Simple Substituted Benzene Analytes

and / -Nitrobenzoic acid isomers were separated and analyzed on a C g column (2 = 254 nm) using an 80/20/0.4 water/IPA/acetic acid (pH 2.99) mobile phase [101]. Linear ranges of 30-1100 pg/mL and detection limits of 5 pg/mL were reported. Baseline resolution was achieved in a run time of 10 min. As noted above, the key here is to make sure the acid level in the mobile phase is always high enough to keep these low-pA j analytes fully protonated. 

Chloroaniline was photochemically decomposed and the degradation products (cyclopenta-1,3-diene-1-carbonitrile, 2-aminophoioxazine-3-one, and three o-phenyl-disubstituted anilines such as 2-chloro-3-aminophenol) were extracted from water and separated on a C g column (A = 280 nm). A 60/40 methanol/water (with 1.8 g/L ammonium acetate) mobile phase resolved all compounds in 15 min [102]. 

The premise of this study was to evaluate a subcritical water extraction process for phenol, chlorophenols, and chloroanilines [103], In the process, excellent separation of each of these classes of compounds was obtained on a column (no wavelength cited but a typical value would be 250-280 nm). Phenol and chlorophenols (4-chloro 2,3-, 2,4-dichloro 2,3,6-, 2,4,5-trichloro) were baseline resolved in 30min using a 60/40 methanol/water mobile phase. Aniline (extremely tailed use acid in the mobile phase to correct) and chloroanilines (4-chloro 2,3-, 2,5-dichloro 2,3,6-, 2,4,5-trichloro) were resolved using a 25-min 40/60 - 90/10 methanol/-watergradient,Workingconcentrationsrangedfrom2to40 xg/g. 

Metol (A -methyl-p-aminophenol) oxidation products were extracted from water and separated on a C g column (A = 271 nm) using a 15-min 95/5 100/0 water 

Screening methods for 44 nitro-, chloro-, and alkyl mono- and disubstituted phenolic compounds in water were developed on three columns cyanopropyl, C,g, and diphenyl (A = 220nm). A 60-min 50/50- 90/10 methanol/water (lOmM acetate buffer at pH 4.8) gradient was used. Not all 44 compounds were baseline resolved, but a subset of 28 were resolved on the C g column using the above gradient. Detection limits were reported individually for all components and ranged from 0.5 to 1.7 ppm [105]. 

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The multiple regression method is most often employed to derive predictive QSRR. However, good predictions of GC retention were obtained by means of factorial methods of data analysis. The PLS (partial least squares) treatment of 17 simple descriptors of analytes, such as the number of atoms of each element, of multiple bonds, of functional groups, etc., made predictions of retention of 100 substituted benzenes and pyridines 188],... 

Simple Substituted Hydrocarbon and Benzene Analytes Retention Studies... 

The aromatic ring is the third type of unsaturated structure, the hydrogenation of which we need to consider. Although it is possible for its hydrogen atoms to be substituted for deuterium, the possible products of the reduction of benzene are effectively but two in number, viz. cyclohexene and cyclohexane somewhat special conditions of catalyst type and reaction conditions are needed to procure the former, so that commonly cyclohexane is the only product observed. In comparison with say the reactions of the butenes or ethyne, the hydrogenation of benzene is simplicity itself, and for this reason it has been the choice of many who have wished for a quick and easy way of assessing the activity of a catalyst. Very simple analytical techniques are all that one needs, and this helps to explain the attractiveness of this class of reaction before the advent of gas-chromatography. 

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