OTE Stain (Oolong Tea Extract), Powder, 10g

Preparation and use of OTE stain from powder: 

The preparation of the OTE solution is similar to the infusion of tea with water @ 70°C. Use a heating magnetic stirrer set to 70°C, dissolve your OTE powder at a concentration of 0,2% (saturation is reached at 0,3%). Complete dissolution takes 15 to 30 minutes with stirring at 70°C.  

1. Filter your OTE extract solution with a 0,45µm filter.
2. Storee.g.in a small Microtube filled to the maximum to reduce air containing oxygen or in any other vessel that assures airless storage. 
3. Store in the darkness at 4 °C (when handling always let your solutions return to RT!)
4. Contrast your grids with OTE for 15 to 25 minutes in the dark at RT.
5. Drain excessive liquid. Do not rinse!
6. Post-stain 1- 2 minutes with lead citrate according to Reynolds (DM11300)
7. Drain,shortrinse, dry. 
8. Your sample is ready to watch.

Uranyl Acetate, which has been used for more than 40 years as an electron microscopy contrast agent, is subject to strict regulations regarding its sale, transport, use and waste disposal due to its toxicity. These health and regulatory constraints have led many researchers to replace it with less toxic EM stains. Today there are many non-toxic and non-radioactive contrast (stain) products, to name just a few: UAR, Uranyless, OTE, ... 

Oolong tea extract (OTE) gives satisfactory results as EM stain. It acts as a Tannin which allows complete post-stain lead citrate mordanting. OTE is a product used in Asia as a beverage extract with reference to the famous Oolong tea. Wulong is a type of tea with incomplete oxidation, halfway between green tea, non-oxidized and black tea, fully oxidized. 

Store in dry, dark conditions. 

Ready to use solutions will be added soon.