Fig. 7.
(A) Spectra of Cr(VI)-containing functionalized monoliths after exposure to diphenylcarbazide. Each gel had been previously exposed for 5 hours to a 20 mL solution consisting of 0.1 M HCl and: (a) 0 ppb; (b) 11 ppb; (c) 51 ppb; (d) 102 ppb; (e) 204 ppb; (f) 308 ppb Cr(VI). (B) The corresponding calibration plot. Data points represent an average of measurements from three gels.