Page 35 - LC-SFC_Pharma_Brochure

C190-E199

Technical Improved Sample Pretreatment Using

Report Of
ine Supercritical Fluid Extraction

Hidetoshi Terada , Takato Uchikata , Takanari Hattori , Keiko Matsumoto , Yoshiyuki Watanabe ,
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Tadayuki Yamaguchi , Yasuhiro Funada 1
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Abstract:
Separation analysis using HPLC, SFC or GC requires a pretreatment step to efÿciently extract a target constituent from the sample in
various forms (e.g., solid). Constituents are usually extracted from solid samples using dissolution or solid-liquid extraction methods.
Dissolution methods can only be used when the sample is soluble in a given solvent, and they are difÿcult to optimize depending on the
analytical conditions. Solid-liquid extraction methods (e.g., Soxhlet extraction) are not suited to the pretreatment of multiple samples as
they require considerable time for extraction and non-extraction (e.g., cleaning, preparation) operations. However, extraction methods
involving supercritical °uids can utilize the characteristics of supercritical °uids (e.g., high solubility, permeability) to achieve the elution of
a target constituent from a solid sample with high efÿciency and also allow automation during the extraction process. This article
describes the utilization of the Nexera UC SFE pretreatment system, which increases the efÿciency of sample pretreatment for analysis.

Keywords: supercritical uid extraction, SFE, of ine SFE

1. What Is Super critical Fluid Extraction? 2. The Nexera UC SFE Pretreatment System
1. What Is Supercritical Fluid Extraction?
Supercritical fluid refers to the state of any substance at temperature The Nexera UC SFE pretreatment system (Fig. 1) is a dedicated pre-
and pressure conditions above its critical point. Supercritical fluids treatment system that performs of°ine SFE. Solid samples are placed
combine the ability of liquids to dissolve materials with high diffusivity in dedicated extraction vessels (Fig. 2) and introduced into the
and low viscosity properties of gases. Supercritical fluid extraction system, after which the system automatically performs the extraction.
(SFE) with carbon dioxide is widely employed as a pretreatment The extraction vessels are available in volumes of 0.2 mL and 5 mL
method for analysis owing to its low critical points (critical tempera- such that they can be selected based on the sample to be analyzed.
ture: 31.1 °C, critical pressure: 7.38 MPa), which makes it easy to The system allows accommodation of a maximum of 48 extraction
handle, along with its incombustibility, inertness, and low cost. Some vessels, which are mounted into a rack changer (Fig. 3). This setup en-
advantages of SFE are shown below: ables extraction pretreatment of multiple samples via automated
• Supercritical °uids have high permeability and diffusion coefÿcients sample transfer and cycling. The automation of the multi-sample ex-
and can therefore be used for highly efÿcient extraction. traction pretreatment using the Nexera UC SFE pretreatment system
substantially reduces the time and labor required for the pretreat-
• Supercritical °uids achieve extraction at mild temperatures at which ment operations while also preventing human error.
target constituents are unlikely to oxidize.
• Carbon dioxide evaporates, which simpliÿes sample treatment after extraction.
• Solvent costs are low compared with solvent extraction and other methods.
• The extraction process can be automated.
While supercritical carbon dioxide is as hydrophobic as hexane and is
suited for the extraction of fat-soluble compounds, it can also be
used for the extraction of compounds with a wide range of polarities Fig. 2 E xtraction Vessels
by adding modifier substances such as methanol and ethanol.

Fig. 1 T he Nexera UC SFE Pretreatment System Fig. 3 R ack Changer

1 Analytical & Measuring Instruments Division 1