Standard Operating Procedure for Detecting MEA Triazine in a Crude Oil Matrix using LONESTAR TM

Transcription

1 Standard Operating Procedure for Detecting MEA Triazine in a Crude Oil Matrix using LONESTAR TM Contact us Owlstone Nanotech Inc 2012 The Owlstone logo, OWLSTONE, LONESTAR, OVG-4 and OHG are trademarks of Owlstone Inc

2 Lonestar Method BHM1 MEA Triazine H2S Scavenger Detection in a Crude Oil Matrix Principles 5g of the retrospective drawn sample is then weighed out into a sampling vial accurately using an analytical balance. The sample is then loaded into a pre-calibrated Lonestar system which continually flushes the headspace with clean dry air. Within the sampling module (GBH) of the Lonestar the air is split and then diluted for the higher concentrations allowing a more dynamic range. The lower concentrations (0ppm 600ppm) do not contain a split as the monoethanolamine (MEA) triazine has not reached saturation. As the headspace replenishment rate is temperature dependent the sample is temperature controlled at 35C. A measurement is taken and converted on screen to an equivalent concentration. Apparatus Plastic Pasteur pipette ( Part number Fisher Scientific FB 55345) Analytical balance (calibrated) 10ml GCMS glass vial (Part Number Fisher Scientific VGA K) O-ring (Part number Owlstone ) Directions Load an empty GC glass vial into the silver insert into the bottle holder of the GBH attached to the Lonestar as pictured below in Figure 1. Fit bottle holder onto interface on the Lonestar and spin the securing nut until snug. (Please ensure the silver GBH insert has an O-Ring attached) Figure 1 Loading sample bottle The Lonestar analyser screen appears as shown in Figure 2 2

3 Figure 2 On the pull down menu labelled Method select the HHTT content ppm 6 mins v4a. Before any sample can be ran on the system it is essential to ensure the system is clean. This is done by clicking the Check Clean button (shown in figure 2). The button will only be selectable if the top banner is green. If it is red, one or more parameters for example system flow or pressure does not match the method file. To solve this issue either consult troubleshooting guide in the Lonestar manual or contact us directly via Zendesk. Figure 2 Lonestar analyser Screen Click the OK button to continue. The software will then check that the system is clean and ready to begin a measurement. (shown in figure 3) Figure 3 clean down sample required and acquisition screen shots If the bottle and system is clean, the light by the Check button will switch from red to green and a time stamped Cleanliness Confirmed message will appear. The system is now ready to receive a sample (it can be left in this state almost indefinitely but if the time exceeds 4 hours it is recommended that the check is rerun before taking the sample). The time to carry out a cleanliness check is approximately 2 minutes. The light will be green and the Measure button will be available to select. Unload the sampling vial by releasing the securing nut on the GBH 3

4 Using a plastic Pasteur pipette weigh 5g of a representative crude oil sample into the glass sampling vessel. Place sampling vial back into the GBH, drop vial into silver insert inside the GBH. Fit bottle holder onto interface on the Lonestar and spin the securing nut until snug Select the Measure button on the analyser screen (shown in figure 4) During analysis of the sample the orange banner should turn to green if all parameters are met. Again refer to the Lonestar manual or contact Zendesk if this does not happen. Figure 4 - Select measure button Analysis time is approximately 6 minutes. Upon completion the screen is updated with the concentrations and a time stamp. The cleanliness of the system will switch to Unconfirmed and the indicator will turn red waiting for another blank bottle Figure 5 Results screen Remove sample and swap in a fresh clean bottle to allow the system to blank Select the Check Clean button on the analyser screen The system is then ready for the next sample 4

5 Lonestar Method BCM2 Calibration check standard Principles In order to check the system functionality a test sample is created at a mid-range concentration for the application. The analyser output for the sample should be within the 10% of the expected signal (the specified accuracy for the method), if it fails then a calibration adjustment will be required. Reagents Hexahydro-1,3,5-tris (hydroxyethyl) triazine CAS No: Crude oil Apparatus µl positive displacement pipette & pipette tips GCMS glass Vials (New vial used for every sample) O-ring (Replace on silver insert once per week) Analytical balance Stirring plate Fridge to store samples Glass double ended magnetic spinner 40mm (Part number Fisher Scientific FB55628) 100ml Duran bottle with lid (Part number Fisher scientific FB 33144) Directions (200ppm check standard) This assumes that the Mea-Triazine content in the sample is 100%, additional calculations may have to be applied if the content is lower The density used in the calculations is 1.16g/ml Place magnetic stirrer into 100ml Duran bottle Using an analytical balance weigh out 100g of crude oil into 100ml Duran bottle using a plastic Pasteur pipette Using the µl positive displacement pipette, pipette 17.2µl of MEA triazine into the 100g of crude oil Place lid on top of Duran bottle & label Invert sample 3 times and place on stirring plate Set plate to 400RPM and leave for 30 minutes Load sample into Lonestar and run sample using HHTT content ppm 6 mins v4a Analyser output should be 200ppm +/-10%. If outside of this range, first repeat sampling on a fresh sample and then refer to the troubleshooting guide in Lonestar manual or via Zendesk. 5

6 Re-stir samples at 400RPM for 10 minutes if sample is left longer than 24hours. 6