Hyphenated Technique
Definition
A single workflow that couples a separation method to a spectroscopic detector, so a complex mixture is resolved and each component identified in one run. GC-MS, LC-MS/MS, GC-FTIR and LC-DAD are the four most common in Indian forensic practice; the hyphen is what allows a viscera extract containing forty compounds to yield clean spectra for each.
- Common hyphenated techniques
- GC-MS, LC-MS/MS, GC-FTIR, LC-DAD
- What the hyphen represents
- An online coupling of separation and detection in a single workflow
Common questions
What does a hyphenated technique do?+
A hyphenated technique couples a separation method with a spectroscopic detector in one workflow. The separation sorts a complex mixture into individual components, and the detector identifies each one, giving you both selectivity and structural information in a single run.
Why are hyphenated techniques important for forensic evidence?+
They deliver court-defensible results. The combination of chromatographic selectivity from the separation stage and spectral selectivity from the detector together make it possible to confirm identification of compounds in complex samples like viscera extracts that may contain forty compounds.
Which hyphenated techniques are most used in forensic labs?+
GC-MS, LC-MS/MS, GC-FTIR, and LC-DAD are the four most common in Indian forensic practice. Each pairs a separation method (GC or LC) with a sensitive detector (MS or FTIR or DAD) to handle different types of evidence.
Related terms
- Atmospheric Pressure Chemical Ionisation (APCI)
- A complementary atmospheric-pressure source that vaporises the LC eluent and uses a corona discharge to ionise a reagent gas, which transfers charge...
- Confirmatory Technique
- An instrumental method capable of identifying a specific molecule with sufficient selectivity to be admissible in court. The accepted gold standards are...
- Electrospray Ionisation (ESI)
- A soft atmospheric-pressure ionisation source that sprays the LC eluent through a charged capillary into a heated counter-current gas, producing protonated or...
- GC-MS Interface
- The physical link between a gas chromatograph and a mass spectrometer. Older designs used jet separators and open splits to manage the...
- Instrumental Technique
- An analytical method that uses an instrument to detect, identify or quantitate an analyte, distinguished from classical wet-chemistry methods such as titration,...
- Limit of Detection (LOD)
- The lowest concentration of analyte that produces a signal reliably distinguishable from the instrument noise, conventionally three times the standard deviation of...
- MRM (Multiple Reaction Monitoring)
- A targeted MS/MS scan mode on a triple quadrupole that monitors specific precursor-to-product ion transitions, with two transitions per analyte (quantifier and...
- Presumptive Test
- A fast, low-cost, class-specific screen used to triage a caseload before instrumental work begins. Examples are Marquis reagent for opioids and amphetamines,...
- Sample Preparation
- The set of steps between the sealed evidence container and the instrument autosampler vial: extraction, clean-up, concentration, derivatisation, dilution, internal standard addition....
- Vapour-Phase IR Spectrum
- The infrared spectrum recorded as a GC analyte elutes into a heated light pipe inside the FTIR cell, with no solvent or...
Explained in these topics
- Hyphenated Techniques: GC-MS, LC-MS and GC-FTIRAny analytical method that couples a separation stage to a structurally informative detector in a single online workflow. The separation provides chromatograph...
- Introduction and Scope of Instrumental Techniques in Forensic ScienceA single workflow that couples a separation method to a spectroscopic detector, so a complex mixture is resolved and each component identified in one run. GC-M...