Coulometric vs Infrared Sulfur Analyzers: Which Fits Your Lab?

Method basics

Coulometric analyzers (GB/T 214, ISO 16994) titrate the SO₂ electrolytically — absolute quantification with no calibration gas, at modest equipment cost. Infrared analyzers (GB/T 25214) burn the sample at 1350 °C and read SO₂ by IR absorption: ~120 s per sample, no electrolyte, ideal for high throughput.

Decision matrix

Choose coulometric if: budget is tight, daily sample count < 50, or you need the classical arbitration method. Choose infrared if: you run hundreds of samples daily, want walk-away automation with 24+ position feeders, or electrolyte handling is a burden.

High-throughput labs increasingly pair both: IR for routine screening, coulometric for confirmation and disputes.

Robotics change the math

Robotic coulometric models now load 25+ samples with unlimited top-up and automatic WO₃ dosing, closing most of the throughput gap while keeping the arbitration method — a strong option for mine-mouth labs with variable truck arrivals.