This page explains the HPLC method used to measure polyphenol content in olive oil. If you have seen the figure 1,004 mg/kg on our product and wondered what it actually represents — this is where to start.
What is HPLC?
HPLC stands for High-Performance Liquid Chromatography. It is an analytical method for separating, identifying, and quantifying individual chemical compounds in a sample.
The method is standard in food chemistry, the pharmaceutical industry, and environmental analysis. Within the olive oil industry, HPLC is the established method for polyphenol analysis — the one referenced by the IOC (International Olive Council) and EFSA in their technical standards.
How an HPLC analysis works
An oil sample is mixed with a solvent to extract polyphenols from the fat. The extract is then injected into an HPLC instrument, which consists of three main parts:
The column. A narrow metal tube packed with a porous material (stationary phase). The different compounds in the sample interact with the column material to different degrees and therefore travel through the column at different speeds — they are separated.
The solvent flow. A mixture of solvents (mobile phase) is pumped through the column at high precision, driving the sample compounds forward at a controlled rate.
The detector. Typically a UV detector. As each compound passes through, it produces a signal proportional to its concentration in the sample.
The result is a chromatogram — a graph showing peaks at the points where each compound passes the detector. Each peak is identified and quantified against reference substances of known concentration.
What a mg/kg value actually represents
The result is expressed in milligrams of polyphenols per kilogram of oil (mg/kg). It is a summed value of the individual polyphenols measured by the method — oleocanthal, oleuropein and its derivatives, hydroxytyrosol, tyrosol, and other identified compounds are added to produce a total.
It is not an index or an estimate. It is a measured quantity of specified chemical compounds in a specified sample, analysed by a specified method at a specified laboratory.
Vala Selection's reference batch 2025-VL-MIR-001 was analysed at the University of Split and measured at 1,004 mg/kg. That is the value stated on the product.
Why values can differ between laboratories
Even though the underlying principle is the same, HPLC values can vary because of:
- Extraction method. Different solvents and procedures capture polyphenols with different efficiency.
- Column and mobile phase selection. Separation characteristics affect which compounds are identified and how.
- Calibration. Quantification against reference substances requires well-calibrated standards; laboratories may use different reference solutions.
- Compounds included. Some laboratories measure a broader spectrum of compounds; others measure a narrower one. The total is affected accordingly.
This means a value from one laboratory is not directly comparable to a value from another unless the method is specified. Our analysis is carried out at the University of Split with a method adapted for olive oil analysis and applied consistently across batches.
What HPLC does not measure
HPLC measures chemical composition, not biological effect. That a sample contains 1,004 mg/kg of polyphenols is a statement about the oil's chemistry — not about what happens in the body.
The relationship between polyphenol content and health outcomes is a separate scientific and regulatory question. The only EFSA-authorised claim relevant to olive oil concerns the protection of blood lipids from oxidative stress — and it requires the oil to exceed a specific threshold of hydroxytyrosol and its derivatives per 20 g. See /fact/polyphenols-and-oxidative-stress/ for a full account.
What this does not mean
An HPLC analysis gives an exact chemical answer to an exactly defined question. It does not answer how the oil tastes, how long it keeps, or what it does in the body. Those are three separate questions requiring three separate methods.
The figure 1,004 mg/kg is traceable to a specific batch, a specific laboratory, and a specified method. It is not a guarantee that the next batch, next year, will yield exactly the same result — polyphenol content varies with harvest year and growing conditions.
Further reading
On polyphenols as a group: /fact/polyphenols/. On the EFSA claim and what the threshold requirement means: /fact/polyphenols-and-oxidative-stress/. Product data and batch number are on the product page.
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Sources: HPLC analysis performed at the University of Split. IOC Trade Standard COI/T.15/NC No 3/Rev. 16. Batch 2025-VL-MIR-001.