Analysis of Volatile Halogenated and

Aromatic Hydrocarbons and

Organophosphorus Pesticides in Water

with a Versatile Agilent 7890B Gas

Chromatography System and an Agilent

7697A Headspace Sampler

Authors

Chunxiao Wang

Agilent Technologies (Shanghai) Co Ltd.

412 YingLun Road

Waigaoqiao Free Trade Zone

Shanghai 200131

P.R. China

Jingqiang Zhang, and ShunNa

Agilent Technologies (China) Co Ltd.

5F, 18F Citic Plaza ShenHong Square

No. 1350 North Sichuan Road

Hongkou District, Shanghai 200080

P.R. China

Application Note

Environmental

Abstract

An Agilent 7890B GC system configured with three detectors: (1) ECD (Electron cap-

ture detector), (2) FID (Flame ionization detector), and (3) FPD (Flame Photometric

Detector) was used for the analysis of volatile halogenated and aromatic hydrocar-

bons and organophosphorus pesticides in water. The headspace sampler (HS) vial

temperature and time for sample equilibration were optimized, allowing simultane-

ous analysis of aromatic and halogenated hydrocarbons with FID and ECD in one HS

injection. The FPD channel with automated liquid sampler (ALS) was used for

organophosphorus pesticides analysis. The repeatability was generally better than

2.0% RSD for each aromatic and halogenated hydrocarbons. The repeatability and

recovery range for organophosphorus pesticides are 1.45–2.74% and 90.4–98.8%,

respectively.

Introduction

Volatile halogenated and aromatic hydrocarbons as well as

organophosphorus pesticides have a variety of harmful health

effects. The U.S. Environmental Protection Agency (EPA) esti-

mates that volatile organic compounds are present in

one-fifth of the nation's water supplies. They can enter

ground water from a variety of sources. Benzene, for example,

may enter ground water from gasoline or oil spills on the

ground surface or from leaking underground fuel tanks.

Usually, a large number of samples need to be processed rou-

tinely, and therefore, a high degree of automation is required

with minimal sample prep for cost reduction Static HS/GC is

well suited and widely used for volatile halogenated and

aromatic hydrocarbon determinations. The FPD performs well

for trace organophosphorus pesticide analysis. Therefore, a

7890B GC system with three channels (ECD, FID, and FPD)

forms a versatile system suited for routine analysis of volatile

aromatic and halogenated hydrocarbons and

organophosphorus pesticides in water.

Experimental

Figure 1 shows a 7890B GC system configured with FID, ECD,

and FPD.

Table 1. Typical GC Conditions

Agilent 7697A

Headspace

Sampler

Inlet

Splitter

Column 3

Column 1

Column 2

FPD

FID

ECD

Figure 1. Agilent 7890B GC three channel configuration.

(1) FID channel with HS: for aromatic hydrocarbons

(2) ECD channel with HS: for halogenated hydrocarbons

(3) FPD channel with ALS: for organophosphorus pesticides

Volatile aromatic and halogenated organic compounds method

Agilent 7890B GC

Inlet Split/Splitless

Temperature: 150 °C

Split vent: 50 mL/min

Column Column 1: 19091s-413UI, HP-5 MS UI,

30 m × 0.32 mm, 1 µm

Column 2: 123-3234, DB FFAP,

30 m × 0.32 mm, 1 µm

Carrier gas N

at 2.5 mL/min constant flow

Oven temperature 40 °C (2 minutes) to 120 °C at 6 °C/min

Detector ECD: Temperature: 320 °C,

Makeup: N

at 30 mL/min

FID: Temperature: 200 °C,

/Air: 40 mL/min/400 mL/min

Agilent 7890B GC7697A Headspace Sampler

20-mL vials

Temperature HS oven: 70 °C

Valve/loop: 70 °C

Transfer line: 100 °C

Time Vial equilibration

time: 40 minutes

Inject time: 0.5 minutes

Vial sampling

parameters

Vial pressurize

value: 15 psi

Vial final sampling

pressure: 10 psi

Loop size: 1 mL

Organic phosphorus method

Inlet Split/Splitless

Temperature: 230 °C

Splitless mode, 30 mL/purge flow at 0.75 minutes

Sample size 1 µL

Column DB-1701, 30 m × 0.25 mm, 1 µm

Carrier gas N

at 1 mL/min constant flow

Oven temperature 100 °C to 170 °C at 25 °C/min to 210 °C (1 minute)

at 15 °C/min to 220 °C at 10 °C/min to 240 °C

(5 minutes) at 15 °C/min

Detector FPD Plus

Temperature: 270 °C

Emission block: 150 °C