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The King's Forensics® Mass Spectrometry Service (KF-MSS) is an analytical group based within the Department of Analytical, Environmental & Forensic Science (AEFS), Faculty of Life Sciences and Medicine in the Franklin-Wilkins Building. The facility was set up in order to encourage and support the use of Mass Spectrometry in bioanalysis research. A wide range of Mass Spectrometers are available to support mainly (but not limited to) analysis on small molecules. Mass spectrometry is one of the most sensitive analytical techniques currently available. Detection can be achieved using full-scan mass spectra and for more sensitive work selective-ion monitoring (SIM). Excellent sensitivity is possible with selective-reaction monitoring (SRM), which also enables additional selectivity compared with SIM operation, and MS/MS analyses provide additional structural information.
Director King's Forensics
Mass Spectrometry (MS) combined with the separation power of liquid chromatography has revolutionised the way we do chemical analysis today. KF-MSS can offer mass spectrometers interfaced directly to ultra-performance liquid chromatography (UPLC)/high-performance liquid chromatography (HPLC) systems facilitating the analysis of molecules with a wide range of different physicochemical properties, including polar and thermolabile compounds.
The triple quadrupole mass spectrometers are extremely sensitive and robust at very low levels (100 pg/mL or less) in SRM mode. They provide extremely good precision and accuracy data. The triple quadrupole instruments are instruments of choice for quantitative work.
High resolution mass spectrometers are designed for compound identification, high-throughput, and high-performance screening and for qualitative and quantitative analysis. They deliver high resolution accurate mass (HRAM) to provide fast, precise, and reproducible results.
Accurate mass data is the current mass spectrometry standard that is being increasingly employed for rapid compound identification of biological markers and chemical products, providing in many cases, unambiguous chemical formula for small molecules and also peptides in complex biological extracts. Such accurate mass measurement is particularly important in work involving the characterisation of drug candidates (pharmaceuticals), endogenous and xenobiotic metabolites, and environmental pollutants.
For this purpose, samples can be directly infused into the mass spectrometer via a syringe pump or injected via a LC system into the Atmospheric Pressure Ionisation (API) source. API offers soft ionisation resulting in little or no fragmentation. A typical API spectrum contains only the protonated (positive ion mode) or deprotonated (negative ion mode) molecular ion.
MS spectra provide valuable molecular weight information of single and multiply charged ions and identification of the charge state of each peak in the charge-state envelope of a given compound.
Gas chromatography-mass spectrometry (GC/MS) combines the fine separating power of GC with the uniquely powerful detection capabilities of MS. This powerful technique is particularly suitable for the analysis of mixtures of volatile and low relative molecular mass compounds (< 800) such as hydrocarbons, fragrances, essential oils and relatively non-polar drugs. Chemical derivatisation, e.g., trimethylsilylation, can often be employed to increase the volatility of compounds containing polar functional groups (-OH, -COOH, -NH2, etc) thereby extending the range of suitable analytes to such compounds as steroids, polar drugs, prostaglandins, bile acids, organic acids, amino acids, and small peptides.
An adequate sample preparation is needed before proceeding with the GC-MS analysis. Samples such as water, soil, urine, blood plasma, etc., have to be subjected to a “clean-up” procedure prior to analysis in order to extract and concentrate the more volatile, low molecular mass components. Extraction can be performed by organic solvents or by solid phase extraction (SPE).
Where considered necessary, the extract can be derivatised with a choice of special reagents. For example, thermally labile and polar carboxylic acids groups can be methylated with BF3/methanol (or TSM-diazomethane) or trimethylsilated with a variety of commercially available reagents.
GC-MS analysis. Typically, a solution of the analyte mixture (1 uL) is injected on to the GC column via a heated injection port, which is normally held at 250-300 °C to facilitate vaporisation Following volatilisation in the heated injector, the mixture is pushed by a pressurized carrier gas (usually helium) through the GC column, which is heated in an oven. Separation relies on the fact that different compounds dissolve to different extents in this liquid and move through the column at different rates depending on their partition between the stationary liquid and the mobile carrier gas.
The GC-MS system currently available in the facility is supported with an electron ionisation (EI) source. The MS detector can operate in 2 different modes: scanning and selected ion monitoring (SIM). Quantitative work can be performed by integration of selected ion chromatographic peaks.
We have gained expertise in method development and validation for a number of analyses applied to different fields of bioanalysis, e.g., identification of Cannabinoids including THC and CBD in both biological and non-clinical matrices. Before we carry out analytical work a scientific assessment will be undertaken using a standard template. The template can be obtained from Ruby Smith. Scientific advise is available from Principal Analyst Dr Erika Castrignanò.
Costs for analytical work will be calculated on a by case-by-case basis to include consumables, analytical time, and instrument/MS time. There will be additional costs for the development of analytical methods and where specific columns/sample preparation are needed.
Standard costs: £350 per day GC-MS/MS and £400 per day HRMS
For more details about our service, and to book services please contact us directly.
0207 848 4848
Franklin-Wilkins Building, , Stamford Street London, SE1 9NH