In 2017,Loucaides, Socratis; Rerolle, Victoire M. C.; Papadimitriou, Stathys; Kennedy, Hilary; Mowlem, Matthew C.; Dickson, Andrew G.; Gledhill, Martha; Achterberg, Eric P. published 《Characterization of meta-Cresol Purple for spectrophotometric pH measurements in saline and hypersaline media at sub-zero temperatures》.Scientific Reports published the findings.Formula: C8H6FNO4 The information in the text is summarized as follows:
Accurate pH measurements in polar waters and sea ice brines require pH indicator dyes characterized at near-zero and below-zero temperatures and high salinities. We present exptl. determined phys. and chem. characteristics of purified meta-Cresol Purple (mCP) pH indicator dye suitable for pH measurements in seawater and conservative seawater-derived brines at salinities (S) between 35 and 100 and temperatures (T) between their f.p. and 298.15 K (25°C). Within this temperature and salinity range, using purified mCP and a novel thermostated spectrophotometric device, the pH on the total scale (pHT) can be calculated from direct measurements of the absorbance ratio R of the dye in natural samples aspHT = – log(kT2e2) + log(((R – e1)/(1 – R(e3/e2)))) Based on the mCP characterization in these extended conditions, the temperature and salinity dependence of the molar absorptivity ratios and – log(kT2e2) of purified mCP is described by the following functions: e1 = -0.004363 + 3.598 × 10-5T, e3/e2 = -0.016224 + 2.42851 × 10-4T + 5.05663 × 10-5(S – 35), and – log(kT2e2) = -319.8369 + 0.688159 S -0.00018374 S2 + (10508.724 – 32.9599 S + 0.059082S2) T-1 + (55.54253 – 0.101639 S) ln T -0.08112151T. This work takes the characterization of mCP beyond the currently available ranges of 278.15 K = T = 308.15 K and 20 = S = 40 in natural seawater, thereby allowing high quality pHT measurements in polar systems.Methyl 4-fluoro-3-nitrobenzoate(cas: 329-59-9Formula: C8H6FNO4) was used in this study.
Methyl 4-fluoro-3-nitrobenzoate(cas: 329-59-9) belongs to methyl benzoate. Methyl benzoate reacts at both the ring and the ester, depending on the substrate. Electrophiles attack the ring, illustrated by acid-catalysed nitration with nitric acid to give methyl 3-nitrobenzoate.Formula: C8H6FNO4
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