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.

In this paper, the separation and determination of four artificial sweeteners (aspartame, sodium cyclamate, acesulfame-K and sodium saccharin) by ion chromatography coupled with suppressed conductivity detector is reported. The four artificial sweeteners were separated using KOH eluent generator. Due to the use of eluent generator, very low conductance background conductivity can be obtained and sensitivity of sweeteners has been greatly improved. Under the experimental condition, several inorganic anions, such as F−, Cl−, NO3−, NO2−, Br−, SO42−, PO43− and some organic acid such as formate, acetate, benzoate, and citrate did not interfere with the determination.With this method, good linear relationship, sensitivity and reproducibility were obtained. Detection limits of aspartame, sodium cyclamate, acesulfame-K, sodium saccharin were 0.87, 0.032, 0.019, 0.045mg/L, respectively. Rate of recovery were between 98.23 and 105.42%, 99.48 and 103.57%, 97.96 and 103.23%, 98.46 and 102.40%, respectively. The method has successfully applied to the determination of the four sweeteners in drinks and preserved fruits.

Effect of mixed eluents which contain zwitterions such as 2-(N-morpholino)ethanesulfonic acid (MES), 3-(N-morpholino)propanesulfonic acid (MOPS), 2-(cyclohexylamino)ethanesulfonic acid (CHES) and 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS) and carbonate for suppressed conductivity ion chromatography (IC) were studied. The retention behaviors of all species were affected with different anion exchange columns when adding some zwitterion into carbonate eluent. The retention time of all species, especially those of strong retetion, was substantially shortened in AS14A column with either Na2CO3/CHES or Na2CO3/CAPS as eluent while a eneral increase in retetion time was noticed in AS9-HC column. Low pH of eluent was achieved when zwitterion was added.Without much changes in the background conductivity after suppressed, CHES could be used as suppressed conductivity ion chromatography eluent for determination of species unstable in strong alkaline, such as determination of phosphate in heteropoly acid (HPA) samples in AS14 column. The mixed eluent could also affect the selectivity when it was applied to the study of simultaneous separation of anions and cations in AS9-HC column by suppressed ion chromatography.

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.

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.

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.

A single-column method for the simultaneous determination of common cations and transition metals in the sample of beer is proposed in this paper. Eleven cations (copper, lithium, sodium, ammonium, potassium, cobalt, nickel, magnesium, calcium, strontium and zinc) were separated and analyzed by means of ion chromatography using an isocratic elution with 2.5mM methane sulfonic acid and 0.8mM oxalic acid as mobile phase, IonPac SCS1 (250mm

New technology is reported here for the synthesis of an effective weak acid-cation exchanger for ion chromatography. Monodisperse macroporous poly(ethylvinylbenzene-co-divinylbezene) (PEVB-DVB) beads of 5m diameter were prepared by a two-step swelling and polymerization method. Then carboxyl groups were introduced by polymerization of maleic anhydride with unreacted vinyl groups on the resin beads, followed by hydrolysis of the maleic anhydride groups. A column packed with the carboxylate beads was used to separate alkali and alkaline earth metal ions in a single isocratic run. Separations were found to be better than those with similar resin particles that are simply coated with maleic acid. The columns containing the new particles were 100% compatible with solvents commonly used for HPLC. Additionally, the prepared column was stable and could be used for a long time in a wide range of pH. The column gave good resolution, low detection limits and good repeatability for the separation of common cations. Satisfactory results were also obtained for separations of organic amines and of common cations in rainwater.

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.

A method is reported for the sensitive, simultaneous determination of mono-(MFA), di-(DFA), and trifluoroacetates (TFA) by ion chromatography (IC). These species were separated using a Dionex AS17 anion-exchange column employed with a potassium hydroxide gradient (via a Dionex EG40 eluent generator) and suppressed conductivity detection. The fluoroacetates were successfully separated from a range of inorganic and organic species likely to be present in environmental samples, in a total analysis time of 35min (including re-equilibration of the column). Detection limits for mono-, di- and trifluoroacetate were 21, 38 and 36μg/l, respectively, determined using a signal-to-noise ratio of 3, and were obtained using a sample injection volume of 50 l. Precision was less than 0.83% relative standard deviation (RSD) for replicate injections performed over a period of 30 days. The method was applied to the determination of monofluoroacetate in river water samples and also in carrot baits.