VICI D-4-I-SH17-R User Manual

Valco Instruments Co. Inc.

Pulsed Discharge
Detector
Model D-4-I-SH17-R
Instruction Manual

North America, South America, and Australia/Oceania contact:

Valco Instruments Co. Inc.

800 · 367· 8424 sales
713 · 688· 9345 tech
713 · 688· 8106 fax
[e-mail]

D4_shim_17.P65

Rev. 5/12

Europe, Asia, and Africa contact::

VICI AG International

Schenkon, Switzerland
Int + 41 · 41 · 925· 6200 phone
Int + 41 · 41 · 925· 6201 fax
[e-mail]

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Table of Contents

Introduction

Description and Operating Principles ..............................................................1

Safety Notes and Information ..........................................................................2

Symbols
Installation Category
Safety

Components of the Detector System .............................................................. 3

System Requirements

Components not Included with the Detector System ...................................... 4

System Purity ..................................................................................................4

Gas Specifi cations ..........................................................................................5

Installation

General Precautions .......................................................................................6

Mounting the Detector on the GC ...................................................................6

Gas Connections.............................................................................................8

Installing and Purging the Gas Regulator ...............................................8

Installing and Purging the Helium Purifi er ...............................................9

Connecting the Discharge Gas to the Detector .......................................9

Capillary Column Connection .......................................................................10

Packed Column Connection ..........................................................................10

Testing for Leaks ........................................................................................... 11

Pulser Module Installation .............................................................................12

Detector Electrical Connections ....................................................................14

Initial Power-Up .............................................................................................15

Mode Selection and Setup

Helium Ionization Mode.................................................................................16

Selective Photoionization Mode ....................................................................16

Troubleshooting ...................................................................................................18

Warranty ..............................................................................................................20

Detector Performance Log ...................................................................................21

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Introduction

Description and Operating Principle

1

The PD-D-4-I-SH17-R is a non-radioactive pulsed discharge ionization detector
(PDID) which is optimized for the Shimadzu GC -17, GC-2010, and GC-2014.
A schematic representation of the basic D4 detector is shown in Figure 1.

The D4 utilizes a stable, low power, pulsed DC discharge in helium as the
ionization source. Elutants from the column, flowing counter to the flow of
helium from the discharge zone, are ionized by photons from the helium
discharge above. Resulting electrons are focused toward the collector
electrode by the bias electrode.

The principal mode of ionization is photoionization by radiation arising from
the transition of diatomic helium

He

1

+

(

∑

)

A

u

2

to the dissociative 2He(1S

1

)
ground state. This is the well-known Hopfield emission. The photon energy
from the He2 continuum is in the range of 13.5 eV to 17.7 eV.

The D4 is essentially non-destructive (0.01 - 0.1% ionization) and highly
sensitive. The response to organic compounds is linear over five orders
of magnitude with minimum detectable quantities (MDQs) in the low
picogram range. The response to fixed gases is positive (the standing
current increases), with MDQs in the low ppb range.

Detector response is universal except for neon, which has an ionization
potential of 21.56 eV. Since this potential is close to the energy of the
He* metastable (19.8 eV) but greater than the photon energy from the
He2 continuum, neon exhibits a low ionization efficiency and low detector
response.

When a dopant is added to the discharge gas, the D4 also functions
as a selective photoionization detector. (Suitable dopants include Ar for
organic compounds, Kr for unsaturated compounds, or Xe for polynuclear
aromatics.)

GROUND PIN

DISCHARGE REGION

HELIUM INLET

HIGH VOLTAGE

SAPPHIRE INSULATORS

BIAS ELECTRODE

CAPILLARY COLUMN

VENT

COLUMN INLET

Figure 1: Schematic of the D4 detector

COLLECTOR ELECTRODE

Introduction

2

Helium Ionization (PDHID)

The PDHID is essentially non-destructive (0.01 - 0.1% ionization) and highly
sensitive. The response to organic compounds is linear over five orders of
magnitude with minimum detectable quantities (MDQs) in the low or sub
picogram range. The response to fixed gases is positive (the standing
current increases), with MDQs in the low ppb range.

The PDHID response is universal except for neon, which has an ionization
potential of 21.56 eV. Since this potential is close to the energy of the He*
metastable (19.8 eV) but greater than the photon energy from the He
continuum, neon exhibits a low ionization efficiency and low detector
response.

2

Photoionization (PDPID)

Changing the discharge gas from pure helium to helium doped with argon,
krypton, or xenon changes the discharge emission profile, resulting in
resonance atomic and diatomic emissions of the rare gas added. Response
is limited to sample compounds with ionization potentials less than or equal
to the dopant gas emission energy. In this configuration, the detector is
essentially functioning as a specific photoionization detector for selective
determination of aliphatics, aromatics, and amines, as well as other species.
Since there is no lamp or window, sensitivity will not change with time.

Safety Notes and Information

CAUTION: During normal operation, the detector pro­duces ultraviolet energy (UVA, UVB), some of which may
be emitted. Do not watch the arc without eye protection.

Symbols

HIGH VOLTAGE

Voltages presenting the risk of electric shock are present in
several places in the equipment. Avoid contact with hazard­ous live parts. Do not probe into openings or attempt to
defeat safety mechanisms.

HOT SURFACE

The surface of the detector body may be hot while in opera­tion (possibly in excess of 250°C). Caution should be
observed.

ATTENTION

Refer to the manual.

Introduction

Components of the Detector System

Detector system components are listed in Table 1. Check the contents of the packages to
verify that everything is present. Contact the factory if anything is missing or damaged.
(NOTE: damaged shipments must remain with the original packaging for freight company
inspection.) Tabl e 2 lists additional items which must be purchased from Shimadzu.

3

Table 1:

Components of the D-4-I-SH17-R system

Description Quantity Product number

Detector cell, PDHID 1 PD-D4-I-RU

Pulse supply module 1 PD-M2

Instruction manual 1 MAN-PDD4-SH17

Fittings kit 1 PD-KIT-D4

Includes: 1/32" polyimide ferrule 5 ZF.5V

1/32" polyimide plug ferrule (no through hole) 1 ZF.5VX

1/16" gold-plated ferrule 5 ZF1GP

0.25 - 0.44 mm polyimide column ferrule 5 FS.4

0.4 - 0.5 mm polyimide column ferrule 5 FS.5

1/16" union, 316 SS 2 ZU1MS6

1/16" tee 1 ZT1

1/8" external to 1/16" internal adapter 2 EZR21

1/8" external to 1/16" internal reducing union 2 EZRU21

1/32" external nut 1 EN.5KN

Fused silica adapter (installed) 1 IZERA1.5

Packed column adapter 1 I-23642-D4RU

Restrictor, 30 cc/min @ 60 psi He 1 TGA-R-30F60P

Helium purifier 1 HP2

Electrometer cable assembly, Shimadzu 1 I-23230-SH

Bias cable assembly, Shimadzu 1 I-23404-SH

Pulser power supply 1 I-23569-1

Heater block assembly, Shimadzu 1 I-23831A

Table 2:

Components not supplied by Valco (may be obtained from Shimadzu)

Description Quantity Product number

For GC-17

Mounting base screws 2

Heater assembly (depending on requirement) 1

120V 221-43346-91

220V 221-43346-93

Electrometer, FID wide range (see page 12) 1 221-43290-91

For GC-2010

10 mm spacers, BSU-410 2 037-38871-72

FID-2010 heater assembly, 220-240V 1 221-47660-98

FID-2010 controller 1 221-46520-91

For GC-2014

10 mm spacers, BSU-410 2 037-38871-72

FID-2014 heater assembly, 220-240V 1 221-70610-34

FID-2014 controller 1 221-46520-92

Introduction

4

System Requirements

Components Not Included with the Detector System

• Helium (99.999% purity) and other support gases

• Ultra high purity grade gas pressure regulator with stainless steel

diaphragm

• Any special adapters required for connection to the gas regulator

• SS tubing to go from gas supply to GC

• Flow measuring device

System Purity

Discharge/Carrier Gas Considerations

The performance of the detector is adversely affected by the presence
of any impurities in the gas streams (carrier, discharge, or dopant). We
recommend that a quality grade of helium 5.0 (99.999% pure or better)
be used at all times. Major gas suppliers offer research grade helium
(99.9999% pure) which is particularly low in fixed gas impurities and should
give good results in a clean system, but even the highest quality carrier
gas may contain some water vapor and fixed gas impurities; hence a
helium purifier is included as part of the detector system.

must always flow through the helium purifier.

The discharge gas

Whenever a new batch of discharge gas is received, we recommend
performing a blank GC analysis of the gas in the PDHID mode to detect
and identify the presence of any impurities. Gas purity requirements
are specified on the next page.

Tubing

Standards of cleanliness that are suitable for many GC applications may
be totally inadequate for the sensitive PDHID/PDPID work. All surfaces that
contact the gas stream must be fused silica or stainless steel. Do not use
copper tubing or brass fittings. All tubes must be thoroughly cleaned and
baked before use.

Flow Controllers

The use of valves or flow controllers in which the gas stream is exposed
to any polymer-based packing or lubricating material is to be particularly
avoided.

Pressure Regulators

We recommend commercial “ultra-pure” grade regulators with stainless steel
diaphragms. Regulators with diaphragms made of neoprene or other
elastomers should never be used.

Gas Specifications

Introduction

5

edoMrotceteD

DIHDPDIPDP-rADIPDP-rKDIPDP-eX

sagegrahcsiD

sagreirraC

Any gas including He which has an ionization potential greater than 12 eV

**

Any gas including He which has an ionization potential greater than 11 eV

**

muileHeHnirA%2eHnirK%5.1eHnieX%8.0

muileH*****

Purity Specifications

• Helium (discharge and carrier gas) must have a minimum purity of

99.999%, with < 20 ppm Ne impurity. For trace analysis of fixed gases,
we strongly recomment 99.9999% purity He with < 0.5 ppm Ne.

• Ar-PDPID mode: 2% ± 0.2% Ar in 99.999% He balance

• Kr-PDPID mode: 1.5% ± 0.1% Kr in 99.999% He balance

• Xe-PDPID mode: 0.8% ± 0.2% Xe in 99.999% He balance

6

Installation

General Precautions

• Do not use plastic/polymer or copper tubes for gas handling and

interconnectons. Use only stainless steel tubing with Valco gold-plated
ferrules.

• Do not turn the unit on until the helium discharge gas is flowing through

the detector.

• Do not shut off or disconnect the discharge gas when the detector is hot,

even if the unit is turned off. Turn off the discharge and allow the detector
to cool down naturally before disconnecting or shutting off the discharge
gas.

• Do not cover the unit with materials or devices which would restrict air

circulation.

• Position the controller unit where the mains switch on the rear panel can

be reached easily.

Mounting the Detector on the GC

1. Insert the heater and temperature probe into the detector’s heater block.

2. Install the detector on the GC using two screws. Refer to Figure 3 or 4,
as appropriate.

TO

PULSER

MODULE

ELECTROMETER

Figure 3: Mounting the detector on a GC-17

BIAS

TO
PULSER
MODULE

FROM UPPER
DETECTOR
ELECTODE

FROM LOWER
DETECTOR
ELECTODE

7

Figure 4: Mounting the detector on a GC-2010 or GC-2014

Installation

8

Gas Connections

Remember these three points discussed earlier: (1) all surfaces that contact
the gas stream must be fused silica or stainless steel; (2) do not use copper
tubing or brass fittings; and (3) all tubes must be thoroughly cleaned and
baked before use. The installation instructions below assume that the
detector discharge gas will be supplied from a nearby cylinder of helium
of the proper purity. If your installation is different, you may need to modify
the instructions appropriately. A number of Valco fittings have been supplied
in the fittings kit to handle different situations.

Figure 5 illustrates gas connections for the D-4-I-SH17-R detector system.
Since the distance from the helium supply to the GC varies from installation
to installation, we do not supply tubing for that purpose.

VENT

TGA-R-30F60P

RESTRICTOR

(30 mL/min minimum)

DISCHARGE GAS
INLET

SAMPLE IN

TEE
(ZT1)

HELIUM

PURIFIER

DISCHARGE GAS
(99.999% He)

COLUMN

INLET

COLUMN

GAS CHROMATOGRAPH

VENT

Figure 5: Gas connections for a D-4-I-SH17-R system

Installing and Purging the Gas Regulator

1. Make sure the on/off valve on the helium cylinder is completely closed.
Screw the CGA fitting nut of the regulator into the helium cylinder. Go
beyond finger-tight, but do not tighten the nut all the way – some leakage
is required for the purging operation.

2. Turn the output pressure regulating knob completely counterclockwise.

3. Open the cylinder on/off valve

4. Adjust the tightness of the regulator connecting nut to allow a pressure
reduction of ~690 kPa/sec (100 psi/sec). With a new bottle, the gauge
should start out at about 14 MPa (2000 psi).

5. When the pressure drops into the 1.4 - 3.4 MPa (200 - 500 psi) range,
open the cylinder on/off valve slightly and quickly close it again.

6. Repeat Step 5 eight or ten times to be certain that all the air is purged.
On the final purge, tighten the regulator connecting nut very securely as
the pressure approaches the 2.1 - 3.4 MPa (300 - 500 psi) range.

slightly

and quickly close it again.

Installation

7. Open the cylinder valve to pressurize the regulator once again. Close the
valve and observe the needle of the high pressure gauge for 15 minutes.
If it doesn’t move, there is no critical leak on the high pressure side of the
regulator.

CAUTION: Never use leak detecting fluids on any part
of this system.

Installing and Purging the Helium Purifier

9

EZR21

1. If the pressure regulator has a 1/8"
the Valco 1/8" external to 1/16" internal reducer (EZR21); if it has a
1/4"

male

cone-type outlet port, install the Valco 1/4" external to 1/16"
internal reducer (EZR41). For other regulator outlet fittings, a wide
variety of Valco adapters is available.

2. Remove the cap from the inlet tube of the Valco helium purifier and insert
the tube fitting into the 1/16" reducer port. (Keep the outlet tube capped.)
Use a 1/4" wrench to turn the nut one-quarter turn past the point where
the ferrule first starts to grab the tubing. Do not remove the fitting. When
made up properly, it should be leak-tight.

3. Turn the output pressure regulating knob clockwise until the gauge
registers 345 KPA (50 psi).

4. Allow five minutes for equilibration, then turn the regulating knob all the
way counterclockwise.

5. Observe the needle of the output pressure gauge for 15 minutes. There
will be a slight initial drop, but if it doesn’t move after that, consider that all
the connections are tight.

6. If necessary, use an electronic leak detector to locate any leaks. If a
leak detector is not available, tighten all the fittings (including the output
pressure guage), and repressurize the system for another test.

7. Upcap the outlet tube of the purifier and purge the system for
15 to 30 minutes at 60 - 80 mL/min to eliminate air from the purifier
getter material.

male

cone-type outlet port, install

Connecting the Discharge Gas to the Detector

1. If you are supplying the GC from the helium purifier, use the Valco
ZT1 tee. Otherwise, use one of the Valco 1/16" unions (ZU1) to connect
the outlet tube of the purifier to the inlet of the supplied discharge gas
restrictor (TGA-R-30F60P).

2. Connect the outlet end of the restrictor to a flow measuring device. Adjust
the helium pressure to 60 psi to obtain a continuous flow of ~30 mL/min.

3. After setting the flow rate, connect the outlet of the restrictor to the
discharge gas inlet tube (labelled “INLET”) which comes out the side
of the detector.

Installation

10

Capillary Column Connection

If the capillary column adapter is installed in the column inlet:

11.4 cm/

COLUMN
INLET

1. Make a mark on the column 11.4 cm from the end.

2. Remove the knurled nut and plug from the capillary column adapter in the

CAPILLARY
COLUMN
ADAPTER
(IZERA1.5)

COLUMN
FERRULE

NUT

CAPILLARY
COLUMN

column inlet at the bottom of the detector. Slide the nut over the end of
the column, followed by the appropriate column ferrule (FS.4 or FS.5, or
ZF.5V for megabore).

3. Seat the ferrule in the detail of the column adapter and begin sliding the
column through the capillary column adapter and into the column inlet.

4. Get the nut started on the threads and tighten it until you feel it contact
the ferrule, then back off half a turn. Slide the column into the column
inlet until the mark is flush with the surface of the knurled nut, and secure
the column in the adapter by tightening the knurled nut

If the capillary column adapter has been removed, reinstall it:

1. Unscrew the liner as far as it will go, then screw the fitting body into the
column inlet fingertight.

2. While using a 1/8" wrench to prevent rotation of the liner (the part with the
seat for the column ferrule), use a 1/4" wrench to tighten the body of the
adapter until the ferrule has sealed. The liner

3. Proceed to Step 1 above.

Packed Column Connection

finger tight only

will deform

.

if it rotates.

9.8 cm/

PACKED

COLUMN

COLUMN
INLET

PACKED
COLUMN
ADAPTER

(I-23642-D4RU)

To prevent detector contamination, we strongly
recommend disconnecting the column from the
detector during column bakeout procedures.

The D4 is optimized for packed columns. The column tubing must be
thoroughly cleaned and baked before the column is packed. Even when
the best care is taken in column tubing cleaning and in the support and
stationary phase selection, a new column will often bleed compounds,
resulting in a considerable increase in the detector baseline. This initial
bleed will usually be reduced to acceptable levels after the column is
conditioned with clean carrier gas flow for several hours at the
recommended bakeout temperature.

1. Loosen and remove the knurled nut and plug of the capillary column
adapter, (or remove the column ferrule and the column if one has been
installed).

2. Use a 1/8" wrench to hold the liner – that part of the adapter in which the
column ferrule sits. While the 1/8" wrench keeps the liner from rotating,
use a 1/4" wrench on the fitting body to loosen the adapter 1/2 turn.

Installation

3. Set aside the 1/8" wrench and completely remove the adapter from the
column inlet.

11

4. Screw the packed column adapter into the column inlet by hand.

caution

with a 1/4" wrench, using an additional wrench on the flats of the column
inlet to support the detector.

5. Connect the 1/8" column to the packed column adapter with the EZRU21
reducing union supplied in the fittings kit.

, as the tip of the adapter is very fragile. Then tighten the adapter

Testing for Leaks

It is critical for the system to be leak-tight, and an additional check at this
point can save many headaches later on. To test for leaks:

1. Cap the tube and pressurize the entire system with helium to 138 kPa
(20 psi).

2. If the system does not hold pressure, check all the fittings with an
electronic helium leak detector. DO NOT use leak detecting liquids.

3. Tighten fittings as required.

Exercise

Installation

12

Pulser Module Installation

1. GC-17: The pulser module can usually be mounted on the bottom plate of
the GC, using existing holes. (Figure 6) If there is no room on the bottom
plate, mount the module on the top of the GC oven.

GC-2014: There is room for the pulser module in a compartment on the
right side (facing the instrument), at the back near the top. (Figure 7)

GC-2010: The best place is a space in the rear on the left hand side.
(facing the instrument). Two screws hold the vented cover in place.
(Figure 8)

2. Power to the pulser module is provided through the pulser power supply
(PN I-23569-1). Plug the 4-pin connector into the pulser module.

OPTIONAL LOCATION FOR

PULSER MODULE

TO DETECTOR

TO PULSER
POWER SUPPLY

PULSER MODULE

Figure 6: Mounting the pulser module in the GC-17

Installation

POSSIBLE
LOCATION FOR
PULSER MODULE
ON GC-2014

13

Figure 7: Possible location for the pulser module on the GC-2014

Figure 8: Possible location for the pulser module on the GC-2010

Installation

1000 meg Ω
RESISTOR

R1

R2

C1

14

Detector Electrical Connections

CAUTION: Do not use a wrench to tighten the SMC
connectors on the bias and electrometer cables.
Connections should be finger tight only.

1. Referring to Figure 9 as necessary, connect the BIAS cable to the top
electrode and the electrometer cable (ELECT) to the bottom electrode.

NOTE: If you have a GC-17 with the standard

linear

range FID electrom-

eter (Shimadzu P/N 221-43289-91), a 1000 Meg
Ω resistor must be soldered across R1 of the
electrometer board. To do this, first remove the
six cover screws and lift off the cover. Locate
R1 on the PC board and solder the resistor as
indicated at right.

2. Connect the high-voltage cable from the detector
to the pulse supply.

3. Connect the heater cable from the detector to “DET” on the wire panel of
the GC.

BIAS CABLE

P/N: I-23404-SH

ELECTROMETER CABLE

P/N: I-23230-SH

PULSER

MODULE

SHIDMADZU
HEATER CABLE

PULSER

POWER

SUPPLY

TO 110/220 VAC

SHIMADZU

ELECTROMETER

BOARD

(OPTIONAL WIDE RANGE)

P/N 221-43290-91)

TO “DET”

ON WIRE PANEL

Figure 9: Schematic of electrical connections

Initial Power-Up

1. Before installing the column, set the gas flow to 30 ml/min (measured at
the detector vent). Let it flow for 15 minutes so that all air is purged from
the helium purifier.

2. Plug in the helium purifier and turn on the GC.

3. Set the detector temperature to 100°C and allow time for the detector and
helium purifier to reach the set temperature.

4. Set the range to 10

5. Plug the 15 VDC output from the power supply (I-23569-1) into the pulser
module (PD-M2).

6. Plug the power supply cord to a 100 - 250 VAC source, and look through
the hole in the detector housing to see that the discharge is on.

Installation

CAUTION: Always make sure that discharge gas is
flowing before heating and powering up the detector.

2

and adjust the voltage to Ø.

15

CAUTION: During normal operation, the detector produces
ultraviolet energy (UVA, UVB), some of which may be
emitted. Do not watch the arc without eye protection.

7. Check the standing/background current. Optimum range is 6.0 - 20.0 mV
(0.60 - 2.0 nA) at 100°C in the HID mode. Lower current indicates a
clean, leak-free system. Record the standing/background current in the
Detector Performance Log on the last page of this manual.

8. The recommended detector temperature is 20°C above the column
temperature, with a minimum of 100°C. Set the detector to the operating
temperature required for the intended analysis. When the detector has
reached the set temperature, read and record the standing current.

9. Install the column as illustrated on page 10, leaving the oven at ambient
temperature. Start carrier flow, then read and record the standing current.

The difference between this reading and the one previous is the ioniza­tion of the combined impurities in and eluting with the carrier gas. The
smaller the difference, the better the quality of the gas exiting the column.

10. Set the column oven to the temperature required for the intended

analysis. When the oven reaches the set temperature, read and record
the standing current.

The difference with the previous reading is the ionization of the column
bleed. The smaller the difference, the better the column is conditioned.

NOTE: Some stationary phases will have a higher bleed than others,
but are still suitable for this detector. However, the lower the bleed, the
lower the chances of contaminating the detector cell.

From this point, the standing current should be observed and logged after
any system change. In addition, logging the standing current (with and
without the column) on a regular basis is an effective monitor of system
integrity (leaktightness and cleanliness). We also recommend tracking the
internal standard (quantity on column/area count) for sensitivity continuity.

16

Mode Selection and Setup

Helium Ionization Mode

If the instructions of Step 1 at the top of page 10 were properly executed,
the column should already be properly positioned. Since there may be
some variation in the flow rate for the different types of capillary columns, the
user may want to optimize the column position within this suggested range.
DO NOT insert the column more than 11.6 cm.

With this flow configuration, only pure helium passes through the discharge
region, minimizing the chance of discharge electrode contamination through
contact with the eluting sample. However, if very high concentrations of
organic compounds are introduced for extended periods of time, they could
diffuse into the discharge region and contaminate the electrodes. Under
normal chromatographic use with capillary columns, such contamination is
negligible even over extended periods.

Selective Photoionization Mode

To maximize detector lifetime, turn off the discharge
power when the GC is not actually analyzing samples.
This is especially important in the Ar/Kr PID mode.

Since the pulsed discharge detector is essentially a windowless helium
photoionization detector, changing the discharge gas from pure helium
to helium doped with argon, krypton, or xenon changes the discharge
emission profile. This results in a change in the photon energy due to
additional resonance atomic emissions and diatomic emissions from the
rare gas added. Thus a single detector can be operated in any of the
three photoionization detector (PID) modes: Ar-, Kr-, or Xe-PID.

Doped helium is used rather than other pure gases in order to retain the
benefits of the helium: namely, its transparency for Ar, Kr, an Xe resonance
radiation and its efficient cooling of the electrodes. Any problems associated
with the presence of a window between the photon source and the ionization
chamber are eliminated. In most applications involving current commercial
PIDs, analyte condensation and decomposition on the window attenuate the
lamp energy, necessitating frequent cleaning and recalibration.

Custom gas blends for the pulsed discharge detector are available from
leading gas suppliers at special prices. Alternatively, they may be form­ulated on the spot by using appropriate fixed restrictors to mix appropriate
amounts of pure helium and pure dopant through a tee. Since all gas
streams must pass through a Valco purifier, the second option requires
an additional purifier for each dopant. This may still be more cost effective
than requesting a custom blend of the more expensive Kr or Xe; since the
typical flow rate required for the pure dopant rare gas is about 0.3 ­a small lecture bottle can last for a long time. In either case, the total dis­charge gas flow rate should be the same as specified in “Gas Connections”
on page 8.

1 mL/min,

Ar-PDPID

Changing the discharge gas from helium to a mixture of 2% argon in
helium changes the photon energy level from the 17 - 13.5 eV range to the

11.8 - 9.8 eV range. The argon emission consists of resonance radiation

at 11.8 eV and 11.6 eV and the diatomic Ar2 emission in the range of

9.2 - 10.3 eV. Except for fixed gases and a few organic compounds like

CH4 (IP = 12.5 eV), CH3CN (IP = 12.2 eV) and some fluro-chloro hydro­carbons, the majority of organic compounds have ionization potentials
lower than 11.8 eV. Thus the Ar-PDPID is nearly universal, like the flame
ionization detector, but without the risks associated with the presence of
an open flame and hydrogen.

Kr-PDPID

The recommended proportion is 1.4% Kr in He as the discharge gas.
The krypton emission consists principally of resonance lines at 10.6 eV
and 10.1 eV. The Kr-PDPID can detect compounds with IP < 10.6 eV,
which includes unsaturated and cyclic hydrocarbons, alcohols, aldehydes,
organic acids, esters, etc.

17

Xe-PDPID

The recommended proportion is 0.8% Xe in He as the discharge gas. The
xenon emission consists principally of resonance lines at 9.6 eV and 8.4 eV,
and can detect compounds with IP < 9.6, like aromatics, ethers, alcohols,
aldehydes, etc.

In addition to the specific compounds named in the three paragraphs
above, certain important inorganic compounds like ammonia, hydrogen
peroxide, arsenic trichloride, hydrogen sulfide, arsine, phosphine, nitric
oxide, carbon disulfide etc. can be selectively detected using the
appropriate photoionization mode.

Each dopant gas requires an additional helium purifier, which must be
purged and conditioned in the same manner as the purifier installed on
the discharge gas supply. If you are using more than one dopant, we
recommend use of a Valco multiposition stream selection valve so that no
fittings have to be disconnected. Not only is this convenient, it keeps the
system closed, minimizing chances of contamination. When changing from
one dopant to another, allow at least one hour for the old gas to be purged
from the system.

18

Troubleshooting

High Background Current

Disconnect the column

Pink

Check
discharge
color

Purple/

blue

Low Sensitivity

Check background current
with column removed and
column inlet plugged

High background current
(> 2.0 nA)

Refer to “Troubleshooting:
High Background Current”

and cap the column inlet

Do a hydrogen leak test
(described on next page)

Normal background current
(£ 2.0 nA)

Reinstall column and check
background current

Baseline current falls to
normal range (< 20.0 mV)

Baseline current is still high
(> 20.0 mV)

Leaks in the fittings of the
PDD plumbing

Leaks inside the detector
cell itself

No detectable leaks.

Background current
increases

Background current
remains in normal range

The detector isn’t leaking.
Check for column bleed
and/or leaks in the GC setup.

Tighten leaking fittings

Consult

Valco

Possible bad carrier gas or
empty He bottle. Install a new
bottle.

Check column inlet for
leaks. Tighten fittings.

Check column position
according to drawing on
p. 12, and run a sample.

Baseline current falls to
normal range (< 20.0 mV)

Baseline current is still high
(> 20.0 mV)

Baseline current falls to
normal range (< 20.0 mV)

Baseline current is still high
(> 20.0 mV)

Baseline current falls to
normal range (< 20.0 mV)

Baseline current is still high
(> 20.0 mV)

Background current
remains high

Background current
drops to normal range

Sensitivity is in
acceptable range

Sensitivity is still
too low

Consult

Consult

Consult

Remove column and
condition it, then run
a sample

Run
a sample

Remove column and
bake detector at
300°C for four hours.
Install column and run
a sample.

Valco

Valco

Valco

Sensitivity is in
acceptable range

Sensitivity is still
too low

Sensitivity is in
acceptable range

Sensitivity is still
too low

Sensitivity is in
acceptable range

Sensitivity is still
too low

No Peaks

If the background current is stable but there are no peaks:

1. Check column flow.

2. Check the column insertion position (11.4 cm for capillary columns,

3. If there are still no peaks, check to make sure that the GC is actually making

4. If there are still no peaks, consult Valco.

9.8 cm for packed columns).

an injection.

Consult

Valco

High Noise Level

If the noise lievel is high:

1. See if it improves with the GC fan turned off.

2. Check the column insertion position (11.4 cm for capillary columns,

9.8 cm for packed columns.)

3. If the noise level is still high, do a hydrogen leak test, described below.

4. If there are no leaks found, or leaks are found and repaired and the noise
level is still high, consult Valco.

Performing a Hydrogen Leak Test

A hydrogen leak test allows you to pinpoint loose fittings and leaks inside
the detector.

1. Connect a length of plastic tubing to a regulated hydrogen bottle.
Establish a flow of 5-10 ml/min.

19

2. Hold the hydrogen outlet tube at a fitting connection for ten seconds while
monitoring the baseline.

3. Tighten the fitting and test it again, repeating as necessary until every
connection has passed the ten second test.

4. If the current remains high, hold the hydrogen outlet close to the detector.

(Do not insert the tube into any detector holes.)

indicated, contact Valco.

NOTE: This method may also be used to test for leaks in other parts of the
system, but remember – a leak upstream from the column will not cause an
immediate baseline change. There must be time allowed for the hydrogen to
pass through the column.

If a leak in the detector is

20

Warranty

This Limited Warranty gives the Buyer specific legal rights, and a Buyer
may also have other rights that vary from state to state. For a period of 365
calendar days from the date of shipment, Valco Instruments Company, Inc.
(hereinafter Seller) warrants the goods to be free from defect in material
and workmanship to the original purchaser. During the warranty period,
Seller agrees to repair or replace defective and/or nonconforming goods or
parts without charge for material or labor, or, at the Seller’s option, demand
return of the goods and tender repayment of the price. Buyer’s exclusive
remedy is repair or replacement of defective and nonconforming goods, or,
at Seller’s option, the repayment of the price.

Seller excludes and disclaims any liability for lost profits, personal
injury, interruption of service, or for consequential incidental or
special damages arising out of, resuiting from, or relating in any
manner to these goods

This Limited Warranty does not cover defects, damage, or nonconformity
resulting from abuse, misuse, neglect, lack of reasonable care, modification,
or the attachment of improper devices to the goods. This Limited Warranty
does not cover expendable items. This warranty is VOID when repairs are
performed by a nonauthorized service center or representative. For infor­mation about authorized service centers or representatives, write Customer
Repairs, Valco Instruments Company, Inc, P.O. Box 55603, Houston, Texas
77255, or phone [phone]. At Seller’s option, repairs or replacements
will be made on site or at the factory. If repairs or replacements are to be
made at the factory, Buyer shall return the goods prepaid and bear all the
risks of loss until delivered to the factory. If Seller returns the goods, they
will be delivered prepaid and Seller will bear all risks of loss until delivery to
Buyer. Buyer and Seller agree that this Limited Warranty shall be governed
by and construed in accordance with the laws of the State of Texas.

The warranties contained in this agreement are in lieu of all
other warranties expressed or implied, including the warranties
of merchantability and fitness for a particular purpose.

This Limited Warranty supercedes all prior proposals or representations oral
or written and constitutes the entire understanding regarding the warranties
made by Seller to Buyer. This Limited Warranty may not be expanded or
modified except in writing signed by the parties hereto.

Detector Performance Log

21

In addition to the occasions indicated in the Comments area of the table below (see

Initial Power-Up

page 15), the standing current should be observed and logged after any system change. Logging
the standing current (with and without the column) on a regular basis is also an effective monitor of
system integrity (leaktightness and cleanliness). To check sensitivity continuity, we recommend
tracking the internal standard (quantity on column/area count). Additional log pages can be down­loaded from the support/manuals section of www.vici.com.

Detector Model: Serial Number: Date of purchase:

Date

Operator Column

D-4-I-SH14-R

Comments

temp

(°C)

Initial power-up (IPU) 100——

IPU, detector to analysis temp — —

IPU, column installed Ambient —

IPU, column to analysis temp —

Detector

temp

(°C)

Noise

level

Sample

Standing

current

(mV)

,