PROTOCOL FOR PREPARING SUPERSATURATED PHOSPHORIC ACID FOR CARBONATE ANALYSES

Protocol for analysis of stable isotope on Kiel 253

Introduction: The following protocol describes the analysis of carbonate samples for 13C and 18O at a Kiel IV carbonate device.

Safety info: Wear cryo-gloves, long sleeve shirts, protection glasses and closed shoes when handling with liquid nitrogen in open dewars. Liquid nitrogen is an extremely cold material. The vapor of liquid nitrogen can rapidly freeze skin tissue and eye fluid, resulting in cold burns, frostbite, and permanent eye damage even by brief exposure.

In the event of spillage of liquid nitrogen on a person: If exposed to liquid or cold gas, restore tissue to normal body temperature, 37°C, followed by protection of the injured tissue from further damage and infection. Remove or loosen clothing that may constrict blood circulation to the frozen area. Rapid warming of the affected part is best achieved by using water at 42°C. Water should under no circumstances be over 44°C, nor should the frozen part be rubbed either before or after rewarming. If in doubt contact Legevakt (phone 116 117 or 113 for emergencies).

If someone get liquid nitrogen it in the eyes, call 113, wash the eyes with appropriate equipment immediately.

Sample identification

A sample list should first be made: total amount of samples, Sample ID (from user), type of material, Lab ID (project no) ect. The analyses project must be registered in the project database http://delta.geo.uib.no:8085

Weighing in standards/sample material

Equipment: Spatula, tweezers, tray, brush, weighing boat, paper box for vials and clean Kiel vials.

Write yourself on the list/check if the microscale is available. Clean the working bench and other weighing equipment with Kim Wips/brush. Do not place vials, racks or other equipment on the anti-vibration table or on top of the microscale to prevent destabilizing the balance. Use a 253-run sequence sheet for plotting information needed (Sample ID, Project no, sample material ect. Find CM12 and NBS18 in the standard desiccator. Open the standard bottle only when you take out standard and close it immediately after use. DO NOT PUT MATERIAL BACK INTO THE STANDARD BOTTLE AND NEVER POUR STANDARD OUT! Weigh in between 30 – 70 μg of the material. Carefully lead the boat towards the microscale by using a tweezer. If the weight is too large: remove the boat from the microscale and pick/pour the extra grains out on the tray/weighing paper. You can reuse standard material if the trey/paper is clean. lean the top of the vials with your fingertip and before you carefully lead the boat towards the bottom of the vial in a horizontal position. Clean the top of the vials with your fingertip before you carefully lead the boat towards the bottom of the vial in a horizontal position. Turn the vial and boat in a vertical position before pouring and carefully knocking the boat towards the wall to ensure that all material are located in the vial. Weight the empty boat again to double-check that it is no material left in the boat. Tap the vial with a tweezer to make sure all sample material is located at the bottom of the vial. Vial 1/1 and 1/2 (pump vials) must be clean and empty because these vials are not used for sample measurement. Placed the vial in the right position in the paper box. Repeat procedure from step 7. When changing to a new standard /sample use a brush and Kim Wips to clean all apparatus thoroughly to avoid contamination of standard. Place the standard back in the desiccator as soon as you are finish. If you leave the weighing room over time, make sure to cover all vials with a paper sheet to prevent dust and other impurities to fall into the vials. Once you are done, clean after yourself.

Running samples on 253

Record date, filename, sample no, quantity of standards, ect in the logbook. Open Isodat 3.0 (if not already open) Click on double arrow symbol “>>” on the right-hand side of the taskbar to get an overview of the different Isodat modules/ programs (Fig. 1). An accessories bar appears on the left-hand side of the window: click on the pop out bottom (Fig. 2) on the “Dual Inlet” panel to open the Dual inlet window. Write down values/information in the blue logbook Dato, analyse nummer, antall prøver, antall std, filnavn ect. Vac and HV (visible in the MS panel on the left-hand side, figure 1) when the changeover valves are closed. Open changeover valves and perform a background scan to check the signal in the reference gas: Adjusting the bellow on the right-hand side in the Dual inlet window to approximate 10 and note the voltage at cup mass 44 (MS panel).

Figure 1: Components of the accessories bar on the left-hand side. The Kiel IV carbonate window shows temperature and pressure (VM1 and VM2) in the device, marked with red circles. All Isodat 3.0 modules can be open on the “>>” sign by the red arrow.

Take out the magazine of the Kiel Device Click on the pop out bottom on the “Kiel IV carbonate” panel to open the Kiel IV carbonate window. Right-click on the Kiel IV carbonate window and click on “Take magazine” (Fig. 1). Pop-up message: “Line not free”  confirm by “yes”. Use thick gloves and be careful to not touch acid dropper capillary and counter spring when you take out the hot magazine/carousel from the oven.

Figure 2: The pop out bottom for the Kiel IV carbonate window is by the black arrow. To add a new visible dialog, click on the administrate Panels on the right-click menu.

Clean the acid valves (Fig. 3): Carefully clean the lower part of the acid pump with rolled kim wips: - The inner part of the acid dispenser - The acid dropper capillaries - The acid drop counter springs

  OBS! Do not change the position of the acid drop counter springs. 

- The black O-ring seals with your fingertips to facilitate the formation of vacuum. Close the oven-door. It takes at least 15 minutes until the vials have oven temperature although the oven shows the correct temperature. Changing vials in the magazine Double-check if measured vials contain acid before putting them in a plastic beaker. Make a note of the vial position if a vial contains unreacted sample material. Place new vials in the magazine. OBS! Vial 1/1 and 1/2 (pump vials) must be clean and empty because these vials are not used for sample measurement. Always make sure you have vials in position 1/1, 1/2, 2/1 and 2/2 when you (re)start a run. Insert the magazine in the Kiel Device Make sure that the two holes of the cover plate are located right above position 2/1 and 1/1. Insert the magazine in the right position in the Kiel oven with the positon 1/1 and 1/2 towards you. Make sure that vial 2/1 and 1/1 are located right above the two pistons. Close the oven-door properly.

Figure 3: Labeled components in the Kiel device/oven: 1= magazine, 2= pistons, 3= O-ring seal (line 1), 4= acid drop counter springs (line 2), 5= acid dropper capillary (line 2), 6= acid pump, 7= Kiel vial, 8= concentrated phosphoric acid reservoir

Prepare to start the measurement Kiel IV carbonate window: Click on ”Load magazine” on the right-click menu (Fig. 1). Confirm pop-up window (magazine loaded) with “OK”. Write down your sequence. Click on “File browser” panel and go to sequence bar. Select right sequence and type down the information (Weight, sample ID in identifier 1, type of material in identifier 2, project no in comment field). Check the method (carbonate.met) and refill time (RR). Log RR c) Control ref. refill (Mark the first sample and for every 5th sample) e) Peak center should be mark on every 10th sample Check level indicator of liquid nitrogen refill device and if the red manual valve/ handle is open. One full run needs at least 50 L liquid nitrogen. check if the dewar is icy Before running you should log: Log the VM1 and VM2 value in the Kiel IV carbonate window. The vacuum VM1 should be around 100 ubar (when it is no gas in the system), while vacuum VM2 should be as low as 10-3 mbar. Box and trap value (mA) (Visible in the MS panel on the left-hand side, fig 1.) Check if the temperature of the Kiel oven is stable at 70 °C  0,1 and the Kiel IV window (73°C). Double-check if all required information is recorded in the logbook. Start the run in acquisition window Select all the sample to run Press “start” Update the week and date, as well as the export filename. Confirm “ok” Make sure it is enough paper in the printer Put the old vials containing acid into a water bath. Leave the water running for a little while to make sure most of the acid is washed away, and remove bubbles in vials by carefully stir with a glass stirrer or using gloves. Soak the vials for at least two hours before placing them in the washing machine. NB! Do not use dishwasher detergent. Stay near 253 at least during the first standard measurement to control the quality of the data. The computer is set to automatically print out results on run sheets.

Written by Anna Tran 06.09.19