A novel transduction chemistry for preparing optical anion-selective polymeric films that respond reversibly and selectively to chloride ion activity is demonstrated. The chloride sensors are prepared by casting thin (5-10 microm) plasticized PVC films containing indium(III) octaethylporphyrin hydroxide, along with optimized levels of a lipophilic tetraphenylborate salt, onto glass slides. When bathed in low-pH buffered solutions void of chloride, the porphyrin species spontaneously forms a hydroxide ion-bridged dimer, with the added lipophilic borate species serving as the counteranion for this complex. The maximum for the Soret absorption band of this dimeric species is shifted to 390 nm, from 410 nm for the initial monomeric porphyrin. Increases in chloride ion levels in the bathing solution results in chloride extraction and ligation to the In(III) center, and concomitant breaking of the dimer into monomeric porphyrin species, yielding a decrease in absorbance at 390 nm and an increase in optical signal at 410 nm. Under optimized conditions, optical selectivity coefficients toward chloride over a wide range of other anions (NO3-, ClO4-, SCN-, SO4(2-), F-, Br-, H2PO4-) are measured to be < 10(-3). Of all anions tested, only salicylate yields a slightly greater response than chloride. This selectivity is shown to be adequate for reversible and accurate sensing of chloride levels in diluted serum samples.

Despite reports of the occurrence of bisphenol A diglycidyl ether (BADGE) and its derivatives in canned foods and consumer products, biomonitoring studies of human exposure to these compounds are lacking. In this study, 127 urine samples collected from the U.S. and China were analyzed for free and total (free plus conjugated) concentrations of BADGE and its three derivatives, bisphenol A (2,3-dihydroxypropyl) glycidyl ether [BADGE·H(2)O], bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) ether [BADGE·HCl·H(2)O], and bisphenol A bis (2,3-dihydroxypropyl) ether [BADGE·2H(2)O], using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BADGE and its three derivatives (collectively referred to as BADGEs) were found in 100% of the urine samples analyzed. Total urinary concentrations of BADGEs in the U.S. ranged from 1.24 to 9.03 ng/mL, with a GM concentration of 3 ng/mL. Concentrations of BADGEs in urine from adults (GM: 1.36 ng/mL) and children (1.02 ng/mL) in China were 3-fold lower than the concentrations found in the U.S. Both free and conjugated forms of BADGEs were present in urine, and the proportion of free form was inversely related to the total concentration of BADGEs. Among the four BADGEs measured in urine, BADGE·2H(2)O was the predominant compound, accounting for 45-60% of the total BADGEs concentration, followed by BADGE (17-24%). The distribution of the four BADGEs varied, depending on age, gender, and ethnicity of the adults and children. Daily intake (DI) and effective daily intake (DI(E)) of BADGEs were estimated based on urinary concentrations, and their respective values were 69.4 and 9.16 ng/kg-bw/day for the U.S. population and 28.4 and 5.69 ng/kg-bw/day for the Chinese population. The concentrations of BADGEs in U.S. urine were 3- to 4-fold higher than the corresponding concentrations of bisphenol A.

The principles, recent achievements and challenges related to the use of metalloporphyrins as ionophores in the development of polymeric anion‐selective membranes are reported. The advantages and disadvantages of dimer‐monomer equilibria existing within the membrane phase when using certain metalloporphyrins are discussed with respect to their effect on the response characteristics of the resulting anion sensors. The influence of membrane composition and pH of sample solution on these equilibria is described. The possibility of employing both potentiometric and optical transduction modes for anion recognition with metalloporphyrin doped polymer membranes is shown.

A novel transduction chemistry for the development of a polymer film-based optical sensor that responds reversibly to gas-phase amine species at sub-ppm levels is described. The sensor is based on the equilibrium of a indium(III) octaethylporphyrin hydroxide ion-bridged dimer species with corresponding monomeric porphyrins within a thin poly(vinyl chloride) film as a function of the level of volatile amine in the surrounding gas phase. The presence of amines causes the dimeric species to be converted to monomer via the ligation of the amine with the In(III) center of the porphyrin structure. This yields a significant change in the visible absorption spectrum of the film, with a decrease in the intensity of the Soret band corresponding to the dimer (lambdamax = 390 nm) and a concomitant increase in the Soret band for the monomer lambdamax = 406-408 nm). Response to different amines is based on their relative partition coefficient into the polymer film and their strength of axial ligation reactions, with a selectivity pattern of 1-butylamine > 1-propylamine > pyridine > triethylamine > ethylamine > methylamine > diethylamine > tert-butylamine > ammonia. It is further shown that a significant concentration of dimeric species within the polymer film can only be achieved if appropriate amounts of lipophilic anionic sites are also incorporated into the polymer in the form of a tetraphenylborate derivative and the resulting film is equilibrated briefly with water prior to gas-phase measurements. With optimized film compositions, 1-butylamine can be detected in the gas phase to levels approaching 0.1 ppm, while less lipophilic ammonia can be monitored down to 10 ppm, with fully reversible responses to each species. A simple mathematical model for the response of the amine sensor is presented and shown to predict the optical behavior observed.

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