C18 column Articles

  • USLC columns put the right tools in your LC method development toolbox

    Understanding Selectivity in Reversed Phase Separations – A Simplified Approach to HPLC and UHPLC Column Selection The most significant influence on chromatographic peak separation, or resolution, is column selectivity. Unfortunately, column selectivity is also the least understood and most underutilized parameter. To improve selectivity, method developers often concentrate on ...


    By Restek Corporation

  • Analysis of Polychlorinated Biphenyls in Fish Oil Using Supelclean EZ-POP NP, Silica Gel SPE, and an SLB-5ms GC Column

    Polychlorinated biphenyls (PCBs) were once widely used in many industrial and commercial applications such as insulating fluids, dielectrics, and lubricants. This included their extensive use in electrical transformers. PCB use has been banned in many countries, and the Stockholm Convention currently prohibits their production and use ...


    By MilliporeSigma

  • Analysis of the Pesticides Carbaryl, Diuron, and Propachlor

    Application Report 208: Analysis of the Pesticides Carbaryl, Diuron, and Propachlor Using Ascentis™ C18 This application demonstrates the suitability of the Ascentis C18 for efficient separation of the pesticides carbaryl, diuron, and propachlor. The analysis is carried out using a 15 cm x 4.6 mm I.D Ascentis C18 column under isocratic ...


    By MilliporeSigma

  • Enhanced Purification of Capsaicins with the CombiFlash® EZ Prep

    Abstract In this application note, capsaicins are used as a model for compounds difficult to resolve with flash chromatography. Capsaicin compounds possess very similar structures making them difficult to resolve from each other. Although these compounds can be resolved on flash chromatography columns, such as the RediSep® Rf Gold C18, preparative high pressure liquid chromatography ...


    By Teledyne ISCO

  • Why Biphenyl should be your first choice in LC.. A perspective from a “ GC” specialist..

    Being in GC for 38 years it made me wonder why in LC mostly C18 columns are used for developing a method. I never understood this as its against the basic rules for selecting the optimal stationary phase. In LC we see that about 95% of the applications is done using reversed phase materials, especially the C18 type. There are many C18 types available, and they all show a different separation ...


    By Restek Corporation

  • Carbonyl Sampling and Analysis by HPLC

    Sampling of Carbonyls Using a Dual-Layer LpDNPH Glass Sampling Tube and HPLC Analysis with an Ascentis Express C18 Column The dual-layer LpDNPH ORBO-555 tube is an effective sampler for measuring airborne carbonyl concentration. The low background levels in the sampler allow for accurate measurements of low concentration samples or samples collected in ...


    By MilliporeSigma

  • Rapid HPLC Analysis of PAH Compounds, Using Porous 3µm Particles

    Polynuclear aromatic hydrocarbons (PAHs) are a severe environmental hazard with a variety of sources. Airborne particles, combustion products, and fossil fuels all contain these toxic aromatic substances. Analysis by gas chromatography (GC) has been problematic because GC phases do not meet the need for shape selectivity in separating PAHs. Conversely, high-density C18 octadecylsilane (ODS) ...


    By MilliporeSigma

  • Chromatography Tips

    No.1 Gas Chromatography Tips  Our Founders and engineers of the company had accumulated more than 60 years experience in the research and development of HPLC instrumentation; HPLC column technology; mass spectrometer installation, training and services; chemical and biochemical separation, detection and quantification, Proteomics and cancer biomarker research and ...


    By AcuTech Scientific Inc.

  • The Clog Blog

    Clogging and over pressuring are definitely problematic for Liquid Chromatography columns. Back in 2005 John Dolan’s sage advice to chromatographers to make an LC column last forever was simple, “Never open the box!” As John pointed out, this is not practical and I have to agree. But as an LC column manufacturer I have seen remarks from customers regarding clogging as though it ...


    By Restek Corporation

  • Complexation Of Mercury(II) In Municipal Wastewater: Insights For The Fate Of Mercury In Effluent-Receiving Waters

    This paper summarizes previous research investigating the chemical speciation of mercury (Hg) in municipal wastewater effluent. Effluent samples were collected from treatment plants in Northern California. The chemical speciation of Hg(II) in these samples was compared to model solutions containing known Hg-ligand composition. Competitive ligand exchange-C18 solid phase extraction was used to ...

  • A high-resolution reverse-phase liquid chromatography method for the analysis of mycosporine-like amino acids (MAAs) in marine organisms

    Mycosporine-like amino acids (MAAs) are a group of about 20 structurally related water-soluble compounds, widely distributed among freshwater and marine organisms. To provide a better assessment of the diversity and concentration of MAAs in aquatic environments a high-performance liquid chromatography (HPLC) method of analysis based on reverse-phase C18 column and trifluoroacetic acid and an ...


    By Springer

  • Effective Use of the ACQUITY QDa Mass Detector with Your LC: A Q and A with Dr. Tom Wheat

    I recently presented a webinar describing some techniques and tools used for effectively using the QDa Mass Detector with liquid chromatography systems. Several attendees submitted questions that may be of general interest to a broader audience. It is better, as you said, to use negative mode for ...


    By Waters Corporation

  • Fluorophenyl LC Phases- what you should know

     They may be called PFP, PFPP, pentafluorophenyl, fluorophenyl or F5 phases. What they all have in common is the structure shown above (the pentafluorophenyl  group) attached to the silica particles. Most modern phases contain a propyl spacer between the above group and the silica, so that the phase looks something like this: ...


    By Restek Corporation

  • LC/MS/MS analysis of metabolites of synthetic Cannabinoids JWH-018 and JWH-073 in Urine

    Abstract A liquid chromatographic method was developed to resolve a comprehensive set of metabolites of JWH-018 and JWH-073. In addition to the chromatographic analysis method, an extraction method was developed to recover a broad range of synthetic cannabinoid metabolites, including carboxylic acid metabolites that are not traditionally recovered using a high pH liquid/liquid extraction. ...


    By Restek Corporation

  • The impact of Toxic Substances Control Act nomenclature on the commercialization of biobased chemicals

    Regulatory Review is a regular column featuring updates on regulatory matters concerning oils- and fats-related industries. Moving from bench to market Many small companies or those new to chemical manufacturing are not aware of their obligations under TSCA. Most biobased chemical companies have likely operated under the research and development (R&D) ...


    By Bergeson & Campbell, P.C.

  • SPE Cleanup of Wheat Extracts Prior to the HPLC Analysis of the Mycotoxin Deoxynivalenol

    Deoxynivalenol (DON) is a mycotoxin produced by the Fusarium fungal species graminearum and culmorum. These Fusariumfungi infect cereal crops primarily in wet conditions when temperatures range from 15–30 °C, resulting in grain head damage and DON contamination ...


    By MilliporeSigma

  • Analysis of Isocyanates using the ASSET EZ4-NCO Dry Sampler

    Introduction Isocyanates are used as a raw material to produce a number of products such as automotive paints, rigid and spray foam insulation, and furniture. Personal exposure can occur while the products made with isocyanates are being applied, or when the materials are removed by grinding or thermal degradation. Workers who are exposed to these compounds are at risk for respiratory ...


    By MilliporeSigma

  • Better tools for fast and convenient Patulin analysis

    Analytical Standards and New SupelMIP SPE Cartridges The mycotoxin patulin is often found in rotten apples. It is mostly produced by Aspergillus, Penicillium and Byssochlamys and shows a variety of short-term and long-term effects in animal studies, ranging from gastrointestinal problems and neurotoxicity to genotoxicity and teratogenicity. Therefore, many countries set limits for patulin ...


    By MilliporeSigma

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