**5. Control of pharmaceuticals and other large anions**

Three diverse groups of compounds can be usefully considered for their impact, but the need to be able to separate them from aqueous solution: Pharmaceuticals, BPA, and food dyes. These will be considered in succession.

### **5.1. Pharmaceuticals**

ously it was of interest to determine whether a metallolig, e.g., Cuprilig, could remove perchlorate ion from aqueous solutions using column chromatography, and it was a success [37]. Using perchlorate solution, the effluent was below detection limit, i.e., <1 ppb. But success also raised the question of a "control" experiment, one kind being to eliminate the role of the metal ion, and use only Octolig®. Doing so, the results were equally good, i.e., > 99% removal

Clearly a different model for understanding the removal process was in order. And the current hypothesis is that nitrogens are protonated at low pH values probably as well, even somewhat above the pH at which Octolig® should not used. A working hypothesis consistent with Figure 5 is that at least two important considerations are involved: (1) The nitrogens must be proto‐ nated, and (2) species to be removed must be anions or if weak acids convertible to anions [39]. Further studies [35, 37, 38] have found that simple anions can be quantitatively removed by Octolig ® at reasonable values of pH, and the order of removal is consistent with an ionic model of anions being attracted to protonated moieties of the Octolig® as represented (Figure 5).

**Figure 5.** Proposed structure of Octolig® -anion (A-) interaction [38]. Reproduced with permissionof the publisher

unfavorable balance. One substance of special interest is BPA (*vide infra*).

with permission

A range of compounds can be quantitatively removed provided the pKa of the material is less than about 8 [40]. Above that value, the per cent removal was less than 20% [40]. This is demonstrated in Figure 6. It may be presumed that for those compounds having pKa values greater than 7+, the anion concentration vs. the degree of protonation of Octolig® reaches an

Compounds in order of increasing pKa values (in parentheses): Amoxicillin (2.4), Eosin Y (2.7), Lissamine Green (~3), Erythrosine (3.6), Rose Bengal (3.9), 4-nitrophenol (7.15), 2-nitrophenol (7.22), 3-nitrophenol (8.36), 4-tert-butylphenol (10.16) 4-isoproplphenol (10.19). From [47] used

with Octolig® alone using deionized water or well water [37].

134 Column Chromatography

The range of anions that can be quantitatively removed by Octolig® and column chromatog‐ raphy include some significant pharmaceuticals. These substances are chemical compounds (inorganic or organic) that can be used in the diagnosis, mitigation, treatment, or prevention of a disease [41,42]. Unfortunately, because of their usefulness and the magnitude of produc‐ tion they can represent a disposal problem [41-43]. Pharmaceuticals have an impressively wide range of applications – human medicine, veterinary medicine, aquaculture, livestock produc‐ tion, and agriculture. [43]. A recent review [42] quoted a statistic that of the 16,200 tons of antibiotics produced in the United States in 2000, about 70-% was used for livestock [40]. Unfortunately, about 75% of the antibiotics involved was not absorbed and was delivered to the environment in the form of urine and feces [41].

On the positive side, a study using Octolig® as a separating agent showed that Amoxicillin (Figure7),averypopularantibioticintheUnitedStateswasamongthosequantitativelyremoved [44], as noted in Table 5. This a result that is consistent with the information provided in Figure 6. It is also noteworthy that results for DI (deionized ) water and well water from the Floridan Aquifer were similar. The lack of a matrix effect, at least for these two solvents may be promis‐ ing if one considers that hospitals can represent a significant source of un-metabolized drugs as well as metabolic products of these drugs /in waste products. The concern raised more recent‐ ly is the fate of such waste materials. One may consider an analogy, i.e., radiator shops in certain localities must be careful not to release zinc ion water laving the establishment lest the concen‐ tration affect bacterial used in sewage treatment. Will a similar concern arise with respect to hospitals? The possible causes for concern were raised in a review on the topic [43].

**Figure 8.** Bisphenol A, BPA. pK values = 9.59, 11.3

water.

( ) ( ) 6 5 <sup>3</sup> 64 3 64 2 2 2 2 C H OH + CH C=O 4- HOC H C CH C H OH-4 + H O

( ) ( ) <sup>2</sup> 64 3 64 <sup>2</sup> <sup>n</sup> BPA + Cl C=O - O-C H C CH C H O C=O -

( ) ( ) 2 2 64 3 64 2 <sup>2</sup> <sup>2</sup> <sup>n</sup> BPA + CH CHOCH Cl - O-C H C CH C H O-CH C OH CH -

**•** BPA is also present in our bodies in detectable amounts in our blood stream.

As noted in the review [45], these plastics can fail with age, and BPA or other substances possessing estrogenic activity (EA) can be released. The review noted other points of signifi‐

**•** It is present in the rivers and estuaries in detectable amounts, despite its low solubility in

**•** Though BPA may have a short half-life in soil, the ubiquity of the substance provides a

**•** A significant concern arises as to the toxicity of this material, which because of the ubiquity of the material and the uncertainty of the toxicity has become a matter of concern and significant debate, which seemingly leads to three choices: ban, restrict, or ignore [45, 46]. **•** Two better approaches are avoidance of exposure to EA-containing polycarbonates or

The potential control of EA materials in plastics needs to be considered because the volume of plastics used annually means that there will be no sudden cessation of use. But there is reason for optimism, based on a recent study. Results of a survey of 455 commercially available plastic products for release of estrogenic active (EA) material gives pause for the thoroughness as well as for the implications [46]. These workers discovered that EA materials could be removed by

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Chromatographic Separations with Selected Supported Chelating Agents

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

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137

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phenol acetone BPA

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phosgene polycarbonate

epichlorohydrin epoxy resin

cance (with documentation provided in the review) including:

continuous supply in the environment.

treatment of EA-containing polycarbonates.

**Figure 7.** Structure of Amoxicillin, pK = 2.4


**Table 5.** Passage of aqueous Amoxicillin samples over a 3.0 (id) chromatography 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 measured spectrophotometrically) [44]
