Innovative Chromatography Products
A better, simpler approach to analyses of trace-level compounds Compared to splitless injection, direct flash vaporization injection – direct injection – offers greater sensitivity, simpler operation, and reduced potential for adsorbing active compounds. This 24-page guide discusses the advantages and disadvantages of direct injection, compared to other techniques, and examines considerations such as modifying a splitless inlet, retrofitting a packed column injection port, and the need for make-up gas. Operating parameters such as flow rates and sample injection volume are reviewed. (PDF - 5608kB)
In some analyses, particularly with pharmaceutical or flavor and fragrance compounds, enantiomer pairs must be resolved for separate quantification. Five cyclodextrin-based Restek chiral capillary GC columns offer a unique range of selectivities, to enable you to accomplish these often-difficult separations. Many example chromatograms in this 24-page guide will help you find the best column—or columns—for your particular need. (PDF - 462kB)
This article provides an introduction to control systems and discusses how control variables influence process variables. Topics include open loop, closed loop, and PID control systems. Simulations illustrate overshoot and undershoot around the setpoint during process control.
A basic understanding of gas flow principles is fundamental to obtaining accurate flow measurements. This primer contrasts mass flow and volumetric flow regimes, and illustrates the effect of flow impedance and loading on the flow source in gas chromatography.
Static headspace analysis will save you time and money when assaying a variety of sample matrices—and often is easier than alternative sampling approaches. This 20-page guide discusses basic principles, instrumentation, applications, and troubleshooting. Restek capillary GC columns and an extensive selection of accessories will simplify getting started. (PDF - 6234kB)
It is commonly known in gas chromatography that many problems can be traced to the injection system (e.g., sample, syringe, inlet), which is often a primary place to look at possible issues. This is a valid statement as 80% of “trouble” is related to injection conditions. One must also be aware that activity may be caused by other contributions. For instance, if we look at nonsymmetrical peaks, there are more important areas to look at. Not only can the columns be overloaded or poorly deactivated, but the contribution of the detector also has a huge impact on peak shape and response. Here, it is shown that flame tips can adsorb up to 90% of components and cause tailing of polar as well as basic/acidic components. Though it looks like columns are not performing, it’s the detector that is the problem.
Content previously published on www.sepscience.com. (PDF - 1801kB)
With Restek's guidance and our comprehensive line of high-quality GC inlet supplies, performing proper GC inlet maintenance to help maximize your lab's uptime and ensure accurate, reproducible data is as easy as replacing a liner (and a few other items).
Because nitrous oxide is a gas under ambient conditions, it will not be retained by liquid stationary phases unless subambient conditions are established, which can be expensive to set up and difficult to maintain. Using an adsorbent stationary phase, such as porous polymers, is a better approach because adsorbents provide very high retention and allow gases to be separated at temperatures above ambient. This article explores best practices and demonstrates the separation of nitrous oxide on several different adsorbent phases.
Content previously published on www.sepscience.com. (PDF - 327kB)
The new Restek methanizer (CH4izer) for Agilent GCs allows ppb-level determination of CO and CO2 using a cost-effective FID instead of more expensive instrumentation. This unit is factory set to 380 °C (± 1 °C) for optimal catalytic conversion, but can be easily adjusted as desired. Less cumbersome than other models, the Restek methanizer is designed for easy installation and fast catalyst tube replacement so you spend more time analyzing samples and less time on maintenance. (PDF - 1426kB)
Application and Limitation of Using Adsorbents as Stationary Phases in Gas Chromatography for the Separation of Volatile Compounds
Adsorbents have unique separation characteristics. The adsorption process allows very volatile components to be retained at higher temperatures that create easier conditions to quantify very volatile compounds. Several adsorbents have found wide application in industry. Molecular sieves are used for the separation of inert gases, and porous polymers based on styrene divinylbenzene are used for the separation of the more polar compounds. These adsorption materials have also been made available in capillary columns where the retention is generated by a layer of adsorbent particles on the inside wall of a capillary. Such capillaries are called PLOT (Porous Layer Open Tubular) columns and are highly efficient. They produce high theoretical plate numbers and have high operation temperatures. The challenge of PLOT columns is to stabilize the layer as particles can be dislodged from the layer and form restrictions. Such restrictions can be measured and the values can be used to control PLOT quality. It was also possible to apply the PLOT technology in metal columns (MXT), allowing the process type of applications to take full advantage of these developments.
Content previously published on www.sepscience.com. (PDF - 1395kB)
Siltek®/Sulfinert® surface treatments improve component performance by significantly reducing corrosion and adsorption problems in the sampling and sample transfer pathways. These treatments improve sampling accuracy, increase component lifetime, and cost less than super alloys. Treatments can be applied to cylinders, valves, fittings, tubing and more, and demonstrably improve detection of low-level sulfur, nitric oxide, and mercury compounds in a wide variety of applications and industries.
Changing from Helium to Nitrogen and Maintaining the Separation Efficiency in the Same Analysis Time
For several reasons, there is interest in replacing helium with a different carrier gas in gas chromatography. Hydrogen is the obvious choice, but there is concern about safety and reactivity. It is also possible to use nitrogen, but this is often not considered because it has a low optimal flow and velocity. Here, we will show that it is possible to replace helium with nitrogen as the carrier gas while separation, peak elution order, analysis time, response, and even oven temperature conditions can be kept the same.
Content previously published on www.sepscience.com. (PDF - 1061kB)
Wide range of options for HPLC systems and pumps. (PDF - 914kB)
What is derivatization and how can is improve your analyses? This note describes the advantages of derivatization and explains how to choose the correct reagent. Includes product information and an overview of silylation, acylation, and alkylation. (PDF - 312kB)
Determining Pesticides in Dietary Supplements with QuEChERS Extraction, Cartridge SPE, and GCxGC-TOFMS
The novel approach used here combines QuEChERS extraction, cartridge SPE cleanup, and GCxGC-TOFMS analysis, resulting in good recoveries for a wide range of pesticides in dietary supplements. Matrices include dandelion root, sage, and a multi-herb finished product.
Recently, I spoke with a customer who was trying to speed up an analysis. He had decided to use a shorter column with a smaller diameter to maintain separation efficiency and decrease run times by a factor of two. However, using this approach, the customer did not get the same separation as peaks moved, even swapping direction. What was happening and how could the risk of peak swapping be reduced? In this article, we discuss the phenomena of relative peak shifting, which can occur because of a possible change in the elution temperature.
Content previously published on www.sepscience.com. (PDF - 2011kB)
QuEChERS is a simple, effective approach to sample prep that can be applied to the analysis of pesticides in dietary supplements. Here, we demonstrate a QuEChERS, cSPE, GC-TOFMS procedure that results in good recoveries for a wide range of pesticides in dandelion root. (PDF - 4944kB)
Restek's Dual Vespel Ring inlet seal gives you a better seal with fewer parts. Data show that the soft Vespel material has a much lower leak rate than a metal seal. Also, since less torque is required for installation, user variability is reduced.
Protect your instrument and improve data quality with this powerful pair from Restek. Checking for leaks with our new electronic leak detector and verifying flows with a ProFLOW 6000 flowmeter before you analyze samples helps you avoid costly problems later. (PDF - 618kB)
The multi-dynode approach of all ETP electron multipliers results in longer lifetimes—and better sensitivity—compared with channel electron multipliers (CEM) or continuous-dynode multipliers. Optimized ion and electronic optics help ensure maximum performance, while the increased surface area offers enhanced sensitivity and extended operational life. (PDF - 4357kB)
A high speed GC-MS method was developed for the analysis of carcinogenic aryl amines derived from reductive cleavage of certain azo dyes using the Rxi-35Sil MS column. The use of azo dyes that break down to form these amines in clothing is a potential exposure risk and is regulated in the European Union (EU) under the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation instated by (EC) 1907/2006. The optimal selectivity, high efficiency, and amine inertness of the Rxi-35Sil MS column make it an ideal choice for high-throughput GC-MS analysis of trace-level azo dye aryl amines.
Fast Screening of Recalled Tylenol® for Tribromoanisole and Related Adulterants Using QuEChERS and GC-TOFMS
Screening methods for consumer product adulteration cases, such as the recent Tylenol recall, can benefit from fast QuEChERS-based sample preparation and sensitive, full mass-range GC/TOF-MS.
QuEChERS dSPE methods simplify extract cleanup, reduce material costs, and improve sample throughput. Here we demonstrate the effectiveness of QuEChERS sample cleanup using a multiresidue analysis of pesticides on strawberries. (PDF - 1180kB)
New reversible Flip Seal inlet seals from Restek last longer than other inlet seals. Simply use—flip—then use again. Review our Flip Seal FAQ page for quick answers on how to install and optimize use of this innovative new GC inlet seal.
Setting up and maintaining an effective gas management system is critical for GC labs. This guide provides an overview of gas management and helps you determine which components are right for your lab. Includes gas generators, regulators, tubing, fittings, gas purifiers, and more. (PDF - 1791kB)
GC Column Installation Made Easier with Extended Reducing Nuts for the Agilent® Split/Splitless Inlet
In order to make GC column installation easier when using an insulating cup in your Agilent split/splitless GC inlet, standard reducing nuts should be replaced with extended reducing nuts. This simple change improves visibility of the nut during column installation and allows you to reap the benefits of using the insulating cup.
The Restek Innovations and Technical Services specialists have found this to be a reliable sequence for avoiding problems when preparing and installing a capillary GC column. (PDF - 1011kB)
With Restek's guidance and our comprehensive line of high-quality GC inlet supplies, performing proper GC inlet maintenance to help maximize your lab's uptime and ensure accurate, reproducible data is as easy as replacing a liner (and a few other items).
This application note directly compares the seven columns most commonly used for phthalate analysis. Rtx-440 and Rxi-XLB columns are the preferred choices for phthalate GC-MS analysis based on their fast analysis times and good resolution for both 18 regulated phthalates and an extended list of 40 compounds. For GC-ECD work, a dual column set of Rtx-440 and Rxi-35Sil MS columns is recommended.
An extensive catalog of consumer-replaceable instrument parts, tools, accessories, and supplies needed to keep your Agilent GC running at top performance. Save time and improve results with Genuine Restek Replacement Parts! Request a printed copy. (PDF - 2955kB)
An extensive catalog of consumer-replaceable instrument parts, tools, accessories, and supplies needed to keep your Bruker/Varian GC running at top performance. Save time and improve results with Genuine Restek Replacement Parts! Request a printed copy. (PDF - 2069kB)
An extensive catalog of consumer-replaceable instrument parts, tools, accessories, and supplies needed to keep your PerkinElmer GC running at top performance. Save time and improve results with Genuine Restek Replacement Parts! Request a printed copy. (PDF - 2083kB)
An extensive catalog of consumer-replaceable instrument parts, tools, accessories, and supplies needed to keep your Shimadzu GC running at top performance. Save time and improve results with Genuine Restek Replacement Parts! Request a printed copy. (PDF - 3596kB)
An extensive catalog of consumer-replaceable instrument parts, tools, accessories, and supplies needed to keep your Thermo Scientific GC running at top performance. Save time and improve results with Genuine Restek Replacement Parts! Request a printed copy. (PDF - 2152kB)
Do you need to connect a GC analytical column to a guard column or transfer line? Or repair a broken column? How about connecting two columns for primary and confirmation analysis from a single injection? Restek’s extensive selection of GC connectors makes all of these connections possible. Here we review differences among our connectors and answer some frequently asked questions about our popular Press-Tight® connectors.
We get always a number of inquiries from customers who see peaks show up in their chromatogram when they do not inject them. There are several sources for these “ghost peaks,” which we will discuss in several articles.
Content previously published on www.sepscience.com. (PDF - 927kB)
In the last issue, we discussed possible sources of ghost peaks related to the carrier gas and gas lines. Here, we move into the injection port itself, as it is a big source of trouble. The injection of the sample is responsible for >80% of the troubles that are experienced in gas chromatography. In the process of rapid evaporation of the sample, several things can go wrong.
Content previously published on www.sepscience.com. (PDF - 1277kB)
Ghost Peaks in Gas Chromatography Part 3: Sample Contamination and Ghost Peaks Formed by the Stationary Phase Itself
In the last issue, we discussed possible sources for ghost peaks related to the carrier gas and the gas lines. The injection port septa and O-rings can also be a source for ghost peaks. Here we look at the sample itself and the different contaminants that can result in unwanted “extra” peaks. Also, the stationary phase in the column can play an interesting role in ghost peak formation.
Content previously published on www.sepscience.com. (PDF - 1619kB)
In the latest issues, we discussed possible sources of ghost peaks related to the carrier gas, gas lines, injection port and parts, degradation, and the column. Here we move onto several other contributions that are not as obvious as the former options.
Content previously published on www.sepscience.com. (PDF - 779kB)
In gas chromatography, 80% of the trouble is caused by the injection system. Also, here we have seen that by degradation of sample components, O-rings, backflash, and septa, extra peaks can be generated. Besides this, the conditions used for injecting the sample can also produce extra peaks.
Content previously published on www.sepscience.com. (PDF - 854kB)
Simplify GC column selection and optimizing GC separations with this companion guide to our popular posters. Detailed discussion of the resolution equation and how it relates to column factors such as stationary phase selectivity, film thickness, internal diameter, and length teach you how to choose the best GC column for your separation easily and effectively. Also includes GC troubleshooting. (PDF - 3598kB)
Analyses of semivolatile organic compounds in environmental samples hold many challenges, particularly during sample preparation and injection onto the capillary GC column. At the same time, quality assurance/quality control requirements can be rigorous. This 28-page guide offers valuable information across the entire scope of the analysis: sample extraction and cleanup, column selection, GC analysis (including hints for reducing discrimination in the injection port), and quantification. (PDF - 6275kB)
New Restek PAL SPME fibers deliver results that consistently meet or exceed the performance of other solid phase microextraction fibers. Our reliable SPME fibers are optimized for PAL system autosamplers and are compatible with most GC inlets. Restek PAL SPME fibers are ideal for many applications in environmental, food, clinical, and other industries. (PDF - 743kB)
Inlet design, including placement of the heating element, differs among manufacturers and as a result the temperature at the septum differs from the actual set point and the degree of this difference varies among manufacturers. Septa brands, however, are given a single maximum operating temperature. Here we demonstrate the temperature gradients within inlets for several popular GC models and discuss the pros and cons of hotter and cooler inlets.
Restek's Electronic Leak Detector is sensitive enough to find leaks below instrument pressure decay test levels and is available at a fraction of the cost of other hand-held units.
Whether you’ve run HILIC methods before or are attempting to for the first time, there are significant differences between reversed-phase and HILIC methods that must be considered. This article addresses common problems that analysts encounter when running HILIC methods and details how to avoid them and successfully use the technique.
How do you choose the GC inlet liner that’s best for your application? With so many options available, selecting the right liner can be a daunting task. In this technical article, Restek makes it easy to choose the best GC inlet liner for each injection technique. Read on and learn how to simplify liner selection!
Choosing the correct chromatography vial helps ensure that your LC and GC analyses are as accurate as possible, but with all the options available how do you select the right vial? Here are a few tips for selecting the best vial for your chromatography needs.
Proper conditioning is essential for optimal performance from a capillary GC column, but inexperienced chromatographers might not know the proper procedures for installing and conditioning a new column. Here, we summarize our recommendations for installation and conditioning procedures.
A common question we get asked by our customers is how they can get longer column lifetime. This can be from a cost perspective (column price) or from a maintenance perspective (downtime, labor, calibration).
Content previously published on www.sepscience.com. (PDF - 729kB)
Simple tips and techniques are presented to improve the accuracy and precision of your data by keeping your column oven at peak performance. Details on reducing variation around the oven set point through calibration and maintenance are given.
Restek offers a wide selection of LC guard columns and choosing the right one is a simple task when you base your decision on your analytical column. By selecting the right guard column system (holder, cartridge, and/or filters) you can provide dependable protection and ensure optimal performance from your analytical column for many analyses to come.
Hub-Cap bottle tops and adapters keep your mobile phase where it belongs and is the easiest, cleanest, safest way to deliver mobile phases for LC applications. (PDF - 1129kB)
In this series, we will discuss the impact of different parameters on the actual separation. We will do this by discussing how they impact and then explain the impact with some practical examples. In GC, there are seven important parameters that we can choose to get a separation. All parameters have an impact and selection of a certain parameter has an impact on the separation.
Content previously published on www.sepscience.com. (PDF - 918kB)
In part 1 of this series, we focused on how to select the stationary phase, which is one of the seven important parameters we need to understand. Once the stationary phase is selected, the column dimensions must be considered. Here, column length, diameter, and film thickness are the key parameters. In this article we turn our attention to the column internal diameter and its relevance.
Content previously published on www.sepscience.com. (PDF - 1423kB)
In parts 1 and 2 of this series we focused on selection of stationary phase and looked at different applications for using different internal diameter. Capillary columns are also available in different length. Here, we look at the third parameter: column length. What is the impact of column length on the separation? If length is changed, what do I have to do to get the results that I anticipate?
Content previously published on www.sepscience.com. (PDF - 1442kB)
In parts 1–3 of this series, we focused on the selection of stationary phase, column length, and internal diameter. The stationary phase is deposited as a film or a layer and its thickness is the fourth parameter we need to understand that impacts the separation. The thickness of the layer determines the amount of the stationary phase that is present in the capillary. Retention is directly related to the amount of the stationary phase; thicker films equal more retention. When do we choose thin or thick films and how do they impact the chromatography? Changing film thickness will impact several parameters: retention, loadability, bleed, efficiency, and even inertness.
Content previously published on www.sepscience.com. (PDF - 1086kB)
In parts 1–4 of this series, we focused on the selection of stationary phase, column length, column ID, and the film thickness. Besides the column-specific parameters, there are three non-column specific parameters that impact the separation. These are the type of carrier gas, its linear velocity, and the temperature of the column. Here we look into the effects of temperature on separations.
Content previously published on www.sepscience.com. (PDF - 1135kB)
In parts 1–5 of this series, we focused on the selection of the column dimensions and stationary phase. We also saw that temperature has a big impact on chromatography. The last two factors to consider, which are somewhat related, are the choice of carrier gas and the setting of carrier gas linear velocity.
Content previously published on www.sepscience.com. (PDF - 604kB)
Regular injection port maintenance helps ensure the best results from your analyses, and helps minimize downtime. Each FastPack inlet kit includes all the parts you need to perform routine maintenanceinlet liner (choose from four styles), O-ring, inlet seal and inlet seal washer, and septumin a sealed Mylar bag.
A quick reference for ordering the top-quality supplies you need to service and maintain your GC inlet. (PDF - 2028kB)
A quick reference for ordering the top-quality supplies you need to service and maintain your GC inlet. (PDF - 2058kB)
A quick reference for ordering the top-quality supplies you need to service and maintain your GC inlet. (PDF - 2025kB)
A quick reference for ordering the top-quality supplies you need to service and maintain your GC inlet. (PDF - 2039kB)
A quick reference for ordering the top-quality supplies you need to service and maintain your GC inlet. (PDF - 2032kB)
Injecting a liquid sample into a hot GC inlet is a dynamic and complex event. Of the many parameters that affect the success of an injection, inlet temperature is one of the most significant. Raising or lowering the inlet temperature setpoint can have a profound effect on how much sample is transferred onto the column depending on sample volatility and thermal sensitivity. But, once the inlet temperature is set, how much of the inlet is actually kept at that setpoint? Moreover, how might thermal profiles change between inlets?
Analysts should use an electronic leak detector when installing a new column or fitting, changing a cylinder, or troubleshooting the system. The portable, reliable, easy-to-use Restek Electronic Leak Detector reveals minute leaks without contaminating the system.
This handy GC liner selection guide provides easy-to-read, informative comparisons of packing options, geometries, and dimensions, as well as types of injections and how they relate to liner choice. Keep this guide at your fingertips to make finding the right inlet liner a quick and easy decision. (PDF - 1180kB)
Method Development and Column Selection: How the FluoroPhenyl Phase Provides the Power of HILIC and Reversed-Phase Modes in One Column
Column selection is an important part of method development as the quality of critical separations is determined in large part by the retention and selectivity of the analytical column. Although C18 columns are commonly employed, FluoroPhenyl columns provide an orthogonal alternative for method development because they incorporate multiple retention mechanisms and can be used in both reversed-phase (RP) and HILIC modes. This paper explores how FluoroPhenyl columns can be used to improve separations, especially for compounds that are difficult to analyze on a C18, such as basic analytes or small, polar compounds.
Restek’s new Thermolite Plus septa offer advanced technology for optimal performance. The ultra-low bleed characteristic of these new septa minimizes the background signal, and the plasma coating prevents the septa from sticking in the injection port. Precision molding ensures a consistent, accurate fit. In addition, select Thermolite Plus septa feature a CenterGuide design to minimize coring. (PDF - 856kB)
A popular Restek guide revised, updated, and expanded What design of inlet liner is best for analyzing dirty samples by split injection? What design minimizes analyte breakdown in splitless injections? Learn about the advantages of these commonly used sample injection techniques – and their disadvantages – to obtain the best results and avoid problems. This 36-page guide is focused on system optimization, maintenance, and troubleshooting. An extensive selection of inlet liners and other products is included. (PDF - 473kB)
This 72-page guide offers a concise, but thorough, overview to analyzing volatile organic compounds in environmental samples. Sections describe purge and trap theory, adsorbents and traps, troubleshooting purge and trap systems, GC system configurations for narrow-bore or wide-bore capillary columns, and detection systems and how they work. A large selection of chromatograms shows analyses obtained through various approaches and illustrates results of changing chromatographic parameters to achieve specific goals. Invaluable to new chromatographers; experienced analysts will find justification for updating methodology. (PDF - 2705kB)
Outfit your Agilent MSDs with Restek chromatography supplies including high-temp EI filaments; fittings, connectors, nuts & transfer lines; ETP electron multipliers; pump oil & cleaning powders; and more. (PDF - 1149kB)
Parker Balston FID gas stations produce 99.9995% hydrogen from deionized water and UHP zero air (<0.1 ppm hydrocarbons) from house compressed air, eliminating inconvenient, costly, hazardous cylinders. The note describes models available from Restek. (PDF - 563kB)
Replace inconvenient, costly, hazardous gas cylinders with a safe, reliable Parker Balston hydrogen generator that produces 99.9995% pure hydrogen from deionized water at up to 510 cc/minute. This note describes all models available from Restek. (PDF - 655kB)
Eliminate the inconveniences, costs, and hazards of gas cylinders – reliable Parker Balston zero air generators produce UHP zero air (<0.1 ppm hydrocarbons) from house compressed air. This note describes all models available from Restek. (PDF - 473kB)
Do you scratch notations or other marks into tubing? You shouldn’t—scratches can allow corrosion or stress to dangerously weaken the tubing. This guide includes many other things you should know to avoid installation problems, damage to system components, or leaks. (PDF - 1501kB)
In chromatography the analysis methods are becoming more and more challenging. Lower detection limits are required, especially if quantification is required at trace levels. As soon as activity develops in a GC system, the first components that start to lose response will be ones that have polar functionality. These can be hydroxyl, amine, or carboxyl groups or combinations. Peaks usually start to tail and retention times can even change.
Content previously published on www.sepscience.com. (PDF - 1402kB)
Restek has developed the first QuEChERS-based method for determining pesticide residues in dietary supplements. This simple, cost-effective procedure reduces matrix interferences as well as sample prep variation among technicians.
Prepare Olive Oil Samples for Pesticide Residue Analysis in Half the Time With a Fraction of the Solvent Using dSPE
Simplify and speed up sample preparation with Resprep dSPE tubes! Here we show the extraction and clean-up of pesticide residues from olive oil samples—twice as fast as GPC, with only a fraction of the solvent required for conventional SPE.
As concerns about mercury in the environment grow, new regulations and testing requirements emerge. To ensure accurate results, sample storage and transfer systems must be inert to elemental mercury. Here we demonstrate that Siltek® treatment provides an unreactive surface compared to stainless steel. Data shown demonstrate that Siltek® treatment of sampling systems will improve analytical accuracy. Siltek® treatment is available on many stock items and custom components can be treated upon request.
Handy tips for choosing the right septum for your application and instrument. Includes an overview of common GC septum problems including coring and bleed. Guidelines help you avoid extraneous peaks and optimize your system’s performance.
Wondering why you are seeing differences in flowmeter readings or trying to change gas flow units? You’ll find answers to these and other frequently asked questions on our ProFLOW 6000 electronic flowmeter FAQ page.
Tubing deactivated with Hydroguard and treated with Silcosteel® is preferred for situations in which water vaporization is encountered, such as in purge and trap systems. Hydroguard’s unique deactivation chemistry creates an outer surface that prevents water vapor from contacting the Silcosteel® treated stainless steel surface below. This protected inert surface allows active analytes to pass through the tubing without adsorbing to the surface.
Scaling down column size is simple to do and can help reduce solvent use. Here is an easy-to-follow example that teaches you how to reduce column internal diameter.
Designed for performance, versatility, ergonomics, and accuracy, Restek’s Resprep VM-96 vacuum manifold is perfect for everyday laboratory applications, including SPE, SLE, PPT, and filtration. Features include a heavy-duty, metal body that keeps the unit in place; precision-manufactured parts that assemble quickly and easily; a viewing window that allows easy observation of plate height and drip rate; durable O-ring and gaskets that provide leak-free seals time after time; and a precision height adaptor and five shims so users can customize plate height to their exact requirements. (PDF - 2579kB)
The Restek Advantage is a technical magazine covering industry news and chromatography applications from a wide range of fields. Highlights from this issue include feature articles on speeding up separations, including LC analysis of pain management drugs in less than 5 min, a 9-min run of 144 semivolatiles, a time-saving combined approach for 1,4-dioxane and key nitrosamines, and much more. (PDF - 10468kB)
Our expertise, experience, and enthusiasm is your Advantage. (PDF - 3741kB)
The Restek Advantage is a technical magazine covering industry news, chromatography applications, and guest editorials by leaders from a wide range of fields. Highlights from this issue include feature articles on increasing sensitivity for 1,4-dioxane and semivolatiles, analyzing sulfonamides by HPLC and UHPLC, selecting column/mobile phase combinations for LC-MS, and much more. (PDF - 5152kB)
The Restek Advantage is a technical magazine covering industry news, chromatography applications, and guest editorials by leaders from a wide range of fields. Highlights from this issue include feature articles on the benefits of proper column selectivity for PAHs, dioxins, and furans; overcoming matrix effects for pesticides in food; cutting analysis time in half for TO-15 VOCs; and much more. (PDF - 8436kB)
Restek is your one source for 2D gas chromatography! Also known as GCxGC, 2D gas chromatography is a powerful multidimensional GC technique that combines two independent separations to accurately analyze highly complex samples. By choosing a primary and a secondary column with differing (orthogonal) stationary phases, it is possible to identify analytes using comprehensive two-dimensional gas chromatography that simply cannot be separated through standard one-dimensional GC. (PDF - 8949kB)
Restek GCxGC Columns: Your one source for 2D gas chromatography! GCxGC is a powerful multidimensional GC technique that combines two independent separations to accurately analyze highly complex samples. By choosing a primary and a secondary column with differing (orthogonal) stationary phases, it is possible to identify analytes using comprehensive two-dimensional gas chromatography that simply cannot be separated through standard one-dimensional GC. (PDF - 474kB)
We invite you to look through this highlighted selection of Restek LC columns and accessories. (PDF - 16883kB)
Even when using guard columns, your LC column may become blocked or contaminated by strongly adsorbed sample components. If you observe decreased column performance, increased backpressure, or other signs of blockage or column contamination, these LC column regeneration steps may help restore your column.
Rxi GC columns deliver more accurate, reliable trace-level results than any other fused silica column on the market. Take variation out of the equation and lower detection limits with highly inert, low bleed Rxi gas chromatography columns. (PDF - 1992kB)
The PAL SPME Arrow system is a revolutionary change in microextraction that combines exceptional robustness with faster extraction times and trace-level sensitivity. In contrast to traditional SPME fibers, SPME Arrows contain significantly more sorbent which allows more target analyte to be extracted in less time, significantly increasing sample throughput. In addition, the unique Arrow tip, inner stabilizing rod, and outer sheath design fully protect the sorbent, minimizing both and analyte loss and mechanical damage. (PDF - 1862kB)
Filtering sample extracts with syringe filters will greatly extend the life of costly chromatographic columns and replacement parts, particularly for HPLC systems. This 2-page fact sheet includes helpful membrane, porosity, and size selection guides. (PDF - 487kB)
Now available in multiple languages, this new and improved version of our popular EZGC chromatogram modeler is just as simple to use as the original software, but it now offers advanced options for selecting phases, changing carrier gases and control parameters, further optimizing your results, and much more! Already a favorite of analysts around the world, the software was updated based on user feedback and now helps you develop and optimize methods more efficiently and effectively than ever before. In just seconds, you can generate a customized, interactive model chromatogram that matches real-world chromatograms with exceptional accuracy. (PDF - 2054kB)
Stabilwax-MS Columns—Thermally Stable, High Polarity GC Columns for Flavor, Food, Fragrance, Industrial Chemical, and Solvent Analyses
Low-bleed Stabilwax-MS columns produce excellent results for the analysis of trace levels of polar compounds by GC-MS. These columns are ideal for a wide range of polar analytes including FAMEs, flavor compounds, essential oils, solvents, aromatics, acrolein/acrylonitrile, and oxygenated compounds. (PDF - 7014kB)
Learn why inertness matters and how using Rxi columns can improve your results.
Silcosteel-CR treatment is highly effective protection for stainless steel exposed to hydrochloric acid, nitric acid, or marine environments: in independent tests, Silcosteel-CR treatment upgraded the corrosion resistance of 300-grade stainless steel by an order of magnitude. Now, electropolished stainless steel tubing and a wide selection of world-renowned Swagelok fittings are available with Silcosteel-CR treatment, from stock. Custom treatment of system components also is available.
Using our unique EZ Twist Top Injection Port, Septum Nut Removal Tool, and Inlet Liner Removal Tool, you can reduce maintenance time and frustration, eliminate tangled gas lines that can lead to leaks, and avoid contact with hot surfaces. The gas lines are attached to the EZ Twist Top Shell Weldment, not to the weldment they are under the GC cover and cannot interfere with routine injection port maintenance. Changing inlet liners becomes a quick and simple task.
Learn what de-wetting is, and how to avoid it, by using an Aqueous C18 column, instead of a conventional C18, when analyzing polar compounds by HPLC.
The Effects of LC Particle Choice on Column Performance: Raptor 1.8 µm Superficially Porous Particles (SPP) for UHPLC Analyses
Superficially porous particles (commonly referred to as SPP or “core-shell” particles) have been proven to provide fast and efficient LC separations. These particles feature a solid, impermeable core enveloped by a thin, porous layer of silica that offers significantly higher efficiency and sensitivity than traditional fully porous particles (FPP). At launch, Raptor SPP LC columns were touted for their selectivity and for their ability to help existing HPLC customers achieve faster separations without the need to purchase UHPLC instruments. With the launch of Raptor 1.8 μm columns, this superior Raptor performance has been unleashed on your UHPLC analyses. But, what exactly does that mean? In this technical note, we will explore the benefits of using Raptor 1.8 μm LC columns in your UHPLC instrument with a focus on peak capacity, column lifetime, and selectivity.
The Effects of LC Particle Choice on Column Performance: Switching from 3 and 5 µm Fully Porous Particles (FPP) to
The Effects of LC Particle Choice on Column Performance:
Gas chromatography is a technique that can be used for a wide range of sample types. If the components to analyze can be transferred in the gas phase by increasing the temperature, then there is a high probability that they can be analyzed by gas chromatography.
Content previously published on www.sepscience.com. (PDF - 1343kB)
The new Raptor ARC-18 column resists phase degradation and bleed in MS conditions. It features well-balanced retention without the drawbacks of using an ordinary C18 in acidic mobile phases. After extended use in low-pH, the sterically protected ARC-18 offers consistent retention, peak shape, and response for charged bases, neutral acids, small polar compounds, and more. (PDF - 3182kB)
The innovative Raptor Biphenyl LC column provides greater aromatic selectivity than commercially available phenyl-hexyl columns and a greater degree of dispersion than conventional phenyls. It is particularly adept at separating compounds that are hard to resolve or that elute early on C18 and other phenyl chemistries. (PDF - 3369kB)
Thermal Desorption: A Practical Applications Guide: II. Residual Volatiles & Materials Emissions Testing
Thermal desorption is a convenient, fully automated alternative to solvent extraction for measuring residual volatiles. This 32-page publication from Markes International Ltd. details the testing of a wide variety of products using thermal desorption. (PDF - 1480kB)
Unlike “one size fits all” guard systems, the Trident LC column protection system gives you the power to select the right level of protection for your analysis. With three levels of protection and a variety of guard cartridges and cap frits, you can select the best combination to match your specific analytical needs. The economical, leak-free design provides a highly versatile combination of convenience, economy, and reliability. (PDF - 1160kB)
UltraShield UHPLC Precolumn Filter
Extend UHPLC column lifetime. Negligible effect on column performance.
Universal fit—easily connects directly to any brand column.
Leak tight to 15,000 psi (1,034 bar).
Does not contribute to system backpressure. Does not contribute to band broadening.
UltraLine UHPLC In-Line
Cost-effective protection for UHPLC systems. Installs quickly with standard UHPLC fittings. Includes replaceable filter element.
Low dead volume supports many applications.
Leak tight to 15,000 psi (1,034 bar). (PDF - 476kB)
Micropacked columns are 1-2 meter, 0.75-1.0mm ID packed stainless steel columns with performance characteristics intermediate between conventional packed columns and capillary columns. They are inexpensive, very durable, and easy to install and operate. They have a wide range of applications, but are especially useful for analyses of gas mixes, including sulfur compounds or light hydrocarbons, for which a packed column is needed to obtain baseline separations of sample components.
Restek USLC columns offer the widest range of selectivity available and are an integral part of successful method development. Ideal for column switching systems, these columns provide orthogonal separations to create optimal resolution and robust methods—all in a 4-column set. (PDF - 1813kB)
Quickly and easily choose the right vials, caps, and inserts for your application, even headspace. (PDF - 6858kB)
Background noise in a gas chromatography system can be eliminated by conditioning the system prior to sample analysis. In this article, we discuss warm-up procedures and use liners and liner installation to demonstrate the importance of conditioning the system to remove background peaks. Investing a little time in warming-up the system pays big dividends by preventing costly coelutions and avoidable reanalyses.
When it comes to speeding up method development, Pro EZGC modeling software saves you time, materials, and a lot of frustration. This technical article puts Restek’s GC chromatogram simulator to the test and demonstrates how well it predicts actual experimental outcomes.