Thin Layer Chromatographic Separation of a Few Food Dyes over Scolecite as a new Adsorbent.

P. K. Shrivastava* / R. Prakash

Biomaterial Division, Regional Research Laboratory, (Council of Scientific & Industrial Research), Bhopal University Campus, Bhopal (MP) 462026, India

Key Words

Thin layer chromatography Scolecite Food dyes

Summary

A naturally occurring Zeolite mineral collected from Pawagad (Gujrat) India was shown to be a Scolecite of the natrolite group of Zeolites. After physico chemical characterization it was used as a new adsorbent for the separation of food dyes by TLC.

In chromatography we have to deal with a system of at least three components - adsorbent, solvent and the compound being chromatographed. The behaviour of the compound is dependent upon the adsorbent and the solvent. It is now possible to predict within certain limits, the adsorbents and solvents, most suitable for the chroma- tography of a given substance. In the present communica- tion Scolecite (Zeolite), a crystalline hydrated aluminium silicate of alkali metal, with a three dimensional anion network, was used as a new adsorbent for the separation of food dyes by thin layer chromatography. Food dyes used in this work are those in general bakery use (Viola, India Made).

The Scolecite sample used for the chromatographic studies was obtained from Pawagad [1, 2] near the Varodara area in Gujarat situated in the Deccan Trap formation of Malwa.

The sample was characterised by I.R., T.G.A., D.T.A. and X-Ray diffraction analysis and by chemical analysis before

* P.K. Shrivastava, Rly..Q. No. RB III 167 (M/S) FF/B Khazanchi Ka Bagh, East Rly. Colony, Bhopal (MP) 462010, India

using it as an adsorbent for TLC. Optimum conditions for the separation of food dyes [3] were determined by study- ing the effect of using Scolecite powder of different mesh sizes (100, 200 and Cap 300 microns), different tempera- tures of activation and different, activation times. Scolecite powder as an adsorbent (below 200 mesh) without mixing any binder in it, was slurry-coated onto glass microscopical slides (3"x 1") and was activated at 110~ for one hour after air drying. The migratory behaviour of Carmorine (C.I. No. 479), C. Yellow No. 5 (C.I. No. 19140), Bril- liant Blue FCF (C.I. No. 42090) and Amaranth (C.I. No. 16185) on Scolecite was studied in many solvents. Optimum conditions for best separation were determined by studying various experimental parameters with acetone as the solvent and RF values of individual food dyes were meas- ured under optimum conditions (Table I). For comparison the separation of these dyes has also been studied on Silica gel, under the same conditions. Amaranth (i) and Carmorine (ii) were retained at the spotting point but C. Yellow No. 5 (iii) and Brilliant Blue FCF (iv) gave characteristic Rfvalues. Separation of Amaranth from C. Yellow No. 5, Amaranth from Brilliant Blue FCF, Carmorine from C. Yellow No. 5, Carmorine from Brilliant Blue FCF and several ternary mixtures was achieved, in a single pass, 3-4cm ascending development of the solvent in about 1-2minutes. All these separations were found to be faster and better, than on silica gel G [4], as an adsorbent under the same exper- mental conditions. Thus Scolecite was found to be a good adsorbent for the separation of these four food dyes

Table I RF values of Some food dyes on Scolecite & Silica Gel 'G' Solvent: Acetone

R F value Food dye Scolecite Silica Gel

1. Amaranth (16185) Retained 0.30 2. Carmorine (197) Retained 0.30 3. C. Yellowe No. 5 (1940) 0.50 0.40 4. Brilliant Blue FCF {42090) 0,30 0.50

Chromatographia Vol. 21, No. 11, November 1986 Short Communication 655

0009-5893/86/10 0655 02 ~; 03.00/0 9 1986 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH

studied. K. Srinivasulu and A. K. Sonakia reported earlier

the separation of many organic acids [5], amines [6a],

t rypheny l dyes [6b] , aminoacids [6c], carbohydrates [6d],

d icarbox i l i c acids [6e] on Scolecite and K. Srinivasulu and

P. K. Shrivastava reported the separation of Catecholamines

[7]. The evidence quoted above and our observations show that

Scolecite has a wide potent ia l for use as a TLC absorbent.

Acknowledgements

Thanks are due to Director, Regional Research Laboratory

for prov id ing Laboratory facil it ies, we thank Mr. A. Des-

mukh also for help and assistance.

References

[1] S C. Chatterjee, J. ofGeol.,Surv, o f lnd . 2 ,63(1961) . [2] George, P. L. Walker, Report -- "Some observations and

interpretations on the Deccan Traps, resulting from a visit Jan -- early April 1969, Univ. of Saugar, April 3rd 1969 p. 6, 17.

[3] IV/. Mottier, M. Potterat, Analyt. Chim, Acta 13, 46 (1956). [4] A. Montag, Z. Lebensmittel -- Unters, U. Forsch. 116, 413

(1962). 15J K. Srinivasulu, A. K. Sonakia, Natl. Acad. Sci. India (1978)

paper No. 41. I6] K. Srinivasulu, A. K. Sonakia, Pitts. Conf. Anal. Chem. and

Appl. Spec. U.S.A. [a] 1979 Ib] 1980 [c] 1981 [d] 1982 [e] 1983

[7] K. Srinivasulu, P. K. Shrivastava, Pitts. Conf. Anal. Chem. and Appl. Spec. New Orleans U.S.A. 1984, Paper No. 1080.

Received: March 14, 1986 Revised manuscript received: April 23, 1986 Accepted: May 13, 1986 E

Book Reviews

Riickstandsanalytik von Pf lanzenschutzmitteln

yon Hans-Peter Thier und Helmut Frehse

GeorgThieme Verlag Stuttgart, 1986. DM 98,--, ISBN 3-13-666601-1

Der qualitative und quantitative Nachweis yon Pflanzenschutzmit- teln und ihren R0ckst~nden in Lebensmitteln und der Umwelt stellt wegen der Komplexit~t der Substanzen und der Matrices, in der sie vorkommen, h6chste Anforderungen an den Analytiker. Chromato- graphische Verfahren spielen auf diesem Gebiet eine herausragende Rolle, da sie erlauben, einerseits die zu bestimmenden Stoffe yon st6renden Begleitsubstanzen abzutrennen und daneben qualitative Identifizierung und quantitative Bestimmung ermSglichen. Im vorligenden Buch wird das komplexe Gebiet der R(Jckstandsana- lytik von Pflanzenschutzmitteln umfassend abgehandelt. Nach einer Beschreibung der Chemie der wichtigsten Pestizide, der Formulie- rungstechniken sowie der Anwendungstechniken und -arten werden auch die rechtlichen Regelungen sowie der Verbleib der Pestizide nach ihren verschiedenen Anwendungsarten diskutiert. Hauptaugen- merk wird auf die Besonderheiten der RSckstandsanalytik, der Pro- benahme, Probevorbereitung und -aufarbeitung gelegt, wobei vieles aus der gror~en praktischen Erfahrung der Verfasser miteinfliel&t. Bei den chromatographischen Methoden dominiert wohl die Gas- chromatographie wegen der niedrigen Nachweis- und Bestimmungs- grenzen, abet D0nnschicht- und Hochleistungsfl(Jssigkeitschromato- graphie werden nicht vernachl&issigt. Im Abschnitt ,,Beurteilung von RSckstandsdaten" wird ausf(Jhrlich auf die Probleme mit der Unsicherheit von Ergebnissen eingegangen und vor der Obersch~tzung der Genauigkeit der Ergebnisse durch den Analytiker gewarnt. Eine ausfLihrliche Bibliographie sowie ein ausf0hrliches Wirkstoff- register neben dem Stichwortverzeichnis erleichtern den Zugang zu den Problemen der R(ickstandsanalytik. Das Buch gibt einen ausgezeichneten 0berblick Qber die RiJckstands- analytik yon Pflanzenschutzmitteln und liefert dem erfahrenen Ana- lytiker, aber besonders dem Neuling, viele praktische Hinweise. FSr letzteren, insbesondere wenn er ernsthaft RLickstandsanalytik be- treiben will, ist das Buch eine PflichtlektQre.

H. Engelhardt

Planar Chromatography

Volume 1

Edited by R. E. Kaiser

Published by Huethig Veriag, Heidelberg 1986. ISBN 3-7785-0780-X

This book is apparently the first volume in a series (edited by R. E. Kaiser) in "Planar Chromatography" to be published by Huethig. As such it is to be welcomed by all those interested in the current prac- tice of TLC. This particular volume contains 11 contributions on various aspects of TLC, albeit heavily biased towards instrumental methods. The introductory chapter (R. E. Kaiser) is an attempt to define planar chromatography and place it in some sort of context. The following chapters are concerned with optimization, a compari- son of HPTLC with TLC, OP LC and HPLC, preparative techniques (including centrifugal TLC) and high pressure circular TLC. There are also chapters on automatic multiple development (with some particularly impressive separations), two papers dealing with image processing and one on computer aided TLC. The final contribution discusses the use of cyclodextrin-containing mobile phases for the separation of mycotoxins.

If one were to be critical of this book there are a number of points which deserve attention in future volumes. Firstly, the index is

1 quite inadequate (less than 2 ~E pages of index to 263 pages of text) and omits many of the compounds discussed in the text. There is also little evidence for consistent editing, for example there is no logic in having summaries for chapters 5 and 7 to 11 but omitting them for chapters 1 to 4 and 6. In the contents section the name left out is that of the Editor! D. Kaiser clearly has an almost evage- tical desire to promote the advantages of planar chromatography, it is a pity that he spoils his arguments by overstating his case, and by the inclusion of so much anecdotal material. Thus, even whilst I found myself largely in agreement with the sentiments I found myself irritated by the way in which they were expressed.

Apart from these minor criticisms this is a very interesting volume, crammed full of new techniques and information. It should be read by anyone interested in modern TLC.

I. D. Wilson

656 Chromatographia Vol. 21, No. 11, November 1986 Short Communication