Inductively Coupled Plasma (ICP)

ICP is used for elemental analysis using plasma excitation and optical emission detection.

Working Principle

Sample aerosol enters plasma at ~8000K where atoms emit characteristic wavelengths.

Applications

• Trace metal analysis
• Environmental water testing
• Food safety

Part of Laboratory Engineering Hub

Inductively Coupled Plasma (ICP) spectroscopy is a key elemental analysis technique within our complete laboratory analyzer engineering framework.

Explore the full Laboratory Engineering reference including GC, HPLC, UV-Vis, ICP, Karl Fischer and Titration: Laboratory Analyzers – Engineering Fundamentals

Plasma Generation Mechanism

ICP uses a radio-frequency (RF) coil to ionize argon gas. An oscillating electromagnetic field generates a stable plasma at temperatures between 6000–10000 K.

At these temperatures:

• Sample aerosol is desolvated
• Atoms are atomized
• Atoms are excited
• Characteristic emission wavelengths are produced

Emission Intensity Relationship

In ICP-OES, emission intensity is proportional to concentration:

I ∝ C

Quantification is performed using calibration standards.

Worked Concentration Example

Calibration equation:

I = 1500 C + 20

Measured intensity = 3020

3020 = 1500C + 20 3000 = 1500C C = 2.0 mg/L

This result must fall within validated linear calibration range.

Detection Limits

Limit of Detection (LOD):

LOD = 3 × (σ / S)

Where:
σ = Standard deviation of blank
S = Slope of calibration curve

LOD determination is mandatory under ISO 17025 method validation.

Troubleshooting Logic Flow

• Unstable plasma → RF generator issue
• Drift → Torch alignment problem
• High background → Argon purity issue
• Poor precision → Sample introduction instability

ISO 17025 Technical Control Points

• Calibration verification standards
• Internal standard correction
• Background correction validation
• Repeatability (%RSD) checks
• Uncertainty estimation documentation