Operating Instructions for SKC 224-G5 Sorbent Tube

Quick guide from the manual

The SKC 224-G5 Sorbent Tube is designed for air sampling. To ensure accurate results, always use the tube in a vertical position to prevent sample channelling. When preparing the tube, ensure a minimum hole diameter of 2mm at the ends. During analysis, always test both sections of the tube independently to check for breakthrough; if the backup section contains more than 25% of the analyte found in the main section, breakthrough has occurred.

Flow Rates

Ensure your sampling pump is set within the appropriate flow rate limits for your specific tube size:

• 6 x 70mm: Maximum 500 ml/min (Typical 10-100 ml/min)
• 6 x 110mm: Maximum 500 ml/min (Typical 20-100 ml/min)
• 8 x 110mm: Maximum 1000 ml/min (Typical 20-200 ml/min)

Preparation

Proper preparation is critical to avoid pre-sample contamination:

• Breaking ends: Ensure a minimum hole diameter of 2mm or half the diameter of the tube body.
• Contamination avoidance: Never calibrate or fit tubes in areas where chemicals are present. Ensure clothing (especially lab coats) is free from contamination.
• Capping: After breaking the ends, cap the sampling end until ready for use. Use only a light press for temporary capping; pushing caps fully home makes them difficult to remove.

Sampling

• Orientation: Always use the tube in a vertical position.
• Direction: The arrow on the glass tube indicates air flow direction and must point toward the tube holder. If no arrow is present, the smallest sorbent section should be nearest the holder.
• Post-sampling: Immediately cap both ends with the supplied red plastic caps, pressing them fully home to ensure a good seal.
• Moisture: If high moisture is present, use a trap tube before the sorbent tube.

Storage

• Environment: Never store used tubes in areas where chemicals are present, even if capped.
• Temperature: If storing for more than a few hours, place tubes in a refrigerator at 0°C. Exposed tubes can be stored for up to 1 week, depending on the analyte.
• Blanks: Always store a 'blank' (a tube with ends broken off but capped) in the same way as the samples to confirm no contamination occurred during storage.

Analysis

• GCMS: Use only tubes with glass wool separators.
• Breakthrough Check: Tubes have two sections. Test both independently. If the backup section contains >25% of the analyte present on the main section, breakthrough has occurred.
• Sorbent Removal: Ensure all sorbent is removed from the tube using a charcoal pick if necessary, as some man-made sorbents may stick to the glass.