With the expansion of PFAS target analyte lists into shorter chain compounds, the need for better methods is growing. But, when developing new analytical procedures, which PFAS LC column is best? This article explores the impact of phase, dimensions, and particle types and provides options that ensure fast, accurate results.
New and improved Resprep EPH fractionation SPE cartridges from Restek completely separate aliphatic and aromatic compounds, and they are guaranteed to produce background levels that are below the strict reporting limits of MA and NJ EPH methods. Superior lot-to-lot reproducibility and storage stability mean every lot will perform the same as the lot before it.
Keep your organochlorine pesticides analysis GCs up and running by protecting them against matrix components. CarboPrep Plus cartridges surpass traditional Florisil products in removal of sample matrix compounds that cause analyte degradation and downtime due to failed calibration checks. Since CarboPrep Plus cartridges use the same equipment and procedure as Florisil cartridges, the impact to sample prep labs is minimal while the benefit to analytical lab productivity is tremendous.
Using a PFAS delay column is an effective way to separate target PFAS in samples from interferences caused by PFAS contamination in the LC system. This article explains how the PFAS delay column can improve trace-level PFAS analysis by removing the impact of system-related interferences.
Obtaining consistent results for low-level analysis of glycols in water samples is difficult when using splitless injection due primarily to issues with backflash, poor peak shape, and shifting retention times. The split injection method shown here avoids these problems and reliably produces good chromatographic results. Lifetime testing demonstrated that Rtx-Wax columns produce stable results, even after column integrity was challenged with 600 water injections.
Scaling down GC-MS columns and conditions can result in faster semivolatiles analysis times and increased sample throughput, but only when done correctly. In this technical article we demonstrate how to scale an existing method on a traditional format (30 m, 0.25 mm ID, 0.25 µm df) arylene-type column down to a 20 m long, 0.15 mm ID, 0.15 µm df column. By using a properly scaled column and method along with a GC Accelerator oven insert kit, the same separation was achieved with a saving of six minutes per injection.
Polycyclic aromatic hydrocarbons (PAHs) are analyzed at low levels around the world in order to protect human and environmental health. The PAH GC-MS analysis shown here uses SIM mode and column and method parameters scaled down from a commonly used semivolatiles method. Good chromatographic results were achieved down to 0.05 ng on-column in a fast, 15-minute analysis time.
LC-MS/MS analysis of paraquat and diquat herbicides is an important tool for protecting human and environmental health. However, the ion-pairing reagents that are commonly used to improve retention, resolution, and peak shape have a negative impact on sensitivity and can contaminate the system necessitating frequent cleaning. The LC-MS/MS analysis of paraquat and diquat presented here provides complete separation and good peak response for both target analytes in a fast, 7-minute gradient run without the use of troublesome ion pairing reagents.
Sample throughput for semivolatiles analysis can be significantly increased by employing split injection instead of splitless injection. Split injection allows more samples to be analyzed per shift because it utilizes a higher initial GC oven temperature and faster oven cycle time. Pairing a robust Rxi-5Sil MS column with split injection ensures fast, accurate results for analyzing semivolatiles under procedures such as Method 8270.
Semivolatiles methods, such as EPA Method 8270, place stringent demands on gas chromatography (GC) columns. Here we evaluate the performance of Rxi-5Sil MS columns for semivolatiles analysis in terms of bleed, efficiency, and activity. We demonstrate excellent sensitivity and resolution, even for difficult PAHs such as benzo(b)fluoranthene & benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene. Both basic and acidic compounds show good response even at low levels.
Featured Application: Optimized Volatiles Analysis on an Rtx-VMS Column with Restek CRMs Means Better VOC Data in Less Time
Restek’s Rtx-VMS column and certified reference materials (CRMs) are highly effective tools optimized for GC purge-and-trap analysis of volatiles. The unique column phase provides the best separation of critical compounds available on the market. In addition, our comprehensive CRMs are manufactured and QC-tested in our ISO-accredited labs to assure quality and make your job easier.
Whether labs conducting perfluorinated alkyl acid analysis by LC use longer target analyte lists or focus just on PFOA and PFOS, the excellent peak shapes and separations achieved here result in consistent, accurate quantification in much faster analysis times. By switching to a Raptor C18 column, labs can process more samples per hour while still meeting fluorochemical method requirements.
Pinnacle II PAH columns were developed by Restek as an alternative to C18 columns specifically for the analysis of PAHs by HPLC. These reliable columns provide baseline resolution of key PAHs in a fast ~15 minute analysis without the expense of UHPLC equipment.
Carbamate pesticides can be analyzed much faster on an Ultra Carbamate LC column than on a C18 column. Whether using UV, fluorescence, or LC-MS detection, labs can achieve accurate carbamate determinations in just 5–10 minutes using an Ultra Carbamate column and certified reference materials from Restek.
A Raptor Biphenyl column is a better choice for BPA analysis than a conventional C18 column. On a Raptor Biphenyl column, narrow, symmetrical bisphenol A peaks elute in less than 2 minutes, providing a fast and selective means to isolate and quantitate bisphenol A by LC-MS/MS.
Chromatographic conditions were developed for a fast GC-MS glycol ether analysis on the Rxi-1301Sil MS column. This column provides better resolution and faster run times than the thick film cyanopropylphenyl-type columns commonly used for speciation of the glycol ethers.
Typically, 1,4-dioxane and nitrosamines are analyzed in drinking water following separate extraction and analysis procedures, such as Methods 521 and 522. However, here we present a combined method that uses large volume splitless injection and GC-MS (SIM) to meet low part-per-trillion detection limits for these compounds in a fraction of the time required when running separate methods.
Helium, Hydrogen, or Nitrogen—The Choice is Yours: Unique Rtx-CLPesticides Column Set Provides Optimal Results for Organochlorine Pesticides GC-Micro-ECD Analysis Using Any Carrier Gas
Using an Rtx-CLPesticides column set is the best strategy for labs considering alternate carrier gases as a way to reduce helium consumption. These columns have a unique selectivity and produce faster results than competitor columns when using either helium or hydrogen. In addition, only Rtx-CLPesticides columns can be used with nitrogen, which give labs the freedom to choose the carrier gas option that is best for them.
Analyses of halogenated pollutants can be difficult because samples often are contaminated with nontarget compounds and methods can require rigorous quality control. This technical guide covers sample extraction, cleanup, and GC-ECD analysis. Includes chromatographic analysis of chlorinated pesticides, PCBs, chlorinated herbicides, haloacetic acids and more on a single column set. (PDF - 0kB)
Labs analyzing purgeable organic compounds in water can save money and reduce helium dependence by using Method 524.4 with nitrogen purge gas and an Rtx-VMS column. By making the switch, you can reduce helium consumption by 68%, while meeting all Method 524.4 requirements. (PDF - 0kB)
Half the Column, Same Chromatogram: Maintain Resolution of BDE 49 and BDE 71 with Proper Method Translation After Trimming an Rtx-1614 Column for Maintenance
Column trimming can extend GC column lifetime when analyzing polybrominated diphenyl ethers (PBDEs); however, the method must be adapted to the shorter column length in order to maintain separation of critical congeners. Here we demonstrate that with proper method translation an Rtx-1614 GC column can be trimmed nearly in half and still meet resolution requirements for BDE 49 and BDE 71.
Analyze Seven EPA Methods on One GC Column Pair! Pesticides, PCBs, Herbicides, and More on Rtx-CLPesticides & Rtx-CLPesticides2 Columns
Rtx-CLPesticides and Rtx-CLPesticides2 columns are ideal for multiple environmental ECD methods. Here we demonstrate the effectiveness of this column pair for chlorinated pesticides, PCBs as Aroclors, chlorinated herbicides, and haloacetic acids. Includes EPA Methods 8081B, 8082A, 8151A, 504.1, 505, 508.1, and 552.2. Speed up your analyses and reduce downtime using the versatile Rtx-CLPesticides/Rtx-CLPesticides2 column pair in a dual column configuration. (PDF - 0kB)
Air sampling canisters from Restek are durable, easy to use, and highly inert. They weigh just grams more than canisters from other vendors and cost the same to ship. Check out this weight and cost comparison to see for yourself! (PDF - 766kB)
Successfully monitoring chlorinated dioxins and furans requires the unbiased determination of toxic 2,3,7,8-chlorine substituted congeners. The problem is that other congeners and sample matrix–related compounds often complicate the reliable separation of highly toxic 2,3,7,8-TCDD and 2,3,7,8-TCDF—even when using high-resolution GC/high-resolution MS. Fortunately, Restek offers proven solutions for both initial and confirmatory analyses to help you confidently resolve these problematic substances from other coeluting congeners. (PDF - 914kB)
Fingerprinting Crude Oils and Tarballs using Biomarkers and Comprehensive Two-Dimensional Gas Chromatography
Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) was used to analyze petroleum biomarkers creating unique fingerprints of crude oil samples and tarballs collected after the Deepwater Horizon oil spill.
Improve GC Analysis of Extractable Petroleum Hydrocarbons Using Resprep EPH Fractionation SPE Cartridges
New manufacturing and testing procedures for Resprep EPH fractionation SPE cartridges reduce background levels of extractable contaminants and assure more reliable fractionation of aliphatics from aromatics. (PDF - 0kB)
The efficacy of using a Nutech preconcentrator and a 30 m analytical column for VOC analysis of air samples according to Method TO-15 was evaluated. Results demonstrate that method criteria were easily met and in much faster analysis times than typical methods based on 60 m columns.
Restek-exclusive Ultra-Clean resin is a great alternative to XAD-2 resin for sampling semivolatiles. Learn more about how our GC-tested resin, as well as our polyurethane foam (PUF) plugs, can help you with your ambient, indoor, and industrial hygiene air-sampling applications. (PDF - 0kB)
New Rxi-PAH GC Column; Resolve Important Isobaric Polycyclic Aromatic Hydrocarbons for Food Safety and Environmental Methods
Separate isobaric polycyclic aromatic hydrocarbons, including priority EFSA PAH4 compounds benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene, easily and accurately on an Rxi-PAH column. Whether you need more resolution or faster analysis, these new GC columns offer the selectivity and efficiency you need for food safety and environmental PAH analysis. (PDF - 0kB)
A New Solution for Trace-Level Analysis of 1,4-Dioxane in Drinking Water: Large Volume Injection in an Unmodified Splitless GC Inlet
Quantify 1,4-dioxane in drinking water down to 5.0 ppt using a new approach. The technique described here uses an unmodified split/splitless GC inlet with concurrent solvent recondensation–large volume splitless injection (CSR-LVSI) to lower detection limits. This 8-page brochure details system setup, sample prep, and analysis. (PDF - 0kB)
Florisil SPE tubes are ideal for cleanup of sample extracts prior to GC-ECD analysis of chlorinated pesticides. By using Florisil tubes for extract cleanup, background interferences can be reduced and recoveries can be improved. (PDF - 0kB)
Restek has formulated the most complete set of EPA 524.3 reference standards for the monitoring of purgeable organic compounds in drinking water—using as few as three ampuls! This collection of certified reference materials (CRMs) also covers the seven volatile organic compounds (VOCs) included in UCMR3. (PDF - 0kB)
Analysis of Trace Oxygenates in Petroleum-Contaminated Wastewater, Using Purge-and-Trap GC-MS (U.S. EPA Methods 5030B & 8260)
Determination of oxygenates in a gasoline-water matrix is difficult because analytes such as MTBE and TBA coelute on many columns and share GC-MS identification ions. We developed a sensitive, accurate analysis using an Rtx-VMS column and optimized conditions.
Lowering Detection Limits for 1,4-Dioxane in Drinking Water Using Large Volume Injection in an Unmodified Splitless GC Inlet
Concurrent solvent recondensation–large volume splitless injection (CSR-LVSI) typically requires a special GC inlet. The technique described here uses an unmodified split/splitless inlet with CSR-LVSI to lower detection limits for the analysis of 1,4-dioxane in drinking water.
Rtx-Dioxin2 columns have higher temperature stability (340 °C) than other confirmation columns and also provide isomer specificity for both 2,3,7,8-TCDD and 2,3,7,8-TCDF in a single column. These attributes allowed the Maxxam Analytics HR-MS group to make productivity improvements that resulted their being honored with a Kaizen award. (PDF - 0kB)
Analyze volatile compounds and polar analytes with greater confidence using Rxi-624Sil MS columns. Optimized selectivity, higher inertness, and lower bleed result in reliable separations and accurate, trace-level determinations. Includes environmental and pharmaceutical applications. (PDF - 0kB)
Large Volume Splitless Injection Using an Unmodified Split/Splitless Inlet and GC-TOFMS for Pesticides and Brominated Flame Retardants
Concurrent solvent recondensation large volume splitless injection (CSR-LVSI) GC/MS is used here for analyzing pesticides and brominated flame retardants in drinking water based on EPA Method 527. CSR-LVSI allows a time-consuming sample extract concentration step to be eliminated, but can also be used with extract concentration for lower detection limits.
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 - 0kB)
Confirming sample port integrity with a leak detector is a simple, cost-effective alternative to lab analysis of tracer gas in vapor intrusion VOC samples. Prevent resampling of soil vapors by confirming sample port integrity in the field prior to sampling.
Get improved resolution, faster analyses, and less downtime by using Rtx-CLPesticides and Rtx-CLPesticides2 columns for multiple GC/ECD methods. Instead of changing columns between methods, you can save time by analyzing chlorinated pesticides, PCBs, herbicides, and other halogenated compounds on a single column set. Rtx-CLPesticides and Rtx-CLPesticides2 columns have a unique selectivity and outperform other column sets offered specifically for multiple GC/ECD methods.
Ambient air sampling involves collecting a representative sample of ambient air for analysis. There are two general approaches: 1) “whole air” sampling with canisters or Tedlar bags and 2) “in-field concentration” sampling using sorbent tubes or cold traps. In this guide, we focus on collecting whole air samples in canisters, a flexible technique with many applications. (PDF - 0kB)
Analytical conditions for GC analysis of volatile organic compounds have been optimized to ensure good resolution of critical pairs, while maximizing sample throughput. Rxi-624Sil MS columns are shown to outperform other 624s.
Sample throughput for haloacetic acids in drinking water can be increased significantly using Rtx-CLPesticides/Rtx-CLPesticides2 columns. Target HAAs were fully resolved in under 13 minutes.
Sample throughput for PBDE analysis can be significantly increased using a 15m Rtx-1614 column. Excellent responses and peak shapes are obtained for all congeners, including BDE-209, in just 20 minutes.
Programmable temperature vaporization inlets are versatile, yet normally do not accommodate on-column injection. Now, using a PTV On-Column liner, the capabilities of PTV can be expanded to include true on-column injections.
The Rtx-Dioxin2 column has a unique selectivity for dioxins and furans, including specificity for 2,3,7,8-TCDD and 2,3,7,8-TCDF. Here we characterize all 136 tetra- through octachlorine dioxins and furans and define all possible coelutions. While commonly used cyanopropyl columns are limited by a low maximum operating temperature of 240°C, the Rtx-Dioxin2 column is stable up to 340°C, extending column lifetime and improving the analyses of dioxins and furans.
Analytical methods for underground storage tank testing often pose challenges and require unique mixtures for calibration and matrix spike samples. Restek tracks new developments in UST monitoring and responds with mixes to meet these needs. This flyer features fuel composite standards, single source fuel standards, fuel surrogate standards, fuel internal standards, and standards blended for specific state methods. (PDF - 0kB)
An optimized EPA Method 535 procedure offers superior sensitivity for the ethanesulfonic acid (ESA) and oxanilic acid (OA) degradates of chloroacetanilide herbicides alachlor, acetochlor, and metolachlor. Alachlor ESA and acetochlor ESA isomers are reliably resolved, and the procedure is simplified with a full line of Method 535 products, including reference standards, solid phase extraction cartridges, and HPLC columns.
Thermal Desorption: A Practical Applications Guide: I. Environmental Air Monitoring and Occupational Health & Safety
Thermal desorption is now recognized as the technique of choice for environmental air monitoring and occupational health and safety. This 28-page publication from Markes International Ltd. presents several real world thermal desorption applications. (PDF - 0kB)
The use of carbon disulfide (CS2) extraction as an air monitoring method for vapor-phase organic compounds (VOCs) is fundamentally limited with respect to detection limits. Thermal desorption (TD) is a complementary gas extraction technique whereby sorbent tubes are heated in a flow of carrier gas. Trapped vapors desorb from the sample tubes into the gas stream and are transferred into the GC/MS analyzer. Here, we summarize the key advantages of thermal desorption versus solvent extraction.
Analyses of chlorinated pesticides can be difficult because samples often are contaminated with non-target compounds (e.g., lipids), and the method can require rigorous quality control. Our 24-page guide covers sample extraction methodology, sample cleanup, and chromatography. A chromatographic analysis of widely used chlorinated herbicides also is illustrated. One of our most popular technical guides. (PDF - 0kB)
Semivolatiles methods, such as EPA Method 8270, place stringent demands on gas chromatography (GC) columns. Here we demonstrate the performance of Rxi-5Sil MS columns for semivolatiles analysis in terms of bleed, efficiency, and activity. Excellent sensitivity and resolution are seen, even for difficult PAHs such as benzo(b)fluoranthene & benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene. Both basic and acidic compounds show good response even at low levels.
Polynuclear aromatic hydrocarbons are a significant, and wide-spread, source of pollution. The US EPA mandates testing of the 16 PAHs they designate as most hazardous; the target list in other countries is expanding and includes new compounds that are difficult to separate. Here we demonstrate the ability of the Rxi-17 column to effectively resolve dibenzo pyrene isomers, as well as to separate benzo(j)fluoranthene from benzo(b)fluoranthene and benzo(k)fluoranthene.
Increasing sample throughput is an effective way to reduce operating costs for environmental labs. Here we introduce new film thicknesses for the Rtx-CLPesticide and Rtx-CLPesticide2 GC columns, optimized for complete separations and short analysis times. Using these new columns, all US EPA Method 8081 organochlorine pesticides are resolved in <9 min. We also show complete separation of these compounds in <5 min. using these columns and a Gerstel MACH column heating system.
Liner choice is a critical decision in semivolatiles analysis. Liners containing wool packing are recommended to minimize molecular weight discrimination. Attributes of different types of liners, including the Drilled Uniliner, are discussed.
This flyer give an overview of TD sampling and describes many applications that can be sampled using this versatile technique. Includes a comparison of tube and canister sampling, to help you determine which VOC sampling technique is best for you. (PDF - 0kB)
Using this new column, resolution and peak shapes for 88 semivolatile compounds commonly analyzed in drinking water are exceptionally good at 10ng each on column. Because the Rxi-5ms column performs well with analytes in a diverse range of chemical classes, we highly recommend it for analyzing complex mixtures of semivolatiles.
An Rtx-VMS column provides rapid, baseline resolution of most volatile analytes in the CLP OLM 04.1 analysis for groundwaters or drinking waters from Superfund sites. A particularly challenging stipulation of the method, 90% resolution of the gaseous components, is easily attained.