Original

Chromatography, Vol.24 No.2 (2003)

Original

Separation Studies of Transition Metal Ions with
Cationic Micellar Eluents in Normal PhaseThin−Layer Chromatography
Ali Mohammad*, Vineeta Agrawal and Nahed Jabeen
Analytical Research Laboratory, Department of Applied Chemistry Faculty of Engineering and Technology,
Aligarh Muslim University, Aligarh−202002, INDIA
Received November 11, 2002 Revised manuscript received March 10, 2003 Accepted March 11, 2003

SUMMARY
The analytical potential of surfactant−mediated mobile phase in thin layer chromatographic separation and identification of metal cations has
been investigated. Effects of (a) concentration of surfactant in the mobile phase, (b) acidity or basicity of surfactant−containing developer medium, and (c) the presence of electrolyte and non electrolyte additives in the mobile phase systems on the mobility of metal cations were examined. Better chromatographic performance of hybrid−mobile phase systems comprising of micelle (3% CTAB) −water−alcohol (methanol,
ethanol, propanol or butanol) over aqueous micellar mobile phase systems was observed. The thin layer chromatographic (TLC) system comprising silica gel G as stationary phase and 3% aqueous cetyltrimethylammonium bromide (CTAB) + propanol (80+20) as mobile phase was
identified as the most favourable for the separation of mixtures of Zn2+, Cd2+ and Hg2+. Semiquantitative determination of Zn2+, Cd2+ and Hg2+
by visual comparison of colour intensities on the TLC plates as well as by measurement of spot area was attempted. Identification of Zn2+,
Cd2+ and Hg2+ from river water, industrial wastewater and sulphide sludge with preliminary separation has been achieved. The method has
been successfully applied for identification of Hg, Zn and Cd in synthetic ores such as cinnabar (HgS), zinc blende (ZnS) and greenoekite(CdS). The dilution and detection limits of Zn2+, Cd2+ and Hg2+ on silica gel layers have also been evaluated.

popularity and wider applicability due to operational simplicity,

INTRODUCTION

cost effectiveness, relatively non−toxicity and enhanced separation

Over the years, thin layer chromatography (TLC) has become

efficiency [6−10].

a preferred analytical technique for the separation of closely related
inorganic species using aqueous (acidic, neutral and alkaline sol-

We recently reported [11−14] the chromatographic separation

vents) and mixed organic or aqueous−organic solvent systems asof inorganic species on silica gel and alumina layer, with surfactant

chromatographic eluents. It has been successfully utilized in the−mediated mobile phase systems. It was found that better separa-

analysis of wastewater for total heavy metal contents [1], charac-tion possibilities for cationic and anionic species were on silica gel

terization of hazardous wastes [2], estimation of toxic metals in in-

and alumina layers, respectively. As regards to the nature of surfac-

dustrial sewage [3] and the recovery of thiocyanate from photo-tant in the mobile phase, uncommon separation selectivity for cat-genic wastewater [4]. Incorporation of aqueous micellar solutions

ions was realized with cationic surfactant eluents. Conversely, elu-

pioneered by Armstrong and Terrill [5] as mobile phase systems

ents containing anionic surfactant were found most suitable for se-

has further accentuated the importance of TLC where simultaneous

lective separation of anionic species. In continuation of our earlier

separation of ionic or non−ionic species in a variety of matrices isstudies, we have used cetyl trimethylammonium bromide (CTAB),

required. Micellar liquid chromatography (MLC) where the con-a cationic surfactant as eluent to achieve rapid separation of coex-

centration of a surfactant in mobile phase is kept above the criticalisting Hg2+, Cd2+ and Zn2+ ions from aqueous solutions on silica

micelle concentration (CMC) of the surfactant has gained immense

layer. Simultaneous separation of Hg2+, Cd2+ and Zn2+ bears envi-*E−mail: mohammadali 4 u@rediffmail.com
vineeta_agrawal@yahoo.com―５５―Chromatography, Vol.24 No.2 (2003)

ronmental, biological and metallurgical importance because zinc isphase systems. The present work was therefore undertaken to util-

frequently associated with cadmium and one metal contain smallize the chromatographic performance of cationic surfactant in thequantities of the others with deleterious effects on performance. It

separation of heavy metal cations.

is therefore not surprising that several analytical techniques including ion−exchange chromatography [15], reversed−phase paper

EXPERIMENTAL

chromatography [16], solvent extraction [17] and TLC [11,18]
2+

Chemicals and Reagents: Silica gel ‘G’, sodium dodecyl sul-2+

have been used for the separation of Cd from Zn . However, none

fate (SDS), dimethylglyoxime, methanol, ethanol, propanol and bu-of these studies involve the use of surfactant−mediated mobile

tanol were of Qualigens, India; alumina, cetyltrimethylammonium

Mobile Phase
Table 1. List of solvent systems used as mobile phase
No.

SymbolComposition

(a)
(b)

M1
Aqueous surfactant solutions
M2
M 3a
M4
M5
M6
M7
M8
M9
Buffered micellar solutions
M 10
M 11
M 12
M 13
M 14
Aqueous micellar solutions with added NaCl
M 15
M 16
M 17
M 18
Aqueous micellar solution with added urea
M 19
M 20
M 21
M 22
Aqueous micellar solution with added alcohol
M 23
M 24
M 25
M 26
M 27
M 28
M 29b
M 30
M 31c
M 32
M 33

Water

(c)

(d)

(e)

(f)

1% aqueous CTAB
3% aqueous CTAB
5% aqueous CTAB
7% aqueous CTAB
1% aqueous SDS
3% aqueous SDS
5% aqueous SDS
7% aqueous SDS
3% CTAB in buffer solution of pH 2.3
3% CTAB in buffer solution of pH 4.0
3% CTAB in buffer solution of pH 5.7
3% CTAB in buffer solution of pH 9.0
3% CTAB in buffer solution of pH 11.9
3% aqueous CTAB containing 1 g NaCl per 100 mL
3% aqueous CTAB containing 5 g NaCl per 100 mL
3% aqueous CTAB containing 10 g NaCl per 100 mL
3% aqueous CTAB containing 15 g NaCl per 100 mL
3% aqueous CTAB containing 1 g urea per 100 mL
3% aqueous CTAB containing 5 g urea per 100 mL
3% aqueous CTAB containing 10 g urea per 100 mL
3% aqueous CTAB containing 15 g urea per 100 mL
3% aqueous CTAB + methanol (20+80)*
3% aqueous CTAB + methanol (50+50)
3% aqueous CTAB + methanol (80+20)
3% aqueous CTAB + ethanol (20+80)
3% aqueous CTAB + ethanol (50+50)
3% aqueous CTAB + ethanol (80+20)
3% aqueous CTAB + propanol (20+80)
3% aqueous CTAB + propanol (50+50)
3% aqueous CTAB + propanol (80+20)
3% aqueous CTAB + butanol (90+10)
3% aqueous CTAB + butanol (95+5)*Mobile phase proportions for multi−solvent systems are in parts by volumea) CMC = 0.46%, b) CMC = 0.34%, c) CMC = 0.36%―５６―Chromatography, Vol.24 No.2 (2003)

Nariyasu Mano, Naoki Asakawa and Junichi Goto

bromide (CTAB), potassium ferrocyanide, dithizone and 1,10−phe-were dried again and the spots of cations were visualized as col-nanthroline were of CDH, India. All other chemicals were also of

oured spots using the appropriate spraying reagent. RL (RF of theAnalytical Reagent grade.

leading edge) and RT (RF of trailing edge) values for the detected

Metal Ions Studied: Fe3+, Cu2+, Ni2+, Co2+, Cd2+, Zn2+, Ag+, Pb2+, Bi3+

spots were determined. RF values for metal ions were calculated by

and Hg2+.

use of the formula RF = (RL + RT) / 2.

Test Solutions: Chromatography was performed using standard

Separation: For the separation, equal amounts of metal ionsaqueous solutions (1%) of the chloride, nitrate or sulphate salts of

to be separated were mixed and 10 µL of the resultant mixture wasthe above mentioned metal ions.

spotted on the activated TLC plate which was then dried in air. The

3+

2+

Detection: Fe and Cu with 1% aqueous potassium ferrocyanide;plates were developed to a distance of 10 cm, the spots were de-Ni2+ and Co2+ with 1% solution of alcoholic dimethylglyoxime;

tected and the separated metal cations were identified on the basis

2+

2+

+

2+

3+

2+

of RF values.

Zn , Cd , Ag , Pb , Bi and Hg with 0.5% dithizone in CCl4

Limits of Detection: The limits of detection of metal cations

were detected.

were determined by spotting different amounts of metal ion on theStationary Phase: Silica gel ‘G’

TLC plates, developing the plates and detecting the spot. The
CHROMATOGRAPHY

method was repeated with successive lowering of the amount of(a) Preparation of TLC Plates: The TLC plates were preparedmetal ion until no spot was detected. The minimum amount detectable on the TLC plates was taken as the limit of detection.

by mixing silica gel with demineralized water in 1:3 ratio by
weight with constant shaking to obtain a homogeneous slurry.

Recovery of Cadmium by Spot−Area Method: To deter-

The resultant slurry was applied on the glass plates with themine recovery of cadmium by spot−area measurement method,

help of an applicator to give a 0.25 mm−thick layer. The

0.01 mL from a series of standard solutions of Cd2+ (0.5−2.5%)

plates were first dried at room temperature and then activatedwere spotted on silica layers. The plates were developed with M

at 100 ± 5℃ by heating in an electrically controlled oven for 1

31. After detection, the spots were copied onto tracing paper fromh. The activated plates were stored in a close chamber at room

the chromatoplates and then the area of each spot was calculated.

temperature until used.

The recovery of cadmium was studied by analyzing various sam-(b) Preparation of Spiked, Industrial Wastewater and River

ples spiked with Cd2+. For this purpose, experiments were per-Water: A 20 mL of industrial wastewater (pH, 2.97) collected

formed by spotting 0.01 mL of sample solution containing 100 µg

from lock industries, Aligarh, India or river water (pH, 7.48)

cadmium. The recovery of Cd2+ was 82 ± 2%.

obtained from Ganga river at Naraura, India or sea water (pH,8.47) obtained from Anjana beach, Goa, India was spiked

RESULTS AND DISCUSSION

with 100 µg each of Zn, Cd and Hg salts. About 20 mL of

The results of this study have been summarized in Tables 2−6

0.5% thioacetamide solution was added into spiked sample.

and Figures 1−2. The mobility of ten metal cations was examined

The resultant precipitate of Zn, Cd and Hg sulfides wason silica gel layer using aqueous solutions of SDS and CTAB. In

washed with distilled water, centrifuged and dissolved inorder to optimize the experimental conditions, effect of various fac-minimum possible volume of concentrated HCl. The acid wastors, such as (a) concentration of the surfactants, (b) acidity and ba-

completely dissolved in 5 mL of distilled water. An aliquot

sicity of the medium, (c) the presence of urea and NaCl in the sur-

(10 µL) of each sample was applied on TLC plate and chro-factant−containing mobile phase and (d) nature of the added al-

matography was performed as done for the standard samples.

kanols in the micellar mobile phase on the mobility of cations was(c) Preparation of Synthetic Ores: Cinnabar (HgS), zinc blende

examined.

(ZnS) and greenoekite (CdS) were synthetically prepared by(a) Effect of Concentration of Surfactants:

spiking 50 mL of distilled water (pH 5.6) with Zn, Cd and Hg

To understand the effect of concentration of cationic (CTAB)

salt solutions following the same procedure as describedor anionic (SDS) surfactant on the mobility of metal cations, chro-

above in (b).

matography was performed on silica layers using different concen-

Procedure: Test solutions (10 µL) were spotted on thin layer

trations of surfactant − mediated mobile phase systems (M 2−M 9)plates with the help of a micropipette about 2.0 cm above the lower

as developers. The RF values of metal cations obtained in pureedge of the TLC plates. The spots were dried in air and then plates

water (i.e., zero surfactant concentration, M 1) and in aqueous so-were developed with chosen mobile phase by one dimensional as-

lutions of CTAB and SDS at different concentration levels (M 2−cending technique in 24 x 6 cm glass jars. The development dis-M 9) are listed in Table 2. From the data listed in Table 2, follow-

tance was fixed to 10 cm in all cases. After development, the plates

ing conclusions may be drawn:―５７―

Chromatography, Vol.24 No.2 (2003)

Table 2. RF value of metal cations obtained on silica layers developed with pure water (M 1) and aqueous solutions of
CTAB (M 2−M 5) and SDS (M 6−M 9) at different concentration levels.

Table 3. Mobility of metal cation developed with buffered surfactant solutions of different pH values.
RF value
Metal ions
M 10

M 11

M 12

M 13

M 14

0.07
0.32
0.88
0.81
0.32, 0.69
0.12
0.08
0.05
0.32 T
0.88

0.10
0.22
0.85 T
0.85
0.85 T
0.04
0.05
0.05
0.40 T
0.95

0.11
0.05
0.85 T
0.85 T
0.79
0.07
0.05
0.05
0.30 T
0.96

0.07
0.15
0.86
0.86
0.82
0.16
0.07
0.05
0.20 T
0.95

0.10
0.02
0.82
0.75
0.89
0.11
0.10
0.09
0.35 T
0.96

RF value3+

Metal Ions

Water

CTAB

M1

M2

M3

M4

M5

M6

M7

M8

M9

Fe3+

0.10

0.05

0.06

0.07

0.10

0.06

0.05

0.02

0.05

Cu2+

0.10

0.07

0.27

0.32

0.37

0.05

0.07

0.07

0.10

2+

0.90

0.85 T 0.85 T 0.85 T 0.85 T

0.87

0.90

0.87 T 0.85 T

Co

2+

0.85

0.72

0.87

0.90

0.90

Cd

2+

0.40

0.45 T 0.63 T 0.80 T 0.85 T

0.45 T 0.80 T 0.82 T 0.82 T

2+

0.05

0.06

0.15

0.20 T 0.20

0.07

0.10

0.10

0.10

+

0.30 T

0.00

0.11

0.15 T 0.17 T

0.07

0.10

0.07

0.02

2+

0.02

0.02

0.07

0.10

0.02

0.05

0.00

0.02

Bi3+

0.04

0.07

0.12

0.15 T 0.16 T

0.15 T 0.15 T 0.15 T 0.10

Hg2+

0.02

0.95

0.95

0.95

0.33 T 0.65 T 0.65 T 0.64 T

Ni

Zn

Ag
Pb

0.72

Fe
Cu2+
Ni2+
Co2+
Cd2+
Zn2+
Ag+
Pb2+
Bi3+
Hg2+

SDS

0.77

0.80

0.15 T

0.85 T

3% CTAB solution prepared in borate−phosphate buffers of different pH values (pH = 2.3, 4.0, 5.7, 9.0 and 11.9). The results ob-

0.95

tained with the buffered surfactant solutions have been summarized

T = Tailed Spot (RL−RT>0.30)

in Table 3. The following conclusions may be drawn from these results:
2+

2+

2+

(1) In pure water, all metal ions except Ni , Co and Cd show

(1) Change in pH of mobile phase system had little effect on thelittle mobility and Ag+ was found to produce tailed spot. The

mobilities of Fe3+, Hg2+, Ag+, Zn2+, Bi3+ and Pb2+. Except Bi3+

higher mobility of Ni2+ (RF = 0.90) and Co2+ (RF = 0.85) facili-

and Hg2+, all these metal ions remained near the point of appli-

tates their separations from all other metal ions studied

cation (RF = 0.10) irrespective of the fact whether mobile2+

whereas the mid RF (RF = 0.40) of Cd opens opportunities

phase medium used was of acidic or basic in nature. Bi3+ pro-for its selective separation from multicomponent mixture of

duced tailed spots at all pH values and Hg2+ showed higher

metal cations.

mobility (RF = 0.88−0.96).

(2) When aqueous surfactant (SDS or CTAB) solutions at differ-(2) With strongly acidic mobile phase (M 10−M 11) Cu2+ showed

ent concentration levels (1, 3, 5 and 7%) were used as mobile

relatively higher mobility (RF, 0.32 at pH 2.3 and 0.22 at pH

3+

2+

3+

2+

+

phase, metal ions such as Fe , Pb , Bi , Zn and Ag stayed4.0) while it remained near the point of application withvery close to the point of application. Conversely, Ni2+ andweakly acidic (M 12) or alkaline (M 13−M 14) mobile phase2+

Co show higher mobility (RFsystems.

0.85).

(3) Metal ions such as Ni2+, Cd2+, Ag+ and Bi3+ show occasional(3) Cd2+ exhibited a peculiar behaviour as it gave double spots (RFtailing (RL−RT > 0.3) and their spots appear as elliptical exten-= 0.32, 0.69) with mobile phase M 10 (pH = 2.3), tailed spot

sion in the direction of solvent flow.

(RF = 0.85) with M 11 (pH = 4.0) and exceptionally well2+(4) Cu shows higher mobility in CTAB (M 3−M 5) compared toformed compact spots with relatively higher RF value with M

its mobility in SDS (M 6−M 9).

12 (RF = 0.79), M 13 (RF = 0.82) and M 14 (RF = 0.89).

2+(5) Cd produces badly tailed spots at all concentration levels of(4) Compact spots of Ni2+ and Co2+ were visualized in highly

surfactant irrespective of the nature of the surfactant (cationicacidic (M 10) or basic medium (M 13−M 14). However, whenor anionic).

the nature of the mobile phase was less acidic (pH = 4.0 or

2+(6) Hg shows higher mobility in the presence of cationic surfac-

5.7) both these metal ions gave elongated spots (RF = 0.85).

tant, but in case of SDS it produces tailed spot.

(c) Effect of Non−electrolyte and Electrolyte Additives:(7) 3% aqueous CTAB solution (M 3) was judged to be favour-

The effect of addition of urea (organic non electrolyte) andable for further studies as more compact spots for cations were

NaCl (inorganic electrolyte) at different concentration levels in therealized with this mobile phase system.

eluent M 3 (3% aqueous CTAB) on the mobility of metal ions was(b) Effect of Acidity and Basicity of the Medium:examined. The results obtained with NaCl added mobile phases (MThin layer chromatography of metal ions was performed using

15 − M 18) and urea added mobile phase systems (M 19−M 22) are―５８―

Chromatography, Vol.24 No.2 (2003)

Nariyasu Mano, Naoki Asakawa and Junichi Goto

50 or 80%) or butanol (5 or 10%) and 3% aqueous CTAB. In all

Table 4. Mobility of metal cations on 3% aqueous CTAB containing different concentrations of electrolyte and non−electrolyte additives

cases, a general trend of decreasing RF value with the increase inalcohol concentration was noticed. The representative’s plots are
given in Figures 1(a) and (b). The retention mechanism is con-RF
Metal Ions

NaCl added mobile phase

nected with the adsorption of surfactant on the surface of the sta-

Urea added mobile phasetionary phase. As long as the surface of the silica gel layer is satu-

M 15

M 16

M 17

M 18

M 19

M 20

M 21

M 22

Fe3+

0.05

0.06

0.06

0.06

0.05

0.07

0.05

0.05

Cu2+

0.22

0.27

0.20 T 0.20 T 0.22

0.22

0.22

0.27

Ni2+

0.92

0.92

0.90

0.92

0.85 T 0.84 T 0.85 T 0.85 T

Co2+

0.92

0.92

0.90

0.95

0.70

Cd2+

0.90

0.92

0.92

0.94

0.55 T 0.57 T 0.60 T 0.65 T

Zn2+

0.10

0.07

0.20 T 0.20 T 0.07

0.12

0.10

0.12

of solutes and a change in selectivity. Thus, in the presence of alco-

Ag+

0.00

0.06

0.25 T 0.37

0.10

0.10

0.06

0.11

hol the silica layers are not completely saturated by adsorbed sur-

Pb2+

0.07

0.22 T 0.87

0.65 T 0.05

0.04

0.02

0.02

Bi3+

factant and there are still free silanol groups, the interaction be-

0.06

0.09

0.12

0.15 T 0.06

0.05

0.10

0.12

Hg2+

0.92

0.92

0.90

0.90

0.92

0.95

0.90

0.92

0.77

0.80

rated by the adsorbed surfactant i.e., there are no more free silanolgroups on the layer for the interaction, metal ions move fastershowing higher RF value. The addition of alcohol to the mobile
phase leads to the reduction in the adsorbed amount of surfactant

0.82

on the stationary phase [19], which causes an increase in retention

tween them and the metal cations affects the retention pattern. In
these cases, the nature and the polarity of alcohol play an important

T = Tailed Spot (RL−RT>0.30)

role in the separation. In general, the better separation possibilities
were realized with mobile phase containing 20% propanol (M 31).

summarized in Table 4. From the available data, following trends

Successful separation of Zn2+, Cd2+ and Hg2+ can be achieved withare noticeable:

any of the mobile phase containing alcohols. However, mobile(1) The mobility of Fe3+ remained almost unaffected at all concentration levels of urea and NaCl. The mobility of Ag+ was
found to increase with the increase in NaCl concentration.
However, their mobilities in the presence of urea remained almost unchanged.
(2) Co2+ exhibited slight increase in mobility with the increase of
urea concentration in the mobile phase. However, the presenceof NaCl caused no effect on the mobility of this metal ion (RF(0.95).
(3) Ni2+ and Cd2+ produced tailed spots at all concentration levelsof urea in contrast to the formation of highly compact spots
with NaCl added mobile phases regardless of the NaCl concentration.
(d) Effect of Alkanols:
To investigate the retention of metal cations on silica layer,
hybrid−mobile phase systems comprising of micelle (3% CTAB) −water−alcohol (methanol, ethanol, propanol or butanol) were also
used and better chromatographic performance in terms of promotion of differential migration of metal ions by these mobile phases
over aqueous micellar mobile phase systems was observed. The
values of CMC determined for M 3 (3% aqueous CTAB), M 29
(3% aqueous CTAB + 80% propanol) and M 31 (3% aqueous
CTAB + 20% propanol) were 0.46%, 0.34% and 0.36% respectively. It shows that propanol decreases the CMC value of CTAB
from 0.46% to 0.34%. Hence, CTAB is present in the form of micelles. The RF values of metal cations were determined with mi-

Figure 1(a). Mobility of heavy metal cations on silica gel layers
developed with 3% aqueous CTAB containing different amounts of alcohols.

celle−water−alcohol mobile phases (M 23−M 33) consisting of
methanol (20, 50 or 80%), ethanol (20, 50 or 80%), propanol (20,―５９―Chromatography, Vol.24 No.2 (2003)

Table 5. Separation of coexisting Zn2+, Cd2+, and Hg2+ in the presence of inorganic and organic impurities.
Separation (RF)
Additives (1%)
NaCl
NaBr
NaNO3
HCOONaNaHCO3
NH4Cl
NH4Br
NH4NO3Oxalic acid
Citric acid
Tartaric acidUrea
L−arginine
L−valineL−tryptophan
L−methionine
L−serine
L−glutamic acid
Without additives

Zn2+

Cd2+

Hg2+

0.07
0.08
0.09
0.10
0.02
0.08
0.07
0.07
0.69
0.71
0.72
0.10
0.07
0.11
0.07
0.11
0.09
0.50
0.07

0.90
0.80
0.60
0.71
0.20 T
0.67
0.70
0.70
0.92
0.80
0.95
0.40
0.50
0.56
0.62
0.57
0.45
0.67
0.47

0.95
0.95
0.95
0.98
0.97
0.95
0.95
0.95
0.95
0.95
0.97
0.95
0.95
0.94
0.95
0.95
0.94
0.92
0.95

Stationary phase: silica gel
Mobile phase: M 31

Figure 1(b). Mobility of heavy metal cations on silica gel layers
developed with 3% aqueous CTAB containing different amounts of alcohols.

other mobile phase systems the separation of Cd2+ from Hg2+ ishampered. Conversely, its separation from Zn2+ is improved because of the enhanced mobility of Cd2+. This observation suggests

phase M 31 is most favourable. We successfully separated coexist2+

2+

2+

ing Zn , Cd and Hg on silica layer using M 31 as mobile phase.

that the presence of organic or inorganic impurities in water−mi-

2+

The RF values of the resolved spots were in the order Hg (0.95),

celle−alcohol hybrid mobile phase systems have serious adverse ef-

Cd2+ (0.47) and Zn2+ (0.07). Thus, moderately polar alcohol (e.gfects on chromatographic performance of micellar mobile phases inpropanol) provides superior separation of metal cations compared

regards to the separation of metal cations.
The lowest possible detectable microgram amount along withto more polar alcohol (e.g methanol).
It has been reported [20] that the microenvironment of micel-

dilution limit of metal cation (given in parenthesis) on silica gel

lar system is greatly influenced by the presence of added organic

layer were, Zn2+ (0.017, 1: 5.8 × 105), Cd2+ (0.50, 1: 2 × 104) andsubstance and inorganic electrolytes. To examine this aspect, inor-

Hg2+ (0.05, 1 : 2 × 105).

ganic (NaCl, NaBr, NaNO3, HCOONa, NaHCO3, NH4Cl, NH4Br
Semiquantitative estimation of Cd2+

and NH4NO3) and organic (oxalic, citric, tartaric acid, urea, L−arginine, L−valine, L−tryptophan, L−methionine, L−serine and L−

An attempt has been made to determine the recovery of cad-

glutamic acid) impurities were added in M 31 to obtain mobile

mium spiked into water using spot−area measurement method. A

phase systems containing 1% of each foreign substance. The resul-

linear relationship obtained when the amount of sample spottedtant mobile phase systems were used to examine the effect of im-

was plotted against area of the spot follows the empirical equation2+2+

purities in the eluent on simultaneous separation of Zn , Cd andζ = km, where ζ is the area of the spot, m is the amount of the sol-

Hg2+. The results presented in Table 5 clearly demonstrate that mu-

ute and k is a constant. Representative plot for Cd2+ has been shown

tual separation of Zn2+, Cd2+ and Hg2+ could not be achieved within Figure 2. The linearity is maintained upto 250 µg /spot. At

mobile phases containing 1% citric, oxalic or tartaric acid because

higher concentration a positive deviation from linear law was ob-

2+

2+

2+

served. The accuracy and precision was around ± 12%.

of the co−migration of Zn and Cd with Hg . Similarly, with

―６０―

Chromatography, Vol.24 No.2 (2003)

Nariyasu Mano, Naoki Asakawa and Junichi Goto

REFERENCES[1]

Volynets, M. P. ; Kitaeva, L. P. ; Timerbaev, A. P. Zh. Anal.
Khim, 1986, 41, 1989−1995.

[2]

Stephenes, R. D. ; Chan, J. J. in J. C. Touchstone and D.
Rogers (eds.) Thin−layer chromatography: Quantitative Environmental and Clinical Applications, Wiley, New York p.
363 (1980).

[3]

Thielemann, H. Acta Hydrochem. Hydrobio., 1977, 5, 191−

[4]

Mohammad, A. ; Khan, M. A. Indian J. Environ. Hlth.,[5]

Armstrong, D. W. ; Terrill R. Q. Anal. Chem., 1979, 51,[6]

Borgerding, M. F. ; Williams (Jr.), R. L. ; Hinze, W. L. ;193.
1996, 38, 100−104.
2160−2163.

Figure 2. Calibration curve for semiquantitative determination of
Cd2+
Stationary phase: silica gel
Mobile phase: M 31

Quina, J. Liq. Chromatogr., 1989, 12, 1367−1406.
[7]

Kord, A. S. ; Khaledi, M. G. Anal. Chem., 1992, 64, 1901−
1907.

[8]

Table 6. Recovery and separation of coexisting Zn2+, Cd2+ and Hg2+
ions from spiked water and synthetically prepared metalores and heavy metal sludge samples

Szymanski, A. ; Szczepaniak, W. Chem. Anal . (Warsaw),
1998, 43, 346−349.

[9]Khaledi, M. G. ; Strasters, J. K. ; Rodgers, A. H. ; Breyer, E.
D. Anal. Chem., 1990, 62, 130−136.

RF
Spiked/Synthetic Samples
River water
Sea Water
SulfidesDistilled water2+2+[10] Walker, T. A. J. Liq. Chromatogr., 1996, 19, 1715−1727.
[11] Mohammad, A. ; Agrawal, V. J. Planar Chromatogr. Mod.

2+

Zn

Cd

Hg

0.05
0.03
0.14
0.07

0.46
0.46
0.56
0.47

0.95
0.95
0.96
0.95

−TLC , 2000, 13, 210−216.
[12] Shtykov, S. N. ; Sumina, E. G. ; Tyurina, N. V. C. J. Planar
Chromatogr. −Mod. TLC , 2000, 13, 266−270[13] Mohammad, A. ; Syed, S. ; Sharma, L. M. ; Syed, A. A.
Acta Chromatographia, 2001, 11, 183−195.

Stationaly phase: sillca gel
Mobile phase: M 31

[14] Mohammad, A. ; Sirwal, Y. H. J. Planar Chromatogr. −Mod TLC , 2001, 15, 107−115.
[15] Dingmi, S. ; Suya, L. ; Taohui, L. Fenxi Huaxue, 1984, 12,934; C. A., 1985, 102, 7195 V.

Application:[16] Yeole, C. G. ; Shinde, V. M., Analyst., 1983, 104, 1102−

The proposed method was applied for identification of zinc,1107.

cadmium and mercury in spiked industrial wastewater, river andsea water samples as well as in metal sulphide ores after separation[17] Yoshiaki, S. Anal. Chem. Acta, 1981, 127, 209−212.

on silica layer. The results listed in Table 6 clearly demonstrate that[18] Mohammad, A. ; Fatima, N. Chromatographia, 1987, 23,653−655.

Hg, Cd and Zn which are spiked in the various samples can be re-[19] Dorsey, J. G. ; De Etchegaray, M. T. ; Landy, J. S. Anal.

covered and separated on silica TLC plates developed with M 31.

Chem., 1983, 55, 924−928[20] Borgerding, M. F. ; Hinze, W. L. Anal. Chem., 1985, 57,

Acknowledgment:

2183−2190.

The authors thank the chairman, Department of Applied
Chemistry and CSIR (New Delhi, India) for providing research facilities and financial respectively.

―６１―