|
|
| Line 1: |
Line 1: |
| __TOC__
| |
| == Leaky Chamber ==
| |
|
| |
|
| === Leaky chamber test ===
| |
| :::* When the leakage is so little that cannot be noticed in a short amount of time, we recommend to follow the ''Leaky chamber test'' below:
| |
|
| |
| ::::# Decrease the oxygen concentration down to ~ 50 μM (using [[Dithionite]] or N<sub>2</sub> injection)
| |
| ::::# Let the O2k record overnight with the [[closed chamber|chamber closed]] and illumination switched off
| |
| ::::# The oxygen concentration should decrease overtime due to the O<sub>2</sub> consumed by [[OroboPOS]] as it is shown in the figure. In this case, the chamber is assembled properly.
| |
| ::::# If the oxygen concentration increases over time, a reassemble of the chamber is needed.
| |
| [[File:Leaking_chamber_2020-02-03 P2-03.png|1500px]]
| |
|
| |
|
| |
| === A story about gas bubbles appearing in the closed chamber ===
| |
| [[User:Gnaiger Erich|Gnaiger Erich]] ([[User talk:Gnaiger Erich|talk]]) 16:27, 19 March 2020 (CET)
| |
| ::::* You are an O2k user who assembles the O2k-Chamber carefully following the SOP (manual & video). Usually this works very well - but not always ..
| |
| ::::# You are stressed because you have a persistent problem with a leak after chamber assembly, loosing medium from the chamber (observed by medium dropping out from the OroboPOS holder and connector; or a gas bubble appearing slowly in the closed chamber).
| |
| ::::# ‘Leaky chamber’, therefore, has to be defined: Here it is not just the oxygen leak (as observed in an instrumental O2-background test), it is actual medium leak – two entirely different processes, although medium leak causes simultaneously an O2 leak, but not the other way around.
| |
| ::::# You re-assemble again and again, until the chamber appears to be tight. You have no clue, what you did differently. And you are not 100 % sure, if the chamber is now really tight. (This is meant by “When the leakage is so little that cannot be noticed”).
| |
| ::::# You could test this easily with an instrumental O<sub>2</sub>-background test - SOP! You can do this even in a short amount of time, if you have other tasks to complete meanwhile. But unfortunately it is already evening, and the lab will be closed. (This is meant by “in a short amount of time”). Well, then you may quickly reduce the oxygen level .. the overnight ‘leaky chamber test’ (we will find a better title).
| |
| ::::# You may use dithionite quickly. But probably you performed your tests of loosing medium after chamber assembly with H<sub>2</sub>O, to avoid any sticky medium clogging your sensor connector when medium leaks from the chamber. Do you now titrate dithionite solution into the closed chamber containing H<sub>2</sub>O? YOU WOULD BE IN TROUBLE! This is well explained in our SOPs, but it is a good idea to clarify, that you should use MiR05 (or a highly concentrated phosphate buffer). (Marco: did you actually use MiR05 – I guess absolutely YES).
| |
| ::::# You come back to the lab in the morning – BINGO. The chamber is tight. Does this replace the instrumental O<sub>2</sub>-background test?
| |
