Capillary Zone Research Articles

Influence of ignored and well-known zone distortions on the separation performance of proteins in capillary free zone electrophoresis with special reference to analysis in polyacrylamide-coated fused silica capillaries in various buffers☆II. Experimental studies at acidic pH with on-line enrichment

The separation of acidic and basic model proteins was studied in capillary free zone electrophoresis in a polyacrylamide-coated, electroosmosis-free capillary at pH below their isoelectric points (pI) using various buffers at pH 2.7-4.8 with UV detection at 200 nm. The separation performance was significantly dependent on the coating quality, which may even differ within the same batch of capillaries. In addition, a washing step with 2 M HCl and the storage of the capillary in distilled water was essential for the performance. For high efficiency and resolution the choice of buffer constituents was extremely important which is discussed in quantitative terms in Part I. The most promising buffers were ammonium acetate and ammonium hydroxyacetate at pH 4 (ionic strengths: 0.12 and 0.15 M, respectively) with plate numbers up to 1,700,000 plates/m, corresponding to a zone width (2sigma) of only 1 mm in a capillary with 40 cm effective length, when the injected samples were dissolved in a 10-fold diluted background electrolyte (BGE), a zone even narrower than those obtained in polyacrylamide gel electrophoresis, the characteristic feature of which is remarkably thin zones. In the experiment giving this plate number, the calculated variance for longitudinal diffusion was larger than all the other calculated variances (those for the width of the starting zone, Joule heating, sedimentation and the curvature of the capillary). Interestingly, the effect of capillary curvature was significant. In addition, the sum of all other imaginable variances (corresponding to various types of slow on/off kinetics and hyper-sharp peaks) was in the most successful experiments only 28-50% of the variance for longitudinal diffusion. One hundred- to two hundred-fold dilution of the BGE improved the detection limits and provided high precision in both migration times and peak areas with ammonium hydroxyacetate and ammonium acetate as background electrolytes. However, that high dilution increased the variance 140-400% for these buffers, respectively, at least partly due to conductivity or pH differences between the sample and buffer zones (hyper-sharp peaks). Sedimentation of the enriched sample, a factor that has not previously been treated theoretically or experimentally, was probably another reason for our finding that peak heights did not increase when the sample was dissolved in a buffer diluted more than 200-fold, although pH changes and in some cases thermal expansion in the capillary also may contribute. Loss of protein may occur at the ionic strength 0.01 and lower due to precipitation. Limits of detection were in the range 4-17 pmol of proteins with ammonium acetate as BGE. No indication of denaturation of proteins at pH 4 was observed. However, the separation performance at pH 3 was not satisfactory and loss of proteins was observed, possibly indicating such problems. The protein mobilities decreased unexpectedly from pH 4 to 3--a further indication of conformation changes.

Anatomical relations of root formation in strawberry

Anatomical relations of root formation are traced throughout the life cycle of the strawberry plant from the germinating seed up to the runners of the adult plant. Histological picture of the root changes a lot during the development of the plant. First the radicle of the germ grows to a main root, which makes branches into side roots and later adventitious roots are formed on the growing rootstock or rhizome. The anatomy of the different types of roots is also conspicuously different. First tiny branches appear relatively early after germination on the seedling's radicle, but soon the hypocotyl of the seedling thickens and develops side roots, which are already somewhat stronger. During this interval, the first true leaves are formed. The 4th or 5th of them being already tripartite, and the initiation of new roots extends into the epicotylar region of the shoot. The second years growth starts with the development of reproductive structures, inflorescences and runners starting from the axils of the new leaves. Near the tips of the runners below the small bunch of leaves, new root primordia are initiated. The tiny radicle of the germ develops a cortical region of 5-6 cell layers. Cells of the central cylinder are even smaller than the cortical parenchyma and include 3-4 xylem and 3-4 phloem elements as representatives of the conductive tissue. Roots originating from the shoot region are much more developed; their cortical zone contains 17-20 cell layers, whereas the central cylinder is about half as large. In the next year, new roots are formed at the base of the older leaves. These roots differ hardly from those of the last season in size and volume, however, they are recognised by colour and their position on the rhizome. The roots of the last year are dark, greyish-black, and grow on the lower third length of the rhizome, on the contrary, the new ones, on the upper region, are light brown. Roots starting from the shoot or rhizome are, independently from their age or sequence, mainly rather similar in size and diameter, thus being members of a homogenous root (homorhizous) system, i.e. without a main root. Plants developed and attained the reproductive phase develop in the axils of the leaves runners being plagiotropic, i.e. growing horizontally on the surface of the soil. The runners elongate intensely, become 150-200 mm, where some long internodes bear a bunch of small leaves and root primordia on short internodes and a growing tip. Runners do not stop growing, generally, further sections of 15-25 cm length are developed according to the same pattern, with small leaves on the tip. The growing tip of the runners is obliquely oriented, and small, conical root primordia are ready to start growing as soon as they touch the soil. The roots penetrate the soil, quickly, and pull, by contraction, the axis of the runner downwards, vertically, developing a new rhizome. The short internodes elongate a little and start developing adventitious roots. At the end of the growing season, the plantlets arisen on the rooted nods of runners are already similar to the original plants with homogenous root system. On the side of the adventitious roots, new branches (side-roots) are formed. The root-branches are thinner but their capillary zone is more developed being more active in uptake of water and nutrients. The usual thickening ensues later.

Anatomical relations of root formation in strawberry

Anatomical relations of root formation are traced throughout the life cycle of the strawberry plant from the germinating seed up to the runners of the adult plant. Histological picture of the root changes a lot during the development of the plant. First the radicle of the germ grows to a main root, which makes branches into side roots and later adventitious roots are formed on the growing rootstock or rhizome. The anatomy of the different types of roots is also conspicuously different. First tiny branches appear relatively early after germination on the seedling's radicle, but soon the hypocotyl of the seedling thickens and develops side roots, which are already somewhat stronger. During this interval, the first true leaves are formed. The 4th or 5th of them being already tripartite, and the initiation of new roots extends into the epicotylar region of the shoot. The second years growth starts with the development of reproductive structures, inflorescences and runners starting from the axils of the new leaves. Near the tips of the runners below the small bunch of leaves, new root primordia are initiated. The tiny radicle of the germ develops a cortical region of 5-6 cell layers. Cells of the central cylinder are even smaller than the cortical parenchyma and include 3-4 xylem and 3-4 phloem elements as representatives of the conductive tissue. Roots originating from the shoot region are much more developed; their cortical zone contains 17-20 cell layers, whereas the central cylinder is about half as large. In the next year, new roots are formed at the base of the older leaves. These roots differ hardly from those of the last season in size and volume, however, they are recognised by colour and their position on the rhizome. The roots of the last year are dark, greyish-black, and grow on the lower third length of the rhizome, on the contrary, the new ones, on the upper region, are light brown. Roots starting from the shoot or rhizome are, independently from their age or sequence, mainly rather similar in size and diameter, thus being members of a homogenous root (homorhizous) system, i.e. without a main root. Plants developed and attained the reproductive phase develop in the axils of the leaves runners being plagiotropic, i.e. growing horizontally on the surface of the soil. The runners elongate intensely, become 150-200 mm, where some long internodes bear a bunch of small leaves and root primordia on short internodes and a growing tip. Runners do not stop growing, generally, further sections of 15-25 cm length are developed according to the same pattern, with small leaves on the tip. The growing tip of the runners is obliquely oriented, and small, conical root primordia are ready to start growing as soon as they touch the soil. The roots penetrate the soil, quickly, and pull, by contraction, the axis of the runner downwards, vertically, developing a new rhizome. The short internodes elongate a little and start developing adventitious roots. At the end of the growing season, the plantlets arisen on the rooted nods of runners are already similar to the original plants with homogenous root system. On the side of the adventitious roots, new branches (side-roots) are formed. The root-branches are thinner but their capillary zone is more developed being more active in uptake of water and nutrients. The usual thickening ensues later.

Application of capillary electrophoresis- electrospray-mass spectrometry to the separation and characterization of isomeric lipopolysaccharides of Neisseria meningitidis.

A capillary electrophoresis-electrospray-mass spectrometry technique for the characterization of lipopolysaccharides (LPSs) was developed, permitting the separation of trace-level O-deacylated LPS isoforms for subsequent structural characterization using tandem mass spectrometry (MS/MS). The separation buffer and electrospray interface were optimized first using O-deacylated LPS samples from large-scale preparations. It was found that with microelectrospray or sheath-solution interface, we could separate LPS in anionic forms and detect them using either negative or positive ion mode MS. For negative ion detection mode MS, 30 mM morpholine with addition of 5% v/v methanol was employed as separation buffer. When positive ion detection mode MS was required, 10 mM ammonium acetate with addition of 5% methanol was used as separation buffer. The structural assignments obtained from MS/MS and capillary zone electrophoresis-electrospray-MS (CZE-ESMS) analyses enabled the identification of isomeric glycoforms. Application of this technique to the analysis of LPS from the galE mutants of Neisseria meningitidis strain BZ157 B5+ revealed the presence of isomeric glycoforms, in which the location of a functional group phosphoethanolamine was found to be in either inner core or lipid A-OH regions. The described technique was also applied to the analysis of LPS samples from the galE mutant of N. meningitidis strains F1576 A4+ and A4-. The occurrence of isomeric LPS glycoforms differing by the location or presence of neutral sugar residues, such as hexoses, can also be characterized using MS/MS.

A large-scale experiment on mass transfer of trichloroethylene from the unsaturated zone of a sandy aquifer to its interfaces

A large-scale experiment was conducted to investigate the transport of trichloroethylene (TCE) vapors in the unsaturated zone and to determine the mass transfer to the groundwater and the atmosphere. The experiment involved injection of 5 l of TCE in the unsaturated zone under controlled conditions, with multidepth sampling of gas and water through the unsaturated zone and across the capillary zone into underlying groundwater. The mass transfer of TCE vapors from the vadose zone to the atmosphere was quantified using a vertical flux chamber. A special soil water sampler was used to monitor transport across the capillary fringe. Experimental data indicated that TCE in the unsaturated zone was mainly transported to the atmosphere and this exchange reduced significantly the potential for groundwater pollution. The maximum measured TCE flux to the atmosphere was about 3 g/m 2/day. Observed and calculated fluxes based on vertical TCE vapor concentration gradients and Fick's law were in good agreement. This confirms that TCE vapor transport under the experimental conditions was governed essentially by molecular diffusion. TCE vapors also caused a lower, but significant contamination of the underlying groundwater by dispersion across the capillary fringe with a corresponding maximum flux of about 0.1 g/m 2/day. This mass transfer to groundwater is partly uncertain due to an inadvertent entry of some nonaqueous phase liquid (NAPL) from the source area into the saturated zone. Application of an analytical solution to estimate the TCE flux from the unsaturated zone to the groundwater indicated that this phenomenon is not only influenced by molecular diffusion but also by vertical dispersion. The mass balance indicates that, under the given experimental conditions (e.g. proximity of the source emplacement relative to the soil surface, relatively high permeable porous medium), nearly 95% of the initial TCE mass was transferred to the atmosphere.

Deterioration mechanisms of tuffs in Midas monument

Slightly weathered white and pink tuffs of the Midas monument have deterioration problems. In this study, depths and characteristics of the weathering zones developed within the tuffs are investigated through optical microscopy, X-ray diffractometry (XRD), chemical analyses, scanning electron microscopy (SEM) and some index parameters. Accelerated weathering tests including wetting–drying, freezing–thawing and salt crystallization are performed, and durability assessment methods are used to predict the durabilities of the tuffs. The findings are compared with field observations. By examining quantitative weathering indices and comparing them with thin section studies, it is found that thin section analyses of the crystals, LoI, and WPI are good indicators to quantify the depth of weathering for the tuffs. However, thin section studies have limited value for fine-grained tuffaceous matrix. The chemical weathering of the tuffs produces weathered zones that are 4.5-cm thick within the white tuff and 2.5-cm thick within the pink tuff. Physical weathering causes scaling of outer layers of the tuffs and fracturing of feldspars along their cleavage planes. However, variations of the index properties of the tuffs due to weathering are not so significant to quantify the weathering depths in the tuffs. Among the accelerated weathering tests, salt crystallization is found to be the most destructive environmental condition. Pigeon droppings rich in NO 3 1− are found to be the main source of soluble salt at the Midas monument. The salt transported up by capillary rise due to surface water causes spalling of the tuffs in the capillary zone. Surface water and salt of any kind in the close vicinity of the monument should be totally eliminated for the purpose of conservation. Field observations and the durability equations reveal that the white tuff is less durable than the pink tuff. Wet-to-dry strength ratio yields a better stone durability assessment among various durability methods used in this study.

Separation and determination of homovanillic acid and vanillylmandelic acid by capillary electrophoresis with electrochemical detection

A method of separation and determination of homovanillic acid (HVA) and vanillylmandelic acid (VMA) was developed based on capillary zone electrophoresis/amperometric detection with high sensitivity, good resolution and selectivity. In order to achieve complete separation and good response, several factors including pH, buffer concentration, separation voltage, detection potential and the length of separation capillary, were studied in detail. The method has been used to determine both HVA and VMA in human urine. Uric acid (UA) in human urine did not interference with their determination. The limit of detection of the method was 1.3×10 −6 mol/l (1.4 fmol) for HVA and 7.9×10 −7 mol/l (0.87 fmol) for VMA at a signal-to-noise ratio of 3.

Joule heating calculations in capillary zone electrophoresis.: Reply to “Recalculation of the temperature inside capillaries using high buffer concentrations” by Zhang et al.

Joule heating calculations in capillary zone electrophoresis.: Reply to “Recalculation of the temperature inside capillaries using high buffer concentrations” by Zhang et al.

Separation of Enantiomers by On-Line Capillary Isotachophoresis-Capillary Zone Electrophoresis

Separation of Enantiomers by On-Line Capillary Isotachophoresis-Capillary Zone Electrophoresis

Capillary zone electrophoresis/mass spectrometry of 5-aminolaevulinic acid and porphobilinogen.

A capillary zone electrophoresis/electrospray ionisation mass spectrometry (CZE/ESI-MS) method has been developed for the separation and detection of 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG). Capillaries were 70 cm long with an inner diameter of 75 micrometer and outer diameter of 375 micrometer. The buffer used was aqueous ammonium acetate (50mM, pH 5.2) with a co-axial 'make-up' flow of methanol/aqueous 0.1% formic acid (1:1 v/v) at a flowrate of 6 microL/min. A voltage of 20 kV was used for CZE and an ESI voltage of 3.5 kV. Full scan data was acquired over the range m/z 100-500 in positive ion mode, from which selected ion electropherograms were extracted; at m/z 132 for the protonated molecular ion of ALA and m/z 210 for the methylenepyrrolenine fragment ion of PBG. The protonated molecular ion of PBG, m/z 227, was found to be too facile to monitor, easily losing ammonia in the electrospray source and better sensitivity was achieved by monitoring the resulting fragment ion. The detection limits were circa 100 attomoles of ALA and 10 attomoles of PBG at a signal-to-noise ratio (S/N) better than 10, providing sufficient sensitivity for clinical use and offering advantages over existing techniques.

On-column conductive coating for thermolabile columns used in capillary zone electrophoresis sheathless electrospray ionisation mass spectrometry.

A simple and very mild approach for the application of a conductive layer for sheathless electrospray has been developed. A modified 'fairy dust' method is employed in which 2 microm gold particles are applied by a thin layer of silicone on shaped tips. This novel approach comprises fabrications at room temperature, under atmospheric pressure, and involves no etching, extensive cleaning or otherwise harsh conditions. With this approach, sheathless electrospray emitters have been fabricated from fused silica capillaries with chemically pre-modified inner walls and from heat-sensitive polypropylene hollow fibres. Long term stability for more than two weeks of continuous spraying has been achieved. Capillary zone electrophoresis/time-of-flight mass spectrometry demonstrates attomole sensitivity and no detectable band broadening. A comparison with a chromium-gold coated emitter in terms of chemical noise is made with continuous infusion experiments, showing no significant increase in background from the polymer involved.

Degree and Extent of Wetting Due to Capillary Rise in Soils

Increased water content of subgrade soils can lead to degradation of their quality and result in pavement distress. Pavement performance depends on the modulus of the compacted unsaturated subgrade soil as well as that of the underlying natural soil deposits. The soil modulus is a strong function of water content; therefore, changes in water content over the life of the pavement must be understood. In this study, it has been found that for a relatively near-surface groundwater table, significant potential exists for capillary rise into subgrade soils. For fine-grained soils in particular, the height of this capillary rise can be quite substantial. Results from capillary rise column experiments have shown that soils wetted above the groundwater table through capillary rise remain at a degree of saturation averaging about 60 percent. It has also been found that soil suction within this capillary zone must be determined through the use of soil water characteristic curves or direct measurement. The conventional assumption that negative pore water pressures can be estimated by backward extrapolation above the groundwater table of a line of slope γ w is only appropriate in a very thin region above the groundwater table, where soils are wetted to a degree of saturation of 85 percent or more.

Estimation of hydrocarbon biodegradation rates in gasoline-contaminated sediment from measured respiration rates

An open microcosm method for quantifying microbial respiration and estimating biodegradation rates of hydrocarbons in gasoline-contaminated sediment samples has been developed and validated. Stainless-steel bioreactors are filled with soil or sediment samples, and the vapor-phase composition (concentrations of oxygen (O 2), nitrogen (N 2), carbon dioxide (CO 2), and selected hydrocarbons) is monitored over time. Replacement gas is added as the vapor sample is taken, and selection of the replacement gas composition facilitates real-time decision-making regarding environmental conditions within the bioreactor. This capability allows for maintenance of field conditions over time, which is not possible in closed microcosms. Reaction rates of CO 2 and O 2 are calculated from the vapor-phase composition time series. Rates of hydrocarbon biodegradation are either measured directly from the hydrocarbon mass balance, or estimated from CO 2 and O 2 reaction rates and assumed reaction stoichiometries. Open microcosm experiments using sediments spiked with toluene and p-xylene were conducted to validate the stoichiometric assumptions. Respiration rates calculated from O 2 consumption and from CO 2 production provide estimates of toluene and p-xylene degradation rates within about ±50% of measured values when complete mineralization stoichiometry is assumed. Measured values ranged from 851.1 to 965.1 g m −3 year −1 for toluene, and 407.2–942.3 g m −3 year −1 for p-xylene. Contaminated sediment samples from a gasoline-spill site were used in a second set of microcosm experiments. Here, reaction rates of O 2 and CO 2 were measured and used to estimate hydrocarbon respiration rates. Total hydrocarbon reaction rates ranged from 49.0 g m −3 year −1 in uncontaminated (background) to 1040.4 g m −3 year −1 for highly contaminated sediment, based on CO 2 production data. These rate estimates were similar to those obtained independently from in situ CO 2 vertical gradient and flux determinations at the field site. In these experiments, aerobic conditions were maintained in the microcosms by using air as the replacement gas, thus preserving the ambient aerobic environment of the subsurface near the capillary zone. This would not be possible with closed microcosms.

Quantification of aerobic biodegradation and volatilization rates of gasoline hydrocarbons near the water table under natural attenuation conditions

Aerobic biodegradation and volatilization near the water table constitute a coupled pathway that contributes significantly to the natural attenuation of hydrocarbons at gasoline spill sites. Rates of hydrocarbon biodegradation and volatilization were quantified by analyzing vapor transport in the unsaturated zone at a gasoline spill site in Beaufort, South Carolina. Aerobic biodgradation rates decreased with distance above the water table, ranging from 0.20 to 1.5 g m−3 d−1 for toluene, from 0.24 to 0.38 g m−3 d−1 for xylene, from 0.09 to 0.24 g m−3 d−1 for cyclohexene, from 0.05 to 0.22 g m−3 d−1 for ethylbenzene, and from 0.02 to 0.08 g m−3 d−1 for benzene. Rates were highest in the capillary zone, where 68% of the total hydrocarbon mass that volatilized from the water table was estimated to have been biodegraded. Hydrocarbons were nearly completely degraded within 1m above the water table. This large loss underscores the importance of aerobic biodradation in limiting the transport of hydrocarbon vapors in the unsaturated zone and implies that vapor‐plume migration to basements and other points of contact may only be significant if a source of free product is present. Furthermore, because transport of the hydrocarbon in the unsaturated zone can be limited relative to that of oxygen and carbon dioxide, soil‐gas surveys conducted at hydrocarbon‐spill sites would benefit by the inclusion of oxygen‐ and carbon‐dioxide‐gas concentration measurements. Aerobic degradation kinetics in the unsaturated zone were approximately first‐order. First‐order rate constants near the water table were highest for cyclohexene (0.21–0.65 d−1) and nearly equivalent for ethylbenzene (0.11–0.31 d−1), xylenes (0.10–0.31 d−1), toluene (0.09–0.30 d−1), and benzene (0.07–0.31 d−1). Hydrocarbon mass loss rates at the water table resulting from the coupled aerobic biodgradation and volatilization process were determined by extrapolating gas transport rates through the capillary zone. Mass loss rates from groundwater were highest for toluene (0.20–0.84 g m−2 d−1), followed by xylenes (0.12–0.69 g m−2 d−1), cyclohexene (0.05–0.15 g m−2 d−1), ethylbenzene (0.02–0.12 g m−2 d−1), and benzene (0.01–0.04 g m−2 d−1). These rates exceed predicted rates of solubilization to groundwater, demonstrating the effectiveness of aerobic biodgradation and volatilization as a combined natural attenuation pathway.

Laboratory Modeling, Field Study, and Numerical Simulation of Bioremediation of Petroleum Contaminants

Historical methods of cleaning up petroleum hydrocarbons from the vadose zone, the capillary zone, and the aquifers are not technically true cleanup technologies but rather transfer techniques. In addition, environmental engineers are realizing that the standard remediation techniques are not entirely effective in removing the hazardous material in a reasonable time frame. Long-chain hydrocarbons such as kerosene, diesel, and waste oil are particularly difficult to remediate using conventional techniques. The use of bioremediation as an alternative remediation technology is fast becoming the technique of choice among many environmental professionals. This method offers substantial benefits not found in other remediation processes. Bioremediation is very cost effective, nondestructive, relatively uncomplicated in imple menting, requires nonspecialized equipment, and can be extremely effective in removing recalcitrant petroleum hydrocarbons. This study researched the availability of viable microbial populations in the arid climate in South Dakota. Exponential growth of the bacteria and the ability of bacteria to degrade long-chain hydrocarbons indicated that healthy populations do exist and could be used to mineralize organic hydrocarbons. Experimental results indicated that bioremediation can be effectively enhanced in landfills as well as in the subsurface using a supply of harmless nutrients. The biodegradation rate can be further enhanced with the use of edible surfactant that helped disperse the petroleum products. Also, the use of hydrogen peroxide enhanced the oxygen availability and increased the degradation rate. Interestingly, the bacterial growth rate was found to be high in difficult-to-biodegrade contaminants, such as waste oil. A numerical simulation program was also developed that describes the bacterial growth in the subsurface along with the reduction in substrate (contamination). Results from this program were found to be consistent with laboratory results. Finally, large-scale laboratory tests were performed. A comparison of these two sets of results revealed an interesting scaling correlation. Recommendations are made for proper scaling up of laboratory results.

Evaluation of adsorption preconcentration/capillary zone electrophoresis/nanoelectrospray mass spectrometry for peptide and glycoprotein analyses.

The use of an on-line adsorption preconcentrator coupled with capillary zone electrophoresis/nanoelectrospray mass spectrometry (PC/CZE/nESMS) is described for the analysis of peptides and protein digests. The investigation was focused on the production of disposable preconcentrators made of large particle size (40 microns irregular packing), thereby eliminating the use of a retaining frit without loss of performance. These preconcentration devices were made of commercially available components which can be easily interfaced to current CZE/nESMS systems. Practical issues such as the composition of the stationary phase, the elution volume and sample breakthrough and carry-over were evaluated in order to optimize the analytical performance of this technique. Under optimized elution conditions, the PC/CZE/nESMS technique provided separation efficiencies in excess of 100,000 theoretical plates for a sample loading of 8 microliters. Sample carry-over was minimized by proper reconditioning of the preconcentrator prior to the CZE separation. Alternatively, the sample carry-over resulting from small elution volumes could be used advantageously to provide multiple analyses from a single injection of sample. The application of this technique is demonstrated for the analysis of proteolytic peptides from a Bauhinia purpurea lectin at a concentration level of 30 nM. Further structural information was obtained using on-line tandem mass spectrometry to elucidate the structure of N-linked glycans and the amino acid sequences of the glycopeptides.

Development of separation systems for polynuclear aromatic hydrocarbon environmental contaminants using micellar electrokinetic chromatography with molecular micelles and free zone electrophoresis.

Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodium undecylenic acid (OSUA). We have employed organic additives of acetonitrile, acetone, and tetrahydrofuran in achieving separations of polyaromatic hydrocarbons (PNAs) using molecular micelles. Generally, successful separations are achieved with 20-40% composition as the organic additive in an 8 mM borate buffer. We separated 16 PNAs with 20% tetrahydrofuran in a system of 8 mM borate and 0.125 g/10 mL (ca. 6.25 mM) of OSUA. Typical extracts of environmental samples contain additional analytes besides the typical 16 target compounds. Among these are the nitrogen-containing aromatics that can act as cations under conditions of low pH and additional compounds that can act as anions under basic conditions in free-zone electrophoresis. These additional classes of analytes are separated by capillary zone electrophoresis/laser-induced fluorescence detection using a frequency-doubled laser operated at 257 nm.

Delineation of Air/Water Capillary Transition Zone From GPR Data

Summary Spilled petroleum products spread laterally in the capillary transition zone above the water table. Ground penetrating radar (GPR) is a technique that can potentially delineate the air/water capillary transition zone (CTZ), because a varying water content strongly influences the reflected signal through its effect on the electrical properties. The vertical water distribution is determined on the pore scale by the grain size distribution and on the reservoir scale, mainly, by the permeability distribution. We present the integral equations for the reflected signal from a inhomogeneous slab with a depth-dependent dielectric constant and electrical conductivity. The numerical solution of the equations allows us to compute the signal reflected from different sand profiles. The results show that the reflected signal is strongly influenced by both the grain size distribution and the variation in permeability. A strong frequency dependence is also observed. We present a two-dimensional GPR profile measured in the field that shows a clear effect of the CTZ on the reflection of the radar signal. All these results are considered of importance for the interpretation of GPR data involving the capillary transition zone.

Analysis of high density lipoprotein apolipoproteins by capillary zone and capillary SDS gel electrophoresis

We describe new methods for analyzing the apolipoproteins (apo) of the high density lipoproteins (HDL) of several species by two modes of capillary electrophoresis: size separation using a molecular sieving buffer, and capillary zone electrophoresis (CZE) using neutral coated capillaries. By either mode HDL apos were resolved within 25 min. Results for apoA-I and apoA-II mass agreed with those by electroimmunoassay; intra-assay coefficients of variation were 1.8–4.2%. The migration times of human, rat, rabbit, and bovine apoA-I during CZE were proportional to their net charge/Mr ratios. This enabled human and rabbit apoA-I to be quantified simultaneously in transgenic rabbit HDLs. CZE also resolved human apoA-I isoforms, deamidated apoA-I, and pro-apoA-I.—Stocks, J., M. N. Nanjee, and N. E. Miller. Analysis of high density lipoprotein apolipoproteins by capillary zone and capillary SDS gel electrophoresis. J. Lipid Res. 1998. 39: 218–227.

DNA typing of the D1S80 locus using capillary zone electrophoresis

DNA typing of the D1S80 locus was carried out using capillary polyacrylamide gel zone electrophoresis (CZE). The D1S80 allelic ladder was isolated within 40 min in polyacrylamide gel columns of 50 μm inner diameter and 30 cm length. The PCR products and ladder marker in the injection port were electrophoresed and detected by UV absorption (254 nm). The typing was determined according to migration of DNA fragments on the electropherograms, which permits simultaneous analysis of both the test sample polymerase chain reaction products and the ladder marker. The two-step sample injection method applied in this study allows us to use minute amounts of the ladder maker. This procedure provides a reliable, economical and rapid method for D1S80 typing.