Polymer-coated cation-exchange stationary phases on the basis of silica

Pelcová

J of Separation Science

et al. 2008

We describe ion chromatography (IC) on open tubular cation exchange columns with a controllable capacity multilayered stationary phase architecture. The columns of relatively large bore (75 lm id) are fabricated by coating fused-silica capillaries with multiple layers of poly(butadiene-maleic acid) (PBMA) copolymer and crosslinking the deposited layers by thermally initiated radical polymerisation. Column capacity increases in a predictable manner with increase in the number of successively coated layers. Gravity flow with a modest head (a 2 m) can provide the desired separations within a reasonable period. We provide a minimalist configuration where no suppression is used, the sample is injected hydrodynamically as in CE, and detection is accomplished by an inexpensive homebuilt contactless conductivity detector or a capacitance to voltage digital converter. A 1 m long 75 lm bore column coated with two layers of PBMA allows gravity-flow open tubular IC to separate four alkali cations in a 10 min with a 1 mM tartaric acid (TA) eluent. Simultaneous separation of alkali and alkaline earth metal cations can be accomplished in less than 25 min using 1.75 mM pyridinedicarboxylic acid as an eluent. Contactless conductometric detection (C 4 D) allows LODs down to 150 nmol/L, corresponding to 30 fmol injections. Analysis of real water samples is demonstrated.

Section: Fast Repeated Analysis and System Performancesupporting

confidence: 80%

“…Kolla et al [16] were first to report an isocratic separation of mono-and divalent cations under isocratic elution condition on PBMA-based columns. Nair et al [17,18] have shown several separations of mono-and divalent cations using various combinations of complexing acidic eluents.…”

Section: Eluent Selectionmentioning

confidence: 99%

Gravity‐flow open tubular cation chromatography

Pelcová

J of Separation Science

et al. 2008

Journal of the Brazilian Chemical Society

“…[1][2][3][4] The preparation of phases may occur by cross-linking of a polymer initiated by a chemical agent 5,6 or by immobilization of pre-synthesized organic polymer onto chromatographic support particles. [7][8][9] This latter method is less expensive as does not require the use of specific highcost reagents.…”

Section: Introductionmentioning

confidence: 99%

Self-Immobilization of Poly(methyltetradecylsiloxane) onto Metalized Silica Particles as Stationary Phases for HPLC

Carvalho

Faria

2016

This work presents a study of the sorption of a pre-synthesized polysiloxane, poly(methyltetradecylsiloxane) -PMTDS, onto zirconized and titanized-silica particles that results in efficient stationary phases for reversed phase liquid chromatography. The sorbed materials, after 6 days at room temperature without any chemical or physical agent, denominated as self-immobilized stationary phase, present appropriate polymeric layer thicknesses that cover the metalized silica surfaces. The self-immobilization of polymer onto titanized silica particles produces more homogeneous polymeric coatings and stationary phases without silanophilic activity. Zirconized silica-based phases were more chemically resistant, despite their strong retention of basic solutes. In general, the chromatographic performance and chemical stability of metalized silica-based self-immobilized PMTDS phases were similar to conventional chemically bonded stationary phases.

J of Separation Science

“…A typical environmental case is given by the low amounts of NH þ 4 ion and the high concentrations of Na + that can be present in subsurface brines [1] in seawaters [2] or in waters to be intended for human consumption, treated or from wells. Since traditional cationexchangers (sulphonic [3], carboxylic [4] or silica gel [5]) have similar selectivity for Na + and NH þ 4 , it is not possible to achieve a sufficient resolution if the concentrations of the mentioned ions are too much different.…”

Section: Introductionmentioning

confidence: 99%

“…The use of weak, e.g. carboxylic-based silica cationexchangers allows the elution of Ba 2+ and Sr 2+ by mild acidic complexing agents such as tartaric acid as the eluents and nonsuppressed conductivity detection [8] or ion selective electrode detection [9], but with the high LOD imposed by the detection technique. Only new philosophies and technology in stationary phases development can answer to this demand [10] , spectroscopic techniques such as IPC-MS are usually preferred [11,12].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous determination of alkali, alkaline earths and ammonium in natural waters by ion chromatography

Bruzzoniti

Carlo

Fungi

2008

An ion chromatographic method has been developed for the determination of alkali (Li + , Na + , K + ), alkaline earths (Ca 2+ , Mg 2+ , Ba 2+ , Sr 2+ ) and ammonium ion in waters. The usual difficulties encountered during traditional cation-exchange separations (incomplete resolution for Na + and NH 4 + present in disproportionate concentration ratios) have been overcome tuning the selectivity of the separation by the introduction of 18-crown-6 ether in the mobile phase using an IonPac CS12A (15063 mm id) column. After a detailed study of the effect of mobile phase components on separation, a gradient elution from 26 mM methanesulphonic acid (MSA) with a step change at 9 min to 60 mM MSA (0.5 mM 18-crown-6) provided the required baseline separation for the eight selected analytes. The method developed provides the advantage of the determination, in the same analytical run, also of strontium and barium, which is usually performed by spectroscopic techniques. Within-day and between-day repeatability have been assessed, observing between-day RSD included between 0.3 and 1.8% for retention times and 0.6 and 7.2% for peak areas. The method has been finally tested for the analysis of water samples of different provenience (well, tanks, water system) and results compared with those obtained by the laboratory in charge of the control of drinking water for the city of Torino (Italy).