Liquid Chromatography-electrospray Ion-trap Mass Spectrometry Research Articles

Development of online sampling and matrix reduction technique coupled liquid chromatography/ion trap mass spectrometry for determination maduramicin in chicken meat

An online sampling and matrix reduction technique coupled liquid chromatography electrospray–ion-trap mass spectrometry was developed for rapid analysis of maduramicin (MAD) residue in chicken meat. Multiple-reaction monitoring of mass spectrometry in positive ion mode was used to detect maduramicin. A post-column continuous infusion of internal standard (nigericin) with matrix-matched calibration method was utilised for quantification. The linear concentration range of the calibration curve was 0–10.0ngmL−1 (r2=0.999). The limit of detection (quantification) was 0.08ngg−1 (0.28ngg−1). The analytical accuracy of chicken meat samples for four spiked MAD concentrations (0.5, 1.0, 5.0, and 10.0ngg−1) was 84–97% and their corresponding intra-day and inter-day precisions were 3.7–5.0% and 5.8–7.9%, respectively. The analysis time for one sample was 10min. The application of the method for incurred chicken samples elucidates that MAD residue in chicken meat decreases during the withdrawal period.

Point sources of emerging contaminants along the Colorado River Basin: Source water for the arid Southwestern United States

Emerging contaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the United States. The objective of this study was to evaluate point sources of ECs along the Colorado River, from the headwaters in Colorado to the Gulf of California. At selected locations in the Colorado River Basin (sites in Colorado, Utah, Nevada, Arizona, and California), waste stream tributaries and receiving surface waters were sampled using either grab sampling or polar organic chemical integrative samplers (POCIS). The grab samples were extracted using solid-phase cartridge extraction (SPE), and the POCIS sorbents were transferred into empty SPEs and eluted with methanol. All extracts were prepared for, and analyzed by, liquid chromatography–electrospray-ion trap mass spectrometry (LC–ESI-ITMS). Log DOW values were calculated for all ECs in the study and compared to the empirical data collected. POCIS extracts were screened for the presence of estrogenic chemicals using the yeast estrogen screen (YES) assay. Extracts from the 2008 POCIS deployment in the Las Vegas Wash showed the second highest estrogenicity response. In the grab samples, azithromycin (an antibiotic) was detected in all but one urban waste stream, with concentrations ranging from 30ng/L to 2800ng/L. Concentration levels of azithromycin, methamphetamine and pseudoephedrine showed temporal variation from the Tucson WWTP. Those ECs that were detected in the main surface water channels (those that are diverted for urban use and irrigation along the Colorado River) were in the region of the limit-of-detection (e.g., 10ng/L), but most were below detection limits.

Identification of Main Chemical Components of Tongguanwan Prescription by HPLC-ESI-MS/MS

AIM: To identify the chemical components of Tongguanwan prescription by high performance liquid chromatography-electrospray ion trap-mass spectrometry (HPLC-ESI/IT-MS). METHOD: The chromatographic conditions were as follows:DiamonsilTMC18 (150mm×4.6 mm, I.D.5μm) column; mobile phase Ⅰ: water (A) and acetonitrile(B),gradient elute,the ESI source was used and the data in negative mode were acquired; mobile phase Ⅱ : water containing 0.3% acetic acid(A) and methanol(B),gradient elute, the data in positive mode were acquired. RESULT: The quasi-molecular ions of compounds in both negative and positive modes were observed for molecule mass information, and the potential structures were elucidated by analyzing the mass spectra of compounds through comparing them with the reference data and some stan-dards. Twelve compounds were identified in the prescription, which were neomangiferin, mangiferin, timosaponin B-Ⅱ , anemarsaponin E, timosaponin B-Ⅲ , timosaponin A-Ⅲ , phellodendrine, magnoflorine, menisperine, berberine, jatrorrhizine and palmatine. CONCLUSION: HPLC-MS/MS is a rapid and accurate method to identify the compositions of prescription of traditional Chinese medicine.

Selective and rapid immunomagnetic bead-based sample treatment for the liquid chromatography–electrospray ion-trap mass spectrometry detection of Ara h3/4 peanut protein in foods

Complex matrices commonly affect the sensitivity and selectivity of liquid chromatography–mass spectrometry (LC–MS) analysis. Thus, selective sample enrichment strategies are useful particularly to analyze organic biomarkers present in low abundance in samples. A selective immunomagnetic extraction procedure to isolate trace peanut allergen protein Ara h3/4 from breakfast cereals combined with microwave-assisted tryptic digestion and liquid chromatography–electrospray ion-trap tandem mass spectrometry (LC–ESI-IT-MS/MS) measurement was developed. Using protein A-coated magnetic bead (MB) support, anti-Ara h3/4 monoclonal antibodies (Abs) were used as selective capture molecules. The results obtained by LC–ESI-IT-MS/MS in terms of limit of detection (3 mg peanuts/kg matrix) and a significantly reduced matrix effect demonstrated that the Ab-coated magnetic bead was very effective to selectively trap Ara h3/4 protein in breakfast cereals. The magnetic bead-based sample treatment followed by LC–IT-MS/MS method here developed can be proposed as very rapid and powerful confirmatory analytical method to verify the reliability of enzyme-linked immunosorbent assay (ELISA) screening methods, since the magnetic bead-LC–IT-MS/MS method combines good sensitivity to the identification capabilities of mass spectrometry.

Determination of aristolochic acids in medicinal plant and herbal product by liquid chromatography–electrospray–ion trap mass spectrometry

This paper describes a liquid chromatography–electrospray–ion trap mass spectrometry (LC–ES–ITMS) method for the determination of aristolochic acid I and II (AA-I and AA-II) in medicinal plants and Chinese herbal remedies. A reversed phase C 18 column with gradient elution was utilized. The effects of mobile phase additives, acetic acid and ammonium acetate, on LC separation and ES ionization were investigated. For both AA-I and AA-II, the [M+NH 4] + ion was found to be the precursor ion for target MS/MS analysis. The MS/MS product ion, [M+H−44] +, was used for the quantitative measurement of AA-I and AA-II. The linearity was good from 0.03 to 5 μg ml −1 and good correlation ( r 2=0.999) over the range examined was determined for both AA. The detection limit based on a signal-to-noise ratio of three was 0.012 and 0.015 μg ml −1 for AA-I and AA-II, respectively. Various Chinese herbal remedies obtained from renal failure patients and medicinal plants were examined by this newly developed method.

Quantitative determination of medroxyprogesterone acetate in plasma by liquid chromatography/electrospray ion trap mass spectrometry.

A sensitive and rapid liquid chromatography/electrospray ion trap mass spectrometry (LC/MS/MS) method has been developed for the quantitative determination of medroxyprogesterone acetate (MPA) in human plasma. Plasma samples (1.0 mL) were simply extracted with pentane and the extracts were analyzed by HPLC with the detection of the analyte in the selective reaction monitoring (SRM) mode. The determination of MPA was accurate and reproducible, with a limit of quantitation of 0.05 ng/mL in plasma. The standard calibration curve for MPA was linear (r = 0.998) over the concentration range 0.05-6.0 ng/mL in human plasma. Analysis precision over the concentration range of MPA was lower than 18.8% (relative standard deviation, RSD) and accuracy was between 96.2 and 108.7%.

Quantitative determination of noncovalently bound acridinium in protein conjugates by liquid chromatography/electrospray ion trap mass spectrometry.

A sensitive and robust liquid chromatography/electrospray ion trap mass spectrometry (LC/MS/MS) method has been developed for the quantitative determination of noncovalently bound acridinium free acid in protein-acridinium conjugates. The lower level of quantitation (LOQ) for acridinium free acid was determined to be 0.6 ng. The assay was validated with a linear concentration range of 0.6-60 ng. The method requires minimum sample handling and is specific, reproducible, and provides a new aspect for protein-acridinium conjugate characterization.