My study will make use of Atomic Absorption Spectroscopy analysis and thus accuracy and precision of zinc concentration is a must.
It has been years since I did this analysis. I always mixed and stored standards in glassware, and collected samples to be analyzed in polyethylene or polypropylene bottles, preserved as suggested in standard methods for analysis of water and wastewater. I used glass pipets except for biological tests such as fecal coliform, where the pipets were disposed. I dont remember any warnings in std methods, but if you have critical concerns, just rely on laboratory glassware. Another way is to put low concentration in polyethylene bottle, preserve and store appropriately, and see if concentration changes with time. I also kept standards in cool, dark room, no sunlight, infrequent light to access. Where possible, I would dedicate glassware to specific tests, and was careful in avoiding how glassware exposed to high concentrations or pollutants would be reused.
The pH is essential. In acidic solutions, zinc will not adhere and not precipitate. Glass is worse compared with polyehtylene, which is worse than some other polymers, such as PVA or teflon. However, if you keep the pH below 2, zinc should not adhere to glass or polyethylene walls. All containers, pipettes etc. should be acid-cleaned and rinsed with sufficiently cleaned water, if you do not want contamination from equipment or containers. Zinc is a common contaminant in trace metal analysis.
Polyethylene or polypropylene containers are the most preferable for storage of acidified zinc solutions. It is possible to store solutions in such containers for a long time.
I agree with Ms Yolanda Hedberg and I will repeat her sentences
The pH is essential. In acidic solutions, zinc will not adhere and not precipitate. Glass is worse compared with polyehtylene, which is worse than some other polymers, such as PVA or teflon. However, if you keep the pH below 2, zinc should not adhere to glass or polyethylene walls. All containers, pipettes etc. should be acid-cleaned and rinsed with sufficiently cleaned water, if you do not want contamination from equipment or containers. Zinc is a common contaminant in trace metal analysis.
We regularly measure dissolved zinc in samples collected from the open ocean at concentrations below 100 pmol/L...as suggested, acidifying to below pH 2 (e.g., 0.024 M HCl) will prevent the zinc from adsorbing to the walls.
Depending on the zinc concentrations in your samples, you will need to acid-clean the bottles in advance. Give yourself plenty of time, since the acid-washing process can take 2-4 weeks. See the GEOTRACES cookbook for excellent advice about collecting trace metal samples, especially pages 46-58.
http://www.geotraces.org/images/stories/documents/intercalibration/Cookbook.pdf
Always use glass or plastic flasks with drops of nitric acid. It will not be any adsorcion
to walls.
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