Page 48 - Volume 1, Issue 2, July 2008

Liapis

et al.

100

PAHs (11). Volkers and Pouwels, on the oth-

er hand, have presented a method for de-

termination of PAHs in water samples by

high performance liquid chromatography

with a fluorescence detector (HPLC/FLD)

after an optimization of the solid phase

extraction procedures (12).

The European Union has established

parametric values (maximum acceptable

limits) only for 5 of the PAHs, according

to the directive 98/83/EC. For benzo [a]

pyrene this value is 0.01 μg/l, while for the

sum of benzo [b] fluoranthene, benzo [k]

fluoranthene, benzo [g,h,i] perylene and

indeno [1,2,3-cd] pyrene the respective

parametric value is 0.1 μg/l.

The aim of this study was to develop

and validate a robust method for the de-

termination of 8 PAHs (naphthalene, flu-

oranthene, anthracene, benzo [b] fluo-

ranthene, benzo [a] pyrene, benzo [k]

fluoranthene, benzo [g,h,i] perylene and

indeno [1,2,3-cd] pyrene) in water sam-

ples with GC/MS/MS, using 2 transitions

for each compound. It has to be men-

tioned that fluoranthene functions as an

indicator of the existence of PAHs in water

(3). The method has been used to moni-

tor presence of PAHs in ground and sur-

face water samples.

Materials and Methods

1. Chemicals and reagents

Analytical standards of benzo [b] flu-

oranthene (99%), benzo [k] fluoranthene

(98%), benzo [g,h,i] perylene (99,4%) and

indeno [1,2,3-cd] pyrene (99,5%) were pur-

chased from ChemService (West Chester,

UK). Naphthalene (99,5%), fluoranthene

(99%), benzo [a] pyrene (98,5%) and anthra-

cene (99,5%) were obtained from Dr Ehren-

stofer (Augsburg, Germany). Ethyl acetate,

methanol and acetone were of pesticide

residues grade and water of HPLC grade, all

obtained from Lab Scan (Dublin, Ireland).

2. Standard Solutions

Analytical standard stock solutions of

each compound at 1000 μg/l were made

in acetone and working standard solutions

were obtained at various concentrations

by dilution of the stock solution in eth-

yl acetate. All these solutions were stored

at -20

o

C. Three standard spiking solutions

containing all the compounds at the con-

centration of 0.05, 0.1 and 0.2 μg/ml were

used for the fortification purposes.

3. Sample procedure

The extraction procedure applied was

as previously described by Miliadis

et al.

(10) for the determination of pesticide res-

idues in water. Sample preparation was

performed by solid phase extraction with

pre-packed reversed-phase octadecyl

(C-18) bonded silica contained in cartridg-

es. Isolute cartridges (International Sor-

bent Technology), containing 500 mg of

packing material were conditioned prior

to loading the sample, by passing succes-

sively 1ml/100 mg sorbent (5 ml) ethyl ac-

etate, 5 ml methanol and 10 ml of organ-

ic free water, with a glass syringe. Volumes

of 500 ml of water sample were cleaned

by removal of any floating or insoluble

material and were passed through the

cartridge. A SPE large volume sampler was

connected to a vacuum source equipped

with a gauge and a balast valve to adjust

the vacuum, for the extraction of the sam-

ples in order to obtain a sampling rate of

15 ml water/ml. Teflon tubes were insert-

ed to the sample containers and adapt-

ers to the cartridges connected the other

ends. In this way, up to eight water sam-

ples could pass through cartridges simul-

taneously. After passing the sample, suc-

tion continued for 30 min to dry out the

packing material. The cartridges were dis-

connected and the adsorbed compounds

were eluted with ethyl acetate into 1 mL

volumetric flasks. The extract was then in-

jected to the GC/MS/MS system.