid emulsion) or ultracentrifugation-concentrated native lipemic serum. Mix with delipidated serum to achieve target triglyceride concentrations.
3. Test at increasing lipid levels — typically 5–7 concentrations from baseline to the maximum expected in clinical samples (e.g. 200, 500, 1000, 2000, 3000, 5000 mg/dL triglycerides).
4. Calculate % bias at each concentration vs. your baseline (delipidated serum with no lipid addition). Your acceptance criterion (e.g. ±10% bias) defines your interference threshold.
5. Document and report in your IVD technical file under EU IVDR 2017/746.

Standard Delipidated vs. Double Charcoal Stripped — Which Do You Need?

For CLSI EP7 lipemia interference studies, standard delipidated serum (SP1010) is the correct choice. Charcoal stripping removes more than lipids — it also strips hormones and growth factors, which introduces unnecessary variables into your lipemia study. Use charcoal-treated serum when the application specifically requires hormone or steroid depletion.

The IgG-Free Variant — When It Matters

The IgG-depleted delipidated variant (Humser_delip) removes both lipids and endogenous IgG. This is specifically useful for antibody detection assays where residual IgG in the matrix would produce background signal that masks or distorts the analyte-specific signal. Examples include ELISA-based antibody tests for infectious disease serology, autoimmune markers and allergen-specific IgE assays where high non-specific IgG creates noise in the baseline.

EU IVDR Considerations for Matrix Material Selection

Under EU IVDR 2017/746, IVD manufacturers must document that calibrators and quality controls use matrix material appropriate to the intended analytical system. This means your interference study documentation should include the source of your baseline matrix material, including donor origin and processing method.

Using EU-qualified donor material processed under EU Blood Directive 2002/98/EC gives you the cleanest regulatory pathway. All SeamlessBio delipidated serum variants are from EU-qualified donors with full origin documentation.