InSpectro NIR

Inline Near-Infrared Spectroscopy

Why Inline NIR?

Unlike offline or at-line methods, inline NIR probes are installed directly in the process stream — inside an extruder barrel, a blender, a coating drum, or a pipeline. The material flows past the sensor while being produced, enabling continuous monitoring and immediate feedback for process control. This eliminates sampling errors, reduces waste, and unlocks true Quality by Design.

Practical Applications

What can you actually measure with an inline NIR probe? Here are the most impactful use cases across industries.

1. Moisture / Water Content

NIR is extremely sensitive to O-H bonds, making moisture detection one of the most reliable and widespread inline applications. It is critical in drying, granulation, and extrusion processes where even small variations in water content can affect product quality.

Examples:
• Residual moisture in polymer pellets
• Drying endpoint in fluid-bed granulators
• Water activity in baked goods and snack production
2. Contamination Detection

NIR can flag chemical contaminations or foreign material presence in a product stream, functioning as a continuous quality gate. No manual intervention is required — the system monitors every moment of production.

Examples:
• Foreign polymer detection in recycling streams
• Chemical adulterants in food ingredients
• Cross-contamination between production batches
3. Chemical Composition & Additives

NIR quantifies the concentration of additives, plasticizers, residual monomers, or individual components in multi-component blends as they flow through the process. This ensures formulation accuracy and prevents costly batch failures.

Examples:
• Plasticizer content in PVC extrusion
• Residual solvent in coatings
• Component ratio in polymer blends
4. Blend Uniformity

By tracking spectral variability over time, NIR can determine when a powder blend has reached target homogeneity. This is a core PAT application formally recognized by the FDA and essential for ensuring consistent drug product quality.

Examples:
• API distribution in powder blends
• Additive dispersion in masterbatch mixing
• Homogeneity in dry blending of excipients

InSpectro NIR: ColVisTec's Solution for Inline NIR Spectroscopy

The ColVisTec NIR spectrophotometer operates in the 1000 – 2500 nm wavelength range and delivers real-time analytical data from inside extruders, reactors, mixers, and other process equipment. By continuously "looking inside" the process, it provides 100% control over product quality rather than relying on discrete sampling.

Proven Case Studies

1. Water Content & Throughput Detection in Extrusion

In a real extrusion trial, the NIR inline system clearly distinguished between water-containing and dry polymer melts:

• Water in the polymer → lower NIR signal level
• No water in the polymer → higher, stable signal
• Lower throughput (100 kg/h) → high signal noise, indicating poor homogenization
• Higher throughput (300 kg/h) → low noise, indicating good homogenization

This demonstrates the NIR probe's dual capability: measuring both chemical composition (water) and process quality (mixing efficiency) simultaneously.

2. PE Contamination in Recycled PP

Within the RecyColor project, the NIR system successfully detected polyethylene (PE) contamination in polypropylene (PP) recyclate, with a linear correlation (R² = 0.91) across a 0–10% PE contamination range. This enables real-time flagging of off-spec material in polymer recycling streams.