bluuebunny/crossref_metadata_2025 huggingface dataset:
Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite
Authors: Zardiackas Lyle D. , Teasdall Robert D. , Black R. John , Jones G. Scott , St. John Kenneth R. , Dillon Lance D. , Hughes James L.
Published: May 2005

The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFT15), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFT15 material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFT15 had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFT15. The final conclusion is that in this model, grafting with COLLAGRAFT15 provided torsional properties at one year postoperatively at least equivalent to autogenous bone. © 1994 John Wiley & Sons, Inc.
Fretting corrosion accelerates crevice corrosion of modular hip tapers
Authors: Brown S. A. , Flemming C. A. C. , Kawalec J. S. , Placko H. E. , Vassaux C. , Merritt K. , Payer J. H. , Kraay M. J.
Published: May 2005

The use of multiple‐component systems in orthopedic surgery gives the surgeon increased flexibility in choosing the optimal implant, but introduces the possibility of interfacial corrosion. Such corrosion could limit the longevity of prostheses due either to tissue reactions to corrosion products, or to device failure. The incidence and nature of corrosion of modular total hips was evaluated in a consecutive series of 79 retrieved implants from University Hospitals of Cleveland. Surfaces were examined with stereo‐ and scanning electron microscopy. Several laboratory studies were undertaken to examine mechanisms that might contribute to the initiation of corrosion. The first set of experiments investigated the effect of head neck extension; the second study looked at the effect of material combinations on fretting corrosion and crevice corrosion. Analysis of retrieved implants demonstrated that fretting corrosion played a major role in the initiation of interface corrosion, and that a correlation existed between corrosion and length of neck extensions. Laboratory studies showed that longer head neck extensions may be more susceptible to fretting corrosion because of an instability at the interface. Short‐term mixedmetal corrosion studies demonstrated that the coupling of cobalt and titanium alloys did not render the interface more susceptible to corrosion. It is hypothesized that fretting corrosion contributes to the initiation of modular interface corrosion, and that the problem can be reduced by design changes that increase the stability of the interface. © 1995 John Wiley & Sons, Inc.
Fibroblast seeding and culture in biodegradable porous substrates
Authors: Rivard Charles‐Hilaire , Chaput C. J. , DesRosiers E. A. , Yahia L'H. , Selmani A.
Published: May 2005

A natural poly(hydroxybutyrate‐co‐9% hydroxyvalerate) copolyester was processed into a three‐dimensional porous foam structure by salt leaching/solvent casting with previously sieved sodium chloride salts. Laboratory‐built P(HB‐9% HV) foams and commercial collagen sponges were cut into small rectangular specimens, sterilized, and prewetted using ethanol, rinsed with Dulbecco's minimum essential medium + 10% serum culture media, and seeded with fibroblasts isolated from canine anterior cruciate ligaments. The fibroblast cultures into such porous substrates were performed from 0 to 35 days by incubation (5% CO2) at 37°C. It demonstrated that the P(HB‐HV) sustained a cell proliferation rate similar to that observed in collagen sponges, up to at least 35 days, with a maximal cell density on the day 28 in culture. On the other hand, the P(HB‐HV) materials kept their structural integrity during the culture period while the collagen foams contracted greatly. Further, the total protein production after 4 weeks in culture was found to be twice as high (190 ± 10%) in the P(HB‐9% HV) foam than in the collagen foam. Porous P(HB‐HV) materials appear to be adequate polymeric substrates for cell cultures. However, further evaluations are still required to confirm such preliminary results. © 1995 John Wiley & Sons, Inc.
Innovations in acrylic bone cement and application equipment
Authors: Kindt‐Larsen Ture , Smith Daniel B. , Jensen Jørgen Steen
Published: May 2005

A new bone cement was developed with the purpose of reducing the adverse biological effects during cementation of implants. This bone cement is characterized by lower exotherm, low release of monomer, low residual content of monomer, and retained physical properties. The essential innovation was substitution of half of the methylmethacrylate (MMA) in the monomer with long chain, high molecular weight, less volatile, and less soluble methacrylates (n‐decylmethacrylate, isobornyl‐methacrylate), as well as alteration of the accelerator system to a mix of dihydroxypropyl‐p‐toluidine and N,N‐dimethyl‐p‐toluidine. The powder contains butyl‐methacrylate‐MMA copolymers. These measures lower the glass‐transition temperature, and permit more complete mixing in an integrated package, mixing, and delivery system consisting of a vacuum packed, double chamber pouch. The porosity was reduced to about 2% and the largest voids measured 0.1 mm. The polymerization exotherm was reduced to 58 °C. The compressive strength was 82 MPa, the four‐point bending strength 55 MPa, the flexural modulus 2.24 GPa, the tensile strength 32 MPa, and the shear strength 36 MPa. The fracture toughness was 0.89 MPa √cm. These mechanical properties together with the fatigue life were on level with manually mixed, conventional PMMA bone cements. © 1995 John Wiley & Sons, Inc.
Effects of sublethal metal ion concentrations on osteogenic cells derived from bone marrow stromal cells
Authors: Thompson Gary J. , Puleo David A.
Published: May 2005

Ions released from implant surfaces are suspected of playing some role in osteolysis surrounding metal prostheses. To understand how ions may affect osteogenesis, previous work exposed osteogenic cells to metal ions to study acute cytotoxic responses. The purpose of this study was to assess the long‐term effects of sublethal ion concentrations on osteogenic cell proliferation and function. Bone marrow stromal cells were harvested from juvenile rats and exposed to solutions of ions associated with Co‐Cr‐Mo and Ti‐6Al‐4V implants. Cells were cultured for up to 4 weeks and assayed for total protein, alkaline phosphatase, osteocalcin, and calcium. Other than V+5, none of the ions affected cell proliferation, indicating that the chosen concentrations were sublethal as desired. V+5 elicited delayed gross toxicity not previously observed during acute experiments. At the chosen concentrations, Co+2, Cr+6, Mo+6, and Co‐Cr‐Mo alloy elicited little effect on cell proliferation and moderate effects on matrix mineralization. Cultures exposed to Ti+4, Al+3, and Ti‐6Al‐4V alloy also showed no decrease in cell number, but did show near total suppression of osteocalcin secretion and matrix mineralization. These results suggest that ions released from Ti alloy implants may interfere with osteoblastic cell differentiation, contributing to periprosthetic osteolysis by impairing normal osteogenesis. © 1995 John Wiley & Sons, Inc.
Studies of open tubular micro capillary liquid chromatography. 1. The development of open tubular micro capillary liquid chromatography
Authors: Hibi K. , Ishii D. , Fujishima I. , Takeuchi T. , Nakanishi T.
Published: May 2005

Micro capillary columns were successfully applied to liquid chromatography by employing the principles used in micro high performance liquid chromatography. Fundamental investigations on the use of capillary columns in LC were performed for the various column parameters. Good separations of five aromatic hydrocarbons and four kinds of phthalic esters were obtained on a 62 μm I.D. capillary column, coated with SE‐30.
Computer reconstruction of high resolution gas chromatograms
Authors: Overton E. B. , Steele C. F. , Laseter J. L.
Published: May 2005

This paper describes two programs that are used to plot digital area slice data from glass capillary gas chromatograms. The programs are written in H/P LAB BASIC II, and can be executed on Hewlett‐Packard 3354A Laboratory Data Systems using digital plotting devices. The programs are designed to plot high resolution chromatograms, allow horizontal and vertical scaling, and the plots can be numbered and labelled.
Separation of 28 to 114°C hydrocarbons with glass capillary columns
Authors: Mathews R. G. , Torres J. , Schwartz R. D.
Published: May 2005

Techniques have been developed for the rapid separation (about 20 minutes) of the 39 compounds in crude petroleums, or petroleum distillates, which boil between 28 and 114°C. A 300 meter glass column (0.25 mm i.d.) which is etched, coated with a mixture of normal hexadecane and Kel‐F10157 is utilized to perform this separation at room temperature. The separations obtained with this non–polar liquid mixture and the «inert» glass surface are much more rapid than those previously obtained with stainless steel capillary columns.
Studies of correlation between chemical structure and Rf‐value in high performance TLC
Authors: Bidló‐Iglóy Margit
Published: May 2005

Correlation between chemical structure and Rf‐values was studied in the case of aniline and its derivatives using high performance TLC and a U‐chamber. The characteristic group constants referring to each substituent were determined by chromatographing derivatives with one substituent and aniline in toluene and dibutyl ether respectively. On the basis of these constants the RM and Rf values of derivatives with more substituents were calculated. Comparing the calculated and measured values good agreement was found.
Anticircular high performance thin‐layer chromatography
Authors: Kaiser R. E.
Published: May 2005

The principal analytical details for the third of three possible modes in high performance thin‐layer chromatography are given, namely the anticircular mode. Separation is achieved by allowing the mobile phase to enter the plate layer on a precise outer circle line, from where it flows towards the centre with nearly constant speed. This technique is theoretically and practically the fastest of all three possible in HPTLC. It permits maximum sample capacity with a minimum of time, layer and mobile phase consumption. It is therefore the most economical HPTLC technique.

A new carrier‐free mobile phase transfer principle is used. The conditions for qualitative and quantitative analysis are good: repeatability, reproducibility and accuracy of routine TLC analyses are superior to those achieved by the classical trough technique. The specially narrow spot‐path in anticircular HPTLC facilitates automated quantitation. Compared with the linear and circular modes, the anticircular mode shows better separation and significantly increased sensitivity at higher Rf‐values. The drawback, however, is that the separation power (expressed by the separation number) is lower compared with the other two modes.
Methods in high resolution gas chromatography. Two‐dimensional techniques
Authors: Bertsch W.
Published: May 2005

Basic methodology to effect the separation of complex samples by gas chromatography is discussed from an experimental point of view. Several possibilities are presented which are commonly used to enhance the information content of a gas chromatographic run. These include incorporation of more than one set of retention data, multiple detectors, and special column switching techniques. These and other techniques have sometimes been labeled “multidimensional” in the literature. An attempt is made to define the term “two‐dimensional chromatography”.

The review is divided into sections which point out the different directions which have been taken to deconvolute chromatographically unresolved components. Particular emphasis is placed on technology which is capable of dealing with samples of extreme complexity, and instrumentation for trace‐ and ultratrace analysis is dicussed with specific examples. The future of two‐dimensional techniques in gas chromatography is looked into.
HPLC of antibiotics. 1. Streptolydigin and related compounds
Authors: Brodasky Thomas F.
Published: May 2005

Two new acyltetramic acids related to streptolydigin have been isolated from fermentations of Streptomyces lydicus. The principal members of this complex were resolved by TLC on silica gel. However, the methods of detection, permanganate spray or bioautography, were not suitable for both crude fermentation broths and purified extracts. Gas chromatography is unsuitable for the detection of either underivatized or silylated streptolydigins. High performance liquid chromatography (HPLC) particularly on triethylaminoethyl cellulose is rapid and sensitive and is the method of choice for the analysis of both crude and purified samples. Using high performance liquid chromatography, two components were detected in the complex, which are not observed using any of the other chromatographic procedures.
Systematic and statistical errors in quantitative evaluation using TLC and HPTLC. 2. Internal and external standard methods
Authors: Ebel S. , Glaser E. , Rost D.
Published: May 2005

The error propagation is given for routine analysis by in situ evaluation in TLC using the methods with internal or external standard. The internal standard method will need four different measurements of peak height or area, while the external standard method uses only two measurements. Therefore in the latter case the error of the spotting volume will cause errors in the determined concentration. By error propagation it can be shown, that the internal standard method gives better results, if the error in measuring peak height or area is less than the error of the spotting volume.
On‐column injection onto capillary columns. Part 2: Study of sampling conditions; practical recommendations
Authors: Grob K.
Published: May 2005

During one year continuous use of on‐column injection, the typical advantages described in our first report have fully been confirmed. In addition the analysis of large sample volumes has proved promising. Only minor modifications have been applied to the on‐column injector device. Broad evidence has been gathered showing that full separation efficiency of the capillary columns after on‐column injection is attained only when cold trapping or the solvent effect, as band shortening mechanisms, are working‐ While, under the conditions of on‐column injection, cold trapping is less efficient than with other injection techniques, the opposite holds true for the solvent effect. Compared with splitless injection, the danger of excessive solvent condensation on the column is increased. A working rule is presented for establishing the optimal chromatographic conditions for handling large sample volumes while ensuring full separation efficiency yet avoiding harm to the column.
The influence of the syringe needle on the precision and accuracy of vaporizing GC injections
Authors: Grob K. , Neukom H. P.
Published: May 2005

The discrimination of the high boiling components of a C9 to C44 alkane test mixture in a vaporizing injector (analysed with stream splitting on a capillary column) is mainly due to a selective elution of the sample out of the syringe needle. Different methods of handling the syringe needle are tested. The discrimination is quantitated and correlated with the material left in the needle. The poorest method of injection was found to retain the sample in the needle when the latter is introduced into the vaporizer. The sample should be pulled back into the barrel of the syringe and the needle allowed to warm up in the injector before the sample is transferred into it. The solvent flush technique may be preferred for components sensitive to the hot metal surface of the needle.
Efficiency of composite vs. conically shaped chromatographic columns
Authors: Said A. S.
Published: May 2005

The theory of composite chromatographic columns has been re‐examined and general equations relating their efficiency to those of individual columns were derived. The derivations were based on elementary principles without reference to the principle of variance additivity. Derived also, were general equations for the efficiency of columns with continuously varying diameters, HETP and other properties from which formulae for special cases of practical interest were deduced. An example comparing the efficiencies of two columns, one conical and the other composite was given. The calculations show clearly that the conical column is superior in efficiency for the same total length and total retention volume.
Computer reconstructed gas and liquid chromatograms
Authors: Janssens G.
Published: May 2005

This paper describes a Lab Basic II program which allows the reconstruction of GLC‐chromatograms on a Hewlett‐Packard 2648A graphics terminal, starting from raw data gathered by the HP‐3354A Laboratory Data System. The introduction of a considerable number of automatic parameter selections restricts user's interventions. The program can be run in terminal mode or be recalled as a post‐analysis program when working in autocall mode.
A new approach to the simultaneous multi‐detection technique with electron capture and flame ionization in series
Authors: Poy F.
Published: May 2005

In order to avoid splitting at the column outlet for simultaneous multidetection, a new line of detector heads with the ionization cells coupled in series has been developed.

The electron capture plus flame ionization detector (EC+FI‐D) has been evaluated from the point of view of the sensitivity, the linear dynamic range and separation efficiency in a capillary column GC system. The performances of each section are the same as when a single ionization detector head is used.
Gas‐liquid chromatography of serum bile acids using glass capillary columns
Authors: Karlaganis G. , Paumgartner G. , Schwarzenbach R. P.
Published: May 2005

The proposed combination of a rather simple procedure for sample preparation with capillary gas‐liquid chromatography using a barium carbonate/polyethyleneglycol 20,000 column and a Grob‐type on‐column injector permits measurement of bile acids in serum with high separation efficiency, short analysis time and complete separation of bile acids from cholesterol. The method can be adapted to combined capillary gas‐liquid chromatography ‐ mass spectrometry.
Precision of an automated all‐glass capillary gas chromatography system with an electron capture detector for the trace analysis of estrogens
Authors: Kern H. , Brander B.
Published: May 2005

Subnanogram detection of steroids has become increasingly important today. One applicable method for gas chromatographic determination of subnanogram quantities of estrogens as halogenated derivatives is electron capture detection. HFB‐derivatives of 7 different estrogens were automatically injected onto a prolonged narrow bore wall‐coated glass capillary column. Normal split injection could not be used for this trace analysis because of too much loss of sample. Only small amounts of sample were available from which double analysis had to be performed.

Cross‐contamination of the automatic sampling system as well as precision of retention times and peak areas were determined.

The type of injection described showed better quantitative results compared to the splitless injection technique.

All details of the system used together with the results are this discussed in this paper.
Faster GC analyses performed by flow programming in short capillary columns
Authors: Nygren S.
Published: May 2005

The technique of programming the carrier gas flow rate in gas chromatography, especially in connection with the use of capillary columns shorter than 10 m can significantly accelerate GC analyses. Equations for calculation of the parameters of the exponential flow function and retention data are described. The effects of flow programming in a short capillary column are shown in a few chromatograms. Different programming rates are tested and compared with temperature programming.
High‐temperature (GC)2/MS investigations
Authors: Dielmann G. , Meier S. , Rapp U.
Published: May 2005

The analysis of low volatile compounds by (GC)2/MS using high‐temperature stable glass‐capillary columns and a commercially available GC/quadrupole MS instrument is described.

It will be shown that no special modifications or procedures are required in analyzing organic compounds exceeding carbon numbers of 50. The application to industrially and naturally occuring high boiling mixtures will be discussed.
An investigation of glasses for capillary chromatography
Authors: Dandeneau Raymond D. , Zerenner E. H.
Published: May 2005

An investigation was conducted of various glasses, other than soda lime or borosilicate, for use in glass capillary gas chromatography. The work has uncovered some unique chromatographic qualities in the use of potash soda lead and fused silica glasses as materials for making glass capillary columns. The fused silica proved to be an ideal material for capillary column construction, being inherently more inert than glass containing metal oxides. It has been shown that through the use of thin wall capillary tubing of high flexibility many of the mechanical problems associated with glass capillary columns, such as fragility and column straightening, can be avoided.
Identification and quantitation of trace amounts of barbiturates with glass capillary gas chromatography
Authors: Dünges W. , Langlais R. , Schlenkermann R.
Published: May 2005

Pre‐chromatographic reactions are no longer a necessary evil. Equipment such as the microrefluxer now allows reproducible 7‐μl‐reactions to be carried out in a short time. Thus multiple derivatisations can be used together with glass capillary GC for routine identifications. The method has been succesfully applied to barbiturates. Retention data of their methyl‐, allyl‐ and benzyl‐derivatives are given.

Quantitative blood level determinations are briefly discussed.
Study of open‐tubular micro‐capillary liquid chromatography
Authors: Ishii D. , Tsuda T. , Hibi K. , Takeuchi T. , Nakanishi T.
Published: May 2005

Capillary columns in gas chromatography, first proposed by Golay [1,2], have become well established [3] which have extremely high column efficiencies and separabilities. Everyone could imagine it to be a great tool if such a kind of high efficiency column could be established in liquid chromatography (LC). Microcapillary liquid chromatography (MCLC) may be one way of achieving high‐efficiency in terms of theoretical plates. Few papers were published in this field before 1976 [4–6], but more recently, after 1977 [7–15], this field has become one of topical interest in liquid chromatography. Temporarily there are two microcapillary liquid chromatography, that is: „open‐tubular”︁ [7,8,10–15] and „packed”︁ [9] MCLC. In this presentation we focus on open‐tubular microcapillary liquid chromatography and a review contemporary developments of ours and others.
The use of glass capillary columns for the analysis of polar natural products
Authors: König W. A. , Günther W.
Published: May 2005

Two published procedures for glass capillary column production are applied to produce capillaries for chromatography of polar natural compounds. Soda lime glass capillaries, after leaching with aqueous HCL, are either treated with colloidal silicic acid or with barium carbonate and coated with either Silar 7CP or SE 52. A test mixture as well as polar carbohydrate and peptide mixtures are chromatographed on the different columns and their chromatographic properties are evaluated. Combined capillary gas chromatography‐electron impact and chemical ionization mass spectrometry are used for identification of the peptide sequence.
Gas chromatographic conditions for the linearity of the relationship between σT,t and tR in open tubes
Authors: Smuts T. W. , Buys T. S. , de Clerk K. , du Toit T. G.
Published: May 2005

The linearity of the relationship between σT,t2 and (1 + k)2 is studied with the view of using it for the evaluation of GC equipment. Based on appropriate analytical expressions it is concluded that in general this relationship is not linear and that practical procedures for column evaluation should be developed that take this non‐linearity into account.
Chromatographic peak broadening with a lab‐made splitter: Reproducibility and accuracy studies
Authors: Watanabe Chuichi , Tomita Hiroshi , Sato Kunitaka
Published: May 2005

Sample inlet splitters are used in capillary column gas chromatography. We have investigated the sample band broadening in the splitter and studied reproducibility and accuracy in quantitative analysis using a simple lab‐made splitter. It was found that the results were dependent upon the operating conditions such as split ratio, splitter temperature, glass wool plug, injected sample volume and solvent.
On the estimation of extra‐column contributions to band broadening through measurements on an authentic chromatogram
Authors: Nilsson O.
Published: May 2005

The time constant, τ, is determined from the tail of an authentic HPLC peak through a plot of In U versus time, t, according to the relation

expected at low recorder deflexions, U. The value obtained, τ = 2.43 s, is one order of magnitude larger than an ordinary recorder time constant, which is quite normal for LC detectors. It agrees with the value, τ = 2.44 s, needed theoretically to distort a Gaussian‐shaped peak so as to obtain the experiment‐ally found second moment, σ2 = 11.13 s,2 and the experimental difference between first moment t and peak retention time tmax, t – tmax = 0.78 s. The determination is therefore regarded as a demonstration of the variance addition rule

where σ is the second moment of the non‐distorted peak. The column contribution version

is also considered. This equation was appliied earlier to an estimation of extra‐column contributions to band broadening with the aid of the “abt” concept. An explicitly k‐(capacity ratio)‐dependent expression for the mass exchange contribution, σ is derived from Golay's equation for capillary columns, but the validity of the Golay equation is under discussion.
Ion pairing high‐performance liquid chromatography of catecholamines
Authors: Heady Judith E. , Agee Karl D.
Published: May 2005

Catecholamine standards have been separated by ion pairing reversed‐phase high‐performance liquid chromatography (HPLC). A trace substance was separable from four standards when low concentrations of methanol were used in the elution buffer. This method has allowed separation of an unknown uterine catecholamine, partially purified on a boronate affinity gel column, from the standards: norepinephrine, epinephrine, normetanephrine and metanephrine.
On the applicability of the “abt” concept
Authors: Nilsson O.
Published: May 2005

Kaiser's “abt” concept rests on the experimental establishment of a linear relation between band width at half height, b0.5, and capacity ratio, k, according to

His column specification quantity, hreal, is dependent on the square of the slope a, obtained from a linear regression analysis based on this relation. It is shown in the present paper that an improvement of the experimental conditions leading to a lower extra‐column contribution to band broadening, b, introduces a tendency towards a negative curvature in the plot at low k values. The mean slope increases, and an uncritical linear regression would yield an hreal‐value which is higher than before and which would be in the opposite direction to the requirements of a reliable column specification. Generally the linear regression analysis has to be moved to higher k regions in cases of curvature, especially as it is also shown that hreal is an estimation of the traditional HETP value, H∞, that would be obtained when k approaches infinity. This theoretically expected relation

is a strong motivation for the use of hreal as a column specification, since the b0.5‐value associated with H∞ is expected to be practically independent of b.
Simple conversion of two standard gas chromatographs to all‐glass capillary systems
Authors: Severson R. F. , Arrendale R. F. , Chortyk O. T.
Published: May 2005

Two regular GC instruments were modified with injection port liners, split‐mode injection systems, pressure regulators, effluent traps and needle valves to produce an all‐glass GC‐2 system. This simple and inexpensive system allows the quantitative analyses of phenols, hydrocarbons, acids, sterols, terpenoids, and alkaloids with excellent reproducibility and linear response. Even more impressive was its ability to analyze a C45‐terpenoid alcohol, solanesol, as its TMS‐derivative (M.W. 702).
Effects of solute‐solvent and solvent‐solvent association in liquid adsorption chromatography with binary mobile phase
Authors: Jaroniec M. , Piotrowska J.
Published: May 2005

Analytical equations for the capacity ratio in liquid adsorption chromatography with a binary mobile phase, involving solute‐solvent and solvent‐solvent association in the mobile and surface phases, have been derived. Very simple equations have been obtained for higher values of mole fraction of the more efficient eluting solvent.
High efficiency HPLC with long packed columns
Authors: Dewaele C. , Verzele M.
Published: May 2005

Coupling several 25 cm × 2 mm ID analytical columns together is a simple and easy way to achieve high resolution HPLC (20,000–50,000 plates). How to do this with commercially available instruments, injectors and detectors is described in the paper.

An attractive feature of the long narrow column approach is that the same HPLC set‐up can be used for both fast‐low and slow‐high efficiency separations.

High efficiency is essential for really complex natural mixtures, e.g. the hop and beer bitter acids. Some examples are shown.
Stability of the FID sensitivity during an analysis in capillary GC
Authors: Grob K.
Published: May 2005

The sensitivity of an FID may change when the carrier gas flow rate changes during a chromatographic run. Sample parts which are eluted at reduced FID sensitivity produce a reduced peak area, hence are discriminated as compared to other components. Sensitivity changes were studied for hydrogen as carrier gas. For the detector tested, differences in the carrier gas flow rates of 1 ml/min shifted the FID sensitivity by 1 to 5% (depending on the fuel gas supply). Thus the stability of the sensitivity is no longer ensured as soon as the carrier gas flow rate is changed manually or by an automatic programmer during an analysis. Sensitivity drifts may also occur during temperature programmed runs with a pressure regulated carrier gas supply since the gas flow through the capillary drops with increasing temperature. Such shifts in the response became noticeable as soon as relatively high carrier gas flow rates combined with long range temperature programmes were used. The typical patterns of such discriminations are shown, closing with a discussion on the possibilities for minimizing such undesired effects.
Separation of pesticides by capillary gas chromatography. Part 1: s‐Triazines and substituted urea herbicides
Authors: Deleu R. , Copin A.
Published: May 2005

The authors have shown that capillary columns are perfectly adequate for the separation of s‐triazine herbicides and urea herbicides. The method presented remains adequate when the initial molecules are accompanied by some of their metabolites.
Computer supported comparison of gas chromatographic analyses
Authors: Janssens G. , Beernaert H.
Published: May 2005

The application of a Hewlett‐Packard 3354 B Laboratory Automation System has been studied in order to compare a series of gas chromatographic analyses. A computer program has been designed for the chromatogram reconstruction of all valid sample runs from a system subsequence on an HP‐2648 A graphics CRT terminal. The detector signals of the runs are compensated for variations in injected sample sizes when a number of conditions are met.
Continuous development HPTLC and sequential wavelength scanning for the simultaneous determination of nine clinically important β‐blocking drugs
Authors: Zhou L. , Poole C. F. , Triska J. , Zlatkis A.
Published: May 2005

High performance thin‐layer chromatography was used for the separation of nine therapeutically important and structurally similar β‐adrenoceptor blocking drugs on silica gel plates. In situ scanning of the plate in the reflectance mode gave detection limits in the low nanogram range depending on the individual drug and the wavelength selected for its determination. Scanning the HPTLC plate at several wavelengths can be used to aid the identification of partially resolved components. Continuous development and continuous multiple development techniques are compared for the simultaneous separation of the drug mixture.
Detection of metal ions by glass capillary gas‐chromatographic separation of their volatile chelates
Authors: Sucre Leopoldo , Jennings Walter
Published: May 2005

The utility of several glass capillary columns to separate some trifluoroacetonates, diethyldithiocarbamates, di(trifluoroethyl) dilithiocarbamates and diisopropyldithiophosphates metal chelates was investigated. The increased sensitivity offered by selective detectors was also explored. Most favorable results were obtained with a short highly inert fused silica column, coated with a non‐retentive liquid phase.
Persilylation of glass capillary columns. Part 4: Discussion of parameters
Authors: Grob K.
Published: May 2005

Persilylated glass capillary columns are the most universal GC columns available. They are relatively easy to prepare, but there is nevertheless a great need for helpful practical instructions. In the recent literature, methods and conditions for the preparation of persilylated columns have been recommended, but these might confuse the individual column maker, since they seem to originate from limited observations rather than from comprehensive investigation. They will hardly help to make column preparation safer. This paper attempts a summarized view of the present experience with persilylation and provides basic information for column makers.
Analysis of Alaskan crude oils by glass capillary gas chromatography/mass spectrometry
Authors: Hood L. V. S. , Erikson C. M.
Published: May 2005

Glass capillary gas chromatography/mass spectrometry is used to profile Alaskan crude oil for purposes of origin verification. Alaskan oil, sampled at Valdez, Alaska, and transshipped to the U.S. East Coast, is compared with 21 samples of foreign crude oil using GC/MS techniques in which original data is reconstructed at selected parent and fragment ions to generate a series of chromatographic profiles. Comparison of selected profiles and compositional parameters derived from peak ratios allows distinction of Alaskan oil from many foreign crudes and may be applied to the examination of crude mixtures.
Surface modification of soft‐glass capillaries for gas chromatography by treatment with water vapour
Authors: Neu H. J. , Heeg F. J.
Published: May 2005

“Leaching” or “etching” by strong mineral acids seems to be a necessary pretreatment step for the most commonly used deactivation procedures of glass capillaries by reaction with either polyethylene glycol or silylation reagents. The acidic sites which are formed on the surface during this acid treatment cannot be completely removed by the subsequent deactivation process. This drawback can be overcome by performing the leaching with water vapour, resulting in an accumulation of cations at the surface and a decrease in the number of silanol groups. Capillaries of this type show excellent properties for the chromatography of strongly basic compounds. After the wash‐out of the alkaline surface layer, the acidity of the support is suited for the chromatography of strongly basic as well as strongly acidic compounds. Due to a lack of reactive acidic sites, special deactivation procedures have to be applied to capillaries produced in this way.
Analysis of sludge extracts by high resolution GC with selective detectors
Authors: Lopez‐Avila Viorica
Published: May 2005

Combination of various GC detectors by using a Varian effluent splitter with glass capillary columns has been found to be a rapid procedure for profiling organics extracted from sludges and river sediments. The selectivity and the increased sensitivity of the thermionic nitrogen‐phosphorus detector (TSD), the electron capture detector (ECD), and the flame photometric detector (FPD) over the flame ionization detectors (FID) or mass spectrometers allow the detection of compounds present at trace levels without need for extensive sample cleanup. Furthermore, the combination of two selective detectors may supplement the information with regard to the chemical functionalities required for structure elucidation.
The theoretical basis of column chromatography in multicomponent separations. Part 1: Analytical requirements and peak resolution. Development of a high performance column system
Authors: Peichang Lu , Xiuzhen Li , Yukuei Zhang
Published: May 2005

The point of our published papers since 1957 is reviewed. The relations between the required value of peak resolution, K1 (or R), and peak separation, K3 (eqn 9); K1 and relative accuracy of a peak height quantitative method, Ph (eqn. 10); K1 and relative accuracy of a peak area method, Pa, (eqn. 12) at different concentration ratios, ϕ, are derived. The final result in Table 2 shows a large influence of ϕ on the required value of K1.

The approximately linear relation between peak width and retention value (eqn. 18) exists not only in GC. but also in HPLC. Plate height values H1 and H∞ for a solute with capacity ratio, k′, equal to unity or approaching infinity, respectively, are used to evaluate the column efficiency (eqn. 20). The measuring methods (eqn. 21,22,23) and parameters effecting on H1 and H∞ are given for GC packed column (eqn. 24), GC open tubular column (eqn. 25) and HPLC (eqn. 26). In the light of this, columns of high efficiency were developed. Some typical chromatograms for high speed analysis and separation of complex mixtures are given.
The varigrad and similar apparatus in gradient liquid chromatography: A systematic computational approach. Part 2: Applications
Authors: Said A. S.
Published: May 2005

Part 2 deals with the application of the equations derived in Part 1 to the systematic calculations of the constant volume and hydrostatic Varigrads. Examples are given which illustrate the advantage of using the modified incremental method of gradient elution. The non‐homogeneous Varigrad, where mixing chambers may vary in volume, is also treated.
A quaternary solvent system for the reverse‐phase liquid‐chromatographic separation of polycyclic aromatics
Authors: Smith T. R. , Strickler V. A.
Published: May 2005

Modern liquid chromatographic (LC) conditions which effect a separation of polycyclic aromatic hydrocarbons (PAH) containing up to ten rings are described. The LC conditions include reverse‐phase chromatographic columns in combination with a quaternary solvent system. Methanol and water are combined to form solvent system A, while tetrahydrofuran and acetonitrile form solvent system B. Solvent systems A and B are then combined in a linear gradient relationship to effect the separation. The separation of benzo(a)pyrene and perylene along with benzo(ghi)perylene and indeno (1,2,3‐cd)pyrene is achieved. In the same chromatogram the PAHs, coronene, dibenzo(a,e), (a,i), (a,h)pyrene and tribenzo(a,e,i)pyrene are also separated. An increase in column temperature from 45°C to 55°C is shown to shorten the elution time and increase chromatographic resolution of many of the PAHs examined. At least 25 PAHs ranging in molecular weight from 178 to 536 are examined for their chromatographic behavior. As examples, the application of this method to samples from a coal liquefication process are included. The samples are examined with both a UV detector and fluouescence detector to demonstrate the utility of dual detectors when analyzing for PAHs in complex matrices. With minor modification of the gradient this method is applicable to PAHs containing ring systems other than those reported here.
Thin‐layer adsorption chromatography with mixed mobile phases. 4. Extension of Ościk's equation to heterogeneous adsorbents
Authors: Różyło J. K. , Ościk J. , Ościk‐Mendyk B. , Jaroniec M.
Published: May 2005

In this paper the equation for thin‐layer adsorption chromatography with multicomponent mobile phases, proposed by Ościk in 1965 is extended to energetically heterogeneous solid surfaces. Other forms of this equation, more convenient in practical applications, are presented. Model calculations are made for TLC with binary mobile phases according to the modified form of Ościk's equation. Finally, this equation is compared with that of Snyder.
Quantitative analysis of some preservatives in pharmaceutical formulations by different chromatographic methods
Authors: Koršič J. , Milivojevič D. , Smerkolj R. , Kučan E. , Prošek M.
Published: May 2005

Different chromatographic methods for determination of methyl hydroxybenzoate and propyl hydroxybenzoate in pharmaceutical formulations are compared. Procedures for HPTLC, HPLC and GC/MS are given.
The effect of temperature on the efficiency parameters in adsorptive liquid chromatography
Authors: Herbut Genowefa , Kowalczyk Jerzy S.
Published: May 2005

The effect of temperature on the efficiency of column systems in adsorptive liquid chromatography is reported. The influence of temperature changes on the values of the terms Cm2 and Ck in the HETP equation, which characterizessystems involving silica gel and benzene, ethylene chloride, butyl ether or cyclo‐ hexanone + heptane, is discussed for 9 substances. The results of the study have led to the following conclusions:

Temperature increase will always improve the efficiency of typical chromatographic systems.

As expected, an essential role is played by mass transfer resistance in the mobile phase occupying the pores of the packing material (parameter Cm2).

Mass transfer resistance resulting from sorption‐desorption kinetics (Ck) does not play as essential a role in the systems investigated as does Cm2, but its value is significantly higher than that reported in the literature.
Direct LC analysis of selected priority pollutants in water at ppb levels
Authors: Allan Pinkerton K.
Published: May 2005

Thirty‐two priority pollutants can be analyzed in water with detection limits of 10 ppb by direct liquid chromatography. High sensitivity is obtained by use of an ultra‐violet detector at 202 nm and a reverse phase C18 column with a water‐acetonitrile gradient that is compatible with two milliliter water samples.
Analysis of cardenolides of Convallaria majalis by high pressure liquid chromatography
Authors: Harkiss K. J. , Linley P. A. , Mesbah M. K. M.
Published: May 2005

Cardenolides of Convallaria majalis were separated by reverse‐phase HPLC on Partisil PXS 10/25 ODS columns using 25% acetonitrile as mobile phase. Periplorhamnoside, convallatoxin and either convallatoxol or convalloside were resolved from glycoside mixtures. Convallatoxin and periplorhamnoside were identified in plant extracts, convalloside and convallatoxol were not resolved from non‐cardenolide material present in leaf extracts.
Column chromatography fractionation of complex waste water sample extracts for measurement of ppt levels of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin
Authors: Nowicki H. G. , Kieda C. A. , Current V. , Schaefers T. H.
Published: May 2005

The novel application of azulene as a visual monitor of column chromatography performance during fractionation of complex waste water extracts for measurement of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) at part‐per‐trillion concentrations is described. TCDD elutes directly behind azulene, the blue visual aid, in the 6% ethyl ether/hexane fraction during Florisil column chromatography.
Qualitative evaluation of aromatic herbs by direct head space (GC)2 analysis. Methodology and some preliminary applications
Authors: Gabri G. , Chialva F.
Published: May 2005

A simple, quick method is described for GC head space evaluation of herbs and drugs. The proposed procedure consists of milling a weighed sample of a certain herb in a glass device like a Braun MXK coffee grinder, modified in such a way that a special gas‐tight valve allows the direct sampling of the vapors. Glass capillary columns are used to analyze the head space volatiles. Some preliminary applications of the method are given.
Thermal aqueous liquid chromatography—the TALC technique
Authors: Guillemin C. L. , Millet J. L. , Dubois J.
Published: May 2005

Thermal Aqueous Liquid Chromatography (TALC) using pure water as a mobile phase should be a very attractive technique promoting the use of liquid chromatography in routine analysis, either in the laboratory or in future on‐line process control. This simple form of chromatography, the selectivity of which depends on the fixed phase only, would allow the use of flame ionization as an almost universal, low‐cost detector in liquid chromatography. The potential of the TALC technique is illustrated by selected examples.
The effect of the temperature dependence of mobile phase viscosity on the retention time in series‐coupled gas chromatographic columns
Authors: Buys T. S. , Smuts T. W.
Published: May 2005

A previously established model of a system of series‐coupled columns, incorporating the effects of temperature and mobile phase compressibility, is generalized to take the temperature dependence of the mobile phase viscosity coefficient into account. Expressions are reported for the linear flow velocity, the effective partition coefficient, and the retention time for both the case of constant mass flow rate and that of constant overall pressure drop. Numerical results indicate that the temperature dependence of the viscosity coefficient affects the retention time and pressure drop while the effective mass distribution coefficient remains essentially unchanged.
Glass capillary columns for separation of free organic acids
Authors: Hřivnáč Milan , Sýkora‐Čechová Lenka , Müller‐Aerne Monica
Published: May 2005

Glass capillary columns have been prepared without acidic additive in the stationary phase, from which free organic acids elute as sharp and symmetrical peaks. The required surface in the borosilicate glass capillary was generated by a combination of leaching with aqueous HCl and deposition of colloidal silica particles; it can be coated with stationary phases have a broad range of polarity. Aqueous samples containing free organic acids can also be analyzed in such columns in an isothermal mode.
Thermostable persilylated polar glass capillary columns by the ammonia‐etching method
Authors: Traitler H. , Prévôt A.
Published: May 2005

Static ammonia etching has been used to effect regular surface roughening of glass capillaries. Following such treatment, polar phases could be coated after persilylation with varioussilylation agents such as hexamethyl‐, tetramethyldiphenyl‐, and tetra‐ phenyldimethyldisilazane, respectively. This method produces columns of high thermostability, which is limited only by the maximum applicable temperature for the phase itself.
Effect of some parameters on the liquid chromatographic separation of biogenic amines and their metabolites
Authors: Lammers N. , Zeeman J. , De Jong G. J.
Published: May 2005

The liquid chromatographic separation of some biogenic amines and their metabolites with a reversed‐phase ion‐pair system has been optimized. The effects of the nature of the stationary phase, the column temperature, the pH, and the ion‐pair reagent concentration of the mobile phase have been investigated. The most striking result is the influence of the column temperature on selectivity.