Instrumental Technique
Definition
An analytical method that uses an instrument to detect, identify or quantitate an analyte, distinguished from classical wet-chemistry methods such as titration, gravimetry and colour spot tests where the analyst reads the result directly. The instrument provides a signal (absorbance, mass-to-charge, retention time, fluorescence intensity) that is converted to a concentration through calibration.
- Field
- Forensic analytical chemistry
- Contrasted with
- Classical wet-chemistry methods
- Examples of wet chemistry
- Titration, gravimetry, colour spot tests
- Output
- A measured signal converted to concentration via calibration
Common questions
Why is a colour spot test not considered an instrumental technique?+
A spot test relies on the analyst directly observing a colour change with the naked eye, with no instrument generating or measuring a signal, whereas instrumental methods produce a measurable output such as absorbance or mass-to-charge ratio.
Why do instrumental techniques need calibration before a result is reported?+
The raw signal an instrument produces, such as peak area or absorbance, has no meaning on its own. Comparing it against a calibration curve built from known-concentration standards is what converts the signal into a defensible quantitative result.
Related terms
- Confirmatory Technique
- An instrumental method capable of identifying a specific molecule with sufficient selectivity to be admissible in court. The accepted gold standards are...
- Hyphenated Technique
- A single workflow that couples a separation method to a spectroscopic detector, so a complex mixture is resolved and each component identified...
- 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...
- 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....