ApartSIL C18 Polar is a specialized chromatographic column used in high-performance
liquid chromatography (HPLC). It is designed to offer enhanced separation of both polar and
non-polar compounds, providing a balance between hydrophobic interactions typical of C18
columns and polar interactions due to the presence of polar groups. Below is a
comprehensive overview of ApartSIL C18 Polar:
1. Structure and Composition
C18 Bonded Phase: The ApartSIL C18 Polar column features an 18-carbon long
hydrocarbon chain (octadecyl) chemically bonded to silica particles, similar to
standard C18 columns. This hydrophobic chain provides the reversed-phase
characteristics, which are essential for retaining and separating non-polar and
moderately polar compounds.
Polar-Endcapped or Embedded Groups: What distinguishes the C18 Polar from a
standard C18 column is the inclusion of polar groups, either endcapped or embedded
within the stationary phase. These polar groups enhance the retention of polar
analytes, offering a unique selectivity that is beneficial for separating complex
mixtures of compounds with varying polarity.
Silica Support: The base material is typically high-purity, spherical silica particles.
This provides a stable support matrix with a large surface area for interaction, which
is crucial for achieving high resolution and sensitivity in separations.
2. Applications
Complex Mixture Analysis: ApartSIL C18 Polar is particularly useful for separating
complex mixtures of compounds that include both polar and non-polar components.
This makes it ideal for applications in various industries.
Pharmaceutical Analysis: Frequently used for analyzing drugs, including those with
a range of polarities, as well as their impurities and degradation products.
Biomolecule Separation: Suitable for separating peptides, nucleotides, and other
biomolecules, especially when the sample contains both hydrophobic and hydrophilic
components.
Environmental Analysis: Effective for analyzing pollutants, including those that are
hydrophilic, such as certain organic acids and pesticides, alongside more hydrophobic
contaminants.
Food and Beverage Testing: Used for detecting and quantifying a wide range of
additives, contaminants, and natural compounds in food and beverages, particularly
when these compounds vary widely in polarity.
3. Key Features
Enhanced Polar Retention: The presence of polar groups allows the column to retain
and separate polar analytes more effectively than a standard C18 column, particularly
in mobile phases that contain a significant amount of water.
Versatility: Offers the ability to separate both polar and non-polar compounds in a
single run, making it highly versatile and suitable for a wide range of analytical tasks.
Wide pH Range: Typically operates effectively within a pH range of 2-8, allowing
for flexibility in method development and compatibility with a variety of sample
types.
Temperature Tolerance: The column is usually stable at elevated temperatures,
often up to around 60-80°C, which can enhance separation efficiency and reduce
analysis time.
4. Operating Conditions
Mobile Phases: Compatible with a wide variety of mobile phases, including mixtures
of water, methanol, acetonitrile, and buffered solutions. The column performs
particularly well with mobile phases that have a moderate to high water content.
Flow Rate: Typically operates efficiently at flow rates ranging from 0.5 to 2.0
mL/min, depending on the specific application and column dimensions.
Column Dimensions: Available in various sizes, commonly with diameters of 2.1
mm to 4.6 mm and lengths from 50 mm to 250 mm, providing flexibility based on the
analytical needs.
5. Maintenance and Care
Column Conditioning: Proper conditioning with the intended mobile phase is
essential before use to achieve stable and reproducible performance.
Storage: The column should be stored in a solvent mixture that is compatible with the
stationary phase, typically a mixture of water and organic solvent, to prevent drying
out and degradation.
Preventing Contamination: Regular filtration of samples and mobile phases is
recommended to avoid particulate contamination, which can reduce column efficiency
and lifespan.
6. Limitations
Silica-Based Degradation: The silica support can degrade under highly basic
conditions (pH > 8), limiting the use of highly alkaline mobile phases.
Solvent Compatibility: While versatile, certain solvents, particularly strong acids or
bases, can damage the column or alter its performance.
7. Comparison with Standard C18 Columns
Polar Compound Retention: ApartSIL C18 Polar offers superior retention for polar
compounds compared to standard C18 columns, making it more suitable for complex
mixtures with varying polarities.
Aqueous Mobile Phases: The polar groups in ApartSIL C18 Polar allow it to
function effectively in mobile phases with higher water content, where standard C18
columns might experience phase collapse.
Selective Separation: ApartSIL C18 Polar provides more selective separation for
compounds that have both hydrophobic and hydrophilic regions, which can be
challenging to separate using standard C18 columns.
8. Alternatives
C8 Columns: For applications requiring less retention, a C8 (octyl) column may be
an alternative, though it may not perform as well with highly polar analytes.
Phenyl Columns: If aromatic selectivity is required, phenyl-bonded columns offer
different selectivity and might be more suitable for compounds with aromatic rings.
Hydrophilic Interaction Liquid Chromatography (HILIC) Columns: For even
greater retention of highly polar compounds, HILIC columns may offer superior
performance compared to C18 Polar columns.
ApartSIL C18 Polar is a versatile and high-performing chromatographic column ideal for
complex separations involving compounds with a wide range of polarities. Its unique
combination of hydrophobic and polar retention characteristics makes it a valuable tool in
various fields, including pharmaceutical analysis, environmental testing, and food and
beverage quality control.