Liquid Chromatography
Separation, identification and quantification of non-volatile, polar and thermally sensitive compounds.
O que é LC
How Liquid Chromatography Separates Non-Volatile and Thermally Sensitive Compounds
LC (Liquid Chromatography), most often performed as HPLC or UHPLC, is a separation technique that pumps a liquid sample under pressure through a column packed with a solid stationary phase, where different compounds partition between the stationary phase and the flowing mobile phase and elute at different retention times based on polarity, size or charge. Because separation happens at ambient or mildly elevated temperature rather than by vaporization, LC handles non-volatile, polar, high-molecular-weight and thermally sensitive compounds that GC cannot, from active pharmaceutical ingredients and their degradation products to proteins, sugars and preservatives. Detection is commonly by UV/DAD, fluorescence or mass spectrometry, giving both quantification and, in MS mode, structural confirmation.
Variantes de LC
Configurações disponíveis
HPLC (High-Performance Liquid Chromatography)
High-performance liquid chromatography for separating and quantifying non-volatile and thermally labile compounds across a wide polarity range using pressurised solvent flow through a packed column.
HPLC-ECD (Electrochemical Detection)
High-performance liquid chromatography with electrochemical detection for selective, sub-nanogram measurement of readily oxidised or reduced analytes such as catecholamines and phenols.
HPLC-DAD (UV-Vis Diode-Array Detection)
High-performance liquid chromatography with a UV-Vis diode-array detector that records a full absorbance spectrum for every peak, adding spectral identity and purity checks to routine quantification.
LC-Ion Trap Mass Spectrometry
Liquid chromatography coupled to an ion-trap mass spectrometer, which accumulates ions and fragments them over successive stages for detailed structural elucidation of unknowns and metabolites.
LC-MS/MS Proteomics
Liquid chromatography coupled to tandem mass spectrometry for identifying and quantifying proteins and peptides in complex biological samples through bottom-up digestion and database searching.
LC-QTOF (Quadrupole Time-of-Flight)
Liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer for accurate-mass, high-resolution screening and confirmation of targets and unknowns in a single acquisition.
LC-Orbitrap High-Resolution Mass Spectrometry
Liquid chromatography coupled to an Orbitrap mass analyser delivering resolving power above 100,000 and sub-ppm mass accuracy for confident identification and trace quantification in complex matrices.
LC-QTRAP (Triple Quadrupole-Linear Ion Trap)
Liquid chromatography coupled to a hybrid triple-quadrupole and linear-ion-trap mass spectrometer, combining sensitive MRM quantification with ion-trap scans for simultaneous quantitation and confirmation.
LC-QqQ (Triple Quadrupole Mass Spectrometry)
Liquid chromatography coupled to a triple-quadrupole mass spectrometer operated in multiple-reaction-monitoring mode for highly sensitive and selective targeted quantification of known analytes.
LC-UV/DAD (UV-Vis Diode-Array Detection)
Liquid chromatography with UV-Vis or diode-array detection, the most widely used LC configuration for routine assay and related-substances testing of compounds that absorb ultraviolet or visible light.
LC-ECD (Electrochemical Detection)
Liquid chromatography with electrochemical detection for trace measurement of easily oxidised or reduced species, offering high selectivity in matrices where UV detection lacks sensitivity.
SEC / GPC (Size-Exclusion Chromatography)
Size-exclusion or gel-permeation chromatography that separates molecules by hydrodynamic size to determine molar-mass distributions of polymers, proteins and oligomers.
LC-FLD (Fluorescence Detection)
Liquid chromatography with fluorescence detection for selective, low-level quantification of naturally fluorescent analytes or fluorophore-tagged derivatives.
Amino Acid Analysis (Ion-Exchange LC)
Dedicated ion-exchange liquid chromatography with post-column ninhydrin or OPA derivatisation for quantitative amino acid profiling of proteins, peptides, feeds and biological fluids.
HT-GPC (High-Temperature Size-Exclusion Chromatography)
High-temperature gel-permeation chromatography, run hot in trichlorobenzene, for molar-mass analysis of polyolefins and other polymers that dissolve only at elevated temperature.
LC-MS (Liquid Chromatography-Mass Spectrometry)
Liquid chromatography coupled to mass-spectrometric detection for identifying and quantifying compounds by mass, covering targeted assays and untargeted screening across pharmaceutical, cosmetic and biological samples.
What sets us apart
We don't hand over a spectrum. We hand over the interpretation.
Any lab can return peaks and numbers. Our report reads the data. Three differences define what we deliver — illustrated below with a real, anonymized case.
Multiple techniques, one integrated report
We don't hand back five loose reports. We cross-reference every technique's results into a single reading — each signal checked against the others — to reach an answer, not a pile of data.
- Contamination investigation — identifying and tracing the source of a foreign species.
- Performance degradation — explaining why a batch behaves outside expectations.
- New supplier validation — proving equivalence before switching.
3 LDPE batches · 4 techniques converge, NMR reveals the difference
In semicrystalline polymer systems, thermomechanical processing variables influence chain conformational dynamics¹. Solid-state NMR resolves chemical environments at the nanometer scale², sensitive to changes not detectable by XRD or FTIR³.
Technical justification anchored in the literature
Every technique choice and every inference in the report is backed by peer-reviewed literature — with citations in the text. The conclusion isn't loose opinion: it's a traceable argument, defensible in an audit and in front of the client.
- Numbered citations linking claim to source
- Official standards and methods referenced per analyte
- Auditable reasoning end to end
Conclusion and expert opinion
The report closes with a clear position, signed by the Principal Investigator: what the data shows, what can't yet be claimed, and the next step. It includes an honest caveat on the limits of inference — what separates a technical opinion from a guess.
- Explicit technical position, not just results
- Inference limits declared honestly
- Next-step recommendation signed by the P.I.
Four techniques confirmed equivalence; only the solid-state NMR revealed the subtle conformational change not distinguishable by conventional QC — a molecular signature consistent with the atypical filtration behavior.
Without the industrial line's parameters, no direct causal correlation can be established — a complementary step is recommended for elucidation.
Aplicações de mercado
Onde a LC entrega resultados
Market Applications
Pharma
- API purity and assay testing
- Impurity and degradation product profiling
- Stability and forced-degradation studies
- Excipient identity and purity verification
Materials
- Polymer additive and antioxidant quantitation
- Degradation product analysis
- Raw material quality control
Cosmetics
- Active ingredient quantification in formulations
- Neurocosmetic ingredient analysis
- Bioactive compound profiling
FAQ
Frequently Asked Questions about Liquid Chromatography (LC)
What makes liquid chromatography (LC) different from gas chromatography (GC)?
- LC uses a liquid mobile phase to carry the sample through the column, rather than a gas, which means it does not require the analyte to be volatile or thermally stable. This makes LC the more versatile choice for large, polar, non-volatile or heat-sensitive molecules — including most pharmaceutical actives, proteins, and many natural product compounds — that GC cannot analyze directly.
What detectors can be paired with LC, and why does the choice matter?
- Common LC detectors include UV/DAD (general-purpose, most widely used), fluorescence (higher sensitivity for fluorescent compounds), electrochemical detection (ECD, for electroactive compounds like neurotransmitters), and mass spectrometry (LC-MS, for identification and trace-level quantification). The detector determines both sensitivity and selectivity, so it's matched to the target compound and required detection limit.
What can LC tell me about a pharmaceutical formulation?
- LC is the standard technique for assaying active ingredient content, profiling impurities and degradation products, supporting stability and forced-degradation studies, and verifying excipient identity and purity — covering most of the routine release and stability testing a formulation needs.
What is the difference between HPLC and UHPLC?
- Both are high-performance liquid chromatography, but UHPLC (Ultra-High Performance) uses smaller particle-size column packing and higher operating pressures, which typically delivers faster analysis times and better resolution than conventional HPLC for the same separation.
What sample preparation does LC require?
- Samples generally need to be dissolved or extracted into a solvent compatible with the mobile phase and filtered to remove particulates that could damage the column, at a concentration appropriate for the detector's sensitivity. The specific extraction, dilution and filtration steps depend on the sample matrix and are defined during method development.
Percevia Lab Acceleration
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