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AC OxyTracer Analyzer on 7890 GC
Manual part number 23070.020 version 2011/1.0
Contact addresses:
www.analytical-controls.com www.paclp.com
AC Analytical Controls BV P.O Box 10054, 3004 AB Rotterdam Innsbruckweg 35, 3047 AG Rotterdam, the Netherlands Phone : +31-10-462 4811 Fax : +31-10-462 6330 E-mail : [email protected]
AC Analytical Controls Inc 8824 Fallbrook Dr., Houston, Texas 77064, USA Phone : +1-2815800339 Fax : +1-2815800719 E-mail : [email protected]
AC Analytical Controls Asia Pacific Ltd 30 Robinson Road, Robinson Towers #03-04 048546 Singapore Phone : +65-324-9017 Fax : +65-324-9019 E-mail : [email protected]
Operating Manual
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.
Contents
Contents
Version 2011/1.0 Contents-2
TABLE OF CONTENTS PAGE
Pre-installation ....................................................................... 1
Pre-installation Requirements ...................................................................................... 1-2
Gas Requirements .......................................................................................................... 1-3 Gas Purity ...................................................................................................................... 1-3
Physical Requirements .................................................................................................. 1-4
Electrical Requirements ................................................................................................. 1-5
Pre installation Checklist ............................................................................................... 1-6 System Configuration .................................................................................................... 1-6 Software......................................................................................................................... 1-6
Recording Important Numbers ..................................................................................... 1-7
Installation .............................................................................. 2
Installing the Hardware .................................................................................................. 2-2 Introduction .................................................................................................................... 2-2 Cabling (General) .......................................................................................................... 2-2 Analyzer configuration ................................................................................................... 2-2 Installing columns and jumpers on the Capillary Deans bracket............................... 2-5
Installation of the liner ................................................................................................... 2-8
Installation of capillary column to the TPI. .................................................................. 2-9
Column Installation to the micro fluidic switch ........................................................ 2-10
Installing the AC OxyTracer methods ........................................................................ 2-11 Introduction .................................................................................................................. 2-11 Installing the AC methods ............................................................................................ 2-11 Microsoft Windows Instructions .............................................................................. 2-11
Operation ................................................................................ 3
Introduction..................................................................................................................... 3-2
Summary of Method ....................................................................................................... 3-3
Configuration .................................................................................................................. 3-4
Principle of Analysis ...................................................................................................... 3-5
Instrument setup ............................................................................................................ 3-7 Adjusting flows and pressures ....................................................................................... 3-7 PCM pressure ................................................................................................................ 3-7 Flows ............................................................................................................................. 3-8 Swivel test ...................................................................................................................... 3-8 Pre column analysis..................................................................................................... 3-10 Real pre column analysis............................................................................................. 3-10 Iterative method ........................................................................................................... 3-12 Calibration .................................................................................................................... 3-15 Sample handling .......................................................................................................... 3-16 Calculation ................................................................................................................... 3-16 Detectability ................................................................................................................. 3-17 Minimum Detection limit .......................................................................................... 3-17 Linearity: .................................................................................................................. 3-17
Repeatability ................................................................................................................ 3-17
Samples ......................................................................................................................... 3-18
Method description ...................................................................................................... 3-20
Contents
Version 2011/1.0 Contents-3
Spare parts kit and consumables kit OxyTracer ....................................................... 3-24
1
Pre-installation
Pre-installation
Pre-installation Requirements
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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.
Pre-installation
Gas Requirements
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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
Carrier Gases
Gas type Helium
Pre-
pressure
6 bar 90 psi
Percent
purity
99.995%
Flame Ionization Detector Support Gases
Gas type Hydrogen Makeup gas (Nitrogen)
Air
Percent
purity
99.995% 99.995% (water- and oil- free) from a compressor
Pre-installation
Physical Requirements
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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.
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.
59.40.200) 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.
WARNING
Pre-installation
Electrical Requirements
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Electrical Requirements
A proper earth ground is required for GC operations.
For North America and geographical areas that use 110 - 120 VAC :
• Gas chromatograph: 120 VAC. Please refer to the Agilent Site Preparation Checklist for additional information if required.
• All accessories: 110 - 120 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: 220 - 240 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.
Do not turn on the oven until all electrical and gas connections have been completed and checked for correctness and leaks.
NOTE
NOTE
Pre-installation
Pre installation Checklist
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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
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.
NOTE
Pre-installation
Recording Important Numbers
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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.
2
Installation
Installation
Installing the Hardware
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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
7890Computer
1 LAN interface PC - GC
1
Mouse
Printer
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.
Installation
Installing the Hardware
Version 2011/1.0 2-3 of 11
FID
H2
FID
Air
Make-u
p N
2
Figure 2-2 Rear side connections 7890A GC
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.
WARNING
Installation
Installing the Hardware
Version 2011/1.0 2-4 of 11
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)
10.74.011 325
2 Analysis column (capillary Lowox,
0.8 mm OD)
10.73.030 300
Monitor (0.5 mm OD) 21052.020 350
Table 2-2. Valves Used in the Instrument
Valve Assy 80102.300
Table 2-3. Ferrules / liners
Graphite ferrule 0.8 mm (10 pcs) 21040.007
Graphite ferrule Monitor 0.5 mm (10 pcs) 21041.001
Siltite ferrule 0.8 mm (10 pcs) 21040.026
Siltite ferrule 0.4 mm (10 pcs) 21040.025
Liner Siltek (10 pcs) 21032.007
Installation
Installing the Hardware
Version 2011/1.0 2-5 of 11
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
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 (10.74.011) on the bracket
3. Attach one of the springs to the pre-column.
4. Place the analysis column (10.73.030) 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.
Do not use Liquid leak detector on the capillary connections
WARNING
WARNING
Installation
Installing the Hardware
Version 2011/1.0 2-6 of 11
Figure 2-3 Capillary Deans bracket
It is important to mount the columns in such a way as to minimize the tension in the columns.
Always wear protective glasses when working with fused silica capillary columns.
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.
NOTE
WARNING
NOTE
Installation
Installing the Hardware
Version 2011/1.0 2-7 of 11
Figure 2-4 Cross sectional overview of TPI
Table 2-4. General assay part numbers
Drawin
g
Part number Description
1 30.30.530 TPI Septum Inlet head
2 30.30.520 TPI Inlet head base
3 30.30.500 TPI Inlet housing assy.
4 30.30.510 TPI Inlet heating block
40.01.049 TPI Heater/sensor assy (70W40V)
70.40.200 Nut holder
30.20.064 Septum retainer nut
30.23.005 Capillary Column nut (2pcs)
30.30.550 TPI Isolation
Installation
Installation of the liner
Version 2011/1.0 2-8 of 11
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.
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 15.10.403).
3 Disconnect the column.
4 Use TPI Liner remover (15.10.404) to remove old liner and TPI inlet seal.
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 10.32.007) into the injector by pushing it slowly into the inlet.
6 Place a new seal (10.10.194) on the TPI body. The seal is self-aligning.
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).
Over tightening will damage the sealing beads and possibly cause system leakage.
Note
Note
Warning
Warning
Installation
Installation of capillary column to the TPI.
Version 2011/1.0 2-9 of 11
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.
The inside diameter of the column must be 0.53 mm.
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.
Note
Warning
Installation
Column Installation to the micro fluidic switch
Version 2011/1.0 2-10 of 11
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.
Installation
Installing the AC OxyTracer methods
Version 2011/1.0 2-11 of 11
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.
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.
NOTE
3
Operation
Operation
Samples
Version 2011/1.1 3-2 of 24
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
Operation
Samples
Version 2011/1.1 3-3 of 24
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.
FID
TPI
PCM
pre column
analysis column
monitorVent
Figure 3-1. The AC OxyTracer flow diagram
Operation
Samples
Version 2011/1.1 3-4 of 24
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
Operation
Samples
Version 2011/1.1 3-5 of 24
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.
FID
TPI
Detector
PCM
pre column
analysis column
monitor
1
2
3Vent
Figure 3-3. 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.
Operation
Samples
Version 2011/1.1 3-6 of 24
FID
TPI
Detector
PCM
pre column
analysis column
monitorVent
1
2
3
Figure 3-4. Cutting components - Valve in On position
min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
0
20
40
60
80
100
120
140
FID1 A, (C:\DATAOX~1\D030715B\001F0107.D)
2.9
88
9.8
83 -
E
TB
E 1
0.1
31 -
M
TB
E 1
0.3
32 -
D
IPE
12.0
08 -
T
AM
E
14.2
38 -
M
eth
anol
14.6
11 -
A
ceto
ne
16.0
44 -
M
EK
16.2
35 -
E
thanol
17.6
94 -
Is
o &
n-P
ropanol 18.7
53 -
T
BA
& Iso &
2-B
uta
nol
19.2
77 -
n-B
uta
nol
Figure 3-5. Chromatogram 2.00 to 2.65 min cut from pre column
separated on analysis column (standard containing 14 oxygenates)
Operation
Samples
Version 2011/1.1 3-7 of 24
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.
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.
NOTE
Operation
Samples
Version 2011/1.1 3-8 of 24
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.
Operation
Samples
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min2 2.5 3 3.5 4 4.5 5 5.5 6 6.5
pA
0
10
20
30
40
50
60
70
80
90
FID1 A, (A:\D040209\SIG10098.D)
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.
Operation
Samples
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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.
Operation
Samples
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min0.5 1 1.5 2 2.5 3 3.5
pA
0
100
200
300
400
500
600
FID2 B, (A:\007B0703.D)
2.398
2.686
Methanol
n-Butanol
T1 T2
Figure 3-7. 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.
Operation
Samples
Version 2011/1.1 3-12 of 24
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.
Operation
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min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
5
10
15
20
25
30
35
40
45
FID1 A, (C:\DATAOX~1\D030716\SIG10036.D)
14.1
77 -
M
eth
anol
19.2
67 -
n-B
uta
nol
Figure 3-9. Analysis of pre column standard
min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
5
10
15
20
25
30
FID1 A, (C:\AASEQU~1\013F2201.D)
10.0
31 -
M
TB
E
14.1
93 -
M
eth
anol 1
4.5
07 -
A
ceto
ne
16.2
05 -
E
thanol
Figure 3-10. Calibration chromatogram – containing MTBE, Methanol and
Ethanol (acetone contamination)
The Lowox column can trap impurities in the carrier gas relatively easy.
Therefore a standby temperature of 200 °C is recommended.
NOTE
Operation
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Table 3-1. Elution order of some oxygenated compounds
Component
Trivial name IUPAC name
Ether Diethyl ether
Etbe 2-Ethoxy-2-methyl propane
Mtbe 2-Methoxy-2-methyl propane
Dipe 2-Isopropoxy propane
Tame 2-Methyl-2-methoxy butane
Dipropyl ether n-Propyl ether
Butyl ethyl ether
Butyraldehyde Butanal
Methanol
Acetone 2-Propanone
Iso valeraldehyde 3-Methyl butanal
Valeraldehyde n-Pentanal
MEK 2-Butanone
Ethanol
Diethyl ketone 3-Pentanone
Methyl propyl ketone 2-Pentanone
i-Propanol
propanol
2-Popanol
t-butanol
i-butanol
2-butanol
t-Butyl alcohol
2-Methyl-1-propanol
sec-Butyl alcohol
n-Butanol
Operation
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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-4307. 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.
Used components must be of known purity, hydrocarbons used must also be free
of the components to be analyzed.
NOTE
Operation
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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.
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: Ri = 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)
NOTE
Operation
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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).
Operation
Samples
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Samples
Following are some example chromatograms of various samples.
Figure 3-11. Reformate containing 0.7 ppm MTBE & 2.6 ppm MEK.
Figure 3-12. Virgin Naphtha contains 13.0 ppm MTBE, 19 ppm MEK and
various alcohols
min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
0
10
20
30
40
50
FID1 A, (C:\DATAOX~1\SIG10041.D)
2.2
51
2.3
49
2.5
23
2.6
67
2.9
04
3.4
96
4.7
07 5
.012
5.1
76
5.2
59
6.9
52
7.7
40
10.1
79 -
M
TB
E
13.0
52
13.6
51
15.6
20
15.8
27
16.0
91 -
M
EK
16.8
16
17.0
38
17.3
26
17.7
30 -
Is
o &
n-P
ropanol
18.8
47 -
T
BA
& I
so &
2-B
uta
nol
19.3
25 -
n-B
uta
nol
19.8
67
min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
0
10
20
30
40
50
FID1 A, (C:\AASEQU~1\025F0701.D) 2
.265
2.2
88
2.3
47
2.3
75
2.3
96
2.4
19
2.4
77
2.5
03
2.5
59
2.6
33
9.3
07
9.9
90 -
M
TB
E
14.6
06 -
A
ceto
ne
16.0
65 -
M
EK
17.7
17
Operation
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Figure 3-13. Raffinate contains 35 ppm MTBE and 0.9 ppm Acetone
min0 2.5 5 7.5 10 12.5 15 17.5 20 22.5
pA
0
10
20
30
40
50
FID1 A, (C:\AASEQU~1\024F0403.D)
2.2
63
2.3
36
2.3
61
2.3
91
2.4
82
2.5
10
2.5
96
2.6
64
2.8
33
2.9
28
3.0
52
3.2
34
3.5
44
3.7
96
3.8
54
3.9
76
4.0
57
4.1
64
10.0
32 -
M
TB
E
14.6
28 -
A
ceto
ne
Operation
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Method description
Table 3-2 Oxy 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
Total run time 30 min
Inlet (He) PCM B-1 (He)
Temperature: 200 °C Initial pressure 36 kPa*
Front inlet (He): 38 kPa*
FID
Temperature: 250 °C
Flow (H2): 35 ml/min
Flow (Air): 350 ml/min
Makeup (N2): 20 ml/min
Data rate: 50 Hz
Run Time Table
Specifier Typical Time** Setting Description
Valve 1 initial OFF Sample to monitor
Valve 1 2.00 ON Sample to analysis column
Valve 1 3.50 OFF Sample to monitor
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
**Times will be fine-tuned and included with checkout documentation for each analyzer
Operation
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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 (H2): 35 ml/min
Flow (Air): 350 ml/min
Makeup (N2): 20 ml/min
Data rate: 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
Operation
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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 (H2): 35 ml/min
Flow (Air): 350 ml/min
Makeup (N2): 20 ml/min
Data rate: 50 Hz
Run Time Table
Specifier Typical Time* Setting Description
Valve 1 initial OFF Sample to monitor
Valve 1 2.00 ON Sample to analysis column
Valve 1 2.10 OFF Sample to monitor
Valve 1 2.20 ON Sample to analysis column
Valve 1 2.30 OFF Sample to monitor
Valve 1 2.40 ON Sample to analysis column
Valve 1 2.50** OFF Sample to monitor
Operation
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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)
Operation
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Spare parts kit and consumables kit OxyTracer
Spares parts kit CCG4000.100
Valve Assy 80102.300
Aluminum washer (10 pcs) 21011.040
FTA restrictor 30.40.015
Consumables kit CCG4000.200
Capillary Lowox (analysis column) 10.73.030
Capillary methyl silicone (pre column) 10.74.011
Monitor 21052.020
SilTite ferrule 0.8 (10 pcs) 21040.026
SilTite ferrule Monitor 0.4 (10 pcs) 21040.025
Liner Siltek (10 pcs) 21032.007
Septa, 9.5 mm (50 pcs) 21040.004
Syringe (10 µL) 30.25.001
Sample box 14 oxygenates 20001.520
4
Index
Index
Version 2011/1.0 4-2 of 5
Index
A AC OxyTracer flow diagram ........ 3-3
C cabling ........................................ 2-2
cabling configuration ............... 2-2 calibration
AC Oxytracer analyzer .........3-15 Column configuration .................. 2-4 configuration
AC OxyTracer Analyzer ........ 3-4 configuration, system .................. 1-6 consumables kit .........................3-24
G gas purity .................................... 1-3 gas requirements ........................ 1-3 GC method ................................3-21
Oxy ......................................3-20 GC method: ...............................3-21
H Helium ........................................ 1-3 hydrocarbon
trap ....................................... 1-3 Hydrogen .................................... 1-3
I installation
AC OxyTracer methods .......2-11 hardware ............................... 2-2
Installation AC methods .........................2-11
Introduction ................................. 3-2
L LAN ............................................. 2-2
O Oven Exhaust Deflector .............. 1-4
P physical requirements ................. 1-4 pre installation checklist .............. 1-6 preinstallation requirements ........ 1-2 principle of analysis
AC OxyTracer Analyzer ......... 3-5
R rear side connections .................. 2-3 Requirements
electrical ................................ 1-5
S software ...................................... 1-6
installation ........................... 2-11 Spare parts kit ........................... 3-24 Spare parts kit and consumables kit OxyTracer ................................. 3-24 system configuration ................... 1-6
T trap
hydrocarbon .......................... 1-3 moisture ................................ 1-3 oxygen ................................... 1-3
V valves .......................................... 2-4
