Separation and Identification of Some Metal Cations by TLC using Mixture of urea Formaldehyde Polymer and Starch as a Stationary Phase.

Vijay S. Nagpurkar*, Dr. Lata Deshmukh¹, Dr. l.J. Paliwal²

¹Post Graduate Department of Chemistry, Hislop College, Civil Lines, Temple Road, Nagpur-440001(M.S.) India.

²Department of Chemistry, Mahatma Jyotiba Phule Educational Campus, Rashtrasant Tukdoji Maharaj Nagpur University Campus, Nagpur-440033(M.S.) India.

*Corresponding Author E-mail: Vijay_17nagpurkar@yahoo.co.in

ABSTRACT:

The chromatographic behaviour of eight metal ions has been studied on mixture of laboratory prepared Urea formaldehyde and Starch as adsorbent layers using acidic and organic mobile phase. Starch and Urea formaldehyde are found to be more effective for the binary and ternary separation of metal cations. The effect of mobile phases were also studied on the retention behaviour of metal cations on various mixture of urea formaldehyde and starch as adsorbent layers.

KEYWORDS: Urea Formaldehyde, Starch, Dimethylamine Formic acid, Chromatography, Separation.

INTRODUCTION:

Thin layer chromatography (TLC) is considered to be superior to other chromatographic techniques, because of simplicity and relatively low cost. Success in TLC depends to great extent upon proper selection of the mobile phase. The separation possibilities in TLC are greatly enhanced when chromatoplates are developed with mixed solvent system. TLC has been successfully utilized for various purpose, such as the separation of metal ions from water sample[1], the characterization of the mobility of metal[2], and the estimation of concentration of toxic metal in industrial waste[3]. The use of aqueous surfactants solution as mobile phase in TLC was pioneered by Armstrong and Terrill[4]. Using a surfactant as mobile phase gained popularity and became more widely applied due to its operational simplicity, cost effectiveness, relative non-toxicity and enhanced separation efficiency [5-7]. The use of silica gel and alumina layer with surfactant-mediated mobile phase systems[8-13] has been used to separate various organic species. Number of metal ions were systematically chromatographed on thin layer of urea formaldehyde polymer which is already used for the separation of amino acid [14].

In continuation of our earlier studies, we have used urea formaldehyde polymer as a stationary phase to achieve rapid separation of various metal cations by using different aqueous and organic solutions as a mobile phase. Starches are very popular in pharmaceutical industry in which they are used as binders and disintegrates in tableting. Several non pharmaceutical starches have been investigated as tableting excipients with positive results [15-20]. Most of the commonly used adsorbents may not be easy to produce locally but starch which is very common product can be made readily available hence this research aimed at investigating the suitability of starches as adsorbents for thin layer chromatography.

METHODS:

Reagents:

Urea, formaldehyde solution and starch were obtained from Merck. Dimethylglyoxime, dithizone, potassium ferrocynide, formic acid, silver nitrate, dimethylamine, methanol, acetone, HCl and NaOH were obtained from SD Fine (India). All other chemicals were of analytical reagent grade.

Test solution:

TLC was performed using a standard aqueous solution (1% solution) of the choride, nitrate, potassium or sulphate salts of the metal ions listed.

Detection:

Fe³⁺, Cu²⁺, U⁶⁺,V⁵⁺ were detected using 1% aqueous potassium ferrocynide, Co²⁺ and Ni²⁺ were detected using a 1% solution of alcoholic dimethyloxime , Ag⁺ was detected by 0.5% of dithizone in carbon tetrachloride and Cr⁶⁺ was detected by using saturated solution of alcoholic silver nitrate.

Stationary phase:

Mixture of urea formaldehyde powder and starch powder was used as stationary phase system.

Mobile phase:

Various solvent systems used are found in Table 1.

Thin-layer chromatography:

Procedure:

Test solutions were spotted onto thin layer plates positioned about 1.0 cm above the lower edge of the TLC plates. The spots were air dried and the plates were then developed with the given mobile phase using the one dimensional ascending technique in the glass jars. The development distance was fixed at 10cm in all cases. Following development, the plates were again air dried and the spots of cations were visualized as colouring spots using the appropriate spraying reagent. R_f values were then calculated.

Separation:

For the separation, the metal ions to be separated were mixed in equal amounts. A test solution of resultant mixture was spotted onto the TLC plates, and was then air dried. The plates were developed to a distance of 10 cm. The spots were detected and the separated metal cations were identified by their R_f values.

Limit of detection:

The limit of detection of the metal cations were determined by spotting different amounts of metal ion onto the TLC plates, developing the plates using the method describe above, and then detecting the spots. This method was repeated with successive decrease in the amount of metal ions used until spots were not detected. The minimum detectable amount on the TLC plates was taken as limit of detection.

Semi- quantitative determination by spot-area measurement:

For the semi-quantitative determination by spot-area measurement method, 0.01 ml volume from series of standard solution containing 50 μg/lit -300 μg/lit of Cr⁶⁺ was spotted on thin layer plates. The plates were developed with S₁₂ mobile phase. After detection , the spots copied on to tracing paper from the chromatoplates and then the area of each was calculated. The recovery Cr⁶⁺ was studied by analyzing various samples.

Table 1: List of solvent systems used as mobile phase.

Sr.No.	Symbol	Composition
1	S1	Water
2	S2	1% Formic acid
3	S3	Methanol
4	S4	Acetone
5	S5	Dimethylamine(DMA)
6	S6	1% Formic Acid:Water(2:8)(V/V),pH=3
7	S7	Methanol:Water(2:8)(V/V) ,pH=3
8	S8	Acetone :Water(2:8)(V/V) ,pH=3
9	S9	DMA:Water(2:8)(V/V),pH=3
10	S10	Methanol:DMA(8:2)(V/V),pH=3
11	S11	Methanol:1%Formic acid(8:2)(V/V),pH=3
12	S12	Methanol:1%Formic acid:DMA(8:2:2) (V/V), pH=3
13	S13	Methanol:1%Formic acid:DMA(8:2:4) (V/V) ,pH=3
14	S14	Methanol:1%Formic acid:DMA(8:2:8) (V/V), pH=3
15	S15	Acetone :1%Formic Acid(8:2)(V/V) ,pH=3
16	S16	Acetone:DMA(8:2)(V/V) ,pH=3
17	S17	Acetone:1%Formic acid:DMA(8:2:2), pH=3
18	S18	Acetone:1%Formic acid:DMA(8:2:4) ,pH=3
19	S19	Acetone:%Formic acid:DMA(8:2:8),pH=3
20	S20	Dimethylaniline(DMAL),pH=3
21	S21	Methanol:1%Formic acid:DMAL(8:2:2) (V/V) ,pH=3
22	S22	Methanol:1%Formic acid:DMAL(8:2:4) (V/V),pH=3
23	S23	Methanol:1%Formic acid:DMAL(8:2:8) (V/V), pH=3

RESULT AND DISCUSSION:

The results of this study have been summarized from Table 2 to Table 4 . The mobility of eight cations was examined on mixture of urea formaldehyde and starch layer using different solvent system given in Table 1. In order to optimize the experimental conditions, effect of various factors such as different concentrations of solvent systems, pH of solutions and time required to flow mobile phase with the mobility of cations was examined .

Table 2: Mobility (as R_f value) of heavy metal ions on thin layer of mixture of urea formaldehyde and starch developed with single component mobile phases (S₁-S₅).

Sr. No.	Metal Cations	Rf value
		Time 5 Minuit
		S1	S2	S3	S4	S5
1	Fe^3+	0.90	0.96	0.84	0.00	0.00
2	Cu^2+	0.62	0.93	0.82	0.09	0.05
3	U^6+	0.55	0.50	0.55	0.12	0.00
4	V^5+	0.96	0.00	0.00	0.38	0.00
5	Ni^2+	0.90^a	0.90^a	0.88^a	0.00	0.00
6	Co^2+	0.88	0.93	0.89	0.07	0.00
7	Ag^+	0.00	0.00	0.00	0.00	0.00
8	Cr^6+	0.59^b	0.54^b	0.45^b	0.50^b	0.48^b

^a. Detection clarity is poor

^b. Double spot

^c Tailed spot

The mobility of metal cations chromatographed with water (S₁) and single component organic mobile phases (S₂-S₅) have been summarized in Table 2. It is clear from the table that water induce the migration of all metal cations except Ag⁺. Similarly Formic acid and Methanol induce migration of all metal cations except V⁵⁺ and Ag⁺. Acetone also shows mobility of most of metal cations except Fe³⁺, Ni²⁺ and Ag⁺. DMA induce the migration of Cr⁶⁺only. Use of pure DMA as mobile phase resulted in the formation of double spots Cr^6+.

Table 3: Mobility (as R_f value) of heavy metal ions on thin layer of mixture of urea formaldehyde and starch developed with two component aqueous organic mobile phases (S₆-S₉), two component mixed organic mobile phases (S₁₀ and S₁₁) and aqueous –organic mobile phases containing different concentrations of DMA and fixed concentration of formic acid and organic modifier(S₁₂-S₁₄). .

Sr. No.	Metal Cations	Time 5 Minute pH=3
		Rf value
		S6	S7	S8	S9	S10	S11	S12	S13	S14
1	Fe^3+	0.89	0.70	0.76	0.00	0.70	0.82	0.73	0.90	0.93
2	Cu^2+	0.95	0.62	0.69	0.30	0.00	0.87	0.74	0.00	0.00
3	U^6+	0.60	0.56	0.63	0.00	0.60	0.5^c	0.65	0.00	0.00
4	V^5+	0.92	0.90	0.93	0.00	0.00	0.23	0.75	0.00	0.00
5	Ni^2+	0.96	0.86^a	0.90	0.00	0.00	0.00	0.89	0.00	0.00
6	Co^2+	0.67	0.88	0.88^a	0.00	0.93^a	0.65	0.95^a	0.90^a	0.86^a
7	Ag^+	0.76	0.50^c	0.55^c	0.46^c	0.00	0.46^c	0.00	0.00	0.00
8	Cr^6+	0.45^b	0.52^b	0.59^b	0.50^b	0.59^b	0.48^b	0.55^b	0.60^b	0.64^b

^a Detection clarity is poor

^b Double spot

^c Tailed spot

Table 4: Mobility (as R_f value) of heavy metal ions on thin layer of mixture of urea formaldehyde and starch developed, two component mixed organic mobile phases (S₁₅ and S₁₆) and aqueous –organic mobile phases containing different concentrations of DMA (S₁₇-S₁₉) and DMAL(S₂₁-S₂₃) with fixed concentration of formic acid and organic modifier.

Sr. No.	Metal Cations	Rf value
		Time 5 Minute
		S15	S16	S17	S18	S19	S20	S21	S22	S23
1	Fe^3+	0.78^c	0.00	0.93	0.96	0.00	0.00	0.90	0.85	0.00
2	Cu^2+	0.60	0.00	0.78	0.93	0.00	0.00	0.85	0.78	0.00
3	U^6+	0.14	0.00	0.86	0.95	0.00	0.00	0.86	0.85	0.00
4	V^5+	0.90^c	0.00	0.86	0.93	0.00	0.00	0.86	0.87	0.00
5	Ni^2+	0.00	0.00	0.81	0.64	0.00	0.00	0.00	0.00	0.00
6	Co^2+	0.71^c	0.00	0.00	0.89	0.00	0.86	0.88	0.90	0.90
7	Ag^+	0.36^c	0.23^c	0.05^c	0.00	0.09^c	0.15^c	0.44^c	0.48^c	0.56^c
8	Cr^6+	0.45^b	0.57^b	0.50^b	0.54^b	0.59^b	0.61^b	0.56^b	0.50^b	0.50^b

^a Detection clarity is poor

^b Double spot

^c Tailed spot

The results obtained by use of two component aqueous organic mobile phases (S₆-S₉), two component mixed organic mobile phases (S₁₀ and S₁₁) and aqueous –organic mobile phases containing different concentrations of DMA and fixed concentration of formic acid and organic modifier (S₁₂-S₁₄) are tabulated in Table 3.

From the table it is clear that aqueous organic mobile phases and aqueous organic mobile phase (S₆-S₈ and S₁₁) except S₉, induce migration of all metal cations. Use of aqueous DMA as mobile phase(S₉) resulted in the formation of double spots for Cr⁶⁺ and tailed spot for Ag⁺. Metal ions are strongly retained by stationary phase and remain near the point of applications at higher concentrations of DMA (S₁₀,S₁₃ and S₁₄), except Cr⁶⁺. Cr⁶⁺ shows the mobility with double spot in all mobile phases (S₆-S₁₄). Mobility of metal cation Cr⁶⁺ increased with the increasing concentration of dimethylamine (S₁₂-S₁₄) in the mobile phase irrespective of whether the mobile phase contained methanol or formic acid. The R_f of the metal cation Co²⁺ decreased with increasing concentration of dimethylamine in the mobile phases (S₁₂-S₁₄), on the contrary The R_f of the metal cation Fe³⁺ increased with increasing concentration of dimethylamine in the mobile phases (S₁₂-S₁₄). Thus these mobile phases facilitates selective separation of several metal cations by virtue of the variable mobility of the ions.

The results obtained by use of, two component mixed organic mobile phases (S₁₅ and S₁₆) and aqueous–organic mobile phases containing different concentrations of DMA and fixed concentration of formic acid and organic modifier acetone (S₁₇-S₁₉) are tabulated in Table 3.

It is observed from the table that only formic acid containing mobile phases (S₁₅, S₁₆ and S₁₈) induce migration of all metal cations. All metal ions except Cr⁶⁺ are strongly retained by stationary phase and remain near the point of applications at higher concentrations of DMA (S₁₆ and S₁₉). Cr⁶⁺ shows good mobility with double spot and Ag⁺ shows little mobility in the mobile phases containing higher containing higher concentration of DMA(S₁₆ and S₁₉).

To examine the effect of nature of amino compounds on the mobility of cations , dimethylamine was replaced by dimethylaniline (S₂₀-S₂₃) while maintaining the volume ratio of methanol and formic acid the same. The R_f values of the metal cations were determined after the use of the resulting mobile phases(S₂₀-S₂₃) . The results obtained are encapsulated in Table 3.

Most of the metal cations are strongly retained with increased concentration of dimethylaniline (S₂₀ and S₂₃) except Co²⁺, Ag⁺ and Cr⁶⁺. Induce migration of all the metal cations was observed in the mobile phases containing low concentration of dimethylaniline(S₂₁ and S₂₂). The R_f values of metal cations Co²⁺ and Ag⁺ increased with the increasing concentration of dimethylaniline ,on the contrary The R_f values of metal cation Cr⁶⁺ decreased with the increasing concentration of dimethylaniline.

Figure 1: Mobility of metal cations on mixture of urea formaldehyde and starch layer.

Semi-quantitative estimation of Cr⁶⁺

An attempt has been made to determine the recovery of Cr⁶⁺ spiked into water using spot area measurement method by using S₁₂{Methanol:1%Formic acid: DMA(8:2:2) (V/V) pH=3} mobile phase system. A linear relationship obtained when the amount of sample spotted was plotted against area of the spot follows the empirical equation ξ=km, where ξ is the area of the spot, m is the amount of solute and k is constant. Representative plot of Cr⁶⁺ has been shown in Figure 2 respectively. The linearity maintained up to 300 ug/spot. At higher concentration, a positive deviation from linear law was observed.

Figure 2: Calibration curve for semi-quantitative determination of Cr⁶⁺

Applications:

The proposed method was successfully applied for identification and separation of heavy metal ions in spiked industrial wastewater samples. The results represented in Table 5 and 6 clearly demonstrate the applicability of the method for identification and separation of Cr⁶⁺, Co²⁺, Ni²⁺, Uo₂²⁺, Fe³⁺, Ag⁺ and Cu²⁺ in a variety of industrial wastewater samples using mixture of urea formaldehyde polymer and starch as thin layer.

CONCLUSION:

It is clear from the above observations that amine-methanol-formic acid mobile phases have enormous analytical potential for achieving selective separations of heavy metal cations from their multi-component mixtures, because the nature of added amine has a profound influence on the mobility of cations. Mixture of urea formaldehyde polymer and starch is promising chromatographic adsorbent for the separation of metal cations in organic and aqueous mobile phases .Some separations of metal cations achieved experimentally using different mobile phases have been encapsulated in Table 5, 6, 7.

Experimentally achieved separations on Mixture of urea formaldehyde polymer and cellulose layers developed in Methanol+1%Formic acid+ DMA concentration 8:2:2,at pH=3 as mobile phase with optimum separating conditions.

Table 5: Binary Separation

Mobile Phase:- Methanol+1%Formic acid+ DMA concentration 8:2:2,at pH=3

Sr. No.	Components	Rf Value of metal ions
1	Cr^6+;Fe^3+	Cr^6+=0.54;Fe^3+=0.00
2	Cr^6+;Cu^2+	Cr^6+=0.57;Cu^2+=0.00
3	Cr^6+;UO2^2+	Cr^6+=0.55;UO2^2+=0.00
4	Cr^6+;V^5+	Cr^6+=0.60;VO^2+=0.00
5	Cr^6+;Ni^2+	Cr^6+=0.58;Ni^2+=0.00
6	Cr^6+;Co^2+	Cr^6+=0.65;Co^2+=0.93
7	Cr^6+;Ag^+	Cr^6+=0.61; Ag^+=0.15
8	Co^2+;Ag^+	Co^2+=0.88; Ag^+=0.23

Table 6: Ternary Separation

Mobile Phase:- Methanol+1%Formic acid+DMA concentration 8:2:2,at pH=3

Sr. No.	Components	Rf Value of metal ions
1	Cr^6+;Ag^+;Co^2+	Cr^6+=0.65;Ag^+=0.03;Co^2+=0.92.
2	Cr^6+;Co^2+;UO2^2+	Cr^6+=0.62;Co^2^+=0.96;UO2^2+=0.00.
3	Cr^6+;Co^2+;Cu^2+	Cr^6+=0.59;Co^2^+=0.88;Cu^2+=0.00.
4	Cr^6+;Co^2+;Fe^3+	Cr^6+=0.60;Co^2^+=0.90;Fe^3+=0.00.

Table 7: Quarternary Separation

Mobile Phase:- Methanol+1%Formic acid+DMA concentration 8:2:2,at pH=3

Sr. No.	Components	Rf Value of metal ions
1	Cr^6+; Ag^+; Co^2+; Fe^3+	Cr^6+=0.62;Ag^+=0.025; Co^2+=0.89;Fe^3+=0.00
2	Cr^6+; Co^2+; UO2^2+; Ag^+	Cr^6+=0.64; Co^2+=0.93; UO2^2+=0.00; Ag^+=0.017
3	Cr^6+; Co^2+; Cu^2+; Ag^+	Cr^6+=0.60;Co^2+=0.90; Cu^2+=0.00; Ag^+=0.032

ACKNOWLEDGMENTS:

The authors would like to thank the Principal and Head of the Department of Chemistry, Hislop College, Nagpur, M.S. India for the provision of the research facilities used in our study.

REFERENCES:

1. L.Deshmnukh, R.B. Kharat, separation of metal ions in the tube well water samples by thin layer partition chromatography, Intern J. Environ. Anal.Chem. 36(1988).

2. L.Deshmukh, R.B. Kharat, The effect of substituent groups on the migration of metal ions in thin layer chromatography, Journal of Liquid Chromatography 12(6) (1989) 937-947.

3. H. Thielemann, Opportunities for thin layer chromatographic determination of toxic metal ions in industrial wastewater, Acta Hydrochem, Bydrobio. 5(1977) 191-193.

4. D.W. Armstrong, R.Q. Terrill, Thin layer chromatographic separation of pesticides decachlorobiphenyl and nucleosides with miceler solution, Anal. Chem. 51(1979)2160-2163.

5. M.F. Borgerding, R.L. Williams(Jr), W.L. Hinze, New perspective in miceller liquid chromatography, J.Liq. Chromatography 12 (1989) 1367-1406.

6. A.S. Kord , M.G.Khaledi, Chromatogarphic charecteristics of surfactant- mediated separations; miceller liquid chromatography vs ion pair chromatography, Anal. Chem. 64(1992) 1901-1907.

7. M.G.Khaledi, J.K. Strasters,A.H. Rodgers, E.D. Breyer, Simulteneous enhancement of separation selectivity and solvent strength in reversed phase liquid chromatography using micells in hydro-organic solvents, Anal Chem.62(1990) 130-136.

8. A Mohammad, V.J.Agrawal, Mixed surfactants enable separation of lysine from other essential amino acids in TLC on silica gel, Planar Chromatography-Mod. TLC 13 (2000) 210-216.

9. A. Mohammad, Y.H. Sirwal, Miceller thin layer chromatography of coinage metal cations, J. Planar Chromatography-Mod.TLC 15(2001) 107-115.

10. A. Mohammad, E. Iraqi, I.A. Khan. Miceller thin layer chromatography separation of heavy metal cations effect of organic and inorgani additives on migration behaviour. J. Surfactant and Detergent 2 (4) (1999) 523-529.

11. A.Mohammad, V. Agrawal , N. Jabeen, Separation studies of transition metal ionswith cationic miceller eluents in normal phase thin layer chromatography, Chromatography 242 (2003) 1-7.

12. C.G. Yeole, V. M. Shinde, Reversed-phase paper chromatographic studies of some rare earth elements, Analyst 104(1983) 1102-1107.

13. J.G. Dorset, M.T. Etchegaray , J.S. Landy, Efficiency enhancement in miceller liquid chromatography, Anal. Chem. 55(1983) 924-928.

14. P Janjic, M.Petrovic, T.L. Djakovic, Thin layer chromatography of metal ions on new carbamide polymer, Budapest Chromatography Conference, 1990, pp. 17-24.

15. Esezobo S. , Evaluation of Sweet potatostarch as binder and disintegrant for paracetamol tablets. Nig. J. Pharm Sci. 2(2) (1986),44-51.

16. Iwuagwu M.A. Nwaoshai C.A.and Iseghohi F.E. Investigations in to the binding disintegrant properties of starches from selected Dioscoteaceae plants. Nig.J.Pharm. Sci. 2(2)(1986),10-22.

17. DesphandeA.V. and Panya L.B. Evaluation of Sorghum starch as a tablet disintegrant and binder., J. Pharm. Pharmacol., 39(1987), 495-496.

18. Mitrevej A. Sinchaipanid A. And Faroongsarng D., Spray-dried rice starch; comparative evaluation of direct compression filters. Drug Dev. Ind. Pharm. 22(7), (1996), 587-594.

19. Iwuagwu M.A and Akerele J.O. Microbiological suitability of African bitter yarm starch. Pak. J. Sci. Ind. Res. 44(4)(2001) 227-230.

20. Subhadhirasakul S., Yuenyoungsawad S. Ketyinda W., Phadoongsombut N and Faroongsarng D., Study on tablet binding and disintegrant properties of alterntive starch prepare from Taro and sweet potato tubers. Drug Dev. Ind. Pharm. 27(1) (2001), 81-87.

Received on 02.01.2015 Modified on 12.01.2015

Accepted on 20.01.2015 © AJRC All right reserved

Asian J. Research Chem 8(2): February 2015; Page 126-130

DOI: 10.5958/0974-4150.2015.00023.1