COLUMNS
Sample Prep Perspectives
Trends in Sample Preparation
Ron Majors
A survey of LCGC readers on sample preparation techniques and methodology was conducted in early January 2013. The results obtained were compared to a similar survey conducted a decade ago. Thus, the survey gave insights into trends into sample preparation over this time period. The survey investigated trends in: technologies currently being used, sample loads, sample sizes, automation, the use of SPE devices (cartridges, disks, plates, tips), SPE chemistries, selection criteria, and problems encountered. Respondents were also asked about sample preparation technologies on the horizon; these new directions are summarized.
LC Troubleshooting
Gradient Elution, Part I: Intuition
John W. Dolan
In contrast to isocratic separations, gradient elution sometimes can seem to be counter-intuitive. Yet with the proper perspective, the things we intuitively understand about isocratic methods apply in a similar manner to gradients.
GC Connections
Gas Flow Measurement
John V. Hinshaw
Various gas flow measurement methods in the lab for GC users are compared, namely bubble, mass flow, and volumetric flowmeters as well as the built-in capillary column flow measurements found in GCs.
The Essentials
Column Selection for Reversed Phase HPLC
With so many HPLC columns on the market, we present a simple guide to what’s important when making your stationary phase and column dimension choices.
ARTICLES
Simple and Fast Quantification of Capsaicinoids in Hot Sauces Using Monolithic Silica Capillaries and LC–MS
Simon Forster and Dr. Stephan Altmaier, Merck KGaA
This work describes the simple and fast quantification of capsaicinoids extracted from diverse hot sauces used to spice up sausages. The various capsaicinoids were separated on a robust reversed phase monolithic silica capillary column and then directly transferred to MS. Main analytes obtained via this method and attributing to 90% of chili heat were capsaicin and dihydrocapsaicin. Both were analyzed quantitatively in a set of 10 different sauces. The combined results are displayed in Scoville heat units (SHU) and — as long as available — compared to manufacturer’s data. |
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GC x GC–TOF MS Complements Passive Sampling for the Screening of Pollutants in Water
Anthony Gravell1, Praveen Kutty1, Graham Mills2, David Barden3 and Steve Smith3
1 Environment Agency Wales, Llanelli Laboratory; 2 School of Pharmacy and Biomedical Sciences, University of Portsmouth, and 3 ALMSCO International
This article shows that GC x GC–TOF MS is a valuable analytical method for use with passive sampling techniques for the detection of pollutants in water. We show that it is possible to separate components that would co-elute in one-dimensional (1D) GC, resulting in improved confidence in identification of pollutants. The combination of passive sampling alongside TOF MS ensures high sensitivity, while the information-rich datasets mean that the method can be applied to the detection of non-targeted compounds with little additional effort.
DESI and DART Analysis of Swabs Used for Explosives Detection
Cecile Hubert1, Xavier Machuron-Mandard1, and Jean-Claude Tabet2
1CEA, DAM, DIF, and 2Institut Parisien de Chimie Moleculaire (Chimie Structurale Organique et Biologique), Universite Pierre et Marie Curie
This article describes the capabilities of DART and DESI sources for the analysis of contaminated fabrics. The effect of key parameters including the source conditions, the mesh size of different fabrics and the use of additives to enhance detection limits is investigated and the suitability of both sources is discussed. The successful analysis of real cotton fabric samples illustrates the efficiency of ambient ionization mass spectrometry, which tends to change the instrumental arsenal of the expert laboratories.
Targeted Protein Quantification Using High-Throughput Capillary LC–MS
Reiko Kiyonami and Laurent Rieux, Thermo Fisher Scientific
The verification and validation processes of large batches of complex samples require a sensitive and robust high-throughput method for the quantification of low-abundance peptides and proteins in biological matrices. To that end, a LC–MS method was developed using capillary flow-rate ultra-high-performance LC coupled to a triple-quadrupole mass spectrometer. The combined use of 300-um i.d. columns and a conventional ESI probe allowed the easy use of flow rates between 1 and 10 uL/min and LODs at 10 amol level in complex matrices with great robustness and repeatability. Run times could be kept in every case to less than 30 min.
Rapid and Direct Quantitation of Pharmaceutical Drugs From Urine Using MALDI MS
Ajeet Singh, Nivedita Bhattacharya, Avinash Ghanate, and Venkateswarlu Panchagnula, Chemical Engineering, National Chemical Laboratory
The quantitative estimation of drugs from biofluids in pharmacokinetic studies requires high throughput bioanalytical methods. We report a rapid, simple, and efficient method for simultaneous quantitative and determination of different pharmaceutical drugs directly from urine samples. Acetamiophen, griesofluvin, ampicillin, and verapamil spiked in human urine were characterized directly by MALDI TOF-MS followed by tandem MS to confirm their identities. Furthermore, quantitative profiling of drugs was carried out directly from spiked urine samples using MALDI TOF-MS without any chromatographic separation. Linearity was observed for the relevant concentration ranges of the metabolites found in urine. The quantitative analysis successfully produced acceptable precision and high accuracy of recoveries of drugs.
High Resolution Time-of-Flight Mass Spectrometry for Rapid Petroleum Characterization
Kevin Siek, Joe Binkley, and Jeffrey S. Patrick, Leco Corporation
High-resolution time-of-flight (HRT) mass spectrometry was investigated as an alternative to Fourier transformation mass spectrometry (FT-MS) for the direct analysis of heteroatomic species in crude petroleum. The practical implications of this technique’s advantages and drawbacks were explored. The favorable resolution profile observed for HRT versus FT-MS instruments yields enhanced spectral peak capacity at higher m/z, allowing more extensive characterization of heavy components within crude petroleum. The principal limitation of the HRT in this application is the limited m/z range in the ultra-high resolution operating mode. This compels the operator to select a particular m/z range, or to perform multiple experiments and concatenate the data.
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