Equipment and reagents#

Where to find equipment

Check the Zarges boxes downstairs - most of the equipment should be there, but check specifically for reagents (in the boxes or in the chemical storage, ask Anette Wold)

Lab equipment and instruments#

  • Pyrex precalibrated flasks: Each flask is numbered.

  • 2 pcs Micropipette and tips: 1ml – 10ml and 100µl – 1 000µl

  • 2 pcs. Autopipettes with 25ml syringe incl. user manual

  • Several magnets for the magnetic stirrer

  • 2 pcs. syringes 10ml

  • 1 pc. syringe 50ml (to create headspace before acidification of the sample)

  • 2 pcs. plastic bottles w/ screw cap 250ml for reagent A and B

  • 3 pcs. Reagent dispensers: for the Reagent A (MnCl2), for the Reagent B (NaI/NaOH) and for the Sulfuric Acid Solution. The dispenser containing the NaI/NaOH will require regular attention, because the plunger will begin to stick/bind to the glass. The NaI/NaOH dispenser should be thoroughly cleaned and disassembled for long-term storage between voyages because otherwise the plunger will become stuck.

  • 5 pcs. amber colored reagent bottles: It is recommended to use amber colored reagent bottles to prevent any light effect.

  • Flexible plastic drawing tube or “noodle”: A length of thin-walled Tygon tubing long enough to reach from the petcock of the Niskin water sampler to the bottom of the oxygen sample flask. The diameter of the tubing must be large enough to allow a good rate of overflow of water as the flask is being filled. It is convenient to fit a short piece of highly flexible silicone tubing over one end of the drawing tube to make it easier to slip the tubing over the nipple of the petcock.

  • Digital thermometer

  • 3 pcs. beakers 100mL

  • 1 pc. squirt bottle for distilled water

  • Metrohm Ti-Touch 916 (all manuals are on the USB storage plugged on the Ti-Touch Metrohm)

  • 1 pc. Double Pt electrode (no storage condition)

Reagents and preparation#

Material safety data sheets (MSDS) for all chemicals are available digitally in IMR’s chemical database and in the MSDS folder in the chemical storage.

Danger

Wear gloves and goggles for the preparation of reagents and work in a fume hood!

  1. Manganous chloride (3M): Reagent A
    Slowly add 600g of MnCl2 $\cdot$ 4H2O to a graduated flask containing 500-700ml of DEST, stir until all the crystals have dissolved. The solution becomes cool upon preparation; allow it to reach ambient temperature then make the volume up to the 1L mark with DEST. Filter the solution through a course glass fiber filter to remove any particulate material. If time or staffing is short, a magnetic stirrer can assist enormously.

  2. Sodium iodide (4M)/Sodium hydroxide (8M): Reagent B
    Dissolve 320g of NaOH in a beaker containing roughly 500ml of DEST. Allow the solution to cool. You have to place the graduated flask in a bucket filled with cold water. Then slowly add 600g of NaI and allow the solution to cool again. Then add DEST to make the solution up to 1L. It is particularly important to filter this solution because often there is a great deal of material that does not dissolve and some of this material has been found to be a reducing substance that contributes to the reagent blank.

  3. Sulfuric acid (5M)
    Slowly add 280ml of concentrated reagent grade H2SO4 to a graduated flask containing roughly 500ml of DEST. You need to cool down the solution with cold water. Allow the solution to cool to ambient and then make up the volume to 1L. A graduated beaker is sufficiently accurate for the preparation of this solution.

  4. Thiosulfate (0.05N)
    Given that the formula weight of Na2S2O3 $\cdot$ 5H2O is 248.17g mol-1 you weigh out 25.0g and make the volume up to 2L in a volumetric flask. For some reason, it has been found that the thiosulfate solution is more stable and consistent if it is left to age (say 2 – 5 days). This leads to more consistent blanks and calibrations day to day, saving time and frustration. As such it may be advisable to make it up in quantities >1L.

  5. Potassium iodate (0.00167M or 0.0100N)
    Weigh out roughly 0.5g of KIO3 and dry in an oven at 170°C for several hours. Weigh out 0.3567g of the dried KIO3, dissolve in DEST and make up to exactly 1L in an “A-grade” volumetric flask. Measure the laboratory temperature and denote it as TP. It cannot be overstated that the absolute accuracy of your oxygen analyses are dependent on the care you take with the preparation of KIO3 standard solution.

    Note: You can also buy KIO3 standard solutions, e.g., from OSIL.