Operating Manual. AC OxyTracer Analyzer on 7890 GC Manual part number version 2011/1.0

Transcription

1 Operating Manual AC OxyTracer Analyzer on 7890 GC Manual part number version 2011/1.0 Contact addresses: AC Analytical Controls BV P.O Box 10054, 3004 AB Rotterdam Innsbruckweg 35, 3047 AG Rotterdam, the Netherlands Phone : Fax : acbv@paclp.nl AC Analytical Controls Inc 8824 Fallbrook Dr., Houston, Texas 77064, USA Phone : Fax : acinc@paclp.nl AC Analytical Controls Asia Pacific Ltd 30 Robinson Road, Robinson Towers # Singapore Phone : Fax : ac-asia@paclp.nl

2 Copyright Analytical Controls 2011 All Rights Reserved. Reproduction, adaptation, or translations without prior written permission is prohibited, except as allowed under the copyright laws. First edition, December 1995 Printed in the Netherlands MS-DOS and Microsoft are registered trademarks and Windows is a trademark of Microsoft Corporation. Warranty The information contained in this document is subject to change without notice. Analytical Controls makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Analytical Controls shall not be liable for errors contained herein or for incidental or consequential damage in connection with the furnishing, performance, or use of this material. Safety Symbols Warnings in the manual or on the instrument must be observed during all phases of operation, service, and repair of this instrument. Failure to comply with these precautions violates safety standards of design and the intended use of the instrument. Analytical Controls assumes no liability for the customer's failure to comply with these requirements. WARNING A warning calls attention to a condition or possible situation that could cause injury to the user. CAUTION A caution calls attention to a condition or possible situation that could damage or destroy that product or the user's work. Safety Information Throughout this manual, the reader and/or system operator will be required to utilize hazardous chemicals. During the performance or routine maintenance, the reader and/or system operator may be exposed to potentially dangerous electrical voltages and/or other hazards. To reduce the personal risk involved, the following guidelines are established. These requirements are within accepted standards for general analytical laboratory operation. Please refer to established safety requirements and government safety and disposal for additional information. Chemical Hazards WARNING HYDROCARBONS ARE TOXIC. UTILIZE THE CONTENTS OF ALL AC STANDARDS ONLY IN A FUME HOOD. AVOID INHALING FUMES AND CON-TACT WITH ANY PART OF THE BODY. WARNING LIGHT HYDROCAR- BONS ARE EXTREME- LY FLAMMABLE. THE FUMES AND VAPORS FROM LIGHT HYDRO- CARBONS ARE EASILY IGNITED. KEEP THE CONTENTS OF ALL AC VIALS AWAY FROM FLAMES, SPARKS, OR SOURCES OF HEAT. WARNING HYDROGEN IS A FLAMMABLE GAS. IF HYDROGEN OR ANY OTHER FLAMMABLE GAS IS USED, PERIODIC LEAK TESTS SHOULD BE PERFORMED. BE SURE THAT THE HYDROGEN SUPPLY IS OFF UNTIL ALL CON-NECTIONS ARE MADE AND ENSURE THAT THE INLET FITTINGS ARE EITHER CONNECTED TO A COLUMN OR CAPPED AT ALL TIMES HYDROGEN GAS IS PRESENT IN THE INSTRUMENT. DO NOT USE PLASTIC OR RUBBER GAS LINES FOR HYDROGEN. CAUTION All gases are dangerous when compressed. Do not store cylinders where they might be dropped or exposed to excess heat. Always direct the flow of compressed gases away from people. Electrical Hazards WARNING DANGEROUS ELECTRICAL VOLTAGES ARE PRESENT IN MANY PARTS OF THE SYSTEM, EVEN WITH THE POWER SWITCHES TURNED OFF. UNPLUG ALL THE MAIN POWER CORDS FROM THE POWER SOURCE FOR ALL THE SYSTEM COMPONENTS PRIOR TO SERVICING ANY OF THE SYSTEM COMPONENTS. WARNING METAL COLUMNS ARE EXCELLENT CONDUCTORS OF ELECTRICITY. THE OVEN HEATER COILS INSIDE THE OVEN IN THE GAS CHROMA- TOGRAPH ARE NOT ELECTRICALLY INSULATED AND CARRY LETHAL VOL- TAGE. TO AVOID CONTACT WITH LETHAL ELECTRICAL VOLTAGE WHILE CHANGING METAL COLUMNS, TURN OFF THE MAIN POWER TO THE HP GAS CHROMATOGRAPH BEFORE REMOVING OR INSTALLING THE COLUMN. KEEP THIS COLUMN AWAY FROM POTENTIAL LIVE ELECTRICAL SOURCES AT ALL TIMES WHILE HANDLING.

3 Contents

4 Contents TABLE OF CONTENTS PAGE Pre-installation... 1 Pre-installation Requirements Gas Requirements Gas Purity Physical Requirements Electrical Requirements Pre installation Checklist System Configuration Software Recording Important Numbers Installation... 2 Installing the Hardware Introduction Cabling (General) Analyzer configuration Installing columns and jumpers on the Capillary Deans bracket Installation of the liner Installation of capillary column to the TPI Column Installation to the micro fluidic switch Installing the AC OxyTracer methods Introduction Installing the AC methods Microsoft Windows Instructions Operation... 3 Introduction Summary of Method Configuration Principle of Analysis Instrument setup Adjusting flows and pressures PCM pressure Flows Swivel test Pre column analysis Real pre column analysis Iterative method Calibration Sample handling Calculation Detectability Minimum Detection limit Linearity: Repeatability Samples Method description Version 2011/1.0 Contents-2

5 Contents Spare parts kit and consumables kit OxyTracer Version 2011/1.0 Contents-3

6 1 Pre-installation

7 Pre-installation Pre-installation Requirements Pre-installation Requirements This chapter contains pre-installation procedures for the AC Analytical Controls OxyTracer Analyzer. Because the OxyTracer analyzer is based upon the Agilent 7890A Series gas chromatograph (GC), make sure your laboratory meets the environmental, weight, power, and gas requirements as described in the Site Preparation Checklist for the Agilent GC. This section contains gas requirements, physical requirements, electrical requirements, a pre-installation checklist for the AC OxyTracer Analyzer, and a record form. Version 2011/ of 7

8 Pre-installation Gas Requirements Gas Requirements Gas Purity Some gas suppliers furnish instrument or chromatographic purity grades of gas that are intended specifically for chromatographic use. We recommend only these grades for use with Agilent GC detectors. Only very low ppm levels ( 0.5 ppm) of oxygen and total hydrocarbons should be present in the gas supplies. Oil-pumped air supplies are not recommended because they may contain large amounts of hydrocarbons. The addition of high-quality moisture, hydrocarbon, and oxygen traps immediately after the main tank pressure is highly recommended. Refer to the section "Gas Supply" of the Agilent GC Site Preparation Checklist for more information on using traps. Table 1-1. Gas Purity Recommendations Gas type Prepressure Percent purity Carrier Gases Helium 6 bar 90 psi % Flame Ionization Detector Support Gases Gas type Hydrogen Makeup gas (Nitrogen) Percent purity Air % % (water- and oilfree) from a compressor Version 2011/ of 7

9 Pre-installation Physical Requirements Physical Requirements Width - Approximately 2.1 meters (7 feet) for the complete system. Depth - Approximately 0.6 meters (2 feet) for the complete system. Height - Approximately 0.8 meters (2 feet 8 inches) for the complete system. Weight - 70 KG (155 lb.) The analyzer may be installed in any reasonably accessible area. WARNING THE GAS CHROMATOGRAPH WILL VENT HOT OVEN AIR FROM THE REAR OF THE GAS CHROMATOGRAPH WHEN THE OVEN IS COOLING DOWN TO AMBIENT TEMPERATURE. ENSURE NOTHING IS PLACED BEHIND THE GAS CHROMATOGRAPH THAT MAY CONTACT THE HOT EXHAUST AIR. AC MANUFACTURES AN ALUMINUM "OVEN EXHAUST DEFLECTOR" (AC PART NO ) THAT DEFLECTS THE EXHAUST AIR UP, AWAY FROM THE REAR OF THE GAS CHROMATOGRAPH. THIS DEVICE EASILY AND QUICKLY ATTACHES TO THE REAR OF THE GAS CHROMATOGRAPH. PLEASE CONTACT YOUR LOCAL AC OFFICE SHOULD YOU DESIRE TO INSTALL THIS DEVICE. Version 2011/ of 7

10 Pre-installation Electrical Requirements Electrical Requirements NOTE A proper earth ground is required for GC operations. For North America and geographical areas that use VAC : Gas chromatograph: 120 VAC. Please refer to the Agilent Site Preparation Checklist for additional information if required. All accessories: VAC, 4 standard 3 prong grounded outlets. For Europe and geographical areas that use 220/230/240 VAC Gas chromatograph: 220/230/240 VAC, Please refer to the Agilent Site Preparation Checklist for additional information if required. All accessories: VAC, 4 grounded outlets Maximum power consumption of the 7890A gas chromatograph is 2,250 VA for a regular oven and 2,950 for a fast-heating oven. NOTE Do not turn on the oven until all electrical and gas connections have been completed and checked for correctness and leaks. Version 2011/ of 7

11 Pre-installation Pre installation Checklist Pre installation Checklist System Configuration The Agilent system bundle configuration changes on a regular basis (typically every 6 months or so) to be faster, have a faster computer chip, and have a larger hard disk drive (HDD). The following are system guidelines: Mininum PC Configuration Processor: 1.5 Ghz Pentium 4 RAM: 512 MB Hard disc:40 GB Video: 1280 x 1024 resolution (SXGA) Removable Media: ATAPI CD, CD-RW or DVD drive Mouse: MS windows compatible pointing device LAN: 10/100baseT Software Microsoft Windows Windows XP Professional, Service pack 3 Agilent G2070BA ChemStation32bit software for 1 GC Agilent G2071BA ChemStation32bit software for additional GC NOTE The Agilent G2070BA ChemStation software consists of "core" software plus one Agilent GC instrument driver. Each additional Agilent GC requires the Agilent G2071BA additional instrument software, up to a maximum of three add-ons for four instruments per system. Version 2011/ of 7

12 Pre-installation Recording Important Numbers Recording Important Numbers In any verbal or written correspondence with Analytical Controls or Agilent concerning your ChemStation software, you will need to know the following information: Agilent G2070BA Revision Code Example B.04.0X Agilent G2070BA License No. Microsoft Windows Type and Revision Code Microsoft Windows License No. Agilent Gas Chromatograph Serial No. Agilent Computer Serial No. Take a few minutes now to fill in the empty boxes above. The revision code is found on the diskettes or CD-ROM. The license numbers are found on the documentation shipped with the software. Version 2011/ of 7

13 2 Installation

14 Installation Installing the Hardware Installing the Hardware Introduction This chapter contains installation procedures for the AC OxyTracer Analyzer for the Agilent 7890A Series gas chromatograph (GC). Refer to the 7890A GC installation Poster and to the 7890A GC User information for installation information. If the 7890A Automatic Liquid Sampler (ALS) is included, refer to the appropriate sections in the 7890A documentation. Cabling (General) The Agilent GC communicates electronically with other instruments through cables. Again refer to the 7890A GC installation Poster The Agilent 7890A Series GC is connected to the computer via LAN. Automatic liquid sampler Computer Printer Mouse 1 LAN interface PC - GC Figure 2-1 Cabling configuration for the Agilent 7890A Series GC. Analyzer configuration The OxyTracer analyzer based on the Agilent 7890A gas chromatograph is configured with a TPI inlet, a capillary Deans bracket, a capillary pre column, a capillary analysis column, an auxiliary pressure control (PCM), a three way valve with a restrictor and a Flame Ionization Detector. Version 2011/ of 11

15 Installation Installing the Hardware FID H2 Make-up N2 FID Air Figure 2-2 Rear side connections 7890A GC WARNING TEMPERATURE-SENSITIVE ITEMS (GAS CYLINDERS, CHEMICALS, REGULATORS, ETC) SHOULD NOT BE LOCATED IN THE PATH OF THE HEATED EXHAUST. ALSO, EXERCISE CARE WORKING AT THE REAR OF THE INSTRUMENT DURING COOL-DOWN CYCLES TO PREVENT POSSIBLE BURNS. The instrument is factory-tested and is shipped with all columns pre installed. Following description should be followed in case capillary columns are broken or when new columns are installed. Version 2011/ of 11

16 Installation Installing the Hardware Table 2-1. Columns for the AC OxyTracer Analyzer Column Description Part No. for Replacement Maximum temp C 1 Pre column (capillary methyl silicone, 0.8 mm OD) 2 Analysis column (capillary Lowox, 0.8 mm OD) Monitor (0.5 mm OD) Table 2-2. Valves Used in the Instrument Valve Assy Table 2-3. Ferrules / liners Graphite ferrule 0.8 mm (10 pcs) Graphite ferrule Monitor 0.5 mm (10 pcs) Siltite ferrule 0.8 mm (10 pcs) Siltite ferrule 0.4 mm (10 pcs) Liner Siltek (10 pcs) Version 2011/ of 11

17 Installation Installing the Hardware Installing columns and jumpers on the Capillary Deans bracket The capillary Deans bracket (Figure 2-3) consists of a metal assembly and springs that are fixed to the oven shroud. A capillary pre column, a capillary analysis column and a capillary monitor are mounted on this assembly. The columns are connected to the micro fluidic switch which is attached to the oven left side WARNING Before continuing, turn the oven and any heated zones off. Turn off all gases and turn off main power switch of the GC to avoid any potential hazard 1. Open the oven 2. Place the pre column ( ) on the bracket 3. Attach one of the springs to the pre-column. 4. Place the analysis column ( ) on the bracket 5. Attach the second spring to the analysis column 6. Connect the inlet of the analysis column to bottom connector of the micro fluidic switch. 7. Connect the outlet of the analysis column to the FID 8. Connect the pre column inlet to the TPI inlet 9. Connect the outlet of the pre column to middle connector of the micro fluidic switch 10. Connect the monitor column to top connector of the micro fluidic and fix the monitor to the pre column hangar, to prevent breaking it. (0.5 ferrule) 11. Connect the other end of the monitor to the vent connector located in front of the FID. WARNING Do not use Liquid leak detector on the capillary connections Version 2011/ of 11

18 Installation Installing the Hardware Figure 2-3 Capillary Deans bracket NOTE It is important to mount the columns in such a way as to minimize the tension in the columns. WARNING Always wear protective glasses when working with fused silica capillary columns. NOTE The AC OxyTracer Analyzer comes with pre installed and checked-out columns. The capillary analysis column, the capillary pre column and the capillary monitor column are all connected on the bracket to the various connectors and to the Inlet and the Detector. Special heat resistant wire is used to fix the columns to the bracket. Version 2011/ of 11

19 Installation Installing the Hardware Figure 2-4 Cross sectional overview of TPI Table 2-4. General assay part numbers Drawin g Part number Description TPI Septum Inlet head TPI Inlet head base TPI Inlet housing assy TPI Inlet heating block TPI Heater/sensor assy (70W40V) Nut holder Septum retainer nut Capillary Column nut (2pcs) TPI Isolation Version 2011/ of 11

20 Installation Installation of the liner Installation of the liner The TPI in the OxyTracer analyzer uses a special deactivated glass liner to prevent the loss of oxygenated compounds by adsorption. This liner can be installed at the topside of the injector. The top of the TPI is connected to the base using a nickel seal. This seal must be replaced each time the top is removed from the base in order to avoid leaks. Note Before installation of the liner turn oven temperature and Inlet to off, to work in a safe environment. 1 Turn off the inlet temperature regulation and the inlet EPC module. 2 Remove the TPI inlet head base (use wrench ). 3 Disconnect the column. 4 Use TPI Liner remover ( ) to remove old liner and TPI inlet seal. Note Use a clean tissue to handle the liner and seal in order to prevent contamination of the liner. 4 Control liner before installation. Tapered side must be located at the bottom end of the inlet. 5 Place liner (part ) into the injector by pushing it slowly into the inlet. 6 Place a new seal ( ) on the TPI body. The seal is self-aligning. Warning Damage to the sealing beads on TPI body and TPI Septum cap holder will affect the fitting performance and cause system leakage. Handle with care. 7 Check if the liner top is not above the nickel seal. Loosen your column nut to lower the liner. Install the column again after action 8. 8 Reconnect the TPI inlet head base on inlet finger tight and turn max. 1/8 using the wrench. 9 Install the column (see page 9). Warning Over tightening will damage the sealing beads and possibly cause system leakage. Version 2011/ of 11

21 Installation Installation of capillary column to the TPI. Installation of capillary column to the TPI. The TPI uses a special deactivated glass liner to make a direct injection technique possible. The column is attached to the liner by pushing it to the tapered internal side of the liner and tightens using a graphite ferrule. Note The inside diameter of the column must be 0.53 mm. Warning 1 Turn off the GC oven. 2 Turn off the inlet temperature regulation and the inlet EPC module and let the system cool down. 3 Insert the column through the injector nut and graphite ferrule. 4 Cut a small piece of the column using a column cutter to make a clean and nice formed column end. 5 Lead the column end into the column connector and push upwards until the column stops on the liner. Do not apply excessive force. 6 Tighten the column nut. 7 Install other end of column to the middle connector of the micro fluidic switch. Version 2011/ of 11

22 Installation Column Installation to the micro fluidic switch Column Installation to the micro fluidic switch The capillary columns and capillary jumpers are connected to the micro fluidic switch. The micro fluidic switch is made in such a way that there is hardly any dead volume resulting in good chromatography. All connections are made with 0.8 SilTite ferrules, except for the monitor column where a 0.4 SilTite ferrule is used. The SilTite ferrules must be pre-swaged. For instruction on pre-swaging SilTite Ferrules, see Swaging SilTite Ferrules. Version 2011/ of 11

23 Installation Installing the AC OxyTracer methods Installing the AC OxyTracer methods Introduction The AC OxyTracer analyzer does not need extra software besides ChemStation. The methods used for the oxygenates analyses are supplied on a CD. NOTE A working knowledge of Microsoft Windows, and Agilent G2070BA ChemStation is required to operate the AC OxyTracer Analyzer successfully. Installing the AC methods These installation steps assume that the following software is already installed on the computer's hard disk: Microsoft Windows Agilent G2070BA ChemStation revision B.03.0x or higher Microsoft Windows Instructions 1 Turn the computer and monitor on. The computer will boot up and start Microsoft Windows. 2 Insert the CD with the methods and copy the methods to the appropriate directory. Version 2011/ of 11

24 3 Operation

25 Operation Samples Introduction This section describes the operation, configuration, and analysis of the AC Analytical Controls OxyTracer Analyzer. The AC system is based upon the Agilent 7890A Series gas chromatograph (GC). Refer to the appropriate Agilent manuals for detailed information on the Agilent GC. This system is dedicated to the analysis of trace oxygenated compounds in hydrocarbon liquids with a maximum boiling point of 250 C. Oxygenates that can be determined are ethers, alcohols and ketones. The analyzers is designed to the analysis of methanol, ethanol, n-propanol*, i- Propanol, 2-butanol, i-butanol**, t-butanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether, (ETBE), tert-amyl methyl ether (TAME), diisopropyl ether (DIPE), Acetone and methyl ethyl ketone (MEK) in hydrocarbon streams (in particular naphthas) with a final boiling point below 250 C. The individual oxygenates can be determined from 0.1 to 500 ppm. The system allows methods to be developed for the analysis of other oxygenated components. *n-propanol and I-Propanol are not separated and elute as one peak ** I-butanol, t-butanol en 2-butanol elute as one peak Version 2011/ of 24

26 Operation Samples Summary of Method The OxyTracer analyser is based upon the principle described by D.R. Deans (Chromatographia, 1 (1968), 18). The principle of this technique is to control the pressure between two columns and to direct the effluent of a (pre) column to several, usually two, columns. By using columns of a very different nature (e.g. a polar and a non-polar column) difficult separations can be achieved. The sample is injected onto a methyl silicone pre column which elutes lighter hydrocarbons to a monitor column and retains the oxygenated and heavier hydrocarbons. Just before the oxygenated component elutes from this column, the valve and thus a PCM pressure is switched and the components coming from the pre column are directed to the analysis column. After the oxygenated components have eluted from the pre column to the analysis column, the valve is switched back to its original position, switching the pressure again. All the other components remaining on the pre column are now directed to the monitor column and the vent. The oxygenated components are now separated from the remaining hydrocarbons on the analysis column and are detected by the Flame Ionization Detector. The detector response, proportional to the component concentration is recorded. The peak areas are measured and the concentration of each component is calculated with reference to the external standard. PCM analysis column FID TPI pre column monitor Vent Figure 3-1. The AC OxyTracer flow diagram Version 2011/ of 24

27 Operation Samples Configuration The AC OxyTracer Analyzer uses an Agilent 7890A Series GC with electronic pneumatics control (EPC) configured with a TPI inlet, a capillary Column bracket a three-way valve with a capillary restrictor, a micro fluidic switch, a PCM (EPC) pressure regulator, a vent and a Flame Ionization Detector. A second Flame Ionization Detector is optional for monitoring the vent signal. The capillary Column bracket is configured with a methyl silicone pre column, a capillary analysis column (Lowox) and a monitor column. The micro fluidic switch is located in the GC oven. The three-way valve with the capillary restrictor, as well as the monitor vent are located on top of the gas chromatograph. A second FID is optional to monitor the vent. Figure 3-2. The AC OxyTracer capillary Deans bracket Version 2011/ of 24

28 Operation Samples Principle of Analysis In standby, the Valve is in the off position (Fig. 3-3). The PCM pressure is supplied at point 1.This means the pressure at point 1 is higher than the midpoint pressure (2) So the pre column effluent is directed to the monitor column and the vent. After injection of the sample, through the TPI a pre separation on boiling point takes place on the pre column. The light hydrocarbons quickly pass both the pre column and the monitor column to the vent. The heavier hydrocarbons and the oxygenated compounds are retained. The monitor column does not retard any components; its main function is to have an equal pressure as the analysis column making pressure switching between the two channels possible. PCM 1 analysis column Detector FID TPI pre column 2 Figure monitor Pre column analysis - Valve in Off position Just before the oxygenated components elute from the pre column, the valve is switched (Fig 3.4). The PCM pressure is now supplied at point 3, making the pressure at point 3 higher then the midpoint pressure, so the effluent from the pre column is directed towards the analysis column. The oxygenated components together with the hydrocarbons with similar boiling points elute onto the analytical column. After the elution of the last oxygenated component, the valve is switched again. The remaining hydrocarbons are thus directed towards the monitor and the vent. The fraction that was cut from the pre column contains oxygenated compounds and some hydrocarbons with similar boiling points. This fraction is now separated on the analysis column. Separation is done in a two stage oven ramped temperature program. The oxygenates are measured on the Flame Ionization Detector. The capillary restrictor, which is connected to the three-way valve creates a little leak flow thus preventing the diffusion of sample or components in the stainless steel tubing leading to the valve. Vent Version 2011/ of 24

29 Operation Samples PCM 1 analysis column Detector FID TPI pre column 2 Figure monitor Cutting components - Valve in On position Vent FID1 A, (C:\DATAOX~1\D030715B\001F0107.D) pa TBA & Iso & 2-Butanol ETBE MTBE DIPE TAME Methanol Acetone MEK Ethanol Iso & n-propanol n-butanol min Figure 3-5. Chromatogram 2.00 to 2.65 min cut from pre column separated on analysis column (standard containing 14 oxygenates) Version 2011/ of 24

30 Operation Samples Instrument setup The instrument is factory-tested and is shipped with all columns pre installed. If during transportation a capillary jumper or a column breaks, or if later on for some reason a column is changed or any other chromatographic condition changes, the flows and pressures will have to be checked. Also the monitor column length needs to be readjusted or replaced when the analysis column is replaced. Adjusting flows and pressures The Deans principle of switching with pressure will only function properly if there is a pressure balance, meaning identical flows on both the monitor as the analysis channel. Another condition is a suitable pressure difference between the head pressure and the PCM pressure. NOTE The actual Front inlet and the PCM pressures are instrument dependant. The pressures are increased / decreased till an optimal separation of the Ether group (ETBE, MTBE and DIPE) is achieved. See for the actual values the Test document provided with the instrument. PCM pressure The PCM pressure provides the head pressure for both the analysis column as well as the monitor column. Also it provides the switching pressure of the effluent from the pre column. A pressure difference of 2 kpa was found satisfactory for this instrument. If the PCM pressure is too low this may result in no switching at all, causing all components to be directed to the monitor and vent. Another consequence of a low switching pressure may be bad switching, resulting in tailing peaks, or no peaks at all. If the PCM pressure is too high, components are trapped on the pre column and do not elute at all. Version 2011/ of 24

31 Operation Samples Flows The following procedure describes how to setup the flows and pressures in the system. When all the columns have been installed (see installation chapter) the flows/pressures have to be set. Load the pre column method (precol.m). When the GC is ready, switch off the detector flows (air, hydrogen and make-up flow) and measure the column flow on the detector and on the monitor vent. These flows should not differ more than 5 %. To balance the flows, the monitor length has to be tuned, the column flow on the analysis column is fixed and cannot be varied. The default monitor column length is one meter, if the flow through the monitor column is lower than the flow through the analysis column this means the monitor column has too much restriction, so it should be shortened. Undo the monitor column from the vent, cut five centimeters from the column end, remount the column and measure the flows again. Repeat this procedure until the column flows on detector and vent are within 5 % of each other. When the monitor column length has been adjusted, a test has to be performed to establish whether the columns are properly connected. If the flow through the monitor is higher than the flow through the analysis column, the restriction of the monitor is too low. In this case a new length of monitor column has to be mounted and tuned. Swivel test A method to verify that all columns have been correctly mounted is the swivel test. The method to perform this test is Swivel.M. In this method the valve is switched every 0.10 min whilst a pure component (e.g. Cyclohexane) elutes from the pre column. Switching the valve off in this peak must give an immediate drop in signal on the detector. Also it must give an immediate rise, when the valve is switched back again. Load the method SWIVEL.M, adjust the PCM pressure at 36 kpa and inject Cyclohexane. Version 2011/ of 24

32 Operation Samples pa FID1 A, (A:\D040209\SIG10098.D) min Figure 3-6. Swivel test on Cyclohexane Visually check the chromatogram. An example of a good swivel test is given in figures 6. In case of a bad swivel test, this means there is a dead volume somewhere in the system. Most likely one of the capillary connections (column or jumper) is not okay and must be checked. Version 2011/ of 24

33 Operation Samples Pre column analysis With the introduction of electronic pressure control, the retention time stability in capillary gas chromatography increased enormously. Therefore also the cutting times for the OxyTracer analyzer are very stable and hardly need readjusting. However when a new column is installed or when some other chromatographic condition changes or when one wants to setup a method for a specific oxygenate it may be necessary to re-determine the cutting times. There are two ways of determining the correct cutting times. The real pre column analysis of a qualitative pre column standard which allows one to record the cut times from the chromatogram. Or an iterative method whereby a sequence is run with different methods each with varying cut times. Real pre column analysis To establish the correct valve cutting times, a pre column analysis of a cutting time standard has to be run. This qualitative standard has to contain the oxygenates of interest in n-dodecane. In the pre column method the pre column effluent is directed to the monitor column and the FID. So the pre column chromatogram reflects the exact times at which the oxygenates elute from the pre column. To make a pre column chromatogram, the monitor column has to be connected to the FID instead of the vent. The following procedure has to be followed: Cool down the GC oven to ambient Undo the analysis column from the Flame ionization detector Leave the column end of the analysis column loose in the oven Undo the monitor column from the vent Connect the monitor column to the Flame Ionization detector Heat the oven to 100 C When the GC is ready, the pre column analysis can be performed. Version 2011/ of 24

34 Operation Samples FID2 B, (A:\007B0703.D) pa Methanol 2.3 n-butanol 2.6 T1 T Figure Pre column chromatogram Load the pre column method (PRECOL.M), set the pcm pressure to 36 kpa and inject the pre column standard. From the obtained chromatogram, determine the two cut times. (Figure 8) T1 and T2. Run the standard a second time to make sure the correct cut times are obtained. Now before samples can be analyzed, first the column and monitor have to be reconnected: Cool down the GC oven to ambient Undo the monitor column from the Flame ionization detector Connect the analysis column to the Flame ionization detector Connect the monitor column to the vent Heat the oven to 100 C The earlier established cut times must then be entered in the analysis method. (OXY.M). Load the method OXY.M, Select: View, Instrument, Edit Parameters, Runtime and edit (Replace) the Valve 1 On and Off time. (see figure 8) Valve 1 On time = T1 Valve 1 Off time = T2 Finally Save the method. min Version 2011/ of 24

35 Operation Samples Figure 3-8. Edit runtime table Iterative method In this method the cut times are determined by iteration. A set of cut times is tried, and depending on the result a new adapted set of cut times is tried, this step is repeated until the final cut times are found. This method of cut times determination can be automated. Different methods are made, each only differing in cut times. For each method T1 and T2 should be varied with steps of 0.05 min. Starting for instance with a T1 of 2.50 minutes and a T2 of 3.00 minutes. These methods are all saved with unique names. (e.g. Cut_1 etc.) Then make a sequence and analyze the pre column standard with the different methods. Afterwards review the chromatograms that were obtained and select the one with the proper cut times. An example can be found in figure 5. If n-butanol is missing, T2 should be increased. If Methanol is missing T1 should be decreased. Version 2011/ of 24

36 Operation Samples FID1 A, (C:\DATAOX~1\D030716\SIG10036.D) pa Methanol n-butanol Figure 3-9. Analysis of pre column standard min pa FID1 A, (C:\AASEQU~1\013F2201.D) MTBE Methanol Acetone Ethanol min Figure Calibration chromatogram containing MTBE, Methanol and Ethanol (acetone contamination) NOTE The Lowox column can trap impurities in the carrier gas relatively easy. Therefore a standby temperature of 200 C is recommended. Version 2011/ of 24

37 Operation Samples Table 3-1. Elution order of some oxygenated compounds Component Trivial name Ether Etbe Mtbe Dipe Tame Dipropyl ether IUPAC name Diethyl ether 2-Ethoxy-2-methyl propane 2-Methoxy-2-methyl propane 2-Isopropoxy propane 2-Methyl-2-methoxy butane n-propyl ether Butyl ethyl ether Butyraldehyde Butanal Methanol Acetone Iso valeraldehyde Valeraldehyde MEK 2-Propanone 3-Methyl butanal n-pentanal 2-Butanone Ethanol Diethyl ketone Methyl propyl ketone i-propanol 3-Pentanone 2-Pentanone 2-Popanol propanol t-butanol i-butanol 2-butanol t-butyl alcohol 2-Methyl-1-propanol sec-butyl alcohol n-butanol Version 2011/ of 24

38 Operation Samples Calibration After the correct cut times have been set and the method has been saved, a calibration should be performed. To calibrate the method, a calibration standard has to be analyzed. This calibration standard should contain the oxygenates of interest at low level. An external calibration is performed. Prepare a calibration standard as described in ASTM D Inject the calibration standard using method Oxy.m. Make sure the proper concentrations are filled out in the calibration table, check the chromatography (integration) and calibrate Data Analysis Calibration Recalibrate The response factors are now calculated and stored in the calibration file. The method is now ready for sample analysis. NOTE Used components must be of known purity, hydrocarbons used must also be free of the components to be analyzed. Version 2011/ of 24

39 Operation Samples Sample handling Effort must be taken to assure representative samples and standards are obtained. Some oxygenated compounds are very reactive. Methanol is a very good example, at very low concentrations it can readily be lost in the vials it is put into. This means that sampling becomes very critical. Also calibration samples can change in time. So it is necessary to make fresh standards on a regular basis. NOTE Store calibration standards capped below 5 C when not in use. Another point of attention therefore is the injection. It is necessary to use the washing options and vials of the auto sampler to flush the syringe after an injection and prior to an injection. Fill the washing vials with an oxygenate-free hydrocarbon (e.g. n-nonane, or Cyclohexane) Calculation Quantitative results are based on calibration analyses obtained by injecting a fixed volume of a reference blend. With the reference blend, the relation between peak area and component concentration is determined. This response factor is calculated by ChemStation as follows: Ri= Ci/Ai Where: R i = Response factor (ppm Wt/µV) Ci = concentration compound (ppm Wt) Ai = peak are of the compound (µv) The unknown concentration of a component x in a sample is calculated as follows: Cx = Ax * Rx Where: Cx = concentration component (ppm Wt) Rx = Response factor component (ppm Wt/µV) Ax= peak area of the component (µv) Version 2011/ of 24

40 Operation Samples Detectability Minimum Detection limit This is defined as the smallest concentration that can be distinguished from a blank analysis. (With a 95 % confidence level) LDL is 0.1 ppm Wt Linearity: Linear response from 0.1 to 500 ppm Wt Repeatability The repeatability at a 10 ppm concentration level for Methanol and Ethanol is better than 5 % (RSD), for MTBE the repeatability at the same level is better than 1 % (RSD). Version 2011/ of 24

41 Operation Samples Samples Following are some example chromatograms of various samples. pa FID1 A, (C:\AASEQU~1\025F0701.D) MTBE Acetone MEK min Figure Reformate containing 0.7 ppm MTBE & 2.6 ppm MEK. pa FID1 A, (C:\DATAOX~1\SIG10041.D) MTBE MEK Iso & n-propanol TBA & Iso & 2-Butanol n-butanol min Figure Virgin Naphtha contains 13.0 ppm MTBE, 19 ppm MEK and various alcohols Version 2011/ of 24

42 Operation Samples pa 50 FID1 A, (C:\AASEQU~1\024F0403.D) MTBE Acetone min Figure Raffinate contains 35 ppm MTBE and 0.9 ppm Acetone Version 2011/ of 24

43 Operation Samples Method description Table 3-2 Initial temperature: Oxy Method Oven 100 C Initial time: 5 min Rate: 5 C/min Final temp 130 C Final time 0 min Rate 10 C/min Final temp 225 C Inlet (He) Final time Total run time 9.5 min 30 min PCM B-1 (He) Temperature: 200 C Initial pressure 36 kpa* Front inlet (He): 38 kpa* FID Temperature: 250 C Flow (H 2 ): Flow (Air): Makeup (N 2 ): Data rate: 35 ml/min 350 ml/min 20 ml/min 50 Hz Run Time Table Specifier Typical Time** Setting Description Valve 1 initial OFF Sample to monitor Valve ON Sample to analysis column Valve OFF Sample to monitor GC Injector Sample washes 3 Injection volume: Sample pumps 6 PostInj Solvent A washes µl *See the Test document provided with the instrument for the actual pressure settings for the instrument **Times will be fine-tuned and included with checkout documentation for each analyzer Version 2011/ of 24

44 Operation Samples Table 3-3 Precol Method Oven Initial temperature: 100 C Initial time: 5 min Rate: 5 C/min Final temp 130 C Final time 0 min Rate 10 C/min Final temp 225 C Final time 9.5 min Inlet (He) PCM B-1 (He) Temperature: 200 C Initial pressure 36 kpa* Front inlet (He): 38 kpa* FID Temperature: 250 C Flow (H 2 ): Flow (Air): Makeup (N 2 ): Data rate: 35 ml/min 350 ml/min 20 ml/min 50 Hz Run Time Table Specifier Typical Time** Setting Description Valve 1 initial OFF Sample to monitor GC Injector Sample washes 3 Injection volume: 0.1 µl Sample pumps 6 PostInj Solvent A washes 4 *See the Test document provided with the instrument for the actual pressure settings for the instrument **Times will be fine-tuned and included with checkout documentation for each analyzer Version 2011/ of 24

45 Operation Samples Table 3-4. Swivel method Oven Initial temperature: 100 C Initial time: 5 min Rate: 5 C/min Final temp 130 C Final time 0 min Rate 10 C/min Final temp 225 C Final time 9.5 min Inlet (He) PCM B-1 (He) Temperature: 200 C Initial pressure 36 kpa* Front inlet (He): 38 kpa* FID Temperature: 250 C Flow (H 2 ): Flow (Air): Makeup (N 2 ): Data rate: 35 ml/min 350 ml/min 20 ml/min 50 Hz Run Time Table Specifier Typical Time* Setting Description Valve 1 initial OFF Sample to monitor Valve ON Sample to analysis column Valve OFF Sample to monitor Valve ON Sample to analysis column Valve OFF Sample to monitor Valve ON Sample to analysis column Valve ** OFF Sample to monitor Version 2011/ of 24

46 Operation Samples GC Injector Sample washes 3 Injection volume: 1.0 µl Sample pumps 6 PostInj Solvent A washes 4 *See the Test document provided with the instrument for the actual pressure settings for the instrument ** To be repeated until the run table is full (maximum is 75 settings) Version 2011/ of 24

47 Operation Samples Spare parts kit and consumables kit OxyTracer Spares parts kit CCG Valve Assy Aluminum washer (10 pcs) FTA restrictor Consumables kit CCG Capillary Lowox (analysis column) Capillary methyl silicone (pre column) Monitor SilTite ferrule 0.8 (10 pcs) SilTite ferrule Monitor 0.4 (10 pcs) Liner Siltek (10 pcs) Septa, 9.5 mm (50 pcs) Syringe (10 µl) Sample box 14 oxygenates Version 2011/ of 24

48 4 Index

49 Index Index A AC OxyTracer flow diagram C cabling cabling configuration calibration AC Oxytracer analyzer Column configuration configuration AC OxyTracer Analyzer configuration, system consumables kit G gas purity gas requirements GC method Oxy GC method: H Helium hydrocarbon trap Hydrogen I installation AC OxyTracer methods hardware Installation AC methods Introduction L LAN O Oven Exhaust Deflector P physical requirements pre installation checklist preinstallation requirements principle of analysis AC OxyTracer Analyzer R rear side connections Requirements electrical S software installation Spare parts kit Spare parts kit and consumables kit OxyTracer system configuration T trap hydrocarbon moisture oxygen V valves Version 2011/ of 5