New polar bonded liquid chromatography phase

Grushka, Eli; Kikta, Edward J.

doi:10.1021/ac60347a054

Cited by 54 publications

(18 citation statements)

References 21 publications

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“…The most widely accepted figure [I 51 calculated for the number of silanol groups available for bonding is about 4 Si-OH groups/100A2. Measured levels of coverage reported in the literature [7,16,17], compare well with this figure, generally being in the region of 1-4 groups/100 A 2 for phases prepared under conditions which should not lead to polymerization (absence of water). It should be noted that reaction of all three Si-CI groups in a trichlorosilane with surface Si-OH groups seems to be impossible on steric grounds [9,18] and that steric interaction between bulky organic groups may prevent derivatization of all Table 1 Bonded Phases Prepared adjacent silanol sites.…”

Section: Coverage Levelssupporting

confidence: 82%

HPLC with chemically bonded stationary phases. 1. ω‐hydroxyalkyl silicas

Matlin¹,

Tinker²

1979

J. High Resol. Chromatogr.

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Section: Coverage Levelssupporting

confidence: 82%

HPLC with chemically bonded stationary phases. 1. ω‐hydroxyalkyl silicas

Matlin¹,

Tinker²

1979

J. High Resol. Chromatogr.

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“…Combining eqs 4 and 7 yields sum = Iref(RCLF, + RCLF,) (8) where Zref is the photocurrent using the reference solvent, and RCLF, and RCLF2 are the relative collected light flux a t wavelengths X1 and X2, respectively, in the context of Figure 3. Changing the solvent refractive index by changing the temperature, mobile-phase composition, or pressure results in new relative collected light flux conditions, RCLFB and RCLF4, for wavelengths X1 and X2, respectively, to yield sum,,,, = Iref(RCLFI -RCLF, + RCLF, -RCLF4) (9) where sumcurr is the signal measured relative to the baseline condition before and after the change in solvent conditions, i.e., baseline-corrected sum signal (23).…”

Section: Theorymentioning

confidence: 99%

Thermal gradient microbore liquid chromatography with dual-wavelength absorbance detection

Renn¹,

Synovec²

1991

Anal. Chem.

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and consequently that this process (which may involve the formation of carbon-carbon double bonds or of cross-linking between the polymer chains) or a similar one might be more common in the case of ion bombardment than in the case of atom bombardment. The exaggerated difference in time dependence behavior for ion beams, as compared to atom beams, observed for PTFE, as compared to PET, certainly suggests that particle-surface electronic interactions are a major contributor to this preferential sputtering of fluorine. CONCLUSIONSComparison of spectral time-dependence behavior for PET and PTFE has provided data concerning the nature of polymer degradation during particle bombardment. In particular, electronic particle-surface interactions have been shown to be a key contributing factor to degradation. In PET, this degradation is by straightforward physical degradation (random segmentation of polymer chains), which is accelerated by the use of charged primary particles. For PTFE, in addition to this process, an additional chemical degradation mechanism operates, which is, to a large extent, the consequence of electronic particle-surface interactions. This involves the preferential sputtering of fluorine and is manifested by the observation of a rise in peaks with a low fluorine to carbon ratio. At doses less than 1013 particles cmV2, this degradation mechanism may be nearly eliminated by the use of primary neutral particles rather than charged particles.Theoretical relationships are derived relating changes in the refractive index of the mobile phase in liquid chromatography to aperture limited absorbance measurements as applled to a single fiber-optic two-wavelength detector. The detection system was designed for remote sensing in thermal gradient microbore liquid chromatography (TG-pLC). TG-pLC was demonstrated with a reversed-phase separation of an unleaded gasoline sample for a temperature gradient of 25-150 OC over 30 min. The unique two-wavelength difference detection method, along with the single fiber-optic construction, virtually eliminated baseline drift associated with thermal Induced refractlve index ( R I ) aberrations. The detector provides a solution to R I aberrations not only for TEMLC but also for mobile-phase gradient liquid chromatography (MPG-LC) and other flow methods such as flow injection analyds (FIA). The advantages of TG-pLC are presented, including gradient separation capability for MLC, effective control of retention tlme comparable to MPG-LC, and separation efflclency over 72 000 theoretical plates/m using 5-pm packing material.

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“…Several authors (Ref. [48][49][50] showed that retention orders are, in general, function of the solute solubilities in the mobile phase. In order words, in reverse phase chromatography, molecular interactions between the solutes and stationary phase ("solvophobic interactions") play an important part in separations (Ref.…”

Section: ~ ~)mentioning

confidence: 99%

Theoretical and experimental aspects of fractionation mechanisms in liquid chromatography on macromolecular stationary phases (gel or bonded chains)

Lecourtier¹,

Audebert²,

Quivoron³

1979

Pure and Applied Chemistry

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Abstract-In a preliminary part, we deal with the partition mechanism of low or high molecular weight solutes, by selective dissolution in swollen gels. After summing up the theoretical expressions, we present some experimental evidences for a fractionation mechanism based on such a phenomenon, which may interfere , in many cases, with the classical steric exclusion effect in GPC. Most of this paper is devoted to chemically bonded stationary phases which gained increasing importance in H.P.L.C., during the past few years. Owing to our previous works on gels, we theoretically studied the partition coefficient of low or high molecular weight solutes between a mobile phase and a stationary phase, constituted by macromolecular chains bonded to an inert surface. Variations of partition coefficient with the molecular sizes of solute, solvent and graft, and with the molecular interaction parameters between these species, are presented. In a complementary aspect, we describe the recent preparation of model chemically bonded phases of silica/polyethyleneoxide and silica/polystyrene types. The retention data obtained for various solutes on these bonded phases are discussed in terms of silica loading, grafting chain length, solute size and solvent nature. These theoretical and experimental studies lead to practical consequences concerning the relative parts of the dissolution effect into the grafted phase, the adsorption on the mineral support and the steric exclusion effect due to the residual porosity.

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New polar bonded liquid chromatography phase

Cited by 54 publications

References 21 publications

HPLC with chemically bonded stationary phases. 1. ω‐hydroxyalkyl silicas

HPLC with chemically bonded stationary phases. 1. ω‐hydroxyalkyl silicas

Thermal gradient microbore liquid chromatography with dual-wavelength absorbance detection

Theoretical and experimental aspects of fractionation mechanisms in liquid chromatography on macromolecular stationary phases (gel or bonded chains)

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