A Stable Sulfide Standard: And No Precipitate, Too?

The typical sulfide standard is available from many commmercial sources is preserved in an aqueous, alkaline matrix with a small amount of Zinc Acetate. This conventional approach to preparing sulfide standards produces a solution that is stable for a short time only, and generates a precipitate that requires resuspension each time used.

We have developed a new, very stable sulfide standard. The standard is formulated at 10 mg/mL available sulfide in a proprietary buffer matrix in an oxygen free environment. This formulation requires no Zinc Acetate preservation so no precipitate is formed! Without a precipitate, aliquots can be taken without concern for solution heterogeniety. When stored at 4 degrees Celsius, we are estimating this solution is stable for at least 12 months from manufacturing.

To use this standard, mix gently by inversion then perform an appropriate serial dilution to yield the required standard concentrations. The stock standard is supplied at 10 mg/mL to allow for easy dilution up to 100 mg/L as per SM 4500-S2. This can be used for calibration or as an LCS.

Part#: QCI-147 - $180.00/6 x 1.5mL