A comparative study was made of the chromatographic behaviour of nine haloacetic acids, namely mono-, di-, and tri-fluoroacetate (MFA, DFA, and TFA, respectively); mono-, di-, and tri-chloroacetate (MCA, DCA, and TCA, respectively); and mono-, di- and tri-bromoacetate (MBA,DBA, andTBA, respectively), employing anion-exchange chromatography with suppressed conductivity and UV detection, using a Dionex AS17 anion-exchange column employed with a potassium hydroxide gradient (via a Dionex EG40 Eluent Generator). All nine haloacetic acids were completely separated under the optimized gradient elution conditions, and use of selective detection methods or pretreatment with an OnGuard Ⅱ Ag cartridge resulted in the elimination of interferences from chloride and bromide occurring in soil samples. The procedure for the simultaneous determination of the nine haloacetic acids was simple and rapid. The method detection limits for MFA, DFA, TFA, MCA, DCA, TCA, MBA, DBA, and TBA were 21, 40, 40, 28, 48, 86, 67, 55, and 160μgL−1, respectively. Application of this method to the determination of haloacetic acids in real soil samples is illustrated.

Anion chromatography system for the determination of glyphosate was described. Ion chromatograph was carried out by suppressed conductivity detection (DX-100). The eluent contained 9mmol-l Na2CO3 and 4mmol-l NaOH. The detection limit was 0.042μgml (S/N53). The relative standard deviation was 1.99% and the correlation coefficient of the calibration curve for area was 0.9995. The linear range was 0.042～100μgml. Common inorganic ion and organic acids did not interfere. The recovery was 96.4～103.2%. The method was simple, rapid, reliable and inexpensive.

A method has been developed for the simultaneous determination of a range of aromatic amines using cation-exchange chromatography performed on a standard ion chromatography column using d.c. amperometric detection. The analytes separated were 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA), aniline, o-toluidine, benzidine, p-chloroaniline, 4,49-diaminodiphenyl (4,49-DDP), m-nitroaniline and 1-naphthylamine. A Dionex CS12 column was used with gradient elution from an initial eluent of 5% CH CN+35mM H2SO4 to 27% CH3CN+35 mM H2SO4 (at 35min). Detection limits in the range 2.6-22.6μg/l were observed for all analytes except m-nitroaniline, for which the detection limit was 201μg/l. Linear calibrations and good precision were observed and the method was applied to the determination of benzidine, pchloroaniline and 1-naphthylamine in wastewater samples. Further, the separation was also used (after some modification of the eluent conditions) for the determination of 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6-TDI) and 4,49-methylenediphenyl diisocyanate (4,49-MDI) after their hydrolysis to 2,4-TDA, 2,6-TDA and 4,49-DDP. Detection limits for 2,6- and 2,4-TDI and 4,49-MDI were 3.8, 8.2, and 11.2μg/l, respectively. The method was applied to the determination of diisocyanates in air.

Columns suitable for use in anion chromatography can be prepared by coating a packed reversed-phase HPLC column (C silica or polystyrene particles) with a cationic surfactant. The efficiency is improved dramatically by first coating the 18 column with a nonionic surfactant and then subsequently with the cationic surfactant. The thickness of the first coated layer as well as the chemical structure of the surfactant have a major effect on the column performance. Actual separations are included to demonstrate the convenience and practical use of the coated columns. Using this approach, columns with 12 900 theoretical plates for the 15-cm column (or 86 000 plates/m) were produced, giving well shaped peaks with an average asymmetry factor of 1.09. The coated layers were found to be stable, giving retention times with an average relative standard deviation of 1.6% for 12 consecutive runs.

New findings are reported on simple ways to modify an ordinary HPLC column to obtain efficient ion chromatographic (IC) separations. Permanently coating a column with an ionic surfactant is known to produce an effective column for IC.We now show that incorporation of a nonionic surfactant in the coating, or coating in separate layers, results in a dramatic reduction of ion retention times and gives sharper peaks. Dynamic coating by incorporating a small amount of an alcohol, diol or zwitterion in the aqueous mobile phase permits good separations of alkanecarboxylic acids. A mobile phase containing a quaternary ammonium cation and a zwitterion anion provides excellent separations of common anions on a silica C column. An aqueous eluent containing a mixture of a zwitterion 4-(2-hydroxyethyl) acid and methanesulfonic acid 18 can be used in conjunction with a standard cation exchange column. After passing through a membrane suppressor, the mobile phase has a slightly acidic pH, permitting divalent transition metal ions (as well as others) to be detected by conductivity.