A miniature gas chromatograph incorporating a miniaturized chemical trap for enrichment, rapid thermal desorption of the trap, a resistively heated capillary column for programmed GC analysis and a micro-chip-based plasma emission detector (PED) is described. The sampling and chromatographic conditions for the analysis of volatile compounds in air are presented. The performance of the µCAD is illustrated in the universal (carbon) mode and for the selective detection of chlorinated and organo-mercury compounds. Detection limits (DLs) are at the sub-μg/L level in the carbon mode and 10 ng/L for organo-mercury compounds.
The move from conventional particle sizes (5 μm or higher) to smaller diameter packing materials is one of the most attractive approaches to achieve higher separating efficiency. Recently developed 3 μm polysaccharide-derived chiral stationary phases demonstrate characteristics of favourable mass transfer kinetics, high column efficiency and good column permeability. This allows the fast analysis of enantiomers using conventional HPLC instruments.
Mass spectrometry plays an increasingly significant role in the analysis of residues and contaminants in food. Here we will illustrate how the combination of ultrahigh-pressure liquid chromatography (UHPLC) and high-resolution time-of-flight-mass spectrometry (TOF-MS) is used to generate a screen of veterinary drug residues in products of animal origin. The use of UHPLC–TOF-MS and dedicated, workflow directed software allows rapid screening for large numbers of residues and automated quantification of positive samples. In addition, we illustrate how the data generated using MSE acquisition mode enable critical structural information to be collected, which offers additional selectivity and confirmatory data for compound identification and facilitates elucidation of the structure of newly discovered compounds.
Despite the advantages of soft ionization ion-source technologies for improving confidence in the identification of a range of challenging analytes, soft ionization remains a niche technique for gas chromatography–mass spectrometry (GC–MS).
Heating is a common and essential requirement in most biopharmaceutical production methods. Chitosan is an amino polysaccharide obtained by alkaline deacetylation of naturally abundant chitin.
The addition of a light scattering detector dramatically increases the capabilities of gel permeation chromatography/size-exclusion chromatography (GPC/SEC) analysis. However, the complexity of the system also increases. This instalment of Tips & Tricks discusses column issues when working with light scattering detectors.
What can chiral capillary GC do for you? The answer lies in what analysis one is attempting to accomplish. Here, we discuss the utility of chiral capillary GC and where the technique is most valuable, focusing on three application areas in particular.
Advances in nano-ultrahigh-performance liquid chromatography–mass spectrometry (nUHPLC) and micro–UHPLC (?UHPLC) are described and evaluated, with reference to the analysis of veterinary drugs and steroids in porcine meat and urine, respectively.
The increasing use of pesticide testing coupled with reductions in maximum permissible residue levels of pesticides in food have driven demand for fast, sensitive, and cost-effective analytical methods for high-throughput screening of multiclass pesticides in food. Detection of 510 pesticides at low parts-per-billion levels can be achieved within minutes using orbital trap technology. The high resolving power of these systems enables accurate mass confirmation of all compounds, including isobaric pesticides. This article will provide an overview of current legislation and illustrate how mass spectrometry instrumentation can enable fast and accurate pesticide screening.
Industry veteran and 2009 LCGC Lifetime Achievement Award Winner Harold McNair writes about the early days of gas chromatography and his experiences through the years.
This article describes a space-saving, quick, and inexpensive sample preparation technique followed by a high performance liquid chromatography (HPLC) method with a 100% water mobile phase and photodiode array (PDA) detection for quantifying acetamiprid and its N-desmethyl metabolite, IM-2-1, in cow’s milk. The analytes were extracted from the sample and deproteinized using a handheld ultrasonic homogenizer with 5% (w/v) trichloroacetic acid solution, purified using a centrifugal monolithic silica spin minicolumn, and quantified within 20 min per sample. The accuracy and precision are well within the international method acceptance criteria.
This article discusses the unique properties of ILs and their potential impact as GC stationary phases.
LCGC NA - The Quantification of Clopidogrel in Human Plasma
The authors use headspace SIFT-MS to target and identify volatiles in various malt aldehydes. The specificity and speed are compared to current methodology.
A rapid and environmentally friendly LC method for the simultaneous determination of 12 UV filters in cosmetic samples using ethanol as the mobile phase.
A rapid and simple high performance liquid chromatography (HPLC) method with basic extraction assays was developed to investigate free diazepam levels in the plasma and urine samples of patients medicated with this drug for the management of alcohol withdrawal syndrome. The HPLC analysis was optimized and evaluated for linearity, imprecision, recovery, detection and quantification limits. The method showed linearity between 50–500 ng/mL (r2 ≥ 0.990). Coefficients of variations (%CV) were calculated to be in the range of 1.77–9.60. According to ICH guidelines, theoretical limits of detection (LOD) and quantification (LOQ) for plasma and urine were calculated as 8.3 ng/mL, 27.5 ng/mL and 8.2 ng/mL, 26 ng/mL respectively. Diazepam monitoring in plasma and urine displayed remarkable variations. The importance of adjusting doses according to individual requirements and the routine monitoring of plasma or urine for patients under medication is highlighted.
Flash chromatography is a purification technique that is designed for rapid separation by using air pressure as opposed to slow and inefficient gravityfed chromatography. It differs from the conventional column technique by using slightly smaller silica gel particles and pressurized gas at 50–200 psi.
Although supercritical fluid chromatography (SFC) is not a new technique, preparative SFC is becoming increasingly more popular with advances in instrumentation, software and chemistry.
A recent trend in the design of LC instrumentation is the move towards miniaturized and portable systems.
Collision-induced dissociation (CID) and electron transfer dissociation (ETD) are complementary mass spectrometric fragmentation techniques. We have used CID and ETD in different approaches to analyse tyrosine phosphorylation using a Thermo Scientific LTQ Orbitrap XL equipped with ETD.
LC-MS monitoring of the drug clozapine is detailed along with a description of the overall system architecture, workflow, and maintenance routines that spport a large-scale drug monitoring program.
Grapefruit juice was analysed by gradient UHPLC for naringin - a major flavanoid in grapefruit juice that gives it its bitter taste. A ZORBAX Rapid resolution HD (RRHD) StableBond-C18 2.1 ? 150 mm, 1.8 ?m column was able to resolve over 60 peaks, including naringin in 7 minutes, and was re-equilibrated in just three minutes by operating at a high flow rate (0.8 mL/min). The high pressure generated (965 bar) is well within the 1200 bar operating range of the RRHD column and 1290 Infinity LC.
This article reviews advances in the analysis of persistent halogenated organic compounds over the last century.
The composition and analysis of fragrance components in home and personal care (HPC) products is very complex and unquestionably time consuming.
Non-targeted metabolite profiling by ultrahigh-performance liquid chromatography coupled with mass spectrometry (UHPLC–MS) is a powerful technique to investigate the influence of genetic and environmental influence on metabolic phenotype in plants. The approach offers an unbiased and in-depth analysis that can reveal molecular markers of desirable phenotypic traits which can be complementary to genetic markers in plant breeding efforts. Here, the power of non-targeted metabolite profiling is illustrated in a study focused on the determination of molecular markers in malting barley that are predictive of desirable malting quality for brewing applications.
Most plants used in traditional Chinese medicine must be processed before their medicinal usage; hence the effective ingredients may differ from those in the freshly harvested plant extracts. In this work, we present a fast and generic approach using sub-2-?m liquid chromatography–time-of-flight–mass spectrometry (sub-2-?m-LC–TOF-MS) coupled with multivariate statistical data analysis to systematically profile ingredient changes between fresh and processed samples of huang jing.