High performance liquid chromatography mass spectrometer

High Performance Liquid Chromatography Part

- Chromatographic column: C18/C8 reversed-phase column (such as Waters ACQUITY UPLC BEH C18, 1.7μm particle size, improving separation efficiency), with an inner diameter of 2.1mm and a length of 100mm;- Mobile phase: Water-acetonitrile/methanol system, containing 0.1% formic acid/ammonia water to adjust pH, with gradient elution (e.g., acetonitrile rises from 5% to 95% in 0-5min);- Pump system: High-pressure infusion pump (withstand pressure ≥1000 bar, suitable for ultra-performance liquid chromatography (UPLC)), with a flow rate of 0.3-1 mL/min.

Interface System (Ion Source)

- Electrospray Ionization (ESI):  Principle: The mobile phase is sprayed through a capillary to form charged droplets, and gas-phase ions (such as [M+H]?, [M-H]?) are generated after solvent evaporation, suitable for polar molecules (such as polypeptides, nucleic acids);  Modes: Positive ion mode (for basic compounds), negative ion mode (for acidic compounds);- Atmospheric Pressure Chemical Ionization (APCI):  Corona discharge ionizes the mobile phase, and ion-molecule reactions occur with sample molecules to generate quasi-molecular ions, suitable for moderately polar and easily vaporized compounds (such as fatty acids).

Mass Spectrometry Part

- Mass analyzer:  Quadrupole (Q): Most commonly used, with a scanning range of m/z 50-2000, supporting selected reaction monitoring (SRM);  Triple quadrupole (QqQ): The front Q screens parent ions, the collision cell q fragments them, and the rear Q screens daughter ions, realizing multiple reaction monitoring (MRM) with strong anti-matrix interference ability;  Time-of-flight (TOF): High resolution (>40,000 FWHM), capable of accurately determining mass-to-charge ratio (error < 5 ppm), used for unknown compound screening;- Detector: Electron multiplier or photomultiplier tube, with a detection limit up to the fg level.

Data System

- Workstation software (such as Thermo Xcalibur): Synchronously controls HPLC gradients and MS parameters, supporting MRM method establishment and metabolite identification (such as element composition prediction).

Biomedical

Monitoring of drug concentrations in blood (such as anticancer drug paclitaxel), polypeptide/protein sequencing (such as insulin structure analysis), characterization of antibody-drug conjugates (ADCs).

Food and Agriculture

Melamine in milk powder, antibiotics in honey (such as chloramphenicol), pesticide residues in fruits and vegetables (such as imidacloprid, which is highly polar and difficult to analyze by GC-MS).

Environmental Monitoring

Antibiotics in water (such as sulfonamides), polar organic compounds adsorbed on microplastics (such as bisphenol A), polar pesticides in soil (such as glyphosate).

Metabolomics

Profiling analysis of metabolites in urine/tissues (such as screening of cancer markers), qualitative and quantitative analysis of plant secondary metabolites (such as flavonoids).

Cosmetics and Daily Chemicals

Hormones in skin care products (such as estradiol), potassium sorbate preservatives in shampoos, sensitizing polar components in fragrances (such as phenoxyethanol).

Separation Objects

Polar, thermally unstable compounds (such as polypeptides, antibiotics)

Volatile, thermally stable compounds (such as VOCs, pesticides)

Compounds with ultraviolet absorption (weak qualitative ability)

Qualitative Ability

Strong (can obtain molecular ions and fragments)

Strong (fragments match standard spectral libraries)

Weak (only retention time + ultraviolet spectrum)

Detection Limit

0.1-10 fg (trace)

1-10 pg

1-10 ng (lower)

Sample Pretreatment

Simple (no derivatization required)

Some require derivatization (such as polar substances)

Simple (only filtration needed)