Synthesis and characterization of a novel cross-linking complex of beta-cyclodextrin-o-vanillin benzoylhydrazone and its selective spectrofluorimetric determination of trace amounts of zinc.

Article abstract of DOI:10.1016/S1386-1425(03)00039-8

A novel host inclusion complex of beta-cyclodextrin-o-vanillin benzoylhydrazone (beta-CDP-OVBH) was prepared and characterized by IR and 1H-NMR spectra. A highly selective and sensitive fluorescent determination of trace amounts of zinc was proposed based on the reaction between Zn(2+) and beta-CDP-OVBH in sodium hydroxide-ammonium acetate buffer medium of pH 8.3. The molar ratio of beta-CDP-OVBH to Zn(2+) was 1:1.The maximum excitation and emission wavelengths were 396 and 486 nm, respectively. The linear range of this method was 2.5-500 microg l(-1) with a detection limit of 0.60 microg l(-1). The effect of interferences in the determination of zinc was investigated, the results showed that the host reagent had a quite high identifying capacity on Zn(2+). This method was successfully applied to the determination of trace amounts of Zn(2+) in tea and human hairs.

Full text of DOI:10.1016/S1386-1425(03)00039-8

Spectrochimica Acta Part A 59 (2003) 2519ꢀ2526
/
www.elsevier.com/locate/saa
Synthesis and characterization of a novel cross-linking complex
of b-cyclodextrin-o-vanillin benzoylhydrazone and its selective
spectrofluorimetric determination of trace amounts of zinc
Bo Tang *, Jie Zhang, Zhenzhen Chen
College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, China
Received 10 July 2002; accepted 11 November 2002
Abstract
A novel host inclusion complex of b-cyclodextrin-o-vanillin benzoylhydrazone (b-CDPꢀ
characterized by IR and 1H-NMR spectra. A highly selective and sensitive fluorescent determination of trace amounts
of zinc was proposed based on the reaction between Zn2ꢁ and b-CDPꢀ
OVBH in sodium hydroxideꢀammonium
acetate buffer medium of pH 8.3. The molar ratio of b-CDPꢀ
OVBH to Zn2ꢁ was 1:1.The maximum excitation and
/OVBH) was prepared and
/
/
/
emission wavelengths were 396 and 486 nm, respectively. The linear range of this method was 2.5ꢀ
500 mg lꢂ1 with a
/
detection limit of 0.60 mg lꢂ1. The effect of interferences in the determination of zinc was investigated, the results
showed that the host reagent had a quite high identifying capacity on Zn2ꢁ. This method was successfully applied to the
determination of trace amounts of Zn2ꢁ in tea and human hairs.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Host inclusion complex; b-Cyclodextrin-o-vanillin benzoylhydrazone; Spectrofluorimetry; Zinc determination
1. Introduction
[8,9]. The cross-linking complex of b-CD (b-CDP)
has advantage over b-CD in fold and identifying
capacity, and has a wide application foreground in
the field of molecule identification [10,11]. In this
paper, we synthesized the inclusion complex of b-
In recent years, aroylhydrazones which contain
the group ꢀ
/
CONHNÄ
/
CHꢀ have played more and
/
more important roles in determining metal ions as
fluorimetric reagents, but their development was
restricted because of their low sensitivity and
cyclodextrinꢀ
/
o-vanillin benzoylhydrazone (b-
CDPꢀOVBH), characterized its structure with IR
/
1
selectivity [1ꢀ/5]. With characteristic structures
and H-NMR spectra and studied the fluorescent
reaction of b-CDPꢀ
OVBH with Zn2ꢁ. The b-CD
cavity in the b-CDPꢀOVBH protected the single
/
[6,7], b-cyclodextrin (b-CD) has received much
attention as a fine natural host reagent nowadays
/
state molecule of the formative fluorescent com-
plex from the quenching of water and soluble
oxygen and improved the quanta yield. The steric
* Corresponding author. Fax: ꢁ
/
86-531-2962-643.
E-mail address: tangb@sdnu.edu.cn (B. Tang).
effect of b-CDPꢀ/OVBH made it difficult to fold
1386-1425/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S1386-1425(03)00039-8

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B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ2526
/
with big substance, so the selectivity was greatly
improved. In the determination of zinc with b-
2.2. Synthesis of host molecule reagent
CDPꢀ
/
OVBH, the linear range was 2.5ꢀ
/
500 mg lꢂ1
2.2.1. Preparation of b-CDP
with a detection limit of 0.60 mg lꢂ1. The effect of
interferences in the determination of zinc was
investigated; the results showed that the host
reagent has a quite high identifying capacity on
b-CD (10.50 g) was dissolved in 25.0 ml of
sodium hydroxide solution (35%), then 8.50 ml of
epichlorohydrin was added dropwise. The reaction
mixture was stirred and kept at 90 8C for 5 min.
After the solution was cooled to room temperature
and neutralized with 6.00 mol lꢂ1 of muriatic acid,
it turned into a transparent yellowish solution.
This solution was dialyzed with a dialysis bag
(molecular weight less than 3500) in order to
eliminate sodium chloride and remnant material.
The solution was concentrated to 50.0 ml. Twenty
five milliliters of the concentrated solution was
freeze-dried under low pressure, then 4.3 g of b-
CDP was obtained. The product decomposed at
240 8C. The average molecular weight of the
complex is 5300, measured by gelatin chromato-
gram. It could be concluded that there are four b-
CD cells in one complex molecule [18].
Zn2ꢁ. The determination of small guest ionꢀZn2ꢁ
/
with host reagent has advantage of high sensitivity,
good selectivity and stability over aroylhydrazones
[12ꢀ17]. To our knowledge, there is no paper
/
dealing with this inclusion complex, so the search
of the new pattern of host molecule reagent using
b-CDP as matrix has a better application fore-
ground.
2. Experimental
2.1. Instruments and reagents
All fluorescent measurements were carried out
Elmer (Norwalk, CT, USA) LS-50
2.2.2. Preparation of OVBH
on a Perkinꢀ
/
Benzoyl hydrazine (1.36 g) was added into 40.0
ml of ethanol, and the mixture was heated until it
was dissolved completely; 1.52 g of o-vanillin was
added into 20 ml of ethanol, then it was heated to
dissolve. The solution of o-vanillin was added into
the benzoyl hydrazine solution, then the mixture
was refluxed for 2.5 h, cooled and filtered under
reduced pressure. The precipitation was washed
with 10 ml of 70 8C ethanol for three times. Two
grams of yellowish acerous powder was obtained
with a yield of 86%. The melting point of the
spectrofluorimeter, equipped with a xenon lamp,
1.0 cm quartz cells, The slit widths of excitation
and emission were 5 and 3 nm, respectively. All pH
measurements were made with a pHS-3C digital
pH-meter (Shanghai Lei Ci Device Works Shang-
hai, China) with a combined glassꢀ
trode. Elemental analysis was obtained using a
PerkinꢀElmer 2400 elemental analyzer. IR spectra
Elmer
/calomel elec-
/
were recorded as KBr pellets on a Perkinꢀ
/
PE983 spectrometer. 1H-NMR spectra were re-
corded on a JEOL FX-90Q NMR spectrometer
using DMSO as solvent.
powder was 193ꢀ194 8C.
/
b-Cyclodextrin was purified by recrystallization;
a stock standard solution of zinc (100 mg lꢂ1) was
prepared from metal zinc; a buffer solution (pH
2.2.3. Preparation of host molecule (b-CDPꢀ
OVBH)
o-Vanillin benzoylhydrazone (0.20 g) was dis-
/
8.3) of sodium hydroxideꢀ
prepared; cross-linking complex of b-CDPꢀ
OVBH (5.0ꢃ
10ꢂ4mol lꢂ1) solution and OVBH
(2.0ꢃ
10ꢂ3mol lꢂ1) solution were prepared by
dissolving 0.2920 g of b-CDPꢀOVBH and 0.0540
g of OVBH (synthesized by ourselves) in 100 ml of
N,N-dimethylformamide, respectively. All chemi-
cals used were of analytical-reagent or higher
grade. De-ionized water was used throughout.
/
ammonium acetate was
solved in 10 ml of methanol, then 6 ml of
concentrated b-CDP solution was added. The
color of solution changed from yellowish to
yellow, and precipitation was observed simulta-
neously. The mixture solution was kept at 40 8C,
stirred for 30 min, cooled and filtered under
reduced pressure, then the precipitation was
washed with 10 ml of de-ionized water for three
times. After drying, 0.20 g of yellow-clubbed
/
/
/
/

B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ
/
2526
2521
crystal was obtained with a yield of 11%. The
melting point of the powder was 210ꢀ212 8C.
Table 2
The IR spectra of OVBH and b-CDPꢀ
/
OVBH (cmꢂ1
)
/
Compound
Band and group
OH
CÄ
2.2.4. Confirmation of host molecule reagent
ꢀ/
/
O
Arꢀ/O
CÄN
/
2.2.4.1. physical properties. The physical proper-
ties such as melting point, crystal shape and color
OVBH
3420, 3250
3450, 3269
1655 1245, 1295
1660 1250, 1300
1605
1608
b-CDPꢀOVBH
/
of OVBH and b-CDPꢀ
/
OVBH were listed in Table
1, which indicated a new reagent had been formed.
b-CDP, their chemicals shifts are little affected.
The result of H-NMR spectra showed that the
1
2.2.4.2. The IR spectra of OVBH and b-CDPꢀ
OVBH. The IR spectra showed that the wave
numbers of hydroxybenzene ꢀOH, CÄO, Arꢀ
and CÄ
N increased 30 cmꢂ1 (ꢀOH), 19 cmꢂ1 (ꢀ
OH), 5 cmꢂ1 (CÄO), 5 cmꢂ1 (ArꢀO), 5 cmꢂ1
(Arꢀ N), respectively (Table 2).
O) and 3 cmꢂ1 (CÄ
For hydroxybenzene ꢀOH and ArꢀO jointed with
/
double-host phenyl group of OVBH had entered
into hydrophobic cavity of b-CDP and a new host
reagent had been formed.
/
/
/
O
/
/
/
/
/
2.3. Spectrofluorimetric determination of zinc
/
/
/
/
Into a 10-ml color comparison tube were added
1.5 ml of buffer solution (pH 8.3), 1.0 ml of 1.0 mg
mlꢂ1 zinc standard solution, 5.0 ml of DMF and
benzene directly, the rich-electron cavity of b-CDP
increased the density of electron cloud and led to
the increment of wave number. While CÄ
/
N and
0.20 ml of 5.0ꢃ
2.0ꢃ
10ꢂ3 mol lꢂ1 OVBH or 5.0ꢃ
b-CDP and 2.0ꢃ
10ꢂ3 mol lꢂ1 OVBH),then it
/
10ꢂ4 mol lꢂ1 b-CDPꢀ
10ꢂ4 mol lꢂ1
/
OVBH (or
CÄO formed a conjugated system with benzene,
/
/
/
which led to the increment of the density of
electron cloud. The results of IR spectra showed
that the new host reagent had been formed.
/
was diluted to volume. The solution was mixed
thoroughly and equilibrated at room temperature
for 15 min, and then the fluorescent intensity was
2.2.4.3. The 1H-NMR spectra of OVBH and b-
1
OVBH. The H-NMR spectra showed that
measured at lex/em
blank. A calibration graph was prepared under the
ꢄ396/486 nm against a reagent
/
CDPꢀ
/
the chemical shift of phenyl group moved to a
higher field while the chemical shifts of ArꢀOH,
NꢀH, ArꢀOCH3, CHÄN groups were not chan-
same conditions for the determination of zinc.
/
/
/
/
ged (Table 3). The reason was that the rich-
electron cavity of b-CDP increased the density of
the electron cloud and as a result, the phenyl group
was shielded by the electrons, which caused the
resonance occur at relatively high field. On the
3. Results and discussion
3.1. Excitation and emission spectra
contrary, the groups of Arꢀ
/
OH, Nꢀ
/
H, Arꢀ
/
Under the selected condition, the maximum
excitation and emission wavelengths were 396 nm
and 486 nm respectively (Fig. 1). We found that
OCH3, CHÄN were located outside the cavity of
/
Table 1
changes of physical properties
the complex of b-CDPꢀ
strong fluorescent intensity, which indicated that
b-CDPꢀOVBH had a high signal-to-noise than
/
OVBHꢀ
/
Zn2ꢁ had very
/
Compound
Melting point
Crystal
shape
Color
OVBH in the determination of zinc. With the
driving force of hydrophobic interaction, van der
Waals force and hydrogen bond, the OVBH
molecule entered into the cross-linking b-CD
OVBH
b-CDP
193ꢀ
Decomposed at
240 8C
/
194 8C
Pine needle Yellowish
White
Powder
cavity and formed a supermolecule host reagentꢀ
b-CDPꢀOVBH. The b-CD cavity in b-CDPꢀ
OVBH offered a non-polar microenvironment,
/
b-CDPꢀ
/
210ꢀ/212 8C
Stick
Dark-
yellow
OVBH
/
/

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B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ2526
/
Fig. 1. (a) Excitation and (b) emission spectra 1 and 1? were the fluorescent spectra of b-CDPꢀ
and 2? were the fluorescent spectra of OVBHꢀ
Zn2ꢁ and blank, respectively; 3 and 3? were the fluorescent spectra of b-CDPꢁ
Zn2ꢁ and blank, respectively. The concentration of reagents were: 5.0ꢃ10ꢂ5 mol lꢂ1 of b-CDPꢀ 10ꢂ4 mol lꢂ1 of
OVBH; 2.0ꢃ
OVBH; 5ꢃ
10ꢂ5 molꢂ1 b-CDP; 100 mg lꢂ1 of Zn2ꢁ
/
OVBHꢀ
/
Zn2ꢁ and blank, respectively, 2
OVBHꢁ
/
/
/
/
/
/
/
.
the movement freedom of the formed fluorescent
complex molecule and the relaxation effect of the
water molecule were both greatly depressed, which
reduced the mutual collision of molecules and the
nonradiative transition. Furthermore, the b-CD
cavity could also protect the fluorescent single
into the cavity of b-CDP, so the rigidity and plane
of OVBHꢀ
Zn2ꢁ could not be well improved. In b-
CDPꢀOVBH, the steric effect made it difficult to
fold with big substance, hence, the smaller guest
(for example Zn2ꢁ) was easier to enter the cavity
[19], and the selectivity was greatly improved.
/
/
state molecule of b-CDPꢀ
/
OVBHꢀ
Zn2ꢁ from the
/
quenching of water and soluble oxygen. Two b-
CD cells of the b-CDP cooperate to fold two
phenyl rings of OVBH, which improved the
rigidity of the formed fluorescent complex.
3.2. Effect of pH
The pH of the medium had a great effect on the
/
fluorescent intensity of the b-CDPꢀ
/
OVBHꢀ
Zn2ꢁ
complex. The experimental results (Fig. 2(a))
showed that the optimum pH for the complex
If we simply added the same dosage of b-CDP
and OVBH into the reaction system rather than b-
CDPꢀOVBH, b-CDP could still offer a feasible
/
formation was 8.0ꢀ
chosen.
/
8.9. Therefore, a pH of 8.3 was
microcircumstance of weaker polarity and stron-
ger rigidity, so the quenching effect of water and
soluble oxygen on the fluorescent single state
molecule of OVBHꢀ
Zn2ꢁ was reduced, and the
fluorescent intensity was improved relative to the
/
3.3. Effect of amount of buffer solution
system without b-CDP. However, the steric effect
The influence of the amount of buffer solution
on the fluorescent intensities of the solutions
of b-CD restrained OVBHꢀ
/
Zn2ꢁ from entering
Table 3
The 1H-NMR spectra of OVBH and b-CDPꢀ
/
OVBH (d ppm)
Compound
Function group
ArꢀOH
/
Nꢀ
/
H
Phenyl
Arꢀ/OCH3
CHÄN
/
OVBH
12.03
12.01
11.01
10.99
6.86ꢀ
/
8.01
7.99
3.83
3.82
8.66
8.65
b-CDPꢀ
/OVBH
6.76ꢀ
/

B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ
/
2526
2523
Fig. 2. Effect of experimental variable on the fluorescent intensity of the b-CDPꢀ
/
OVBHꢀ
/
Zn2ꢁcomplex. The concentration of Zn2ꢁ
OVBH.
was 100 mg lꢂ1 in DMFꢀ
/
water (1ꢁ1 v/v) medium. (a) Effect of pH; and (b) effect of amount of b-CDPꢀ
/
/
containing 100 mg lꢂ1 of Zn2ꢁ and 1.0ꢃ
/
10ꢂ5 mol
studied under the conditions established above
(Fig. 2(b)). The fluorescent intensity increased
lꢂ1 of b-CDPꢀ
/
OVBH in DMF-water (1ꢁ
/
1
v/v) medium was studied. The fluorescent intensity
remained constant between 1.0 and 2.0 ml and
decreased slowly thereafter. Thus, 1.5 ml was
selected throughout the experimental work.
with the amount of b-CDPꢀ
ml, remained constant between 0.15 and 0.25 ml
and decreased slowly thereafter. suitable
amount of b-CDPꢀOVBH was advantageous to
form fluorescent complex, while superfluous b-
CDPꢀOVBH could absorb on the fluorescent
intensity of b-CDPꢀOVBHꢀ
Zn2ꢁ. Thus, 0.2 ml
of b-CDPꢀOVBH was selected throughout the
experiment.
/OVBH up to 0.15
A
/
/
3.4. Effect of organic solvent
/
/
/
The effect of organic solvent on the fluorescent
/
intensity of the Zn2ꢁ ꢀ
b-CDPꢀ/OVBH complex
was studied. Table 4 showed that the complex had
stronger fluorescent intensity in dimethylforma-
mide than any other organic solvent. The fluor-
escent intensity of the complex increased when the
dimethylformamide content increased from 1 to 5
ml and remained constant between 5 and 7 ml.
Therefore, 5 ml of dimethylformamide was se-
lected.
3.6. Effect of temperature and time
The influence of temperature was tested. The
experimental results showed that higher tempera-
ture increased the collision of molecules and
resulted in the declination of fluorescent intensity,
so the room temperature was selected. The fluor-
escent intensity reached a maximum after 15 min
and remained constant for at least 1 h, then
decreased slowly. Hence, all chelating reactions
were carried out for 15 min at room temperature.
3.5. Effect of amount of b-CDPꢀOVBH
/
The influence of the amount of b-CDPꢀ
/
OVBH
on the fluorescent intensity of the complex was
Table 4
Effect of organic solvent on fluorescent intensity (F) of the Zn2ꢁ ꢀ
/
b-CDPꢀOVBH complex and the reagent blank
/
F
Organic solventa
Methanol
Ethanol
Isopropanol
DMF
Acetone
Aether
Acetonitrile
Blank
Complex
16.7
68.4
14.2
55.6
20.4
55.2
9.5
79.3
15.0
57.7
5.9
24.8
12.6
50.6
a
The amount of every organic solvent was 5.0 ml.

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B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ2526
/
Fig. 3. Model structure of the complex.
We added different amounts of methanol,
ethanol and n-propylalcohol, respectively, into
the system of b-CDPꢀ
/
OVBHꢀ
Zn2ꢁ in order to
/
prove the formation of the complex (Fig. 4). The
fluorescent intensity declined obviously with the
increasing amounts of alcohol, the reason is that if
alcohol existed in the system, it is easier to form
complex with b-CDP than OVBH [21,22]. As a
result, superfluous alcohol inhabited the hydro-
phobic cavity of b-CD in b-CDP and drove more
OVBH molecules entering into water phase from
the cavity of b-CDP, and most OVBH molecules
had combined with Zn2ꢁ to form OVBHꢀZn2ꢁ
/
compound in water phrase. The water and soluble
oxygen have a quenching effect on the fluorescent
Fig. 4. Influence of alcohol on the fluorescent intensity of the
complex.
single state molecule of OVBHꢀ
Zn2ꢁ, which
would reduce the fluorescent quanta yield. The
/
3.7. Stoichiometry of the complex
Table 5
Effect of interferences on the spectrofluorimetric determination
The stoichiometry of the complex was studied
under the established experimental conditions by
the molar ratio and continuous variation methods.
Both of the methods showed that the composition
of the complex was 1:1. For the b-CD cavity is
hydrophobic, it would reduce the stability of the
complex if the guest has a greater polarity or
electric charge, so the neutral host molecule is the
best match to the b-CD cavity [20]. As prescribed
above, there are four b-CD cells in one b-CDP
molecule, so there are two OVBH molecules in one
host reagent molecule. It is easy to see that the
complex is neutral and stable for the composition
of the complex is 1:1. So we concluded the model
structure of the complex was as follows (Fig. 3).
of zinc (100 mg lꢂ1) (tolerable error 9
/
5%)
Tolerance ratio (m/m)
Interferences
ꢀ/
3000
2000
1000
700
500
250
100
20
SO42ꢂ, Iꢂ, NO3ꢂ, Fꢂ, NO2ꢂ
CO23ꢂ, PO34ꢂ
Mo(VI), SO23ꢂ, C2O24ꢂ, Hg2ꢁ
Mg2ꢁ
Cd2ꢁ, CH3COOꢂ
Ba2ꢁ
Citric acid, tartaric acid
Sr2ꢁ
10
5
MnO4ꢂ, Ca2ꢁ, Agꢁ
Cu2ꢁ, Co2ꢁ, Sn2ꢁ, Be2ꢁ, V(V)
Al3ꢁ, Fe3ꢁ
1

B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ
/
2526
2525
replacement capability was more remarkable with
the carbon chain lengthening of the linear ethanol.
The result proved the model structure of the
complex (Fig. 3) was reasonable.
From the table, we could conclude that the
selectivity and sensitivity of the determination of
Zn2ꢁ with b-CDPꢀ
greatly.
/
OVBH were both improved
3.8. Effect of interferences
4. Determination of zinc in tea and human hairs
samples
A systematic study of the interferences in the
determination of zinc (100 mg lꢂ1) was carried out
under the conditions established above. For this
study, various amounts of different interferences
were added by firstly testing a 3000-fold inter-
ference with zinc (m/m). If interference occurred,
the ratio was reduced gradually until the inter-
ference ceased. The criterion for interference was
A dry tea sample (0.5000 g) [GBW(E)080001]
was incinerated in porcelain crucible after clean-
ing, then it was charred at 1500 8C in a muffle for
2 h. After being cooled, four drops of 6 mol lꢂ1
muriatic acid were added. The solution was
adjusted to neutrality and transferred to a 100-ml
measuring flask and fixed to volume. Fifty milli-
liters of this tea solution was fetched and added 5 g
of ammonium chloride, 6 mol lꢂ1 of ammonia
fixed at a 95.0% variation of the average fluor-
/
escent intensity calculated for the established level
of Zn2ꢁ. The results are shown in Table 5. From
these results, we can see that the host reagent (b-
liquor was dropped up until the pH reached 8.0ꢀ
/
CDPꢀ
/
OVBH) has a better selectivity and finer
9.0, then it was filtered, the precipitation was
washed for three times with de-ionized water, the
washings were added into the filtrate, the mixture
solution was adjusted to neutrality and diluted to
250 ml.
An abluent hairs sample (0.2500 g)
(GBW07601) was put into a 100-ml beaker and
2.5 ml of nitric acid was added. The solution was
marinated for 1 night, then 0.25 ml of perchlor-
icacid was added. The mixture was heated slowly
until copious white fumes appeared. After being
cooled, 15 ml of de-ionized water was used to
dissolve the residue, and then the solution was
transferred into a 100-ml measuring flask and
fixed to volume. Twenty milliliters of this solution
identifying capacity on the small guestꢀ
/
Zn2ꢁ
.
Under the optimum experimental conditions,
there was a linear relationship between the fluor-
escent intensity and Zn2ꢁ concentration in the
range 2.5ꢀ
(r) of 0.9985. The regression equation was Fꢄ
0.642C (mg lꢂ1)ꢁ
1.409. The detection limit, as
/
500 mg lꢂ1 with a correlation coefficient
/
/
defined by IUPAC [23], was determined to be 0.60
mg lꢂ1. The relative standard deviation (Sr) was
2.1% obtained from a series of 11 standards each
containing 50 mg lꢂ1 of Zn2ꢁ
.
In Table 6 this new method characteristics were
compared with those of similar fluorescent meth-
ods for zinc determination reported previously.
Table 6
Comparison of the method characteristics reported in this paper with those published previously
Reagent
Linear range
(mg lꢂ1
Detection limit Major interferences
(mg lꢂ1
)
Ref.
[12]
)
1,2,4-Trihydroxyan-thraquinone
5-Br-salicyl fluorine
50ꢀ/500
2.31
4.0
Sn2ꢁ, Mg2ꢁ, EDTA, Al3ꢁ, La(III)
0ꢀ/400
Cu2ꢁ, Co2ꢁ, Ni2ꢁ, Fe3ꢁ, Pb2ꢁ, Cr(VI), V(V) [13]
5-Br-salicylaldehyde-salicyloylo-
hygrazone
2-Furaldehyde 2-pyridylhdrazone
0ꢀ/400
1.3
MnO4ꢂ, Cu2ꢁ, Co2ꢁ, Pb2ꢁ, Ni2ꢁ, EDTA
[14]
15ꢀ/120
15
Mn2ꢁ, Cu2ꢁ, Co2ꢁ, Pd2ꢁ, Cr3ꢁ, Mg2ꢁ
Ga3ꢁ, Bi3ꢁ, Co2ꢁ, Al3ꢁ, EDTA, EGTA
[15]
[16]
Pyrocatechol-1-aldehyde-2-pyridyl- 12ꢀ
/250
5.5
hydrazone
Thiophene-2-aldehyde-2-quinolyl-
hyarazone
20ꢀ
/
200
10
V(V), Ga3ꢁ, Sn2ꢁ, Agꢁ, Cu2ꢁ, Hg2ꢁ, Ni2ꢁ
Al3ꢁ, Fe3ꢁ
[17]
b-CDPꢀ
/
OVBH
2.5ꢀ
/
500 0.60
This work

2526
B. Tang et al. / Spectrochimica Acta Part A 59 (2003) 2519ꢀ2526
/
Table 7
Determination of zinc in tea and human hairs samples (Pꢄ0.95)
/
Sample
Standard value
(mg lꢂ1
Measured value
(mg lꢂ1), nꢄ
Zn2ꢁ added
Found
(mg lꢂ1
Recovery
(%)
)
/6
(mg lꢂ1
)
)
Human hairsa
Teab
38
22.6
37.59
/
0.4
5
10
5.22
9.78
104
22.390.3
/
97.8
a
GBW07601, Graduate School of Material Exploration, Department of Geology and Mineral Product (Langfang).
GBW (E)080001, Research Center of Environment of CAS (Beijing, China).
b
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was fetched and added 2 g of ammonium chloride,
6 mol lꢂ1 of ammonia liquor was added up until
Chem. 25 (6) (1997) 683.
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Analyst 123 (2) (1998) 283.
the pH reached 8.0ꢀ9.0, then it was filtered, the
/
precipitation was washed for three times with 10
ml of de-ionized water, the washings were added
into the filtrate, the mixture solution was adjusted
to neutrality and diluted to 250 ml.
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(1998) 9617.
To 1.0 ml of this prepared hairs sample solution
(or tea sample solution), various amounts of
standard zinc were added, which were then deter-
mined fluorimetrically by the method developed
above, the results were showed in Table 7.
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5. Conclusion
In this paper, we applied b-CDPꢀ
host molecule to determine Zn2ꢁ successfully. The
use of b-CDPꢀOVBH as a host molecule to
determine small guest has the advantage of high
sensitivity, good selectivity and stability. The
search of the new pattern of host molecule reagent
using b-CDP as matrix has a widely applying
foreground.
/OVBH as a
/
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Acknowledgements
Founding by the National Natural Science
Foundation of China (no. 29975016) and the
Main Nature Science Foundation of Shandong
Province in China (no. Z2000B03) are gratefully
acknowledged.
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