---
title: Sample preparation by mixed-mode SPE using ISOLUTE® HAX
description: This technical note describes the extraction of acidic drugs from biological fluids using ISOLUTE® HAX mixed-mode SPE products.
---

[Literature ](https://www.biotage.com/literature)

# [Sample preparation by mixed-mode SPE using ISOLUTE® HAX](https://www.biotage.com/literature/technical-note/sample-preparation-mixed-mode-spe-isolute-hax)

 Written by [Biotage](https://www.biotage.com/literature/author/biotage) | Dec 11, 2025 1:58:02 PM

This technical note describes the extraction of acidic drugs from biological fluids using ISOLUTE® HAX mixed-mode SPE products.

Sample preparation techniques such as protein precipitation, supported liquid extraction or non-polar SPE may not be selective enough to give extracts of sufficient purity for low level analysis. In these cases, the selective mixed-mode approach to the extraction of acidic drugs is a suitable alternative, giving very high purity extracts with minimal levels of co-extracted material.

ISOLUTE HAX mixed-mode SPE sorbent is based on a combination of strong anion exchange and non-polar chemistries. Acidic drugs are retained by two primary retention mechanisms (see Figure 1). This allows a rigorous interference elution regime to be used to elute interferences retained by either non-polar or anion exchange interactions alone. Only analytes with both non-polar and acidic characteristics are extracted using the ISOLUTE HAX sorbent, providing an extremely pure final extract.

Literature number: TN127.V.2

[View full post](https://www.biotage.com/literature/technical-note/sample-preparation-mixed-mode-spe-isolute-hax)

```json
{
  "@context" : "http://schema.org",
  "@type" : "BlogPosting",
  "author" : {
    "@type" : "Person",
    "name" : "Biotage"
  },
  "dateModified" : "2025-12-11T13:58:02.612Z",
  "datePublished" : "2025-12-11T13:58:02Z",
  "headline" : "Sample preparation by mixed-mode SPE using ISOLUTE® HAX",
  "image" : {
    "@type" : "ImageObject",
    "height" : 60,
    "url" : "/hs/hsstatic/content_shared_assets/static-1.4092/img/default-amp-logo.png",
    "width" : 60
  },
  "mainEntityOfPage" : "https://www.biotage.com/literature/technical-note/sample-preparation-mixed-mode-spe-isolute-hax",
  "publisher" : {
    "@type" : "Organization",
    "logo" : {
      "@type" : "ImageObject",
      "height" : 60,
      "url" : "/hs/hsstatic/content_shared_assets/static-1.4092/img/default-amp-logo.png",
      "width" : 60
    },
    "name" : "Literature"
  }
}
```