Electrospray

Polymerase chain reaction electrospray ionization mass spectrometry (PCR/ESI-MS) was tested for its ability to accurately identify a blinded panel of 156 diverse bacterial isolates, mostly human and/or animal pathogens. Here, 142/156 (91%) isolates were correctly identified to the genus level and 115/156 (74%) were correctly identified to the species level. Only 9% were misidentified. This study shows that multilocus PCR/ESI-MS has the potential to be a useful technique for identifying a broad range of bacteria.

A method was validated for the multi-residue analysis of 82 pesticides in grapes at ≤25 ng/g level. Berry samples (10 g) mixed with sodium sulphate (10 g) were extracted with ethyl acetate (10 mL); cleaned by dispersive solid phase extraction and the results were obtained by liquid chromatography–tandem mass spectrometry. Reduction in sample size and proportion of ethyl acetate for extraction did not affect accuracy or precision of analysis when compared to the reported methods and was also statistically similar to the QuEChERS technique. The method was rugged (HorRat < 0.5) with <20% measurement uncertainties. Limit of quantification was <10 ng/g with recoveries 70–120% for most pesticides. The method offers cheaper and safer alternative to typical multi-residue analysis methods for grape.

A simple method was developed and validated for the trace determination of 2-isopropylthioxanthone (ITX) in packaged drinks. Samples were extracted from the food matrix using acetonitrile:water (60:40, v/v), and further subjected to clean-up and preconcentration using solid-phase extraction prior to analysis by liquid chromatography–tandem mass spectrometry using multiple reaction monitoring (MRM) mode. The use of 2-isopropyl-[2H7]thioxanthen-9-one was incorporated into the method as an internal standard. Excellent 3-day interday precision data (RSD 0.72%, n = 10), and intraday precision data (RSD 0.52%, n = 10) were obtained on a 0.10 μg/L standard solution. Spiked samples (n = 8) were used to gauge the accuracy of the method at the concentration levels of 2.5, 100, and 500 μg/kg in food; recoveries ranged from 97.0 to 103.0%. These excellent validation data suggest the exciting possibility of using this method for the determination of low levels of ITX migrating from printed food packaging materials into beverages with a method quantitation limit of 0.50 μg/kg. For the first time, analysis on a range of milk, juice, tea and yoghurt drinks, as well as their respective food packaging materials were performed for comparative studies on their ITX content.

A rapid, selective, and sensitive LC-MS/MS method has been developed and validated for quantification of lansoprazole (LZ) in human plasma using esomeprazole as an internal standard (IS). The analyte and IS were extracted by single solvent liquid-liquid extraction using tert-Butyl methyl ether and separated by isocratic elution on C18 analytical column with 90:10 v/v acetonitrile, and 20 mM ammonium acetate (flow rate of 1 mL/min) as the mobile phase in the positive ion mode. Selected Reaction Monitoring transitions for LZ, internal standard and their daughter ion were observed at 369, 346, 252, and 198 m/z, respectively. The lower limit of quantification was 3.997 ng/mL and total run time for the analysis was 1.2 minutes. Linear calibration was observed in the range of 3.997 ng/mL to 2002.5 ng/mL. The method was validated for its selectivity, stability, accuracy, precision, and recovery.

This review addresses the determination of the internal energy of ions produced by electrospray ionization (ESI) sources, and the influence of the internal energy on analyte fragmentation. A control of the analyte internal energy is crucial for several applications of electrospray mass spectrometry, like structural studies, construction of reproducible and exportable spectral libraries, analysis of non-covalent complexes. Sections II and III summarize the Electrospray mechanisms and source design considerations which are relevant to the problem of internal energy, and Section IV gives an overview of the inter-relationships between ion internal energy, reaction time scale, and analyte fragmentation. In these three sections we tried to make the most important theoretical elements understandable by all ESI users, and their understanding requires a minimal background in physical chemistry. We then present the different approaches used to experimentally determine the ion internal energy, as well as various attempts in modeling the internal energy uptake in electrospray sources. Finally, a tentative comparison between electrospray and other ionization sources is made. As the reader will see, although many reports appeared on the subject, the knowledge in the field of internal energy of ions produced by soft ionization sources is still scarce, because of the complexity of the system, and this is what makes this area of research so interesting. The last section presents some perspectives for future research. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:566–587, 2005

Controls in food industry are fundamental to protect the consumer health. For products of high quality, warranty of origin and identity is required and analytical control is very important to prevent frauds. In this article, the “state of art” of mass spectrometry in enological chemistry as a consumer safety contribute is reported. Gas chromatography-mass spectrometry (GC/MS) and liquid-chromatography-mass spectrometry (LC/MS) methods have been developed to determine pesticides, ethyl carbamate, and compounds from the yeast and bacterial metabolism in wine. The presence of pesticides in wine is mainly linked to the use of dicarboxyimide fungicides on vineyard shortly before the harvest to prevent the Botrytis cinerea attack of grape. Pesticide residues are regulated at maximum residue limits in grape of low ppm levels, but significantly lower levels in wine have to be detected, and mass spectrometry offers effective and sensitive methods. Moreover, mass spectrometry represent an advantageous alternative to the radioactive-source-containing electron capture detector commonly used in GC analysis of pesticides. Analysis of ochratoxin A (OTA) in wine by LC/MS and multiple mass spectrometry (MS/MS) permits to confirm the toxin presence without the use of expensive immunoaffinity columns, or time and solvent consuming sample derivatization procedures. Inductively coupled plasma-mass spectrometry (ICP/MS) is used to control heavy metals contamination in wine, and to verify the wine origin and authenticity. Isotopic ratio-mass spectrometry (IRMS) is applied to reveal wine watering and sugar additions, and to determine the product origin and traceability. © 2006 Wiley Periodicals, Inc.