Showing papers in "Chromatographia in 1982"
TL;DR: Porous glassy carbon (PGC) as discussed by the authors is a new carbon for liquid and gas chromatography, which is made using a porous template filled with carbonizable resin.
Abstract: A new carbon for liquid and gas chromatography, called “porous glassy carbon” (PGC) is described. The material is made using a porous template filled with carbonizable resin. After firing in an inert atmosphere the template is removed. PGC has been made with surface area ranging from 20 m2/g to 400 m2/g. It is of adequate strength for gas and high-performance liquid chromatography. In gas chromatography it is similar to the commerical graphitized thermal carbon black (GTCB) “Carbopack B”, but has somewhat less retention per unit surface area and is much more robust. It gives symmetrical peaks for hydrocarbons with k′-values up to at least 100. In liquid chromatography it is similar to the GTCB's coated with pyrolytic carbon described by Guiochon. It behaves as a strong reversed phase adsorbent. Fairly good peak symmetry is maintained for k′-values up to at least 10 but trace additives to the eluent may be necessary to control peak asymmetry. PGC has considerable potential as a new packing material in both gas and liquid chromatography.
183 citations
TL;DR: In this article, the stepwise procedure described previously for the selection of optimal mobile phase compositions in reversed phase liquid chromatography (RPLC) is improved in two ways: the optimization criterion is modified to account for variations in analysis time, and the iterative approach to the optimal solvent composition makes a more efficient use of previous data.
Abstract: The stepwise procedure described previously [1] for the selection of optimal mobile phase compositions in reversed phase liquid chromatography (RPLC) is improved in two ways. The optimization criterion is modified to account for variations in analysis time. The iterative approach to the optimal solvent composition makes a more efficient use of previous data. An example illustrates the resulting gain in speed and accuracy.
147 citations
TL;DR: In this article, a reaction detector with non-segmented flow in open tubes as reaction track is described, where the open tubes are arranged in a three dimensional coiled structure by knitting.
Abstract: A reaction detector with non-segmented flow in open tubes as reaction track is described. To minimize peak broadening the open tubes are arranged in a three dimensional coiled structure by knitting. At low volume flow rates the h-values in these open tubes are independent of flow rate and are significantly lower than predicted by theory. The applicability of this reactor for classical colorimetric detection with corrosive reagents is shown.
142 citations
TL;DR: In this article, a stepwise gas extraction procedure is described for quantitative gas chromatographic analysis of volatile compounds in solid and liquid samples, which can be carried out with the same equipment, provided a pressure and time controlled sampling system is used.
Abstract: A stepwise gas extraction procedure is described for the quantitative gas chromatographic analysis of volatile compounds in solid and liquid samples. This procedure is a modification of the usual headspace analysis and can be carried out with the same equipment, provided a pressure and time controlled sampling system is used. This procedure is called ‘Multiple Headspace Extraction (MHE)’ therefore. This method has first been developed for the analysis of monomers in polymers and residual solvents in printed films, but it is shown that can be applied to various other sample types also including even liquid samples.
125 citations
TL;DR: In this article, the effect of the properties of the silica gel matrix, and of the octadecylsilane used, on the chromatographic selectivity of C18 bonded phases is described.
Abstract: The effect of the properties of the silica gel matrix, and of the octadecylsilane used, on the chromatographic selectivity of C18 bonded phases is described. Preparation of bonded phases with monochlorodimethyloctadecylsilane is easier because absolute water exclusion is not required in this case. The surface coverage (μmol/m2) is smaller than with dichloromethyl- or trichlorooctadecylsilanes, but in these cases a secondary silanization with HMDS is essential to remove newly formed silanol groups. Bonded phases on Si 60 give the largest amount of hydrocarbon per unit column volume, large k′ values and good selectivity, however, surface coverage and efficiency of these packed columns is less than with Si 100 silica. The chemical properties of the silica surface also influence bonded phase selectivity. Bonded phases should not be compared with only a single eluent, because properties of bonded phases differ with test solutes and test conditions, i.e. eluent composition.
104 citations
TL;DR: In this paper, a simplified theoretical model for the detector response is suggested on the basis of detailed studies of the concentration changes in the eluted mobile phase, and a combination of two UV absorbing probes with different charge gives a considerable improvement of the response for samples with low retention.
Abstract: Compounds without own detector response can be detected and quantified by a UV-absorbing or fluorescent, ion-pairing probe in reversed-phase liquid-solid systems. Charged as well as uncharged samples give response by affecting the distribution of the probe between the phases. The probe is usually a hydrophobic organic ion. It is included in the mobile phase, which also contains a counter ion and an ion of the same charge as the probe, both fairly hydrophilic. The choice of properties and concentrations of the hydrophilic ions is essential for the response since too low and too high distribution of the mobile phase ions to the adsorbent will make the system insensitive. It is with UV-absorbing probes possible to get a response corresponding to a molar absorptivity of more than 3000 for ionic samples. Fluorescent probes have given 3–5 times higher sensitivity. Uncharged compounds give as a rule lower response. A combination of two UV-absorbing probes with different charge gives a considerable improvement of the response for samples with low retention. A simplified theoretical model for the detector response is suggested on the basis of detailed studies of the concentration changes in the eluted mobile phase.
88 citations
TL;DR: In this paper, a simple rapid procedure is described for estimating optimum compositions of ternary mobile phase mixtures for the separation of samples by reversed-phase liquid chromatography (RPLC).
Abstract: A simple rapid procedure is described for estimating optimum compositions of ternary mobile phase mixtures for the separation of samples by reversed-phase liquid chromatography (RPLC). Retention data in two iso-eluotropic binary mobile phase mixtures (mixtures with equal retention times) are required to initiate the procedure. The logarithm of the capacity factor is assumed to vary linearly with the composition of isoeluotropic ternary mixtures formed by mixing the two limiting binaries. Using the product of resolution factors of adjacent peaks as the criterion, an optimum ternary composition is then calculated. After a chromatogram has been obtained with the predicted optimum ternary mobile phase, the procedure is repeated until no further improvement can be achieved. Examples of the application of the present procedure are described to illustrate its effectiveness.
84 citations
TL;DR: In this paper, various chiral chemically bonded stationary phases for the separation of amino acid enantiomers by high performance ligand exchange chromatography are described, synthesized by treating silica gel with 3-glycidoxypropyltrimethoxysilane and bonding L-amino acids such as L-azetidine carboxylic acid, L-pipecolic acid or L-phenylalanine to the product.
Abstract: Various chiral chemically bonded stationary phases for the separation of amino acid enantiomers by high performance ligand exchange chromatography are described. The phases were synthesized by treating silica gel with 3-glycidoxypropyltrimethoxysilane and bonding L-amino acids such as L-azetidine carboxylic acid, L-pipecolic acid or L-phenylalanine to the product. The best results were obtained with L-pipecolic acid as a fixed ligand. Nearly all common amino acid enantiomers could be separated.
81 citations
TL;DR: Eluate transfer between coupled columns by flow switching, backflushing of the pre-column, and other procedures of multidimensional chromatography are invaluable techniques to save analysis time to improve resolution, to gain more and better chromatographic information and to prevent contamination of main (high resolution) column and detectors such as ECD and TID as discussed by the authors.
Abstract: Eluate transfer between coupled columns by flow switching, backflushing of the pre-column, and other procedures of multidimensional chromatography (MDC) are invaluable techniques to save analysis time to improve resolution, to gain more and better chromatographic information and to prevent contamination of main (high resolution) column and detectors such as ECD and TID. It is of advantage to maintain the coupled columns at different temperatures. Double oven instruments should therefore be used with advantage in multidimensional gas chromatography (MDGC). Flow switching can be done in between and after the system of coupled columns. Also, reactors can be coupled to high resolution columns with advantage [5].
79 citations
TL;DR: In this paper, the solubility parameter concept is briefly discussed and used to explain some of the current features of liquid partition and adsorption chromatography, and some practical rules for the selection and operation of stationary and mobile phase systems are formulated.
Abstract: The solubility parameter concept is briefly discussed. It is then used to explain some of the current features of liquid partition and adsorption chromatography. Various phase systems are discussed on the basis of three characteristics.retention, selectivity (the general separation power of a system) andspecificity (increased separation power towards certain pairs of solutes). The emergence of two essentially different techniques, the ‘normal phase’ and ‘reversed phase’ modes, will appear as a logical consequence of simplified theory. It also becomes obvious why ‘reversed phase’ applications are so much more numerous. Some suggestions are given for the development of new stationary phases and the improvement of existing ones. The usefulness of the solubility parameter concept to predict the solvent strength of mixed eluents in reversed phase liquid chromatography (RPLC) is demonstrated. Some practical rules for the selection and operation of stationary and mobile phase systems are formulated.
79 citations
TL;DR: In this paper, the synthesis of methylphenylpolysiloxane polymers and their use in the preparation of crosslinked, non-extractable stationary phases for fused-silica capillary columns are described.
Abstract: The synthesis of methylphenylpolysiloxane polymers and their use in the preparation of crosslinked, non-extractable stationary phases for fused-silica capillary columns are described. By preparing more viscous phenyl-containing polymers than are commercially available, stationary phase films of these polymers could be efficiently coated on fused-silica capillary columns and stabilized by a free radical crosslinking mechanism using peroxides. Four methylphenylpolysiloxane polymers containing different phenyl concentrations were prepared. These included three polymers containing 50% phenyl and one polymer containing 70% phenyl. Two of the 50% phenyl polymers had one phenyl and one methyl group attached to each silicon atom. One of these also had 1% vinyl incorporated. The third 50% phenyl polymer was synthesized in such a way that one half of the silicon atoms had two phenyl groups attached while the rest contained dimethyl groups. The 70% phenyl polymer also had 4% vinyl incorporated. Due to the intrinsic thermal stability of these phenyl phases and the enhanced film stability achieved by crosslinking, the 70% phenyl phase could be utilized up to 400 °C. Using the methods described in this paper, highly efficient and thermally stable fused silica capillary columns coated with crosslinked methylphenylpolysiloxane stationary phases can be successfully prepared.
TL;DR: In this article, a pre-and post-column reaction is performed using a divinylbenzene-styrene copolymeric sorbent as packing material for both pre and analytical columns.
Abstract: A specific HPLC method has been developed for the trace analysis of lower chlorinated aromatic compounds. The method consists of an on-line preconcentration and a post-column reaction step. On-line preconcentration of mono- and dichlorophenols from aqueous samples has been performed using PRP1, a divinylbenzene-styrene copolymeric sorbent as packing material for both pre-and analytical column. Enrichment factors of over 300 were obtained compared to regular (100 μl) loop injections, even for the highly polar monochlorophenols. After reversed-phase separation, post-column photochemical dechlorination is carried out directly in the eluent stream, using a photochemical reactor. Upon dechlorination, fluorescent products are formed, which can be detected selectively. The resulting fluorescence signal shows a linear response to the quantity of solute present over 2 to 3 orders of magnitude (correlation coefficients: 0.990–0.98). For the mono- and dichlorophenols, the detection limit of the photoconversion method is in the lower nanogram range. The method is especially suitable for the analysis of complex matrices such as effluent water samples or biological fluids containing traces of the polar chloroaromatic compounds together with large amounts of other constituents, which interfere when using more general methods of detection like UV absorption. The potential of this technique for automation has been demonstrated by using a microprocessor-controlled column switching unit.
TL;DR: In this article, a linear dependence of the logarithmic retention factor on the carbon number for homologous series in reversed-phase chromatography was analyzed. And the results showed that at fixed mobile phase composition and temperature the free energy increments due to methylene groups upon retention by alkyl-silica stationary phases are identical.
Abstract: Linear free-energy relationships are manifest in the linear dependence of the logarithmic retention factor on the carbon number for homologous series in reversedphase chromatography and allow the comparison of the free-energy increments of substituents for retention of a given elute by different stationary phases. Three methods were used for such comparison. In the first two, methylene group selectivities obtained from retention data obtained with homologous series on different hydrocarbonanceous bonded phases were compared by using different approaches. In the third method the energetics of retention of the end groups such as phenyl-, bromo- and disulfide-moieties of homologous series were examined. The results show that at fixed mobile phase composition and temperature the free energy increments due to methylene groups upon retention by alkyl-silica stationary phases are identical. Only hydrocarbonaceous bonded phases with short (C1–C2) alkyl chains or functional groups of unusual shape show consistent differences from octyl- or octadecyl-silicas. The results broaden the theoretical basis for the development of quantitative structure-retention relationships to be used for the prediction or interpretation of retention data in reversed-phase chromatography.
TL;DR: In this paper, a chiral counter ion, N-benzoxycarbonyl-glycyl-L-proline (ZGP), was used for separation of enantiomers of amino alcohols with LiChrosorb DIOL as the solid phase.
Abstract: A new chiral counter ion, N-benzoxycarbonyl-glycyl-L-proline (ZGP), added to the organic mobile phase (dichloromethane) has been used for separation of enantiomers of aminoalcohols with LiChrosorb DIOL as the solid phase. Separation factors of 1.2 to 1.4 for enantiomers of β-adrenergic blocking agents (e.g., alprenolol, metoprolol and propranolol) were obtained. Some structural requirements in the solutes and the counter ion essential for chiral resolution were observed. The retention was regulated by the concentration of counter ion or by the addition of triethylamine to the mobile phase. The chiral counter ion was utilized to determine the enantiomeric impurity of less than 0.1% in S-alprenolol and for the analysis of propranolol enantiomers in plasma samples.
TL;DR: In this paper, a profile analysis of trace impurities of illicit heroin samples has been developed, which consists of extracting the impurities by toluene from acidic solution and examination by capillary GC.
Abstract: Glass capillary gas chromatographic methods for profile analysis of trace impurities of illicit heroin samples have been developed. The procedure consists of extracting the impurities by toluene from acidic solution and examination by capillary GC. Derivatized and nonderivatized extracts of illicit heroin from different sources are reported. The reproducibility of the procedure and the detection with FID and N-FID are studied. Results obtained by application of the profiling procedure, as an additional pattern for comparison of samples in forensic casework, have shown the distinct advantage of this method.
TL;DR: In this article, the Aufspaltung des Eluenten in zwei Phasen is described, in which the gebundenen Aminogruppen zuruckzufuhren, die sonst nicht an der Trennung beteiligt sind.
Abstract: Die Zuckertrennung mit chemisch gebundenen Aminophasen beruht auf einer Verteilung der Proben zwischen einer stehenden wasrigen Phase und dem bewegten Eluenten, einem Acetonitril-Wasser-Gemisch. Die Aufspaltung des Eluenten in zwei Phasen ist auf die gebundenen Aminogruppen zuruckzufuhren, die sonst nicht an der Trennung beteiligt sind. Mit der Aminophase erhalt man so eine Belegung von 0,15 g/g stationarer Phase. Die Belegung steigt mit zunehmendem Stickstoffgehalt der gebundenen Phase. Bei der Triamiphase erhalt man eine Belegung von 0,25 g/g. Die k'-Werte der Proben steigen — bei gleicher Eluentenzusammensetzung — mit der Wasserbelegung an. Daher kann zur Reduzierung der Analysenzeit, bei identischer Auflosung, der Wassergehalt im Eluenten bis auf das Doppelte-verglichen mit der Aminphase-erhoht werden. Dies erleichtert die Zuckeranalyse, da die Loslichkeit der Proben im Eluenten steigt.
TL;DR: In this paper, the effect of the γ-radiation crosslinking-procedure was investigated in comparison to the peroxid method in regard of: decrease of stationary phase content by solvent rinsing, separation efficiency, tailing behaviour, and bleeding of the columns obtained.
Abstract: Crosslinking of alkylpolysiloxane stationary phases, especially in thick film capillary columns, is useful for the homogenous coating of fused silica and pretreated alkaliglass surfaces. The films of the stationary liquid are immobilized against solvent rinsing using CH2Cl2, pentane, and acetone, and maintain homogenity even at high temperature. Various doses of γ-radiation from a60Co. source were used for the crosslinking instead of the thermal peroxid treatment recently described by other authors. The effect of the γ-radiation crosslinking-procedure was investigated in comparison to the peroxid method in regard of: decrease of stationary phase content by solvent rinsing, separation efficiency, tailing behaviour, and bleeding of the columns obtained. Similar results as with the cumylperoxid-treatment were achieved using the γ-radiation-method. By γ-radiation no polar functional groups or moleculs are introduced into the stationary phase, however, as with the peroxid method. Less than 20% of the various stationary liquids are usually removed from the columns by solvent rising after crosslinking using both methods depending on the doses of radiation and the cumylperoxid concentration applied respectively.
TL;DR: A new method for the analysis of inorganic anions is presented that uses the most conventional liquid chromatographic system and the most common detector and allows detection of all anions.
Abstract: A new method for the analysis of inorganic anions is presented. It uses the most conventional liquid chromatographic system (reverse-phase chromatography) and the most common detector (ultraviolet). The nature of the ammonium ions used and their counter ions lead to different selectivities. The use of the indirect photometry allows detection of all anions.
TL;DR: In this paper, the mass detector was investigated as an alternative to RI detection for carbohydrate and lipid analyses with high pressure liquid chromatography, and it was found to be more sensitive than most RI detectors and, as gradient elution could also be carried out, the resulting chromatograms showed improved resolution.
Abstract: The mass detector was investigated as an alternative to RI detection for carbohydrate and lipid analyses with high pressure liquid chromatography. The instrument was found to be more sensitive than most RI detectors and, as gradient elution could also be carried out, the resulting chromatograms showed improved resolution.
TL;DR: In this paper, a new class of stationary phases for high-performance liquid chromatography (HPLC) is described which simulate in their retention chracteristics ion-pair separations.
Abstract: A new class of stationary phases for high-performance liquid chromatography (HPLC) are described which simulate in their retention chracteristics ion-pair separations. The phases consist of mixtures of chemically dissimilar ligands chemically bonded to silica supports. These phases are largely reversed-phase in nature, but also contain significant ion-exchange properties, at levels similar to those demonstrated to occur in ionpairing. By bonding both ionic and hydrophobic groups in the correct proportions, mixed retention mechanisms are created, resulting in unique selectivities, while retaining the excellent stabilities and efficiencies characteristic of bonded phases. The ratio of hydrophobic to ionic character can be controlled during the synthesis, and is used as a tool to vary the stationary phase, rather than only the mobile phase, to effect the separation desired. The synthesis and behavior of both anionic and cationic/reversed-phase materials are described, and are applied to the simultaneous separation of nucleosides and nucleotides, and to the separation of the catecholamines.
TL;DR: In this paper, the theory of band broadening of reaction detectors and some criteria for the choice of the proper type are brieffly discussed and it seems that with a proper construction of the phase separators segmented systems have a wider range of applicability.
Abstract: Reaction detectors are considerably enhancing the application potential of HPLC particularly when dealing with trace analysis in complex matrices. In principle one distinguishes between segmented and non-segmented reactor system. The theory of band broadening of these designs and some criteria for the choice of the proper type are brieffly discussed. It seems that with a proper construction of the phase separators segmented systems have a wider range of applicability. Applications of reaction detectors in the areas of pharmaceutical and environmental analysis are discussed.
TL;DR: In this paper, the stereoselectivity arising from inclusion in β-cyclodextrin molecules is found to be significant (α = 1.02÷1.05) only for the compounds showing at the asymmetric carbon atom the presence of first, an intact carboxylic group and second, a functional group capable of hydrogen bonding with the hydroxyl groups of β-cycle.
Abstract: β-Cyclodextrin is applied as the chiral component of the mobile phase in a systematic study of the resolution —into enantiomers — of mandelic acid and its derivatives by reversed-phase liquid chromatography. It is found that the stereoselectivity arising from inclusion in β-cyclodextrin molecules is significant (α=1.02÷1.05) only for the compounds showing at the asymmetric carbon atom the presence of first, an intact carboxylic group and second, a functional group capable of hydrogen bonding with the hydroxyl groups of β-cyclodextrin. Results are discussed in the light of the three-point attachment model of stereoselectivity as well as of the structure of the inclusion complexes.
TL;DR: The development of a computer-aided rapid-scanning detector for HPLC based on the linear photodiode array UV-visible spectrophotometer and the novel use of second and higher derivative spectra for the qualitative characterisation of drugs and contaminants separated by HPLC are described.
Abstract: The development of a computer-aided rapid-scanning detector for HPLC based on the linear photodiode array UV-visible spectrophotometer is described. Chomatograms monitored at up to three wavelengths, with automatic capture of spectra for eluted peaks and post-run processing of spectral data to generate log10 (A) spectra, second derivative and fourth derivative spectra, are described. Methods are reported for the analysis of forensic samples of diacetylmorphine (heroin) in the presence of the degradation products and potential contaminants caffeine, papaverine, 6-acetylcodeine, thebaine, 6-acetyl-morphine, procaine and morphine separated by HPLC. The novel use of second and higher derivative spectra for the qualitative characterisation of drugs and contaminants separated by HPLC is described.
TL;DR: The factors influencing the performance of the reactor, such as contribution to peak broadening and optimization of the photochemical reaction, are discussed leading to a new and versatile design.
Abstract: It is well known that UV-absorbing substances can be transformed into fluorescent substances by irradiation with UV-light. This principle is used for HPLC by means of a post-column reactor. The factors influencing the performance of the reactor, such as contribution to peak broadening and optimization of the photochemical reaction, are discussed leading to a new and versatile design.
TL;DR: In this paper, a photochemical reaction method for the on-line fluorimetric detection of natural vitamin K homologs was developed, and the results indicate that the method is 4 times more sensitive than UV detection, and at least as selective as fluorescence detection after post-column chemical reduction.
Abstract: A new photochemical reaction method for the on-line fluorimetric detection of natural vitamin K homologs was developed. In addition to its high sensitivity, the method features an interesting selectivity for the determination of these compounds in a complex matrix such as human serum. The formation of different photolysis products as a function of reaction conditions, and the optimalisation of a segmented flow reaction system will be discussed. The results indicate that the method is 4 times more sensitive than UV detection, and at least as selective as fluorescence detection after post-column chemical reduction.
TL;DR: The use of a linear photodiode array as the elemental detector for an HPLC UV/Visible detector can provide both quantitative and semi-qualitative information for the analytical chemist.
Abstract: Use of a linear photodiode array as the elemental detector for an HPLC UV/Visible detector can provide both quantitative and semi-qualitative information for the analytical chemist. This paper discusses the primary needs of the analyst, the goals to be achieved in hardware and software, and possible applications for such a detection system.
TL;DR: The dependence of the chloride distribution coefficient on the co-ion of solutions of different alkali fluorides up to 11M is tested on the strongly basic anion-exchange resin AG1-X10 as mentioned in this paper.
Abstract: The dependence of the chloride distribution coefficient on the co-ion of solutions of different alkali fluorides, MF, up to 11M is tested on the strongly basic anion-exchange resin AG1-X10. Under the same experimental conditions the distribution coefficient decreases in the following order for M+: Na+>K+>Rb+>Cs+. This can be explained by the different co-ion-chloride interactions. The consequence of this interaction for a chromatographic separation of chloride is shown with 5M KF and CsF solutions, used as eluants. Depending on the fluoride concentration, the distribution coefficient passes through a minimum value to increase again at higher electrolyte concentration. The non-exchange electrolyte in the resin phase is responsible for this effect. In addition, the bromide and the iodide distribution coefficients up to 10M KF solutions are determined. One results is that the selectivity coefficient between halide ions increases at higher electrolyte concentrations.
TL;DR: From these equations a linear relationship between Van der Waals' volume and connectivity index is obtained which indicates that the two parameters are equivalent.
Abstract: The relationships between retention index and Van der Waals' volume and between retention index and connectivity index have been studied for 58 different alkanes (C1−C9) on squalane. The correlation coefficient for the former is higher than for the latter. From these equations a linear relationship between Van der Waals' volume and connectivity index is obtained which indicates that the two parameters are equivalent. A simple method for calculating the Van der Waals' volume of alkanes is proposed.
TL;DR: In this paper, a silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-amide-N″-polypropyltrimethoxyselane (3), N-(3-triectoxysilanepropyl)-N, N-diacetic dimethylester (4), N(3-trisodiumsilanolatepropyl)-ethylenediamine (5), N
Abstract: A silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-aminopropyltrimethoxysilane (2), N-aminoethyl-N′-aminoethyl-N″-aminopropyltrimethoxysilane (3), N-(3-triethoxysilanepropyl)-N, N-diacetic dimethylester (4), N-(3-trisodiumsilanolatepropyl)-N, N-diacetic acid disodium salt (5) and N-(3-trisodiumsilanolatepropyl)-ethylenediamine-N, N′, N′-triacetic acid trisodium salt (6). The reaction of silanes 1–4 with the silica was carried out under anhydrous conditions (procedure A). Silanes 1–6 were subjected to surface modification under essentially hydrous conditions applying a two-step procedure (procedure B). Procedure B is much simpler to perform and allows binding of high and definite amounts of silane onto the surface. Complexation of all bonded phases with Cu2+ was examined by measuring the sorption isotherms at constant pH. The pH-dependence of Cu2+ uptake at constant Cu2+ concentration was evaluated. Tests on the chemical and chromatographic stability of the packings showed that only the silicas with bonded iminodiacetate and ethylenediaminetriacetate groups remain hydrolytically stable. Retention of aliphatic and α-amino acids on these two packings was found to be mainly controlled by the pH and the ionic strength of the eluent.
TL;DR: In this article, the retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are compared. And the influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on methylsilicone liquid phases is discussed.
Abstract: The influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on the retention index values of hydrocarbons on methylsilicone liquid phases is discussed. Data obtained on methylsilicones and squalane are compared. Retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are listed.