**6. Batch separations versus column chromatography using Octolig®**

Removal of metals by immobilized ligands frequently involves a choice of two techniques, a batch method or column chromatography. The batch method can be faster when samples are taken from the supernatant for replicate analyses. This method also can establish when equilibrium (or stasis) has been established. One flaw is that the sample of solid may not be adequate to remove all the sample in the supernatant (which is an asset for measuring capaci‐ tyofthesolid).Butthereareatleastthreeapplicationsofthebatchmethodthatcanbeconsidered.`

Using the *standard method*, noted earlier, quantitative removal (100.1+±0.04 %) of FD&C No 1 was achieved [58] This is one of seven food dyes approved for use in the United States under the Pure Food and Drug act of 1906 (abbreviated as FD&C), the other six dyes also appear to be easily removable by Octolig® based column chromatography based on an consideration of

**Matrix pH Concentration., µM % Rermoved** DI water 8.66 78.8 99.9 **±**0.0 Tap water 7.76 94.9 99.9 ± 0.0 Well water 8.33 105.5 98.6 **±** 0.1

**Table 6.** Column chromatography of aqueous Erythrosine B samples over a 3.0 cm (id) column packed with ~130 mL of Octolig® at a flow rate of 10 mL/min (50-mL aliquots were collected and concentrations of fractions 4-10 were

Similarly, using our standard method for column chromatography, quantitative separation was obtained. for Erythrosine, but also for the other food dyes in contemporary use It is also

Removal of metals by immobilized ligands frequently involves a choice of two techniques, a batch method or column chromatography. The batch method can be faster when samples are taken from the supernatant for replicate analyses. This method also can establish when equilibrium (or stasis) has been established. One flaw is that the sample of solid may not be

notable that there was no significant matrix effect observed for DI, tap or well water.

**6. Batch separations versus column chromatography using Octolig®**

their structure.

140 Column Chromatography

**Figure 11.** FiFD&C No 3., Erythrosine B, R1 = I ; R2 = H

measured spectrophotometrically) [44]

*One application* was determining the time course for of the batch methods. The example (Figure 13) shows the time course of removal can be fairly rapid, and an estimate of the capacity is indicated by the "plateau phase."

**Figure 12.** method with Octolig®: Percent removed by Octolig® as a function of time for aqueous 3-nitrophenol. Octo‐ lig® was suspended in 100 mL of aqueous 3-nitrophenol) and shaken (.at a rate of 240 rpm. Aliquot portions taken periodically as noted and analyzed. (Figure from [47], used with permission of the author).

A *second application* of the batch method was being able to evaluate a mechanism of sorption, as noted by Gao and co-workers [13].

A *third application* was that of comparison. Many in academe seem to have favored batch methods. In contrast, a valued colleague [9, 10] noted that information obtained from column chromatography was more applicable to the needs of industry. Column chromatography was used with Octolig® in practical applications as noted previously.

Accordingly, a series of experiments was designed and performed to evaluate comparisons of batch versus column chromatography (cf. Table 7). A *standard batch method* is presented here for the sake of comparison [59]. A sample of Octolig ® (5 g as received) was placed in a 250 mL Erlenmeyer flask covered with 100 mL of about 1600 ppm phosphate as NaH2PO4. The samples were placed in a gyrotory water bath and subjected to shaking (>170 rpm) overnight. At the end of the shaking period, an aliquot was removed, and diluted ca. 1:8 for phosphate. Mean and SD values were calculated. The result was subtracted from the initial phosphate concentration to determine the capacity, expressed as moles per kg of Octolig®.

Results of the study with Octolig®, summarized in Table 7 indicate that there was no statisti‐ cally significant difference [59] between the two methods. Similar results were obtained for a capacity for arsenate [59]. The results (Table 7) were also used to see if there was a major difference between different preparations of Octolig® by comparing capacity for phosphate (Sample 1 vs. Sample 2),

and most assured. The range of separations --- metals ions, simple anions, pharmaceuticals, industrial dyes, and food dyes – seem impressive, and indicates the utility of separation by

Chromatographic Separations with Selected Supported Chelating Agents

http://dx.doi.org/10.5772/55521

143

I am grateful to the collaborators/co-authors who worked with me over the past two decades. I have valued the association with Mr. Robert L. Alldredge (dec) and Mr. Mark H. Alldredge. I thank Mrs. Barbara B. Martin for helpful comments and encouragement. I am grateful for the

Institute for Environmental Studies, Department of Chemistry-CHE, University of South

[1] Chelex 100 and Chelex 220 Chelating Ion exchange Resin Instruction Manual, http:// www.biorad.com/webmaster/pdfs/9184\_Chelex.PDF) (accessed 26 May 2012).

[2] Ceo RN, Kazerouni MR, Rengan K. 1993. Chelex 100 as a Medium for Simple Extrac‐ tion of DNA for PCR-based Typing from Forensic Material. Biotechnique 1993; 10

[3] Pai SC, Whung PY, Lai RL. Preconcentration Efficiency for Chelex-100 Resin for Heavy Metals in Sea Water, parts 1 and 2 Analytica Chimica Acta 1998; 211 257-280.

[4] Florence TM, Batley GE. Trace Metal Species in Sea Water-I. Removal of Trace Meals

[5] Figura P, McDuffie B. Characterization of the Calcium Form of Chelex-100 for Trace

[6] Ryan DH, Weber JH. Comparison of Chelating Agents Immobilized on Glass with Chelex-100 for Removal and Preconcentration of Trace Copper. Tantala 1985; 32

from Seawater by a Chelating resin. Tantala 1976; 23 179.

Metal Studies. Analytical Chemistry 1977; 49 1950-1953.

column chromatography using appropriately supported chelating agents.

**Acknowledgements**

**Author details**

Dean F. Martin

**References**

506-513.

859-863.

Florida, Tampa, Florida, USA

encouragement of Ms. Viktorija Zgela.

Address all correspondence to: dfmartin@usf.edu


**Table 7.** Selected removal capacities (moles/kg) calculated for phosphate comparing the chromatography method versus a batch method (= 3) [59]

A *fourth application* is a convenient assessment of the removal of a transition metal by a supported chelator vs sorption on the substrate. It appears that the supported chelators were able to remove copper ion in a quantitative manner, but a goodly proportion (83%) was removed by sorption on silica gel. In contrast, a Linde molecular sieve (alone) with fairly defined pores removed about half of the copper ion through sorption.


**Table 8.** Extraction of 5 ppm copper from ammoniacal solution using supported chelating agents and supported chelators prepared by the corkscrew method as noted above. Modified from [26] Summary

Supported chelating agents can effectively satisfy three needs: concentration for analysis, removal from solution, and removal coupled with regeneration. Their use on a commercial scale has been demonstrated for many years with Chelex as well as Octolig® for removal of transition metals ions and other uses. It seems likely that Octolig® could be competitive with a highly selective ion- exchange resin and, perhaps, commercially competitive, but this remains to be demonstrated. The examples demonstrated indicate a number of chelating agents can be attached using one of three different methods, though covalent attachment seems the easiest and most assured. The range of separations --- metals ions, simple anions, pharmaceuticals, industrial dyes, and food dyes – seem impressive, and indicates the utility of separation by column chromatography using appropriately supported chelating agents.
