Technical Details

PYRO-SA Sulphate Ashing System

Ashing test procedures performed on pharmaceutical, polymer, and food samples frequently involve the use of H₂SO₄. Hot sulphuric acid vapor released during these procedures is both hazardous to analysts and corrosive to equipment. In addition to these complications, sulphate ashing procedures are typically labor-intensive and time-consuming, requiring manual fuming of acid from crucibles and 8–12 hours to complete.

Milestone has engineered a unique microwave system for sulphate ashing procedures. The PYRO SA^TM Microwave Sulphate Ashing System enables analysts to add H₂SO₄ to samples and place crucibles directly into the microwave muffle furnace without a preliminary charring step. Tedious handling/monitoring of samples, and operator exposure to acid fumes, are eliminated. The labstation is designed for complete operator safety and long life, and performs the complete procedure in only 60–90 minutes.

Sulphuric acid fumes released from crucibles inside the muffle furnace are continuously removed, through a quartz tube connected to an air-cooled quartz collection vessel outside the unit, and to the VAC-1000 acid scrubber module. (See photo.)

In operation, H₂SO₄ is added to the samples in the crucibles, which are then placed directly into the PYRO unit. The ashing temperature of 550 °C is achieved in 20 minutes, and ashing is completed in 60–90 minutes. Charred components, condensed in the quartz cooler and vessel, can be easily removed by simply placing them in the muffle and burning them off at high temperature.

Typical Sulphate Ashing Times
Sample	Microwave Ashing Temperature (°C)	Microwave Ashing Time (minutes)	Traditional Ashing Time (minutes)
Lactose	600	60	480
NFT	800	50	480
Cellulose	800	80	500
Heavy oil	550	230	960
Antibiotics	850	65	480
Tartaric acid	800	80	500

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