Formation mechanism of dip peaks in nonsuppressed ion chromatography

Abstract

The two dip peaks which were observed In nonsuppressed anion chromatography by using low pH eluent were Investigated In detail by conductivity and UV spectrophotometric detectors. The eluent anion fixed on the Ion-exchange resin was transferred to the sample water zone, and this rate was especially fast at the low pH of the eluent. Consequently, the first dip peak was caused by the Ion exclusion effect of the sample cation from the anion exchange resin and by the elution of the sample water. The second dip peak was caused by the "compensating effect" for the first dip zone and by the "absent effect" of the eluent anion eluted at the position of the second dip peak.

Potassium hydroxide eluent for nonsuppressed anion chromatography of cyanide, sulfide, arsenite, and other weak acids

“…Figure 1 shows a typical ion chromatogram of seven anions obtained with 1 mM potassium hydroxide as eluent. The first large negative peak is the "dip peak" which is caused by sample water, sample cations ion-excluded by the anion exchange resin, and an eluent anion (OH-) replaced by sample anions (23). This peak often interfere with anions which elute rapidly.…”

“…Organoarsenic compounds were not investigated, but the separation of arsenite from organoarsenic species should be possible since separation using the Dionex system and atomic absorption spectrometric detection were reported by Ricci et al (15). The peak of arsenate was broadened and overlapped with the "absent peak" of carbonate contained in the eluent as an impurity (17,23). Therefore, arsenate could not be determined accurately by this system.…”

Characterization of warfarin unusual peak profiles on oligoproline chiral high performance liquid chromatography columns

“…This result in desorption of some additive molecule migrating along the column to generate system peak. System peak also termed as pseudo peak, ghost peak, eigenpeak, vacancy peak, induced peak, dip peak, or perturbation peak has been studied since 1970s [34][35][36][37][38][39][40][41][42][43][44]. Levin and Grushka realized the system peaks were produced in relaxation process to a new state of equilibrium [41].…”

Effect of injection matrix concentration on peak shape and separation efficiency in ion chromatography

“…Generally, mobile phase components are selected such that they do not cause a detector response. Hence, no peak is observed at the retention time of the mobile phase component, but baseline disturbances known as system peaks may be observed [34][35][36]. The nearer an analyte peak elutes to system peak, the more it may be distorted [37,38].…”