1
56
D. Liu et al.
For GC analysis, the toluene extracts were analyzed on
a Hewlett Packard 5890 gas chromatograph equipped with
a nitrogen±phosphorus detector (3008C) and a ¯ame ioniz-
ation detector (3008C) utilising an oven program with a
curic chloride. The possible mechanism involved in
the catalyzed hydrolysis of Irgarol 1051 is also dis-
cussed.
2
min hold at 808C and a temperature ramp of 108C/min
to 1508C followed by a temperature ramp of 48C/min to
808C and a ®nal temperature ramp of 88C/min to 3008C.
MATERIAL AND METHODS
2
The columns used were dual DB5 coated capillary col-
umns (0.25 mm 27 m) which had been installed into the
injector (2008C) in the splitless mode with a constant
helium carrier ¯ow of 0.8 ml/min.
For mass spectral analysis of the toluene extracts, the
work was performed via two GC-MS instruments. The
Chemicals
Irgarol 1051 [(2-methylthio-4-tert-butylamino-6-
cyclopropylamino-s-triazine), identi®cation No.
8
4611.0] of high grade (95%) was a gift of Ciba-
Geigy Canada, Mississauga, Ontario. All the test ®rst one used the same temperature program and column
stationary phase (0.25 mm 30 m) as the above GC analy-
inorganic and organic chemicals were obtained
sis on a Hewlett Packard 5971A mass selective detector
from BDH Chemicals (Toronto, Canada). The inor-
(
electron impact (EI) mode with an ionization potential of
70 eV and a source temperature of 1908C. The scan range
MSD) and MS Chem Station. The MSD was operated in
ganic salts used in the test experiments included
AgNO CdCl O, CuSO O, HgCl
PbCl and ZnCl
were obtained from Caledon Laboratories,
Georgetown, Ontario. The sodium sulphate used
for drying organic extracts was heated to 5008C for
3
,
2
Á2.5H
2
4
Á5H
2
2
,
. Pesticide grade organic solvents was 50±500 amu. The second GC-MS instrument was a
HP 5890 Series II, coupled to a Jeol GC Mate. The dual
2
2
columns used were HP-5MS (0.25 mm Â30 m), with a
temperature programming isothermally at 508C for 2 min,
then at 408C/min to 2008C and at 108C/min to 3008C.
For HPLC analysis, an Hitachi L7000 system equipped
with a Develosil ODS UG-5 column (2 Â 150 mm) and
photodiode array detector (225 nm) was used. The mobile
phases were 10 mM ammonium acetate (pH 4.6) and
MeCN, with a linear gradient increase of MeCN concen-
tration from 30 to 100%. The ¯ow rate was 0.2 ml/min
and the volume of sample injected was 10 ml. For LC-MS
analysis, an Hitachi M-1200H system equipped with
2
4 h before use. All glassware were also rinsed with
pesticide grade solvents before use. All other chemi-
cals used in the experiments were reagent grade or
better.
Experimental procedure
Hydrolysis of Irgarol 1051 was tracked by observing the
disappearance of the parent compound and the appear- Develosil ODS UG-5 column (4.6Â 150 mm) and photo-
ance of its degradation products in the reaction mixture. diode array detector (225 nm) was used. The mobile phase
The measurement was made by using HPLC (high per-
consisted of 50% ammonium acetate and 50% MeCN.
formance liquid chromatography), LC-MS (liquid chroma- The ¯ow rate was at 1.0 ml/min with the sample volume
tography mass spectrometry), GC (gas chromatograph), injected being 10 or 20 ml. The ionization was APCI (ato-
GC-MS (gas chromatography mass spectrometry) and UV mospheric pressure chemical ionization), with the aperture
(ultraviolet) spectrophotometric analysis. Typically, 5 mg
temperature at 1308C and the needle voltage at 3000 V.
of Irgarol 1051 in 1 l of distilled water or in buered sol-
ution (20 mM ammonium acetate±acetic acid±sodium hy-
The scan range was 10±500 amu.
Interactions between heavy metals and Irgarol 1051
droxide for pH 5.0, 7.0 and 9.0) was treated with HgCl
20 mg/l). The reaction mixture was kept at room tempera- Shimadzu model UV-260 double beam UV-VIS recording
2
were also studied spectrophotometrically using
a
(
ture (218C) for 2 h before analyzing for Irgarol 1051 and
its hydrolysis products.
spectrophotometer. An absorbance spectrum was typically
taken between 190 and 400 nm.
To study the eect of various heavy metals (in the salt
form) on the hydrolysis of Irgarol 1051, a ®nal concen-
tration of 10, 20 and 100 mg/l of AgNO Á2.5H
3
, CdCl
2
2
O,
, was each
RESULTS AND DISCUSSION
CuSO O, HgCl , MeHgCl, PbCl or ZnCl
2
4
Á5H
2
2
2
individually tested in the Irgarol solution (5 mg/l). To
assess the concentration eect of mercuric chloride on the
hydrolysis of Irgarol 1051, HgCl at ®nal concentrations
2
of 0, 0.1, 1, 10, 20 and 100 mg/l was used. Kinetic studies
of hydrolysis were conducted by removing an aliquot (50±
To exclude as much as possible the interference
among chemicals in the reaction mixture, distilled
water was used as the medium in which the eect
of pH on the stability of Irgarol 1051 was investi-
1
00 ml) of the reaction mixtures at dierent times (0, 1, 10 gated. Fresh distilled water was adjusted to pH
and 60 min, 2, 6, 24, 48 and 120 h). The percentages of values of 5.0, 7.0 and 9.0 with diluted acid (0.05 N
remaining Irgarol 1051 and the hydrolysis products
formed (mainly M1) were measured through GC, GC-MS,
cing Irgarol 1051 to the test solutions. Figure 1
HPLC and LC-MS analysis.
HCl) and/or base (0.05 N NaOH) prior to introdu-
shows that Irgarol 1051 was very stable in distilled
Sample preparation and chemical analysis
water at the acidic, neutral and alkaline pH tested
For the analysis of Irgarol 1051 and its degradation (5.0, 7.0, 9.0). No signi®cant change in Irgarol con-
products by GC or GC-MS, an aliquot (100 ml) of the
reaction mixture was transferred to a 500-ml separatory
tures during the 48-h test period, implying its
funnel containing 50 ml of DCM (dichloromethane). The
centrations was observed in all the reaction mix-
inherent stability in aqueous solution. Since the pH
extraction was repeated once with another 50 ml of DCM
and the combined DCM extracts with a toluene keeper for most natural waters ranges from
5 to 9
were reduced to 5 ml on a rotary evaporator. Further con- (Miyamoto et al., 1990), the continuous use of
centration and solvent exchange into toluene were per-
formed under a nitrogen stream. For analysis by HPLC or
result in its accumulation in the natural aquatic en-
LC-MS, the combined DCM extracts were evaporated to
dryness and then the residue was re-dissolved into 0.3 ml
of MeCN (acetonitrile).
Irgarol 1051 as an antifouling agent may eventually
vironment. Irgarol 1051 has been found to be
highly stable in the marine environment and has