Stainless Steel Capillary Column Research Articles

A microchip gas chromatography column assembly with a 3D metal printing micro column oven and a flexible stainless-steel column

In this work, a microchip gas chromatography (GC) column assembly utilizing a three-dimensional (3D) printed micro oven and a flexible stainless steel capillary column was developed. The assembly's performance and separation capabilities were characterized. The key components include a 3D printed aluminum plate (7.50 × 7.50 × 0.16 cm) with a 3-meter-long circular spiral channel, serving as the oven, and the column coiled on the channel with an inner diameter of 320 μm and a stationary phase of OV-1. A heating ceramic plate was affixed on the opposite side of the plate. The assembly weighed 40.3 g. The design allows for easy disassembly, or stacking of heating devices and columns, enabling flexibility in adjusting column length. When using n-C13 as the test analyte at 140 °C, a retention factor (k) was 8.5, and 7797 plates (2599 plates/m) were obtained. The assembly, employing resistance heating, demonstrated effective separation performance for samples containing alkanes, aromatics, alcohols and ketones, with good reproducibility. The reduction in theoretical plates compared to oven heating was only 2.95 %. In the boiling point range of C6 to C18, rapid temperature programming (120 °C/min) was achieved with a power consumption of 119.512 W. The assembly was successfully employed to separate benzene series compounds, gasoline and volatile organic compounds (VOCs), demonstrating excellent separation performance. This innovative design addresses the challenges of the complexity and low repeatability of the fabrication process and the high cost associated with microchip columns. Furthermore, its versatility makes it suitable for outdoor analysis applications.

Second-Dimension Temperature Programming System for Comprehensive Two-Dimensional Gas Chromatography. Part 1: Precise Temperature Control Based on Column Electrical Resistance.

A second-dimension temperature programming system (2DTPS) for comprehensive two-dimensional gas chromatography (GC × GC) is introduced, and its performance is characterized. In the system, a commercial stainless-steel capillary column was used for the separation, as a heating element, and as a temperature sensor. The second dimension (2D) column was resistively heated and controlled using an Arduino Uno R3 microcontroller. Temperature measurement was accomplished by measuring the overall 2D column's electrical resistance. A diesel sample was used to compare the 2D peak capacity (2nc) and resolution (2Rs), while a perfume sample was used to compare the reproducibility of the system for within-day (n = 5) and day-to-day (n = 5) results. The 2nc improved by 52% with the 2DTPS compared to the secondary oven. The GC × GC system utilizing the 2DTPS had an average within-day and day-to-day relative standard deviation (RSD) of 0.02 and 0.12% for the 1D retention time (1tR), 0.56 and 0.58% for the 2D retention time (2tR), and 1.18 and 1.53% for the peak area, respectively.

Second dimension temperature programming system for comprehensive two-dimensional gas chromatography with true temperature control

A proof-of-concept second dimension (²D) temperature programming system for comprehensive two-dimensional gas chromatography (GC × GC) with true temperature control is introduced and its performance characterized. The ²D temperature programming system utilized a commercial stainless-steel capillary column that was resistively heated and controlled using an Arduino UNO microcontroller. Temperature measurement was accomplished using a differential thermocouple system attached to the ²D column. Diesel was injected in triplicate to compare the reproducibility of the GC × GC system without additional ²D heating, with ²D temperature programming, and with a constant offset, all accomplished using the ²D temperature programming system. Relative standard deviations for the ²D temperature programming were 0.02%, 0.49% and 1.2% for the first dimension (¹D) retention time, ²D retention time, and peak area, respectively. The estimated ²D peak capacity improved by 48% with ²D temperature programming compared to the separation without additional ²D heating.

Dynamic Control of Gas Chromatographic Selectivity during the Analysis of Organic Bases.

A novel method for controlling selectivity during the gas chromatographic (GC) analysis of organic bases is presented. The technique employs tandem stainless steel capillary columns, each coated with a pH adjusted water stationary phase. The first is a 0.5 m trap column coated with a pH 2.2 phase, while the second is an 11 m analytical column coated with a pH 11.4 phase. The first column traps basic analytes from injected samples, while the remaining components continue to elute and separate. Then, upon injection of a volatile aqueous ammonia solution, the basic analytes are released as desired to the analytical column where they are separated and analyzed. Separations are quite reproducible and demonstrate an average RSD of 1.2% for analyte retention times in consecutive trials. Using this approach, the retention of such analytes can be readily controlled and they can be held in the system for periods of up to 1 h without significant erosion of peak shape. As such, it can provide considerable control over analyte selectivity and resolution compared to conventional separations. Further, by employing a third conventional GC column to the series, both traditional hydrocarbon and enhanced organic base separations can be performed. The method is applied to the analysis of complex mixtures, such as gasoline, and much less matrix interference is observed as a result. The findings indicate that this approach could be a useful alternative for analyzing such samples.

Packed column supercritical fluid chromatography using stainless steel particles and water as a stationary phase.

Stainless steel (SS) particles were demonstrated as a novel useful support for a water stationary phase in packed column supercritical fluid chromatography using a CO2 mobile phase. Separations employed flame ionization detection, and the system was operated over a range of temperatures and pressures. Retention times reproduced well with RSD values of 2.6% or less. Compared to analogous separations employing a water stationary phase coated onto a SS capillary column, the packed column method provided separations that were about 10× faster, with nearly 8-fold larger analyte retention factors, while maintaining good peak shape and comparable column efficiency. Under normal operating conditions, the packed column contains about 131 ± 4 μL/m of water phase (around a 5% m/m coating), which is over 25× greater than the capillary column and also affords it a 20-fold larger sample capacity. Several applications of the packed column system are examined, and the results indicate that it is a useful alternative to the capillary column mode, particularly where analyte loads or sample matrix interference is a concern. Given its high sample capacity, this packed column method may also be useful to explore on a more preparative scale in the future.

Columns for gas chromatography: performance and selection

Preface. Acknowledgments. 1 Introduction. 1.1 Evolution of Gas Chromatographic Columns. 1.2 Central Role Played by the Column. 1.3 Justification for Column Selection and Care. 1.4 Literature on Gas Chromatographic Columns. 1.5 Gas Chromatographic Resources on the Internet. References. 2 Packed Column Gas Chromatography. 2.1 Introduction. 2.2 Solid Supports and Adsorbents. Supports for Gas-Liquid Chromatography. Adsorbents for Gas-Solid Chromatography. 2.3 Stationary Phases. Requirements of a Stationary Phase. USP Designation of Stationary Phases. Kovats Retention Index. McReynolds and Rohrschneider Classifications of Stationary Phases. Evaluation of Column Operation. Optimization of Packed Column Separations. 2.4 Column Preparation. Coating Methods. Tubing Materials and Dimensions. Glass Wool Plugs and Column Fittings. Filling the Column. Conditioning the Column and Column Care. 2.5 United States Pharmacopeia and National Formulary Chromatographic Methods. References. 3 Capillary Column Gas Chromatography. 3.1 Introduction. Significance and Impact of Capillary Gas Chromatography. Chronology of Achievements in Capillary Gas Chromatography. Comparison of Packed and Capillary Columns. 3.2 Capillary Column Technology. Capillary Column Materials. Fused Silica and Other Glasses. Extrusion of a Fused-Silica Capillary Column. Aluminum-Clad Fused-Silica Capillary Columns. Fused-Silica-Lined Stainless Steel Capillary Columns. 3.3 Preparation of Fused-Silica Capillary Columns. Silanol Deactivation Procedures. Static Coating of Capillary Columns. Capillary Cages. Test Mixtures for Monitoring Column Performance. Diagnostic Role Played by Components of Test Mixtures. 3.4 Chromatographic Performance of Capillary Columns. Golay Equation Versus the van Deemter Expression. Choice of Carrier Gas. Measurement of Linear Velocity and Flow Rate. Effect of Carrier Gas Viscosity on Linear Velocity. Phase Ratio. Coating Efficiency. 3.5 Stationary-Phase Selection for Capillary Gas Chromatography. Requirements. History. Comparison of Columns from Manufacturers. Polysiloxane Phases. Polyethylene Glycol Phases. Cross-Linked Versus Chemically Bonded Phase. Chemical Bonding. MS-Grade Phases Versus Polysilarylene or Polysilphenylene Phases. Sol-Gel Stationary Phases. Phenylpolycarborane-Siloxane Phases. 3.6 Specialty Columns. EPA Methods. Chiral Stationary Phases. Gas-Solid Adsorption Capillary Columns: PLOT Columns. 3.7 Capillary Column Selection. Practical Considerations of Column Diameter, Film Thickness, and Column Length. Capillary Columns of 0.53mm i.d.: Megabore Columns. Correlation of Column Dimensions and Film Thickness with Parameters in the Fundamental Resolution Equation. Column Selection for Gas Chromatography by Specifications. 3.8 Column Installation and Care. Carrier Gas Purifiers. Ferrule Materials and Fittings. Column Installation. Column Conditioning. Column Bleed. Retention Gap and Guard Columns. Column Fatigue and Regeneration. 3.9 Special Gas Chromatographic Techniques. Simulated Distillation. Multidimensional Gas Chromatography. Computer Modeling of Stationary Phases. References. 4 Column Oven Temperature Control. 4.1 Thermal Performance Variables and Electronic Considerations. 4.2 Advantages of Temperature Programming over Isothermal Operation. 4.3 Oven Temperature Profiles for Programmed-Temperature Gas Chromatography. 4.4 Role of Computer Assistance in Optimizing Separations in Gas Chromatography. DryLab (LC Resources). ProezGC (Restek Corporation). GC-SOS (Chem SW). 4.5 Fast or High-Speed Gas Chromatography. Selectivity Tuning. Resistively Heated Columns and Column Jackets. 4.6 Subambient Oven Temperature Control. References. Selected References. Appendix A: Guide to Selection of Packed Columns. Appendix B: Column Selection. Index.

Chromatography with Two Mobile Phases

Experimental results for the investigation of chromatographic columns containing two mobile phases are presented. The eluent was composed of mixtures of methanol and carbon dioxide. The column was an uncoated fused-silica-lined stainless steel capillary column. At certain experimental conditions, the eluent divided into two phases, both of which moved through the column. The predominant component of the liquid phase was methanol whereas the gas phase was composed of at least 93 mol % CO2. The columns were studied over a range of feed compositions (45-95 mol % CO2), pressures (61-101 bar), and temperatures (30-100 degrees C). The compositions and densities of each phase were calculated from the Peng-Robinson equation of state. The residence times of the two mobile phases were determined by tracer pulse chromatography. The partition coefficients of a probe solute, benzene, were measured along with the retention times of neon and the total volume of the chromatographic column as a function of temperature, pressure, and stoichiometric feed composition. The calculated column volumes, that is the volume of the liquid and gas, were constant over the full range of feed composition. The partition coefficient of benzene was constant at fixed pressure and temperature, varied logarithmically with density at fixed temperature and feed composition, and displayed a maximum at intermediate temperatures at fixed pressure and feed composition. The measured retention times of neon were consistently equivalent to the calculated residence times of the gas phase, indicating that neon did not dissolve in the liquid phase and could thus serve as an accurate dead time marker. The implementation of chromatography with two mobile phases produces a chromatographic "window". There is a lower limit for the retention volume of all solutes, viz., the residence time of the gas phase, exactly the same as normal chromatography. However, elimination of the stationary phase produces an upper limit to the retention volumes of solutes. This upper limit is the residence time of the liquid phase, so there is a retention window such that tG < or = ti < or = tL for all solutes.

Automated solid phase dynamic extraction--extraction of organics using a wall coated syringe needle.

Extractions of liquid samples were carried out using wall coated needles prepared from stainless steel capillary columns instead of syringe needles. This micro extraction technique was applied to the analysis of pesticides in water. Important parameters influencing the extraction such as sample velocity, extraction time and also the desorption parameters were investigated and optimized. Automation of this technique was realized using a conventional automatic sampler. Limits of detection were improved using the multiple extraction/desorption technique. Chromatographic data and limits of detection were compared with those obtained by solid phase micro extraction (SPME). Using a needle with a 7 microns film yielded limits of detection varying from 0.001-0.1 microgram/L and were in the same range as those resulting from the extraction using a 100 microns polydimethylsiloxane (PDMS) SPME fiber. The main advantages of the needle extraction technique were the significantly higher extraction speed and the practical aspects of a stable steel needle compared to those of a fragile fiber. The extraction speed using a needle with a 7 microns film was up to five times higher than the speed of SPME using a 100 microns PDMS fiber. The steel needle could be stressed mechanically in a higher extent than a SPME fiber. Sample volumes and aliquots of liquid media could be handled and moved from one bottle to another using the automatic sampler.

Confirmation of the xanthone structure in thermally treated polycarbonates by reactive pyrolysis-gas chromatography/mass spectrometry

Reactive pyrolysis-gas chromatography/mass spectrometry in the presence of tetramethylammonium hydroxide was used to confirm the existence of xanthone structures in polycarbonate (PC) samples thermally treated at 300 and 400 °C. The predicted characteristic product ( M W=492) of the xanthone structures was successfully eluted on the resulting pyrogram by use of a deactivated stainless steel capillary column whose temperature was programmed up to 370 °C leading its positive assignment by its mass spectrum. Further, unequivocal identification of the specific product was carried out from the retention index data for the whole main degradation products observed on the pyrograms of the PC samples. Finally, the amounts of the xanthone structures formed in the PC samples are quantitatively discussed.

Gas chromatographic separation of bile acid 3-glucosides and 3-glucuronides without prior deconjugation on a stainless-steel capillary column

A method for the gas chromatographic (GC) separation of the 3-glucoside and 3-glucuronide conjugates of bile acids without the necessity for a hydrolytic step is described. The bile acid glycosides were derivatized to their complete methyl ester trimethylsilyl (Me-TMS) or methyl ester dimethylethylsilyl (Me-DMES) ether derivatives, which in turn were chromatographed on an inert and thermostable stainless-steel capillary column, Ultra ALLOY-1 (HT), coated with a thin film (0.15 μm) of chemically bonded and cross-linked dimethylsiloxane. They exhibited a single peak of the theoretical shape without any accompanying peaks due to thermal decomposition, even at oven temperatures of 320–330°C. Excellent GC separation of isomeric bile acid glycosides was achieved by the combined use of suitable derivatives and column. This method, which does not need the prior deconjugation of the glycosidic moiety, could be usefully applied to biosynthetic and metabolic studies of bile acids in biological materials.

A novel focusing injection technique for chemiluminescent detection of volatile sulfur compounds separated by HRGC

A one meter stainless steel capillary column coated with a 20μm film of polydimethylsiloxane was used to replace the Teflon gas sampling loop of a HRGC – flameless SCD system. This column trap was equilibrated with the gaseous sample and then purged with carrier gas while being sequentially, resistively heated in ten 10 cm sections. The sequential heating of the 10cm sections was timed such that the velocity of the moving heated zone was approximately the same as the velocity of the carrier gas. The thick stationary phase film served to retard the front end of the injection band while the ballistic heating accelerated the back end. The net result was focusing of the injection, which gave rise to a narrower injection profile than that obtained with the original Teflon loop.

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A gas chromatographic (GC) method was developed for the identification of grayanotoxins (G), I, II, and III, which are toxic diterpenoids of Leucothoe grayana MAx. GC was done with stainless steel capillary columns (CB17-M 15-025, 15m, which corresponds to OV-17), with programming from 200 to 300°C at 10°C/min. Grayanotoxins with C3-OH and C6-OH gave split peaks on chromatograms. The concentration of grayanotoxins and their GC peak area were directly proportional. This method was used for the identification of grayanane compounds in toxic honey.

Stainless steel capillary columns for high temperature gas chromatography

AbstractA layer of elemental silicon has been deposited on the surface of stainless steel tubing by means of chemical vapor deposition (CVD). Two kinds of capillary column were prepared from the deactivated tubing: cross‐linked, silanol‐terminated polydime‐thylsiloxane wall coated open tubular (WCOT) columns and molecular sieve 13X porous layer open tubular (PLOT) columns. Unlike fused silica capillary columns, stainless steel WCOT and PLOT columns can be operated at temperatures in excess of 400°C. High temperature simulated distillation has been performed successfully with a macro bore WCOT column and rapid PNA (paraffin, naphthene, and aromatic) analysis with a multidimensional gas solid chromatographic (GSC) system using PLOT columns.

Quantitative gas chromatographic analysis of mandelic acid enantiomers

A procedure was developed for the quantitative gas chromatographic (GC) analysis of mixtures of mandelic acid enantiomers. Past methods for the GC resolution of α-hydroxy acid enantiomers on optically active stationary phases are systematically reviewed, with special attention to mandelic acid, which is particularly prone to racemization during derivatization. Modification of an earlier procedure involving the conversions: mandelic acid → mandelyl chloride → N-propylmandelamide → O-trimethylsilyl-N-propylmandelamide finally permitted the preparation of O-trimethylsilyl-N-propylmandelamide on a macro scale with negligible racemization and allowed the precise GC analyses of mandelic acid enantiomers on a stainless-steel capillary column coated with N-docasanoyl-L-valine tert.-butylamide.

High-performance packed glass-lined stainless steel capillary column for microcolumn liquid chromatography

High-performance packed glass-lined stainless steel capillary column for microcolumn liquid chromatography

A convenient, rapid method for the resolution of enantiomeric amino acids using chiral phases on stainless-steel capillary gas chromatographic columns

An improved method is described for the resolution of enantiomeric isopropyl esters of N-trifluoroacetyl-α-amino acids of nonbasic amino acids using N-docosanoyl- l-valyl- t-butylamide and N-octadecanoyl- l-valyl- l-valine cyclohexyl ester as mixed chiral phases on 150-ft stainless-steel capillary columns. Enantiomers of Ala, Val, Ile, Leu, Ser, Thr, Asp, Met, Glu, and Phe are resolved in 105 min. This method avoids the fractionation problems and high costs encountered with the diastereometric method and difficulties and costs encountered in loading and maintaining glass capillary columns. It is particularly useful for studies involving a large number of resolutions as in a study of the kinetics of racemization of amino acids.

The Lipid Fatty Acids of Proteolytic Clostridia

Capillary gas-liquid chromatography (g.l.c.) and g.l.c./mass spectrometry (g.l.c./m.s.) were used to study the fatty acid composition of the lipids of the following 23 species of proteolytic clostridia grown in a Trypticase/yeast extract medium: Clostridium bifermentans, C. cadaveris, C. caloritolerans, C. cochlearium, C. difficile, C. ghoni, C. glycolicum, C. histolyticum, C. lentoputrescens, C. limosum, C. lituseburense, C. malenominatum, C. mangenotii, C. propionicum, C. putrefaciens, C. putrificum, C. scatologenes, C. sordellii, C. sporogenes, C. sticklandii, C. subterminale, C. tetani, C. tetanomorphum. These species contained a total of 55 fatty acids in the range C12 to C18. The methyl esters were separated on a 152 m stainless steel capillary column coated with poly(1,4-butanediol succinate) and characterized by their equivalent chain lengths and by g.l.c./m.s. The predominant acids were n-C14:0 and n-C16:0. There were two groups of organisms: those which contained fatty acids of the n, iso and anteiso series and those which contained only those of the n series. All the organisms which contained iso and anteiso acids also oxidized valine, leucine and isoleucine to the corresponding branched-chain volatile fatty acids. The iso acids found had both even and odd numbers of carbon atoms and were probably derived from valine and leucine, respectively; the anteiso acids all had odd numbers of carbon atoms and were probably derived from isoleucine via 2-methylbutyric acid. These organisms also produced small amounts of monoenoic iso acids. Of the seven species which contained only acids of the n series, C. histolyticum produces acetic acid as its only end-product whereas the other six ferment glutamic acid and produce acetic and n-butyric acids; they also form propionic acid from threonine.

Separation of 28 to 114°C hydrocarbons with glass capillary columns

AbstractTechniques 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.

The Use of Capillary Columns for the Detection of Barbiturates in Clinical Chemistry

Abstract A gas chromatographic (GC) method involving the use of a capillary column and methylattng agents for the qualitative analysis of ten barbiturates has been developed. The method includes the use of a hydrogen flame ionization detector (FID), a 15.24 m × 0.76 mm stainless steel capillary column coated with OV-17 stationary phase, and two methylating agents, trimethylanilinium hydroxide (TMAH) and methyl iodide (MI) in the presence of potassium carbonate as a condensing agent. The results obtained with this method were compared to a standard GC technique. Improved results from the use of MI and a mixed solvent system, acetone/methanol, rather than acetone alone, were observed. Applications of this technique to clinical samples have been made.

1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonane; A host-specific substance in Norway spruce under attack byTrypodendron lineatum Oliv.

The isolation and identification of the title compound was carried out in the following manner: Twenty kilograms of the bark from T. lineatum-infested Norway spruce were collected and put directly into pentane after the entrance holes of boring beetles were thoroughly cut out. After standing for 72 h at room temperature the solvent was removed through a 1-m Vigreux column and the residue was distilled under N z at 15Torr. All volatiles up to 100 ~ were collected, yielding 5.2 g of mainly monoterpene hydrocarbons, oxidized monoterpenes, and sesquiterpene hydrocarbons. GLC analysis was carried out on a Carto-Erba 2100, using a 50-m stainless steel capillary column with Marlophen 87 under program from 50 to I40 ~ at a rate of 3 ~ mass spectra were obtained from a Varian MAT 111 GCMS coupling system. A trace substance (0.2Zo) eluting between 7-terpinene and terpinolene furnished a mass spectrum which strongly resembled the known 1-methyl-6,8dioxabicyclo[3.3.1]octanes [1, 2]: 43 (100), 54 (11), 55 (12), 58 (22), 67 (11), 68 (16), 71 (26), 81 (12), 87 (40), 114 (28), 156 (6, P). Preparative GLC on a Carlo-Erba 2400 with a stainless steel column (8 m, 8 mm i.D., 10% PPG on Chromosorb G AW-DMCS 60-80 mesh) yielded 0.2 mg of the substance, the IH-NMR spectrum (Bruker WH 270, 15,000 scans) of which showed two characteristic signals at b 4.09 (1 H) and 4.21 (1 H), suggesting a bicyclic ketal structure together with the molecular formula C9H1602, obtained by high-resolution mass spectrometry (Varian MAT SM 1). None of the probable 6,8-dioxabicyclo[3.2.1]octane structures which were prepared for comparison were completely in accord with all data of the natural compound. But 1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nouane, a ketal belonging to a bicyclic system recently found in tobacco flavor [3], was identical in all respects with the natural compound. The substance was prepared in low yield by Diels-Alder reaction of 3-buten-2-one and 4-penten-2-ol followed by cyclization. Results of our investigations concerning the exact stereochemistry will be reported later. As the new compound is permanently and exclusively present in Norway spruce attacked by I". lineatum it is now l~ioassayed to clarify whether it serves as a primary attractant beside other chemical messengers such as 3hydroxy-3-methylbutanone [4, 5] and c~-pinene/ethanol [6].