How to Achieve Acceptable
Tune Criteria for BFB and DFTPP
How to Achieve an Acceptable BFB Tune......................................................... 2
Autotune of the Mass Spectrometer ....................................................................... 2
MS Conditions ..................................................................................................... 2
GC Conditions ..................................................................................................... 2
Tuning the Mass Spectrometer for BFB ................................................................. 3
Analytical Conditions for BFB Tune and VOC Analysis .......................................... 3
Purge and Trap Conditions.................................................................................. 3
GC Conditions ..................................................................................................... 4
MS Conditions ..................................................................................................... 4
Meeting Resolution Criteria ................................................................................. 5
Meeting Ion Ratio Criteria .................................................................................... 6
How to Achieve an Acceptable DFTPP Tune .................................................... 7
Autotune of the Mass Spectrometer ....................................................................... 7
MS Conditions ..................................................................................................... 7
GC Conditions ..................................................................................................... 7
Analytical Conditions for DFTPP Tune and SVOC Analysis................................... 8
8400 AutoSampler (if used) ................................................................................. 8
GC Conditions ..................................................................................................... 8
MS Conditions ..................................................................................................... 9
Improving Resolution Criteria ............................................................................ 10
Obtaining Ion Ratio Criteria ............................................................................... 11
03-914952-00:1
1
How to Achieve an Acceptable BFB Tune
To obtain EPA specified Tune criteria for BFB, the instrument conditions suggested in the
Varian Environmental Manual (PN: 03-914895-00) need to be followed. Using these
conditions will allow the generation of passing results most of the time; however occasional
modifications may be necessary. A summary of the analytical conditions is described below.
It is essential that the:
Ion Trap temperature be set properly
Column flow rate be set properly
Autotune, particularly Mass calibration has been successfully performed under
proper conditions (see details below)
The MS acquisition method parameters are set as specified in the manual or as
indicated below
The suggested amount of BFB has been injected with the specified split rate
Autotune of the Mass Spectrometer
Before autotune can be performed reliably, certain basic conditions need to be
established.
MS Conditions
Trap temp.
Manifold temp.
Transfer line temp.
Electron multiplier
Axial modulation
150 °C
60 °C
200 °C
10^5 Gain Setting
4.0V
GC Conditions
Flow/Pressure
1.2 mL/min (constant flow)
Column oven
150 °C isothermal
Perform autotune under these conditions. It will help to establish proper Electron
Multiplier setting and mass calibration. The same conditions, with the exception of
column temperature, will be used for BFB Tune and VOC analysis also.
How to Achieve an Acceptable BFB Tune
2
Tuning the Mass Spectrometer for BFB
The amount of BFB entering the ion trap should be 2-5 ng.
If 1 µL BFB tune mix is introduced by syringe injection (split 1:20) the solution
should be 50-125 ng/µL concentration.
If the Purge and Trap apparatus introduces the BFB, the water sample concentration
should be 2-5 ppb for 25 mL and 5-20 ppb for 5 mL sample volumes (split 1:20).
Deviation from these levels will make it difficult to pass BFB tune requirements.
Analytical Conditions for BFB Tune and VOC Analysis
Purge and Trap Conditions
5 or 25 mL Purge Vessel
VOCARB 4000 Trap
40 mL/min He Purge Flow
Line temp.
Valve temp.
Mount temp.
MCS line temp.
Purge ready temp.
120 °C
130 °C
40 °C
120 °C
30 °C
Sample heater
Prepurge time
Sample preheat time
OFF
0.00 min
0.00 min
Purge time
Dry purge time
MCS desorb temp.
GC start option
GC cycle time
Cryo focuser
Desorb preheat
Desorb time.
Desorb temp
Sample drain
Bake time
Bake temp.
Bake gas bypass
MCM bake temp.
Sample fill
11 min
0.0 min
40 °C
start of desorb
35 min
OFF
250 °C
4 min
250 °C
ON
7 min
260 °C
Off
250 °C
0.0 min
How to Achieve an Acceptable BFB Tune
3
GC Conditions
Type 5 EFC with split insert if 1177 or 1079 injectors are used.
Direct connection of P&T transfer line to GC column if no injectors are connected.
CP624 column, 60m x 0.32 mm 1.8 µm film (PN: CP7415)
Injector
Temperature (if present) 140 °C
Split ratio
Initial
20:1
3 min
50:1
4.1 min
20:1
Flow/Pressure
12 psi for 2 min
1.2 mL/min for 30 min
Column Oven
35 °C hold 6 min
8 °C/min to 220 °C, hold 6 min, or until all compounds elutes
(Follow this column programming if the BFB is introduced via the Purge and Trap
system. Faster column oven ramping may cause the sudden coelution of the
concentrated water vapor and hinder performance.)
MS Conditions
Parameters in Instrument Control
Trap temp.
Manifold temp.
Transfer line temp.
Electron multiplier
Axial modulation
150 °C
60 °C
200 °C
Autotune conditions
4.0V
MS Acquisition Method Parameters
Filament/multiplier delay
VOC acquisition segment
Mass range
Ionization mode
Ion preparation
How to Achieve an Acceptable BFB Tune
3 min
3 min to 33 min
47-280 m/z
EI Auto
None
4
Segment Set Points
Scan time
Multiplier offset
0.7 second/scan
0V
Emission current
Count threshold
Mass defect
Cal gas
10 µA
1
0
Off (unchecked)
Electron Ionization Mode Parameters
Target
12000 counts
Max ionization time
25000 µsec
Prescan ionization time
Background mass
RF dump value
100 µsec
45 m/z
650 m/z
Low Mass (m/z)
High Mass (m/z)
Ionization Storage
Level (m/z)
Ionization Time
factor (%)
1
10
70
35
120
2
71
78
35
70
3
79
150
35
100
4
151
650
35
70
The BFB peak will be checked by EnviroPro software (PN: 03-930359-91) or by the
Custom Reports software included in the Saturn WS software for BFB Tune criteria.
The tune may be checked on a single scan or on the average of 3 or 5 scans. Use
background correction when checking for acceptance criteria. The tune maybe
checked on the spectrum at the apex of the peak (retention time), or at any time (not
necessarily at the apex) as entered by the user.
If the tune criteria are not met while using the suggested parameters, additional
adjustment may be necessary to meet EPA tune requirements:
Meeting Resolution Criteria
If the resolution criteria for ions 96, 173, 175, 176, 177 are not met, the most common
reason is that the multiplier voltage is set too low for the required mass spectral
resolution. Increase the multiplier voltage by 50-100V and repeat the injection.
How to Achieve an Acceptable BFB Tune
5
Lower than optimum multiplier voltage will decrease the resolution of neighboring
ions, resulting in the specified ratios exceeding the requirements. This may happen
even if the multiplier voltage was set recently by autotune. Increasing the multiplier
voltage by 50-100V will not have adverse effects.
Adjusting AM Voltage: The default AM voltage is 4.0V in the system. The
adjustment (± 1V in decimal increments) of this voltage also will help to achieve the
required ion ratio criteria.
NOTE: If the AM voltage is changed, verify that the resolution of ions 131/132 does
not deteriorate. This can be viewed by turning on the cal gas and monitoring the
spectrum in manual page of system control of the Saturn module.
A new mass calibration must be carried out to maintain correct mass assignment if the
AM voltage has been changed.
Improved resolution can also be achieved by lowering the AGC Target value. The
suggested target will give a good starting point, but it may be lowered by 1000-2000
count.
Meeting Ion Ratio Criteria
The ion ratios specified in the EPA (particularly the older) methods are based on data
collected on older generation instruments with poor detection efficiencies for the
higher mass ions. To achieve the required criteria, increase/decrease the ionization
time factor to achieve the proper ratios. Increasing the ion time will increase the ion
intensity of the ions in that segment. Once intensity ratios for the major BFB ions at
m/z 50, 75, 95, and 174 have been adjusted, the ion time factors rarely need to be
readjusted.
How to Achieve an Acceptable BFB Tune
6
How to Achieve an Acceptable DFTPP Tune
To obtain EPA specified Tune criteria for DFTPP, instrument conditions suggested in the
Varian Environmental Manual (PN: 03-914895-00) need to be followed. Using these
conditions will allow the generation of passing results most of the time; however, occasional
modifications may be necessary. A summary of the analytical conditions is described below.
It is essential that the:
Trap temperature be set properly
Column flow rate be set properly
Autotune, particularly Mass calibration has been successfully performed under
proper conditions (see details below)
The MS acquisition method parameters be set as specified in the manual or as
indicated below
The suggested amount of DFTPP has been injected. (If DFTPP is not stored
properly, it will decompose. Make sure fresh standard is used for DFTPP tune
testing.)
Autotune of the Mass Spectrometer
Before reliable autotune can be performed, basic conditions need to be established.
MS Conditions
Trap temp.
220 °C
Manifold temp.
50 °C
Transfer line temp.
Electron multiplier
Axial modulation
280 °C
10^5 Gain Setting
4.0V
GC Conditions
Flow/Pressure
1.2 mL/min (constant flow)
Column oven
200 °C, isotherm
Perform autotune under these conditions. It will help to establish proper Electron
Multiplier setting and mass calibration. These will be the conditions for Tune / SVOC
analysis also.
How to Achieve an Acceptable DFTPP Tune
7
Amount of DFTPP
The amount of DFTPP entering the ion trap should be 5 ng or less. If only higher
concentration mixture is available, such as 50 ng/µL, use a 1 µL split injection at 10:1
split or dilute the STD. If more than 5 ng DFTPP enters the ion trap, it will be difficult
to meet DFTPP tune requirements.
Analytical Conditions for DFTPP Tune and SVOC
Analysis
8400 AutoSampler (if used)
Syringe Size:
Injection Mode:
Solvent Penetration Depth:
Sample Penetration Depth:
10 µL
STD Split/Splitless
90%
95%
Default Clean Vial; I (solvent Ethylacetate)
Default Clean Volume:
7.0 µL
Default Clean Strokes:
1
Default Clean Drawup Speed: 5.0 µL/sec
Clean Mode Pre-Inj. Solvent Flushes:
Clean Mode Post –Inj Solvent Flushes:
Clean Mode Pre-Inj Sample Flushes:
Clean Mode Solvent Source:
1
3
0
I
GC Conditions
Type 1 EFC with 4 mm split Siltek frit insert (PN: RT210462145) for the 1177
injector, CP Sil8 MS low bleed column, 30m x 0.25 mm 0.25µ film (PN: CP5860)
Septum Purge Flow: 4 mL/min at 45 psi
Injector
Temperature
280 °C
Splitless injection (1 µL of 5 ng/µL std)
Splitter programming
Initial
ON
20:1 split
0.01 min
OFF
(use the appropriate split ratio for higher concentration of DFTPP)
0.75 min
ON
20:1 split
How to Achieve an Acceptable DFTPP Tune
8
EFC Flow/Pressure
Pressure Pulse is used for optimum sample introduction.
Pressure pulse:
45 psi
Pressure Pulse duration: 0.85 min.
Constant Column flow:
1.2 mL/min (following the pressure pulse, starts at
0.85 min to the end of the run)
NOTE: Do not perform air/water test or mass calibration under pressure pulse
conditions. The MS internal parameters are set for 1.0 mL/min (normal analytical
conditions) to deliver reliable results for these operations. During the pressure pulse
the column flow is much higher and will result inaccurate readings.
Column Oven
70 °C, hold 1.5 min
10 °C/min to 200 °C, no hold
15 °C /min to 300 °C, hold 10 min
The column oven temperature program may be altered to gain DFTTP results faster.
MS Conditions
MS Acquisition Parameters
Filament/Multiplier Delay
Acquisition Segment
Mass Range
Ionization Mode
Ion Preparation
2.0 min
2 min to 40 min
45-450 m/z
EI Auto
None
Segment Setpoints
Scan Time
Multiplier Offset
0.9 second/scan
0-100 volt
(100V multiplier offset increases the spectral resolution
for DFTPP and also increases sensitivity)
Emission Current
Count Threshold
Mass Defect
Cal Gas
10 µA
2
0
Off (Unchecked)
How to Achieve an Acceptable DFTPP Tune
9
Electron Ionization Mode Parameters
Target:
8000 counts
Max Ionization Time:
25000 µsec
Prescan ionization Time: 100 µsec
Background mass:
45 m/z
RF Dump value:
650 m/z
Low Mass (m/z)
High Mass (m/z)
Ionization Storage
Level (m/z)
Ionization Time
factor (%)
1
10
75
37
120
2
76
130
37
240
3
131
270
37
90
4
271
332
37
45
5
333
399
37
70
6
400
650
37
22
The DFTPP peak will be checked by EnviroPro software (PN: 03-930359-91) or with
the Custom Reports software included in the Saturn WS software for the DFTPP Tune
criteria. The tune may be checked on a single scan or on the average of 3 or 5 scans.
Use background correction when checking the tune criteria. The tune maybe checked
on the spectrum at the apex of the peak (retention time), or at any time (not necessarily
at the apex) as entered by the user.
If the tune criteria are not met while using the suggested parameters, additional
adjustment may be necessary to meet EPA tune requirements:
Improving Resolution Criteria
If the resolution criteria of ions 68, 70, 197, 199, 441, 443 are not met, the most
common reason is that the multiplier voltage needs to be increased. Increase the
multiplier voltage by 50-100V and repeat the injection.
A lower than optimum multiplier voltage will decrease the resolution of neighboring
ions; resolution ions ratios then are higher than specified. This may happen even if the
multiplier voltage was set recently by autotune. Increasing the multiplier voltage by
50-100V will not have adverse effects.
How to Achieve an Acceptable DFTPP Tune
10
Adjusting AM voltage: The default AM voltage is 4.0V in the system. The
adjustment (± 1V in decimal increments) of this voltage also will help to achieve the
required ion ratio criteria.
NOTE: If the AM voltage is changed, verify that the resolution of ions 131/132 did
not deteriorate. This can be viewed by turning on the cal gas and monitoring the
spectrum in Manual Control page of System Control for the Saturn MS module.
A new mass calibration must be carried out to maintain correct mass assignment if the
AM voltage has been changed.
Inject less DFTPP, about 2-3 ng on-column.
(Improved resolution can be achieved by lowering the Target value. The suggested
target will give a good starting point, but it may be lowered by 1000-2000 count.)
Obtaining Ion Ratio Criteria
The ion ratios specified in the older EPA methods are based on data collected on older
generation instruments with poor detection efficiencies for the higher mass ions. To
achieve the required criteria, increase or decrease the ionization time factor to achieve
the proper ratios. Increasing the ion time will increase the ion intensity of the ions in
the selected segment. Once ion time factors have been set well, they rarely need
readjustment.
How to Achieve an Acceptable DFTPP Tune
11