Tekran Inlet Manual Injections

 

Purpose:  Follow the steps below to perform Tekran Inlet Manual Injections, also referred to as Inlet Standard Additions.

 

Required Equipment:    2505 Mercury Vapor Calibration Unit

                                              Calibrated Hamilton Digital Syringe

                                              2505 10mm Teflon® backed Silicone Septum

                                              2505 Septum Removal Tool

                                              Inlet Injection Harness with 6mm Silicone Septum

                                                                                               

Reference:        

 

1.       Ensure the Tekran Model 2505 Mercury Vapor Calibration Unit is turned on and allowed to equilibrate for at least 24 hours prior to its anticipated use. Note: During hot weather, inlet injections should be performed during the morning hours when ambient temperatures are cooler. 

2.       Insert the Hamilton digital syringe into the Model 2505 unit once the flask temperature has stabilized and cycle the plunger up and down two times leaving the plunger up with the syringe fully loaded with mercury saturated vapor.  Allow the syringe to equilibrate overnight but at minimum for two to three hours.  Conditioning the syringe overnight is preferred and will help ensure best syringe operation.

CAUTION

If the Model 2505 is moved, bumped, or otherwise disturbed it will be necessary to change the septum and clean the support collar with a cotton swab to prevent small mercury beads from contacting the syringe needle.

CAUTION

Never insert the Hamilton digital syringe into the Model 2505 unit unless the flask temperature is at 15 degrees C. If the flask temperature is warmer than the syringe body, then mercury vapor will condense in and ruin the syringe.

 

3.       When ready to perform inlet injections, temporarily remove the syringe from the 2505.  

4.       Turn off the 2505, disconnect power and carry it up to the shelter roof being careful to keep it level at all times.  Never carry the 2505 with the syringe inserted to avoid damaging the syringe.  Place the 2505 in close proximity to the Tekran inlet, reconnect power, and turn the unit back on.  Keep the 2505 shaded at all times. 

5.       Reinsert the syringe into the 2505 unit as soon as the flask temperature has re-stabilized and cycle the plunger up and down two times leaving the plunger up with the syringe fully loaded with mercury saturated vapor to re-equilibrate for at least one hour.

6.       While waiting for the syringe to re-equilibrate, down the Tekran channel, stop the instrument, and initiate a perm tube calibration.  If 2537 manual injections were performed immediately prior to inlet injections with a perm cal initiated beforehand, then a second perm cal is not necessary.

7.       Remove the external heating boot and standard Tekran inlet, and install the inlet injection harness.

8.       If a perm cal was initiated let it finish, then start the Tekran in run mode, and flip the zero air switch on and the pump flow switch to desorb.  It is also a good idea at this time to turn all heater switches off in case the injections run past the adsorption cycle into the desorption cycle.  If the denuder and RPF heaters are left on, injection results will be unreliable.  Injections performed during the desorption cycle are the same as during the adsorption cycle except that for injections during the desorption cycle, the current scaling factor in the 2537 must be recorded in the Tekran spreadsheet.   

9.       When the run concentrations on zero air are close to or equal to zero, conduct one manual injection on Trap A and one injection on Trap B as follows:

a.       On the 2537 front panel keypad, press the4button until the Timing Display is shown so you can see the current operation being performed on Trap A and Trap B as well as the total duration and time remaining for that step. 

b.      When the Timing Display shows the status of the desired trap to be injected is DONE and there is approximately 30-45 seconds of sampling time remaining in the other trap, quickly go back up to the roof.  The object is to perform the injection as soon as the desired trap to be injected begins the 300 second sampling period to ensure all mercury vapor reaches the analyzer before that 5-minute sampling period ends. 

c.       Turn on the digital syringe and ensure the display reads 0.00 when the plunger is fully depressed.

d.      Cycle plunger slowly up and down two times.

e.      Slowly pull the syringe up to approximately 17 µl and make note of the HgSrc temperature displayed on the Model 2505 unit.

f.        Quickly remove the syringe and position yourself in front of the injection harness.

g.       Using the thumb screw, smoothly decrease the syringe volume to 15 µl.

h.      Fully insert the syringe needle into the inlet injection harness septum port.

i.         Pull the syringe needle back slightly and then fully depress the plunger to inject all mercury saturated vapor.

j.        Remove the syringe needle from the injection port.

10.   Insert the Hamilton syringe back into the Model 2505 unit and pull the plunger up and leave the syringe fully loaded with mercury saturated vapor.

11.   Record preliminary injection information into the Tekran spreadsheet and then read the Hg concentration ng m-3 displayed in the data logging program for the trap that was injected and record results in the spreadsheet to calculate the difference between actual and calculated mercury.

a.       If the concentration on the previous trap was not at zero before the injection, then the decision to subtract this value from the peak area for the trap that was injected should be made by the individual performing the injections.  If concentration was not at zero with zero air on, and the reading is thought to be caused by low level, constant, residual contamination within the sampling line, filters, or instrument, then it would be appropriate to subtract out this value.

b.      Due to the timing of an inlet injection, sometimes all of the mercury vapor may not be captured on a single trap. In these cases, the individual performing the injection will have to determine if the concentration on the following trap should be added to the peak area for the trap that was injected.  

c.       In all such situations described above in 7a. and 7b., individual injection results in the spreadsheet should be annotated to indicate any corrections that were made.

12.   If the difference of the second injection is ≤ 5% then no further action is required.

13.   If the difference of the second injection is ≥ 5% then perform two more injections.

14.   If the difference of the fourth injection is still ≥ 5%, contact Plano for assistance.

15.   When finished with inlet injections, stop the instrument, and remove the injection harness.  Reinstall the standard Tekran inlet and external heating boot.

16.   Restart the Tekran in run mode and ensure you turn the zero air switch, pump switch, and all heater switches back to auto.

17.   Replace the inlet injection harness septum.  Cleaning the injection harness glassware is not required.  Store the harness in a ziplock bag to prevent contamination.

18.   Remove the syringe from the 2505 unit and store the syringe in its protective case.

19.   Turn the 2505 unit off, remove the old septum using the septum removal tool, and install a new septum with the Teflon® side facing down.

20.   Record injection results in the Tekran spreadsheet, attach the document to the SM ticket, and upload it to Sharepoint.