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Impact of GC Parameters

 

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HPLC Solutions #135: Internal Standards: Part 2 - What Makes a Good Internal Standard?

In the previous instalment of HPLC Solutions (HPLC Solutions #134) we took a brief look at why we might decide to use an internal standard and how a calibration plot is constructed and used in HPLC analysis. This time, we’ll consider some properties that are necessary when choosing a compound to use as an internal standard. These are listed in the figure.

 

It’s All Made of Plastic!

‘Plastic’ has become something of a dirty word. It makes us think of trash and environmental pollution, inferior quality, mass-produced goods, and excess. But if you take a look around, you will realize that a lot of the objects that surround us – including those that we couldn’t live without – are also made of plastic.

 

IC-ICP/MS Analysis of Iodised X-ray Contrast Media after Ozonation

The use of contrast media in non-invasive diagnostics facilitates targeted imaging of organs and distinction between healthy and unhealthy tissue. One differentiates between contrast media for magnetic resonance imaging (MRI) and X-ray examinations. IC-ICP/MS is ideally suited to monitor degradation products of contrast media after wastewater treatment procedures such as ozonation.

 

Chromate in Toys, Leather, and Potable Water

Generally speaking, chromate – Cr(VI) – is classified as allergenic, carcinogenic, and extremely toxic and is subject to strict monitoring. Cr(VI) can occur in various concentrations in different areas, e.g., drinking water, toys, or textile and leather products. Metrohm has developed ion chromatographic determination methods for determining Cr(VI) in various concentration ranges (ng/L to mg/L) with inline sample preparation techniques for various matrices. The method can be almost entirely automated. In the following we present the analysis of hexavalent chromium in toys, leather, and drinking water.

 

Ion chromatography: The All-rounder in the Pharmaceutical Sector

High standards have to be met by the pharmaceutical industry when it comes to drug quality and safety. These standards are documented in pharmacopoeias as officially recognized pharmaceutical rules, and published as legal tools of customer protection by authorities such as governments and medical societies. The identification of a drug depends on sensitive, reliable instruments and methods – as does the determination of the drug’s compliance with applicable regulations.

 

Impact of GC Parameters on The Separation: Part 6 - Choice of Carrier Gas and Linear Velocity

In part 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 the chromatography. The last two factors that are somewhat related, are the choice of carrier gas and the setting of linear gas velocity, as shown in Figure 1.

 

Evaluation of performance of Torulaspora delbrueckii, Williopsis saturnus and Kluyveromyces lactis in lychee wine fermentation

Evaluation of performance of Torulaspora delbrueckii Williopsis saturnus and Kluyveromyces lactis in lychee wine fermentation

Food Science Asia 2015 speaker Liu Shao Quan  reports on research conducted for the National University of Singapore. His research centres on the performance of various yeasts in lychee wine fermentation. 

 

Online Monitoring of Atmospheric Inorganic Gases and Aerosols in The Southeastern and Northwestern USA

Atmospheric aerosols exert a large but uncertain negative (cooling) radiative forcing on regional climate. Their chemical composition affects this climate forcing via aerosol hydroscopicity and consequential cloud interactions, as well as providing clues to the chemical origins of the aerosol. A Metrohm Monitor for AeRosol and Gases in Ambient air (MARGA) instrument was used in summer 2013 as part of the Southeastern Oxidant and Aerosol Study (SOAS), a large field campaign that took place in Centerville, Alabama, USA. A MARGA was used to measure the inorganic composition of aerosols and the key gases (HNO3, NH3, SO2) in equilibrium with each aerosol, enabling elucidation of aerosol composition and inferences about origin. The data from this summer field study are compared to data collected in the Pacific Northwest in the fall of 2013, a comparison which helps to isolate the roles of varying regional SO2 sources, humidity, and temperature on aerosol composition and loading.

 

Impact of GC Parameters on The Separation - Part 5: Choice of Column Temperature

In parts 1, 2, 3 and 4 of this series we focused on the selection of stationary phase, column length, 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 as shown in Figure 1.

 

HILIC Solutions #8: Column Equilibration in HILIC

It is matter of fact that the samples most chromatographers have to face are rather complex for sample number and compound variety. In these situations, gradient elution is largely preferred for the separation of analytes with different retention factors. In this way it is possible to narrow the peak width of the later eluted compounds and shorten the run time. In this article, the importance of column equilibration is considered for optimum efficiency.

 

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 a concern on 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.

 

Impact of GC Parameters on The Separation - Part 4: Choice of Film Thickness

In part 1, 2 and 3 of this series we focused on the selection of stationary phase, column length and internal diameter. The stationary phase is also deposited as a film or a layer (Figure 1), which is the fourth parameter that we need to understand its impact. 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.

 

Solutions for Mass Spectrometry: Tips and Tricks to Optimize Quality Spectra

Mass spectrometry (MS) is a common technique used to identify and quantify molecules in complex mixtures because of its high sensitivity and extreme versatility. It is used across diverse research areas, ranging from systems biology and proteomics to environmental analysis. Electrospray ionization (ESI) is by far the most popular ionization technique used for mass spectrometry.
   There are many factors that can influence the quality of spectra obtained with mass spectrometry. This article will present tips and tricks for successful mass spectrometry, including choosing the right solvents and buffers, solvent storage, buffer preparation, maintaining the recommended water content in eluent, mobile phase quality and contamination, equipment cleaning and column washing. 

 

Extractionless Analyses By Direct Analysis In Real Time (Dart) Mass Spectrometry

In 2004 Cooks et al. introduced Desorption Electrospray Ionisation (DESI) [1]. In this technique, a surface is bombarded at high speed by charged solvent droplets, which free analyte molecules. Like in electrospray ionisation (ESI), charge is transferred from the solvent to analytes and charged analytes molecules are transferred into a mass spectrometer for analysis.

 

Impact of GC Parameters on The Separation Part 3: Choice of Column Length

In Part 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 as shown in Figure 1. 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?

 

Impact of GC Parameters on The Separation, Part 2: Choice of Column Internal Diameter

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 (see Figure 1). Once the most interesting 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.

 

Structural Motifs in Primary Oxidation Products of Palmitoyl-arachidonoyl-phosphatidylcholines by LC-MS/MS

Ana Reis from the Mass Spectrometry Center, UI-QOPNA, Chemistry Department, University of Aveiro, Aveiro, Portugal answers questions on her research into structural motifs in primary oxidation products of palmitoyl-arachidonoyl-phosphatidylcholines by LC-MS/MS.

 

Development of a Rapid Liquid Chromatography Tandem Mass Spectrometry Method for Determination of Trace Caffeine in Surface Water

A rapid LC/MS/MS method for the quantification of caffeine in surface water samples is presented. This method employs large volume injection on a single LC reversed-phase column with detection in ESI positive mode. The method is robust and has the advantage of requiring no extensive sample preparation steps. 

 

Impact of GC Parameters on The Separation, Part I: Choice of the Stationary Phase

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 by 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.

 

Advances in The Development of Organic Polymer Monolithic Columns and Their Applications in Food Analysis—A Review

Pavel Jandera from the Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic provides a review on advances in the development of organic polymer monolithic columns and their applications in food analysis.

 

GPC/SEC Troubleshooting #9: Baseline Column Detector Peak System -Wavy RI Baseline

Q: The baseline of my refractive index detector, RI, shows maxima and minima and looks wavy. What can be the reason for this? 

 

Analysis of Naphthenic Acids in Filtered Oil Sands Process Water (OSPW) Using LC/TOF with No Sample Preparation

Naphthenic acids are water soluble weak acids that occur naturally in crude oils and bitumen and are the primary toxicants in wastewaters associated with oil refineries and oil sands extraction. Oil sands are large natural deposits that contain sand, clay, water and bitumen. Separating the bitumen from the sand requires an extraction process that uses large amounts of water. This results in the large production of oil sand process water containing naphthenic acids.

 

How New Particle Chemistries and Morphologies are Expanding the Application of HPLC in Environmental Separations

Historically, GC and GC/MS have been the primary analytical techniques for the analysis of organic compounds in environmental samples. Now, however, high-performance liquid chromatography (HPLC) is rapidly becoming the technique of choice for new method development for various applications in the field of environmental analysis. 

 

Ghost Peaks in Gas Chromatography Part 5: Impact of Injection and Oven Parameters During Injection

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, back flash and septa, extra peaks can be generated. Besides this, the conditions used for injecting the sample can also produce serious extra peaks.

 

SFC Solutions: Enantioselective Resolution and Analysis of Chiral Pesticides in Formulations by UltraPerformance Convergence Chromatography

Analytical method development for the separation of chiral compounds is important in many areas of research because it is known that enantiomers can exhibit different biological activity. The study of enantioselectivity is important to the agricultural chemicals manufacturing industry since the knowledge of the efficacy of each individual enantiomer could facilitate a significant reduction in the total amount of pesticide applied.

 

Strategies for the Determination of Flavour and Off-flavour Compounds

The smell of a product (food or non food) is one of the most influencing parameters for the acceptance or the rejection of products by consumers. The olfactory sensation is processed in the limbic system, which is highly linked to emotions and, therefore, highly subjective. A more objective approach is the analytical determination of odour active substances by gas chromatographic techniques because only volatile substances can show odour activity and substances above a molecular weight above 300–350 Dalton do not show odour activity at all. Nevertheless for setting up analytical methods for odour active substances the methods must be able to reach the concentration ranges of the sensory thresholds.

 

Automated LC/MS/MS Bioanalysis of β-blockers in Human Plasma

Mixtures of biological compounds with varying partition coefficients (log P) present difficulties in preparation for liquid chromatography with tandem mass spectrometry (LC/MS/MS) analysis, owing to interference from lipids and proteins. It is, therefore, essential that analyte-independent methods are used for sample preparation including precipitation techniques, and that these systems should be rapid and easy to automate. 

 

The Analysis of Aflatoxin M1 in Dairy Products

Animal feed occasionally has some degree of contamination by Aspergillus spp . Even pasteurized milk at times contains aflatoxin M1 (AFM1). Recently the incidence of aflatoxins in animal feed ingredients has increased thus increaasing the possibility of the occurance of Aflatoxin M1 in milk. However, Aflatoxin M1 is a toxic (100% as Aflatoxin B1), carcinogenic (33% as Aflatoxin B1) and mutagenic (3.3 %  of  Aflatoxin B1) metabolite compound. This article is a general review of Aflatoxin M1, its characteristics, its methods of analysis and performance characteristics  of  different  methods  of analysis for aflatoxin M1 in milk.

 

Chromatographic Methods for The Therapeutic Monitoring of Amitriptyline and Its Active Metabolite Nortriptyline

Amitriptyline (3-(10,11-dihydro‑5H ‑dibenzo[a,d]cycloheptene-5-ylidene)-N,N-dimethylpropan-1-amine) is a centrally acting re-uptake inhibitor of various neurotransmitters. Its complex pharmacodynamic profile makes it a potent antidepressant, as well as a drug with versatile adverse effects. Its therapeutic range has been established along with its active metabolite nortriptyline (also marketed separately) as 120–250 ng/mL

 

Ghost Peaks in Gas Chromatography Part 4: Reactivity in The Column While Doing Separations

In the last issues we discussed possible sources for 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.

 

SFC Solutions #4: Reaction Monitoring with UltraPerformance Convergence Chromatography

In this article we will discuss the use of UltraPerformance Convergence Chromatography (UPC2) coupled with mass spectrometry for monitoring and optimization of several synthetic routes of three pharmaceutical active ingredients. We will discuss the utility of UPC2 for chiral and achiral separations, synthetic route optimization, and separation orthogonality compared to common reversed-phase liquid chromatography (RPLC).

 

New GC Capillary Column Chemistries Drive Improvements in Environmental Laboratories

In this article, we explore the progression towards novel, application-specific GC column chemistries for the environmental industry, and the potential performance and productivity gains that can be achieved.

 

Fast and Reliable Results in Pesticide Analysis Fast GC/MS/MS Analysis with Full-scan/MRM Switching

Efficient residue analysis requires fast and timesaving solutions. At the same time, the analysis method should be reliable and consistent in order to provide meaningful results. This article presents a fast and reliable method for pesticide analysis.

 

Arsenic Speciation Analysis in Brown Rice by HPLC/ICP-MS

Arsenic (As) is a well-known toxic element that has been highly regulated, especially for drinking water. Although regulatory limits have been enforced for total arsenic, its toxicity varies widely and is dependent on its chemical form.

 

GPC/SEC Troubleshooting #8: Slow Pressure Built-up After Column (Re-)instalment

Q: I had my columns stored in the refrigerator for a few months. Now I re-installed them and the pressure of the system does not build up. What can be the reason?

 

Automated, High-Throughput Analysis of Seawater Samples Using ICP–MS

As seawater quality fluctuates in waters around the world, monitoring our seas is an increasingly important concern due to factors such as marine life and aquaculture industries, tourism, environmental pollution and public health standards.

 

How Solid-Phase Chemistries are Enabling Broader Adoption of SPE in Environmental Applications

Recent separation technology advances, particularly those resulting in more sophisticated analytical instrumentation, have opened new possibilities for environmental monitoring. As analytical technologies improve, laboratories have the ability to identify and quantify harmful toxins and contaminants that had previously gone undetected. However, methods may fall short of unlocking the full potential of newer technologies, including LC–MS–MS and GC–MS, if they do not adopt advanced sample preparation techniques in parallel. Environmental laboratories face unique challenges compared to other industries, such as pharmaceutical discovery or toxicology. 

 

HILIC Solutions #4: HILIC Mobile Phase: Solvents

In HILIC, small variations of the elution conditions often result in differences in the retention greater than the ones observed in RPLC. Therefore, particular attention has to be paid to the selection and the preparation of the eluents. 

 

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, O-rings can also be a source for ghost peaks. Here we look at the sample itself and the different “contaminations” that can result in unwanted “extra” peaks. Also the stationary phase in the column can play an interesting role in ghost-peak formation.

 

Chromatographic Methods for The Therapeutic Monitoring of Amiodarone and Its Active Metabolite N-desethylamiodarone

Amiodarone (AMD) ((2-{4-[(2-butyl-1-benzofuran-3-yl)carbonyl]2,6-iiodophenyl}ethyl)diethylamine) is a Class III antiarrhythmic drug according to the Vaughan Williams classification scheme. Currently, this substance is considered as one of the most powerful antiarrhythmic agents. It is marketed in several countries for treating ventricular and supraventricular arrhythmias. In addition, it seems like amiodarone may be beneficial in various life-threatening syndromes such as cardiac arrest and post-myocardial infarction status

 

Identification Potential of Direct-EI LC–MS Interfacing in Small-Molecule Applications

Mass spectral interpretation is a key tool for sample characterization whether provided by a single stage (MS) or a tandem analyzer (MS/MS). The development of benchtop high-resolution MS analyzers has further improved the ability to reveal unknown analytes or confirm a supposed composition in a large variety of samples, especially when the molecular ion is the only mass signal available.

 

Toxicity and Quality Assessment of Alcoholic Beverages Using an Optofluidic Device

Praveen Ashok from SUPA, School of Physics & Astronomy, North Haugh, University of St Andrews, St Andrews, Fife, Scotland, UK discusses his research into determining the toxicity and quality of alcoholic beverages and describes an optofluidic device that makes this analysis possible.

 

SFC Solutions #3: Using Convergence Chromatography for Natural Product Analysis and Purification

UltraPerformance Convergence Chromatography (UPC2) is a separation technique that uses compressed carbon dioxide as the primary mobile phase. It takes advantage of sub-two micron particle chromatography columns and an advanced chromatography system design to achieve fast and reproducible separation with high efficiencies and unique selectivity. It also generates much lower solvent wastes as compared to liquid chromatography (LC). Examples of using UPC2 for fat-soluble vitamins (FSV) are presented here to illustrate the advantages of UPC2 technology over current techniques in SFV analysis.

 

Comparison of Regulated Methods Using Ion Chromatography for Bromate Analysis in Drinking Water

Ozone is a powerful drinking water disinfectant that is effective in treating chlorine resistant organisms, such as Cryptosporidia [1]. For bottled water, ozonation is generally preferred over other available disinfection treatment methods because it does not leave a taste or residual disinfectant, due to the short lifetime of ozone.

 

Selective Therapeutic Monitoring of Drugs and Their Pharmacologically Active Metabolites by Liquid Chromatography

Following administration the majority of pharmaceutical substances undergo metabolism. Some of the emerging metabolites bear significant pharmacological activity, giving rise to a complex pharmacological profile which can be controlled effectively in certain cases only by monitoring the blood levels of both the parent and the active transformation products.

 

Identification of Flavour and Fragrance Allergens in Common Snack foods using Transportable Single-quadrupole GC–MS

Cinnamon-derived volatile oils are used as flavouring agents in foodstuffs and as fragrance enhancers in toiletries but can cause allergic reactions in sensitised individuals. Identification and quantification of these allergens in potentially contaminated products is essential to avoid consumer harm. A method using a portable single-quadrupole gas-chromatograph-mass spectrometer (GC–MS) has been developed that enables identification and semi-quantitative evaluation for 24 of the 26 cinnamon-derived compounds listed as flavour and fragrance allergens in the EU cosmetic directive. The method achieved identification of the allergens at 8 parts per million (ppm), 20% below the EU limit set for fragrance and cosmetic products. Transportable GC–MS instrumentation may be useful in on-site testing, reducing sample processing and data generation times. This may be valuable in situations where rapid decisions relating to product safety need to be taken.

 

Ghost Peaks in Gas Chromatography Part 2: The Injection Port

In last article we discussed the problem of “flash back”, which is a serious source for creating ghost peaks or “carryover”. It is important not to exceed the liner volume when the sample is introduced.

 

QuEChERS: Beyond the Basics

QuEChERS is a sample preparation approach that was designed to be easy, cheap but effective and rugged at the same time. It is most often used for pesticide residue analysis but its beneficial features have assisted it in branching to other fields such as environment, bioanalytical and clinical. QuEChERS was originally designed for fruits and vegetables and proven to work especially well for high water content fruits and vegetables (>80 %) with slightly acid pH.  However, there are commodities that don’t fit into this food type. 

 

Development of A Rapid Liquid Chromatography Tandem Mass Spectrometry Method for The Determination of Triclosan in Animal Tissue Matrices

A rapid LC–MS–MS method for the quantification of triclosan in animal tissue samples has been developed. This method uses large volume injection, ESI negative mode and a Poroshell LC column to improve the method limits of detection (LOD) and quantification (LOQ). The method is robust and has no complicated sample preparation steps. 

 

Quantification of Aroma Compounds in Wine Based on The Automated Multiple Headspace In-Tube Extraction: Comparison of Release Behaviour in Different Wines

Multiple headspace in-tube extraction (ITEX) is a completely automatic solventless extraction technique for headspace sampling in which a headspace syringe with a needle body filled with a sorbent is used. The analytes are extracted from the sample headspace by repeatedly pumping it through the sorbent. The needle body is surrounded by a heater that is used for the thermal desorption of analytes into the injection port of a GC system. 

 

Compound Based Scanning Makes Environmental Analysis Easier

Environmental analysis provides a constant challenge for the analytical chemist. Testing laboratories across the globe are required to do more and more with less resources. Being asked to detect lower levels of contaminants in dirtier matrices, and to improve sample throughput in less time, means that the need for reliable instrumentation and automated methods is more timely than ever. Triple quadrupole mass spectrometers (TQ-MS) operated in multiple reaction monitoring (MRM) mode have now proven their utility for multi-residue analysis. With their ability to screen for hundreds of target compounds in a single run, improving both workflow and productivity, they are rapidly becoming a must-have for the modern environmental laboratory. 

 

Analysis of Steroid Residues in Wastewater

Pharmaceuticals are consumed in increasingly high quantities worldwide and the potential for entry into the food supply or drinking water is of concern. Steroids are among the most frequently detected synthetic residues in water due to incomplete removal in sewage treatment plants. They can then enter the environment where they can have a negative impact on aquatic and terrestrial eco-systems. Environmental and food industry testing programmes need highly sensitive, reliable methods to enable detection of pharmaceutical substances that may inadvertently enter the food chain or environment. 

 

Ghost Peaks in Gas Chromatography Part I: The Carrier Gas and Carrier Gas Lines

We get always a number of inquiries from customers that 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.

 

A Simple Pre-analytical Strategy For Blood Glutathione Preservation in A Multi-centre Clinical Trial Setting

The ratio of glutathione disulfide (GSSG) to glutathione (GSH) in human blood is used as a biomarker in the pathogenesis or progression of human diseases. GSSG blood levels are easily affected by pre-analytical artefacts. In a multi-centre trial setting, local small differences in handling of samples may introduce large variation in laboratory results. Therefore, preservation of whole blood samples should be simple and easy to do, especially in multi-centre clinical trials.

 

Analysis of Macromolecules using Two Dimensional Liquid Chromatography

Two-dimensional liquid chromatography is a powerful tool that can be used to analyse complex mixtures. This article considers the challenges encountered when analysing macromolecules and describes a fully automated system, capable of the analysis.

 

Ion Chromatography with Pulsed Amperometric Detection for Determining Intestinal Permeability to Lactulose and Mannitol

This article explains how it is possible to detect lactulose and mannitol in urine easily and reliably using an ion chromatograph with pulsed amperometric detection. The lactulose/mannitol test is used to diagnose leaky-gut syndrome and chronic inflammatory bowel diseases associated with it.

 

Ion Chromatography coupled to Universal Detectors for The Analysis of Pharmaceutically-related Anions

This article demonstrates the potential of ion chromatography (IC) as a complementary separation method to reversed-phase high performance liquid chromatography (HPLC) for the determination of impurities in pharmaceutical active ingredients.

 

Environmental Analysis by GC–MS for Pesticide Residues

The widespread over use and illegal application of pesticides can have a serious impact not only on human health but the environment too. As a result, many regulatory bodies such as the US Environmental Protection Agency (EPA), the European Union and the US Food and Drug Administration (FDA) have adopted stringent screening regulations to minimize the impact that this has on our society and environment [1–3].

 

Simultaneous Analysis of Greenhouse Gases by Gas Chromatography

Greenhouse gases are gases in the atmosphere that absorb and emit radiation in the thermal infra-red range. This is the fundamental basis of the greenhouse effect. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are considered the main greenhouse gases in the Earth’s atmosphere. Without them, the Earth’s average surface temperature would be 33°C lower than the current average of 14°C [1]. However, since the Industrial Revolution fossil fuel consumption, large-scale agricultural industry and the use of halogenated compounds in manufacturing and refrigeration processes have contributed to an increase in the atmospheric levels of CO2, CH4 and N2O [2, 3, 4]. Monitoring of greenhouse gas emission trends is essential in order to combat climate change effectively.

 

A Generic Method Development Strategy for Liquid Chromatography

This article describes a novel method development strategy that still works when the compounds are not available individually, when no mass spectrometer is available and/or when the number of compounds is not known.

 

GPC/SEC Troubleshooting #7: Elution Volume/Retention Time Shift

Q: I have measured my calibration standards and samples and the elution volume/retention time has significantly changed. All signals are shifted to higher elution volume. What could be the reason for that?

 

Analysis of Multiresidue Pesticides from Food Using the QuEChERS Sample Preparation Approach, LC–MS–MS and GC–MS Analysis

Analysis of food products is challenging due to the variety and complexity of both the matrices and the compounds of interest. Sample preparation and downstream analysis require careful consideration to ensure method robustness as well as accurate and precise quantification. In this study we explore the analysis of multiple pesticide residues in spinach samples. This article will walk through the step-by-step process of developing the analytical method, from sample preparation to analysis, best suited to the data requirements.

 

Multidimensional Gas Chromatography — A Technology For Today’s Analytical Challenges

Today, the discerning chromatographer should expect that with modern instrumentation, the gas chromatography (GC) method should deliver an advanced capability to assess the chemical constituents of a sample, with precision, and a significant coverage of sample components present in trace to major amounts.

 

Time of Flight Mass Spectrometry for The Modern Lab: Qualitative Analysis, Quantitative Measurement and Rapid Screening and Identification

This article explains the use of a TOF‑MS system that provides an MS technology that enables the scientist to rapidly screen, identify and quantify compounds with accurate mass, screening speed and ease of use.

 

Sample Preparation Optimization

The analysis of drugs in biological fluids presents the modern analytical chemist with many challenges. One of the most common fluids that is routinely analysed is plasma. This matrix is incredibly complex with thousands of components ranging from very complicated structures such as high molecular weight proteins to simple inorganic salts. The analytical system itself is also changing from one injection to the next [6], which adds further complexity to the analysis as this article will demonstrate.

 

QuEChERS: A Primer

Quick, Easy, Cheap, Effective, Rugged and Safe, the QuEChERS (pronounced “catchers”) method is based on work done and published in 2003 by Anastassiades et al.1 This QuEChERS approach offers a user-friendly alternative to traditional liquid-liquid and solid-phase extractions.

 

Analytical Techniques in Food Safety and Quality

In this era of globalization in which the food supply knows no boundary, consumers are increasingly interested in the safety, quality and authenticity of everything they purchase. Recent alerts reported in the media regarding food imports from specific countries have put sharp focus on the identification of origin as a first step in ensuring food safety.

 

Rapid Ultra High Performance Liquid Chromatography Method Development Through Proper Column Selection

This article describes the importance of selecting an optimal column stationary phase, by demonstrating changes in selectivity of various types of samples including synthetic mixtures, forced degradation reactions and natural product extracts across different columns. This work demonstrates how improved separations can be developed in less time by systematically screening different sub 2 µm column chemistries early in the method development process.

 

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.

 

A Blind Study of Pesticides in Vegetables by SampliQ QuEChERS GC/MSD

In this study, blind added multipesticides in cherry tomato and cucumber were investigated. Deconvolution Reporting Software software, RTL pesticides library, and fast QuEChERS sample preparation allow quick onsite pesticides diagnostics with GC/MSD. This work describes a method for quick identification of target pesticides in vegetables onsite by the transportable GC/MSD.

 

Overcoming Challenges in Carbohydrate Separations

Carbohydrates are the most abundant class of organic compounds found in nature. They play essential roles in many biological processes such as providing storage and transport of energy. The analysis of sugars and other carbohydrates has always been plagued with difficulties. In this article we discuss the issues and show new solutions to these old problems.

 

Exploring New Sampling Techniques to Provide Simplified Material Emissions Assessment to the Manufacturing Industry

The need for product certification regarding chemical emission levels is on the rise. Large-scale reference methods cited by regulations are too impractical and expensive for routine product testing. Innovative new solutions are being explored to afford practicality and reliability of in-house emissions screening. Such new technology will aid R&D, routine QC and provide an indication to the outcome of large-scale certification methods.

 

High Volume Mass Spectrometry Proteomics Results Require Robust Platforms and Powerful Software

Q: Making sense of the vast amount of data generated in mass spectrometry-based proteomics now requires computing power far beyond what ordinary desktop PCs can offer. Are there specialized IT infrastructure solutions available to still efficiently and accessibly manage this data?

 

Potential of Modified Silica Nanoparticles with RATP as a New Solid Sorbent for the Preconcentration of Trace Amounts of Co(II) Metal Ion

The present paper reports on the application of modified silica nanoparticles with RATP as a new, easily prepared and stable sorbent for the preconcentration of trace Co(II) metal ion. Factors influencing the sorption and desorption of Co(II) were investigated.

 

IC-ICP/MS Analysis of Gadolinium-based MRI Contrast Agents

This article looks at the extent to which iron flocculation performed in wastewater treatment releases toxic gadolinium ions from MRI chelates. Gadolinium speciation is performed by ion chromatography coupled to inductively coupled plasma mass spectrometry (IC-ICP/MS).

 

Implementing Robustness Testing for HPLC Methods: Part 1

This article is the first in a series about a practical approach to the implementation of robustness testing for HPLC analytical methods. In this first article the concept of robustness is introduced and an overview of the procedure for investigation of robustness is described. In subsequent articles practical advice will be provided on how to perform robustness testing following the described procedure.

 

How Silica Hydride HPLC Columns Can Benefit the Modern Pharmaceutical Laboratory

A variety of analytes relevant to pharmaceutical analyses were selected in order to demonstrate the chromatographic capabilities of HPLC columns based on silica hydride. 

 

Practical Issues in Developing Chromatographic Methods to Assist Therapeutic Drug Monitoring

This article discusses an integrative approach to developing chromatographic techniques for therapeutic drug monitoring. This framework involves concepts fundamental to meeting the special quality goals raised by the clinical environment both by generating clinically significant assay results and meeting the general quality standards of analytical performance. The most important practical issues specifically related to the bioanalytical application of chromatographic techniques that have the greatest impact on analytical performance are also discussed.

 

GPC/SEC Troubleshooting: #6 Pressure is too low

Q: I have set the flow-rate to the usual conditions but the pressure does not build up to the normal value. What can I do?

 

Method 8260C by Purge and Trap Gas Chromatography–Mass Spectrometry

The improvement and protection of the environment from human activity is recognized by many as a duty we owe to future generations. Organizations such as the US Environmental Protection Agency (EPA) are created to provide guidance for the protection of the natural environment through regulation of pollution and analytical methodology.

 

Characterizing (bio-)Macromolecules Using Hyphenated and Comprehensively Coupled Gas Chromatography-Based Techniques

Polymers are important materials in modern life. Synthetic polymers are used for clothing, to provide housing and shelter, for packaging materials, biomedical implants etc.

 

Screening Sediment for Pyrethroid Insecticides using GC–MS/MS

A simple screening method for pyrethroid insecticides in sediment samples is described. Electron impact ionization (EI) with tandem MS/MS in combination with programmed temperature vaporization injection (PTV) were used to obtain excellent specificity and low limits of detection.

 

The Importance of Sample Preparation in Food Analysis

Across the world, food safety testing has become a growing concern as more and more contamination scares arise. Melamine in milk products, carbendazim in orange juice, fish tainted with PCBs, mercury-tainted milk powder and food supplements containing unauthorized food ingredients are just a few of the most recent alerts and scandals. 

 

How to Increase the Linear Application Range of Your GC–MS Method Using Smart Ion Selection?

With the introduction of lean thinking, 6-sigma and other related strategies*, laboratory managers have to apply new approaches in order to meet the stringent requirements imposed by these management philosophies. Particularly the large day-to-day variability in volume and mix of samples arriving in an analytical laboratory is often hard to address appropriately. A common approach to reduce the ‘waste’ of applying too many different methods is based on the use of generic methods. 

 

Size-Exclusion Ultra Performance Liquid Chromatography for the Analysis of Covalent High Molecular Weight Insulin

This article describes the advantages realized by using a 125 Å pore size, sub-2-µm ethylene-bridged hybrid (BEH) silica packing material and a low dispersion UHPLC system for the analysis of high molecular weight (HMW) protein in therapeutic insulin samples. Among these advantages are faster run times, higher sensitivity, and higher resolving separations of insulin and covalent insulin HMW, while at the same time greatly reducing acetonitrile containing waste-stream volumes. 

 

How to Develop a Method using In-tube Extraction (ITEX) For GC and GC/MS?

Throughout our lives we are continuously exposed to substantial quantities of volatile organic components (VOC). Residual solvents from carpets, paints and glues largely determine the quality of the indoor air we daily inhale. Offices, workspaces and even our living rooms, it’s practically impossible to breathe clean air nowadays. Perhaps we are luckier with the food we eat and the beverages we drink? Unfortunately, I am afraid not. Solvents from packaging foils and printing inks may pose a severe risk for the foodstuff they contain, while the water we drink or use to make soda, beers, etc. is polluted with traces of disinfection agents and other environmental contaminants. No wonder ‘VOC analysis’ plays such a vital role in many QC laboratories around the globe.

 

Optimization of Analytical Methods Using Factorial Designs -- Part 1: An Introduction

The conventional approach for optimizing analytical methods in the laboratory is the one-factor-at-a-time approach, where each experimental factor or parameter is optimized separately and independently of other factors. In contrast, factorial designs involve simultaneous optimization of all factors at once. Factorial designs offer a simple, efficient, and statistically valid method for optimizing analytical methods. In this article, the first of a three-article series, we will take an introductory look at factorial designs and its benefits to the analytical laboratory.

 

Optimization of Analytical Methods Using Factorial Designs -- Part 2: A Deeper Look at Factorial Designs

In the first article in this series on using factorial designs for optimization of analytical methods, we examined the basic principles of factorial designs and its advantages over the traditional one-factor-at-a-time optimization approach. In this article, we will take a look at some important concepts related to factorial designs, as well as examine several factorial designs that can be easily implemented in the laboratory as an efficient, cost-effective and simple approach to analytical method optimization.

 

Things to Consider When Selecting HPLC System Tubing

HPLC is one of the most versatile analysis “tools” in the laboratory. Even so, there are common ‘hurdles’ many chromatographers face – such as band broadening, poor resolution, and undesirable peak shapes – that often lead to frustration. With the advent of advanced chromatographic techniques, such as UHPLC, the frequency of challenges experienced by the chromatographer has only increased.

 

Implementing Robustness Testing for HPLC Methods: Part 3 -- Mobile Phase Buffers

When testing the robustness of an HPLC method, factors which may have an effect on the routine performance of the method are investigated. Previously, the effect of the organic volume fraction of the mobile phase for reversed phase methods was considered. In this article, we stay with reversed phase HPLC, and consider the effect of buffers used in the mobile phase.

 

Considerations in the Development of Chromatographic Methods to Assist Individualized Pharmacotherapy

The revolutionary emergence of novel fields in the framework of systems biology referred to as “omics” (genomics, proteomics, metabolomics etc.) has started driving clinical sciences towards a concept called personalized medicine ((also referred to as individualized medicine).

 

Analysis of Propionic and Acrylic Acids by Reversed Phase HPLC with Anion Suppression and Conductivity Detection

The aim of the present work was to develop a chromatography method which combines three techniques: HPLC reversed-phase separation, anion suppression and conductivity detection to improve the separation and determination of acrylic and propionic acids in environmental samples.

 

Trends in Separation and Preconcentration Techniques for Mycotoxins: A Review

In this article an overview of methods for the analysis and measurements of mycotoxins in the last ten years is given for the most often encountered mycotoxins in different samples.

 

Method Transfer and Routine-Use Study of the USP Impurities Method for Donepezil Tablets

Compendial methods are often used in the analysis of generic drugs. Typically, methods are developed and submitted based on a specific formulation. However, when the excipients are changed, the method specified in a United State Pharmacopeia-National Formulary (USP-NF)[1] monograph may be inadequate in eluting all components off of the column. The result can be deteriorating peak shape and premature method failure due to a build-up of poorly soluble excipients on the column. In this article we investigate some of the sample-matrix-related issues encountered when transferring a long drug final formulation separation method to a faster, more sustainable LC method. The geometrically-scaled gradient method presented in this article is 80% faster than the original compendial HPLC method and consumes 92% less mobile phase.

 

How to Analyse Unknown Samples by Pyrolysis GC/MS?

Although GC/MS and LC/MS are very powerful analytical techniques, they generally lack the ability to analyse and characterize insoluble materials, such as polymers and other high molecular weight products. An elegant approach to cope with this type of samples involves a combination of thermal decomposition and online chromatographic analysis of the released breakdown products. This approach is called analytical pyrolysis.

 

How Fittings Can Impact Chromatographic Results

Anyone who has been involved in chromatography has likely struggled with things like band broadening, split peaks, carryover, and loss of sample. Typically, when these challenges are encountered, it’s normal for chromatographers to suspect degradation of the column’s stationary phase or issues with the mobile phase, or even mechanical problems with primary system components (e.g., the injection valve, the pump, etc.). However, after investing hours and precious financial resources towards “fixing” or replacing the suspected components, it’s entirely possible that the initial challenges may still be present, leaving many a chromatographer puzzled and frustrated.

 

Identification of Different Meat Species by Analysis of Restriction Fragment Patterns

During food production, ingredients originating from different animal species might be processed in the same plant or even on the same production line, resulting in a contamination risk. This article describes a method for the detection of mammalian or avian DNA in meat samples.

 

Radio IC for Quality Control in PET Diagnostics

Positron emission tomography (PET) is one of the most powerful noninvasive diagnostic tools for tracing organ functioning from outside the body. Quality control of the short-lived radiopharmaceuticals is challenging, not least because of the tough time limits, the radiation issue, and the near nanomole radiotracer quantities.  
   This article describes how radio IC can control the production of the radionuclide [18F]fluoride (precursor) and the two radiotracers synthesized from it, [18F]fluorodeoxyglucose and [18F]fluorocholine, in accordance with pharmacopoeial regulations.

 

Transferring HPLC Compendial Methods to UHPLC for Routine Generic Drug Analysis

Manufacturers of generic drugs must be able to prove that the products they produce are comparable to the brand-name drug. While the analytical methodologies used to characterize many drugs can be both difficult and costly to develop, generic drug producers can refer to the United States Pharmacopeia-National Formulary (USP-NF)1, as well as the British, European, and Japanese Pharmacopeias for information on how to analyze drug substance, drug product and associated excipients using analytical techniques such as high performance liquid chromatography (HPLC).