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Coupled LC-GC Interface Using a SPE Technique and a Large Volume
Injection Technique with a Spiral Insert

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A new interface using a solid phase extraction (SPE) technique and alarge volume injection technique has been developed for coupling ofreverse-phase liquid chromatography (LC) with capillary gas
chromatography (GC).
The system is shown in the following. With adding water to a LC
fraction, the diluted fraction is loaded on a SPE cartridge. By this means,the analyte is adsorbed on the SPE. After the cartridge was dried withnitrogen gas, the analyte is eluted from the SPE cartridge with a solventthat can be injected into GC. The eluate is directly injected into a GC
injection port via a needle that is fitted with the SPE cartridge. Next, theanalyte is transferred to an analytical column of GC by a large volume
injection technique. The GC injector consists of a PTV injector equippedwith a spiral insert in the shape of a stomach.
The purpose of this study is to decide optimum conditions of thevolume of water adding to the LC fraction in order to make an analyte
adsorb on the SPE cartridge and the volume of eluate in order to elutethe analyte from the SPE cartridge. And then, the precision of this LC(SPE)-GC system has been evaluated under these optimum conditions.
Coupling of reverse-phase LC with GC has been accomplished by a
new interface using the SPE technique to change the LC fraction eluent
into small amount of solvent that can be injected into GC and the stablelarge volume injection system with spiral insert.

Abstract Template
11/13/2004

ISCC28th

Coupled LC-GC Interface
Using a SPE Technique and a Large Volume
Injection Technique with a Spiral Insert
Saika Technological Institute Foundation (Japan)
Ryoichi Sasano, Nobby Shikama, Yutaka Nakanishi

28th International Symposium On Capillary Chromatography & Electrophoresis

Abstract• A new interface /using a solid phaseextraction (SPE) technique /and a large
volume injection technique /has beendeveloped/ for coupling of reverse-phaseliquid chromatography (LC)/ with capillarygas chromatography (GC).

1

ISCC28th

LC-GC System
RP-HPLC(polar)

GC(non-polar)

Selective cleanup of sample by LC!

High separation efficiency by GC!

High sample capacity and wide range of separation
performance of LC can be utilized in the selective cleanup ofsample. Analysis is done by GC with high separation efficiency.

The problem at issue• Volume of LC fraction is 0.3 to 1 mL. It is hard to inject allof this large volume eluate into GC.
• The LC fraction contains large volume of water or polar
solvent. This is no good for GC analysis.

SAIKA solution• We have used SPE technique as the interface between
LC and GC. Then we can transfer large volume solventof LC fraction into small volume of solvent to be
injected to GC.
• We have developed new Large Volume Injector withspiral insert and this has shown stable performance.

2ISCC28thLC-（SPE）-GC System
LC-GC Interface (SPE)

Pump

HPLC Column

UV

PTV
Injector
Autosampler

HPLC

GC/MS

LC-GC Interface
Valve 1

HPLC
ColumnSPE
Cartridge

Valve 2

NeedleUV

Waste Port

Syringe
Pump（Solvent）
Solvent）

Waste

Pump(Water)

N2 Gas3

ISCC28th

Diluting＆Concentrating
SPE
Cartridge
HPLC
ColumnNeedleUV

Waste Port

Pump(Water)With adding water to the LC fraction, the diluted fraction isloaded on the SPE cartridge.
The target compound is adsorbed on the SPE.

Dilution＆Concentration

SPE C18Cartridge
NeedleWaste Port

4

ISCC28thDrying

N2 GasThe SPE cartridge, the tube and the valve
are dried by flowing nitrogen gas.

Elution＆Injection

SyringePump（Solvent）
Solvent）

SPE
Cartridge

GC PTV Injector

The target compound is eluted from the SPE with a solvent and theeluate is directly injected into GC injector via the injection needle.

5

ISCC28th

Elution＆Injection

PTV Injector

Cleaning

SyringePump（Solvent）
Solvent）

The SPE cartridge and tube are cleaned with a solvent.

6

ISCC28thDrying

N2 GasThe SPE cartridge, tube and valve are dried
with flowing nitrogen gas again.

ConventionalInsert

Spiral Insert

7

ISCC28th

Injected sample can stay
as liquid in the insert.

New PTV Injector for GC
SeptumCarrier Gas Line

Septum Purge LineO-Ring

The injection system consisted of aprogrammed-temperature vaporizing
injector withSpiral Insert.
TubeHeater

HotAirTemp.
SensorO-RingGC OvenMulti-Injector
・Split, Splitless Injection
・Cold Split, Cold Splitless
Split Purge Line・On-column Injection
・Large Volume Injection
・Derivatizating
Derivatizating Injection
Capillary Column
・Interface of On-Line GC8

ISCC28th

Large Volume Injection Method
TargetSplit Purge

Splitless

MatrixSplit Purge

1st Stage

2nd Stage

3rd Stage

4th Stage

InjectingConcentrating

Transferring

Eliminating

Target compounds
are transferred tothe column at anelevated
temperature withthe splitless mode.

Matrix compounds
are eliminated fromthe insert at further
elevated injector
temperature withthe split mode.

The injector is kept at atemperature lower thanthe boiling point ofsample solvent.
The sample is injected
into the insert, and isstayed with liquid state.

While the evaporated
sample solvent isexhausted with thesplit mode, the sample
is concentrated in theinsert.

Over 100 µl sample can be injected in one injection.
Stable results independent of injection speed.

The Scheme of GC Conditions forLarge Volume Injection
Temperature
Injector Temperature

HighSolvent Boiling Point
Column Oven Temperature
Low

Split
1st stage
Injecting
Hexane40uL

Splitless2nd stage
3rd stage
Concentrating Transferring
0.4 min

Split

Time

4th stage
Eliminating

3〜5 min9ISCC28th

Purpose of this work
• To decide optimum condition of the flow rate of adding water
to the LC fraction in order to make an analyte adsorb on theSPE cartridge• To decide optimum condition of the volume of eluate in order
to elute the analyte from the SPE cartridge.
• Under these optimum conditions, the performance of this LC(SPE)-GC system has been evaluated by inspecting the datawith analyzing chlorpyrifos in foods.

LC-GC/MS Condition
HPLC (MIDAS;Spark, Agilent 1100)
Injection: 100 µL, Sample loop
Column: 3.0 mm i.d. ×100 mm
Inertsil ODS-3Solvents: A: Water
B: Acetonitrile
Flow rate 0.5 mL/min
Detector: UV 210 nm

Interface Injector (LVI-S200; EMINET)
Insert:Spiral Insert
Solvent Vent: 24 sec, Purge flow 150 mL/min
Splitless: 3 min
Inj. Temp.: 70ºC-120ºC/min-220ºC/min(3min)-50ºC/min-260ºC(10min)

GC/MS (QP-5050A; Shimadzu)
Column: 0.25 mm i.d.×30 m, 0.25 µm
Interface SPE（LGI-S100）
Inert Cap 5MS/Sil
SPE Cartridge: 2 mm i.d.×10 mm C18 Oven:
70ºC(3min)-20ºC/min-180ºCFraction Time: 11:40-12:60 (80 sec.)
10ºC/min-230ºC-20ºC/min-300ºC(3min)
Diluting: Water 0.5 mL/min
Carr. gas:He, 1 mL/min
Purge:
N2 gas, 1 min
MS:
SCAN;150-350 mz
Elution Solvent: 20%Acetone/Hexane
Elution Volume: 40 µL

10ISCC28thOptimum condition of the flow rate of adding water

Recovery ( % )100806040
2000.1

0.2

0.3

0.4

0.5

0.6

Flow rate (mL/min)Fig. Relationship between the flow rate ofadding water and the recovery ratio

Optimum condition of the elution volume

Recovery ( % )10080604020001020304050

Elution Volume (µL)

Fig. Relationship between elution volumeand recovery

11ISCC28th

Sample Preparation for LC-GC analysis of pesticides in foodSample 10g
CH3CN 20 mL

Homogenize
Filtration

SpinachGreen PepperCarrot

Green Onion

CH3CN 20 mL
Filtrate
Adj. to 50 mL with water

Extract solution
Take １mL of extract solution（equal to the 0.2g of sample）
90% CH3CN/water 0.5 mL
SPE C18 30mg （cleanup）
Effluent
Adj. to 2 mL with water

Sample solution

10 g portions of homogenized spinach were extractedwith 40 mL of acetonitrile. The extract solution wasadjusted to 50 mL with water.
Then 1 mL of the extract was cleaned up through an C18cartridge (30 mg) for avoiding HPLC column fromdeteriorating, and adjusted to 2 mL with water for LC(SPE)-GC/MS analysis.

LC-UV Chromatogram (Spinach)
mAU
35
30
25
20
15
10
500246810

1214 minTime (min)Fig. HPLC chromatogram of a spinach spiked with 0.1 µg/g ofchlorpyrifos (a) and a standard solution of it (b).
Marked fraction transferred to the SPE cartridge.

12ISCC28thLC-GC/MS Chromatogram (Spinach)
900e3

Chlorpyrifos

800e3

Intensity

700e3
600e3500e3
400e3
300e3
200e3
100e30e389101112131415161718Time (min)Fig. SCAN chromatogram of the LC-(SPE)-GC/MS analysis of aspinach spiked with 0.1 µg/g of chlorpyrifos

LC-GC/MS Chromatogram (ST)
900e3

Chlorpyrifos

800e3

Intensity

700e3
600e3
500e3
400e3
300e3
200e3
100e3
0e3

89101112131415161718Time (min)Fig. SCAN chromatogram of the LC-(SPE)-GC/MS analysis of aspinach spiked with 0.1 µg/g of chlorpyrifos

13ISCC28thLC-UV Chromatogram (Green Pepper)
mAU
3530252015105002468101214 min

Time (min)Fig. HPLC chromatogram of a green pepper spiked with 0.1µg/g of chlorpyrifos (a) and a standard solution of it (b).
Marked fraction transferred to the SPE cartridge.

LC-GC/MS Chromatogram (Green Pepper)
900e3

Chlorpyrifos

800e3

Intensity

700e3
600e3
500e3
400e3
300e3
200e3
100e3
0e3

89101112131415161718Time (min)Fig. SCAN chromatogram of the LC-(SPE)-GC/MS analysis of agreen pepper spiked with 0.1 µg/g of chlorpyriｆos

14

ISCC28th

LC-UV Chromatogram (Carrot)
mAU
3530252015105002468101214 min

Time (min)Fig. HPLC chromatogram of a carrot spiked with 0.1 µg/g ofchlorpyrifos (a) and a standard solution of it (b).
Marked fraction transferred to the SPE cartridge.

LC-GC/MS Chromatogram (Carrot)
900e3

Chlorpyrifos

800e3

Intensity

700e3
600e3
500e3
400e3
300e3
200e3
100e3
0e3

89101112131415

161718Time (min)Fig. SCAN chromatogram of the LC-(SPE)-GC/MS analysis of a
carrot spiked with 0.1 µg/g of chlorpyrifos

15

ISCC28th

LC-UV Chromatogram (Green Onion)
mAU
3530252015105002468101214 min

Time (min)Fig. HPLC chromatogram of a green onion spiked with 0.1µg/g of chlorpyrifos (a) and a standard solution of it (b).
Marked fraction transferred to the SPE cartridge.

LC-GC/MS Chromatogram (Green Onion)
900e3

Chlorpyrifos

800e3

Intensity

700e3
600e3
500e3
400e3
300e3
200e3
100e3
0e3

8910111213

1415161718

Time (min)Fig. SCAN chromatogram of the LC-(SPE)-GC/MS analysis of agreen onion spiked with 0.1 µg/g of chlorpyrifos

16ISCC28thConclusions
Coupling of reverse-phase LC with GC has been accomplished by a newinterface using SPE technique and a large volume injector with spiralinsert.
The SPE technique can transfer the LC fraction eluent into small amount ofsolvent that can be injected into GC.
The spiral insert makes it possible to accept all of the injected eluate fromthe SPE cartridge.
The LC-(SPE)-GC system we have developed provides the pesticide
residues analysis with very high efficiency and selectivity performance,
and then allows automated analysis of pesticide residues in food.

Thank you for your kind attention !!

sasano@saika.or.jp

17ISCC28th

LC-GC/MS SIM Chromatogram (Green Onion)
314.00 (1.00)

Fig. Ion chromatogramof the LC-(SPE)-GC/MS
analysis of a green onion
spiked with 0.1 µg/g ofchlorpyriphos

Intensity

50e3

Chlorpyrifos

40e3
30e3
20e3
10e3
0e3

910

11

12

13

14

15

16

1718Time (min)Fig. Mss spectrum ofthe peak

197

70e3
60e3

Intensity

314
50e3
40e3
258
30e3
125
210

20e3

288

109

10e3
121
0e3

100

125

169
163

142
150

244
180

175

276

224
200

225

250

275

294
300

349
325

350

m/z

18