Page 51 - LC-SFC_Pharma_Brochure

3. Nexera UC SFC-UV System

The Nexera UC platform can accommodate a wide variety of analyses
and pretreatments and includes an (1) SFC system, (2) online SFE-SFC
system, and (3) of’ine SFE system. A major difference between a
Nexera UC system and a conventional HPLC system is the addition of
a back pressure regulator to prevent mobile phase vaporization inside SFC-MS System
the column and the pump that delivers the carbon dioxide. The
Nexera UC platform is based around the Nexera ultra high-perfor-
mance liquid chromatograph, with each Nexera UC system conÿg-
ured by adding a newly developed carbon dioxide delivery unit (LC-
30ADSF), a back pressure regulator unit that allows high-precision
pressure control (SFC-30A), and an extraction unit used for SFE (SFE- Fig. 3 Nexera UC Systems
30A) (Fig. 3). The autosamplers and other units designed for liquid
chromatography can be used in the Nexera UC system. By using the same column packing material for separation in the
(1) SFC system Nexera UC systems as that used in normal phase HPLC analysis (e.g.,
silica gel), normal phase HPLC analyses can be easily transferred to
SFC systems include an SFC-UV system that uses a UV (or PDA) de-
tector, a UFMS system (SFC-MS) that uses a mass spectrometer SFC analyses while improving the resolution and increasing the analy-
(MS) that is suitable for high-speed analyses by SFC, and a chiral sis speed, as shown in Fig. 5. Transferring analyses from normal phase
screening system that automatically switches between multiple col- HPLC to SFC can also substantially reduce the volume of organic sol-
umns and modiÿers to examine the analytical conditions. vents consumed per analysis, as shown in Fig. 6, which also reduces
analysis costs. SFC is an environment- and user-friendly technique as
(2) Online SFE-SFC system it reduces consumption of toxic organic solvents.
Online SFE-SFC systems combine SFE and SFC online to automati-
cally perform all steps from target compounds extraction from solid
samples to analysis. Hexane/Isopropanol
= 99:1
(normal phase LC)
(3) SFE pretreatment system 12.00 mL
Of’ine SFE pretreatment systems are speciÿcally designed to ex- Methanol 0.70 mL 94.2% reduction
tract target compounds from solid samples. (Nexera UC)
The characteristic properties of the supercritical ’uid used in the Fig. 6 Comparison between HPLC and SFC of Organic Solvent Consumption
Nexera UC SFC systems, which include high diffusivity and low viscos-
ity, allow for low column pressures even at high ’ow rates, enabling When using a mass spectrometer for SFC, equipment used for LC/MS
high-speed analyses while maintaining column efÿciency. Because of can be used as is. In SFC, a make-up solution is added after column
these factors, the Nexera UC SFC systems can shorten analysis times separation to promote ionization. Conventional SFC systems used
to between one third and one ÿfth of the time required for HPLC pressure regulators that had a large internal volume. This required the
analysis using the same size column. (Fig. 5). £ow path of the column eluate to be split before entering the mass
spectrometer to suppress the effect of extra-column dispersion (Fig.
CO2 pump Back pressure 7(a)). The Nexera UC systems use a proprietary low-internal volume
UV-VIS detector regulator
Autosample r C olumn oven design for their back pressure regulator (patent pending). This allows
Liquid CO2 the £ow path to enter the back pressure regulator and mass spec-
cylinder
trometer in series, so all the column eluate enters the mass spectrom-
Analytical column eter (Fig. 7(b)). Increasing the volume of eluate introduced to the
Solvent delivery pump
mass spectrometer in this way enables higher sensitivity analysis, and
Modiÿer precludes the effects of split ratio variation, etc., resulting in highly re-
Fig. 4 SFC Flow Diagram
producible SFC/MS analysis (Fig. 8, Table 2).
1. α-Tocopherol 2 3 (a) Column oven Back pressure regulator
2. β-Tocopherol 1 4 Conventional
3. γ-Tocopherol
4. δ-Tocopherol Rs = 1.328 SFC/MS ow path
Rs = 1.703
Normal
phase
HPLC
1 2 3 4 Make-up
solution Make-up pump
SFC
Mass spectrometer
0 2 4 6 8 10 12 min
SFC conditions Normal phase HPLC conditions (b)
Column : Shim-pack UC-SIL Column : Shim-pack HRC-SIL Nexera UC
(4.6 mm I.D. × 250 mm L. 5 µm) (4.6 mm I.D. × 250 mm L. 5 µm) SFC/MS ow path
Modiÿer : MeOH Mobile phase : HEX/IPA 99/1 (V/V) Column oven
Modiÿer conc. : 5 % Flow rate : 1 mL/min
Flow rate : 3.5 mL/min Temperature : 40°C Back pressure
Temperature : 40°C Detection : UV 290 nm regulator Mass spectrometer
Detection : UV 290 nm Make-up Make-up pump
Back pressure : 10 MPa solution
Fig. 5 Comparison between HPLC and SFC Fig. 7 SFC-MS Flow Path
2