The Gastec Sulfide Ion in Solution Detector Tube No. 211, available from Nextteq, provides an accurate and quick method for detecting sulfide ion levels in solution. The direct-reading tubes produce a quantitative color-stain that pinpoints problem areas in 2-3 minutes. The calibration scale, printed directly on each tube, provides on-the-spot results that are easy to read. The sulfide ion tube requires no color comparison chart or laboratory equipment to determine results. Additionally, the color-stain ends with a clearly defined line of demarcation to further eliminate confusion, increasing the accuracy of the results.