Chromatography

Users wishing to operate instruments independently must complete hands-on training with facility staff (Mehdi).

• Training sessions are held quarterly, with additional sessions scheduled on request for time-sensitive projects.

• Following training and staff approval, certified users gain access to schedule instrument time independently.

For researchers who prefer not to run samples themselves, the facility provides complete full-service analysis.

• Staff handle sample preparation, method setup, data collection, and report generation.

• Ideal for one-off projects, complex or unfamiliar sample matrices, or users needing quick results without the time commitment of training.

Gas Chromatography (GC) separates and analyzes volatile and semi-volatile compounds by vaporizing the sample and carrying it with an inert gas through a capillary column. It is a standard technique for identifying unknown mixtures, determining purity, and conducting trace quantitative analysis in organic synthesis, environmental testing, and petrochemicals.

High Performance Liquid Chromatography (HPLC) separates, identifies, and quantifies components in liquid mixtures by passing them under high pressure through a stationary phase column. It is widely used across chemistry, biochemistry, and pharmaceuticals for assay validation, purity determination, and compound isolation.

Particulate matter will rapidly clog column inlet frits, autosampler needles, and injector valves.

• Sample Filtration: Filter all liquid samples through a 0.22 µm or 0.45 µm syringe filter before loading into autosampler vials. Centrifugation at 10,000 rpm for 5 minutes is an acceptable alternative for low-volume samples.

• PTFE Membranes: Provide broad chemical compatibility and are recommended for organic solvents, harsh reagents, and general unknown mixtures.

• Nylon Membranes: Ideal for aqueous solutions and mixed organic-aqueous solvents. Avoid using nylon with strongly acidic solutions or when analyzing proteins prone to non-specific binding.

• Mobile Phase Filtration: Vacuum-filter all lab-prepared aqueous buffers through a 0.22 µm membrane filter before bottle placement to remove suspended salts and microbial growth.

• Silica Column Stability: Standard silica-based columns are stable within the range of pH 2.0 to 8.0. Running below pH 2.0 leads to stationary-phase cleavage and column bleed, while operating above pH 8.0 rapidly dissolves the silica support.

• High-pH Alternatives: If your analytical separation requires basic conditions above pH 8.0, use dedicated high-pH stable polymeric or organosilica hybrid columns.

• Volatile Mobile Phases for ELSD and MS: Evaporative detectors (ELSD, MS) require fully volatile additives to prevent severe baseline noise, burner clogging, and detector fouling.

• Allowed Volatile Additives: Formic acid, acetic acid, ammonium formate, ammonium acetate, trifluoroacetic acid (TFA), and ammonium hydroxide at concentrations of 10 to 20 mM or lower.

• Prohibited Non-Volatile Buffers: Phosphate, borate, citrate, and sulfate salts must never be injected into ELSD or MS systems.

• Water: Polarity index 10.2, viscosity 1.00 cP at 20 °C, UV cutoff 190 nm. Completely miscible with polar organic modifiers.

• Acetonitrile: Polarity index 5.8, viscosity 0.38 cP at 20 °C, UV cutoff 190 nm. Completely miscible with water and produces lower system backpressure than methanol.

• Methanol: Polarity index 5.1, viscosity 0.55 cP at 20 °C, UV cutoff 205 nm. Completely miscible with water; produces a characteristic pressure spike at intermediate water-methanol mixtures due to viscosity.

• Isopropanol (IPA): Polarity index 3.9, viscosity 2.27 cP at 20 °C, UV cutoff 205 nm. Fully miscible with both aqueous and non-polar organic solvents, making it the ideal intermediate flushing solvent when transitioning between reversed-phase and normal-phase modes.

• Tetrahydrofuran (THF): Polarity index 4.0, viscosity 0.55 cP at 20 °C, UV cutoff 212 nm. Miscible with water; verify PEEK tubing compatibility before use.

• Dichloromethane (DCM): Polarity index 3.1, viscosity 0.44 cP at 20 °C, UV cutoff 233 nm. Immiscible with water; requires an intermediate IPA flush before introducing aqueous mobile phases.

• Hexane: Polarity index 0.1, viscosity 0.31 cP at 20 °C, UV cutoff 195 nm. Immiscible with water; standard mobile phase for normal-phase separations.

When co-authorship is expected:

• Substantial intellectual contributions to experimental design, data interpretation, or manuscript preparation
• Specialized technique development or troubleshooting beyond routine support
• Custom method development, extensive troubleshooting, or data analysis assistance

When acknowledgment (not co-authorship) is sufficient:

• Routine training and instrument access
• Standard walkup experiments without significant staff involvement
• Minor troubleshooting or parameter adjustments

Best practice: Discuss authorship expectations early in your project with facility staff to avoid misunderstandings.