• Journal of Environmental Science International
• /
• v.24 no.12
• /
• pp.1569-1582
• /
• 2015

The analytical method for 16 organophosphorus pesticides was developed in this study. The 16 organophosphorus pesticides were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS) using on-line solid phase extraction (on-line SPE) with PLRP- S cartridge. Analysis of all analytes in the MS/MS was processed in the electrospray ioni-zation (ESI) positive mode. They are Azinphos ethyl, Chlorfenvinphos, Ethion, Famphur, Phosmet, Phosphamidon, Terbufos, Aspon, Chlorpyrifos-methyl, Crotoxyphos, Dichlofenthi-on, Dicrotophos, Fonofos, Thionazin, Dimethoate and Iprobenfos. Limits of detection (LODs) and Limits of quantification(LOQs) were obtained as 0.8~2.0 ng/L and 2.6~6.4 ng/L, respectively. All compounds were not detected at the 8 sampling points of the raw water and clean water.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.9
• /
• pp.1347-1353
• /
• 2005

Sets of sialic acid-containing trisaccharides having different internal and terminal linkages have been synthesized to develop a sensitive method for analysis of the reducing terminal linkage positions. The trisaccharides, sialyl($\alpha$ 2-3)Gal($\beta$ 1-3)GalNAc and sialyl($\alpha$ 2-3)Gal($\beta$ 1-X)GlcNAc where X=3, 4 and 6, were synthesized and examined using electrospray ionization (ESI)-collision induced dissociation (CID) tandem mass spectrometry (MS/MS). The compounds chosen for this study are related to terminal groups likely to be found on polylactosamine-like glycoproteins and glycolipids which occur on the surface of mammalian cells. The purpose of this study is to develop tandem mass spectrometral methods to determine detailed carbohydrate structures on permethylated or partially methylated oligosaccharides for future applications on biologically active glycoconjugates and to exploit a faster method of synthesizing a series of structural isomeric oligosaccharides to be used for further mass spectrometry and instrumental analysis.

• Mass Spectrometry Letters
• /
• v.5 no.2
• /
• pp.52-56
• /
• 2014

Glycated hemoglobin (HbA1c) is used as an index of mean glycemia over prolonged periods. This study describes an optimization of enzyme digestion conditions for quantification of non-glycated hemoglobin (HbA0) and HbA1c as diagnostic markers of diabetes mellitus. Both HbA0 and HbA1c were quantitatively determined followed by enzyme digestion using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with synthesized N-terminal hexapeptides as standards and synthesized isotope labeled hexapeptides as internal standards. Prior to quantification, each peptide was additionally quantified by amino acid composition analysis using ID-LC-MS/MS via acid hydrolysis. Each parameter was considered strictly as a means to improve digestion efficiency and repeatability. Digestion of hemoglobin was optimized when using 100 mM ammonium acetate (pH 4.2) and a Glu-C-to-HbA1c ratio of 1:50 at $37^{\circ}C$ for 20 h. Quantification was satisfactorily reproducible with a 2.6% relative standard deviation. These conditions were recommended for a primary reference method of HbA1c quantification and for the certification of HbA1c reference material.

• Mass Spectrometry Letters
• /
• v.11 no.1
• /
• pp.10-14
• /
• 2020

Riboflavin is a water-soluble vitamin, which serves as a precursor to flavin mononucleotide and flavin adenine dinucleotide. This study aimed to develop a simple and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for the quantification of riboflavin in the Beagle dog plasma. This method utilized simple protein precipitation with acetonitrile and ¹³C₄, ¹⁵N₂-riboflavin was used as an internal standard (IS). For chromatographic separation, a hydrophilic interaction liquid chromatography (HILIC) column was used with gradient elution. The mobile phase consisted of 0.1% (v/v) aqueous formic acid with 10 mM ammonium formate and acetonitrile with 0.1% (v/v) formic acid. Since riboflavin is an endogenous compound, 4% bovine serum albumin in phosphate buffered saline was used as a surrogate matrix to prepare the calibration curve. The quantification limit for riboflavin in the Beagle dog plasma was 5 ng/mL. The method was fully validated for its specificity, sensitivity, accuracy and precision, recovery, and stability according to the US FDA guidance. The developed LC-MS/MS method may be useful for the in vivo pharmacokinetic studies of riboflavin.

• BMB Reports
• /
• v.43 no.11
• /
• pp.761-765
• /
• 2010

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-$d_3$ as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9：00-11：00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

• Mass Spectrometry Letters
• /
• v.4 no.4
• /
• pp.67-70
• /
• 2013

The Cu-binding site in the $[Cu{\cdot}dCMP{\cdot}dCMP-H]^{1-}$ complex was investigated. The tandem mass (MS/MS) spectra of the [$[Cu{\cdot}dCMP{\cdot}dCMP-H]^{1-}$ parent ion showed $[dCMP{\cdot}Cu{\cdot}H_2PO_4+CONH]^{1-}$ fragment ions. Therefore, we propose that the Cu cation is simultaneously coordinated to the phosphate site and cytosine moiety in the stable geometry of the $[Cu{\cdot}dCMP{\cdot}dCMP-H]^{1-}$ complex. Three geometries for the complex were considered in an attempt to optimize the structure of the $[Cu{\cdot}dCMP{\cdot}dCMP-H]^{1-}$ complex. The ab initio calculations were performed at the $B3LYP/6-311G^{**}$ level.

• Bioinformatics and Biosystems
• /
• v.1 no.2
• /
• pp.89-94
• /
• 2006

Mass spectrometry (MS) is widely applied for high throughput proteomics analysis. When large-scale proteome analysis experiments are performed, it generates massive amount of data. To search these proteomics data against protein databases, fully automated database search algorithms, such as Mascot and SEQUEST are routinely employed. At present, it is critical to reduce false positives and false negatives during such analysis. In this review we have focused on aspects of automated protein identification using tandem mass spectrometry (MS/MS) spectra and validation of the protein identifications of two most common automated protein identification algorithms Mascot and SEQUEST.

• Mass Spectrometry Letters
• /
• v.5 no.1
• /
• pp.1-11
• /
• 2014

Lipids play important roles in biological systems; they store energy, play a structural role in the cell membrane, and are involved in cell growth, signal transduction, and apoptosis. Phospholipids (PLs) in particular have received attention in the medical and lipidomics research fields because of their involvement in human diseases such as diabetes, obesity, atherosclerosis, and many cancers associated with lipid metabolic disorders. Here I review experimental strategies for PL analysis based on nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MSn). In particular, discussed are lipid extraction methods, nanoflow LC separation of PLs, effect of ionization modifiers on the ESI of PLs, influence of chain lengths and unsaturation degree of acyl chains of PLs on MS intensity, structural determination of the molecular structure of PLs and their oxidized products, and quantitative profiling of PLs from biological samples such as tissue, urine, and plasma in relation to cancer and coronary artery disease.

• Analytical Science and Technology
• /
• v.28 no.5
• /
• pp.317-322
• /
• 2015

Simultaneous analytical method has developed for the determination of anion biocides in soil by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Chlorite and chlorate in soil were extracted with pure water, and cyanuric acid and sodium dodecylbenzenesulfonate (Na-DBS) were extracted with mobile phase (0.25 mM ammonium formate in 20 mM formic acid : acetonitrile (1:1)). The extract was injected into the LC-MS/MS system after filtration. The method detection limits in this study were 0.04 mg/kg for chlorite, 0.04 mg/kg for chlorate, 0.27 mg/kg for cyanuric acid, and 0.05 mg/kg for Na-DBS, respectively. The method was applied to the analysis of 50 soil samples collected from 40 sites sprayed with biocides and 10 background sites. As a result, anion biocides were not detected in all sites.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.575-578
• /
• 2005

Electrospray ionization mass spectrometry (ESI MS) was used, along with gas chromatography-mass spectrometry (GC-MS), to monitor Paal-Knorr synthesis of 2,5-dimethyl-1-phenylpyrrole by condensation of aniline with 2,5-hexanedione. In addition to 2,5-dimethyl-1-phenylpyrrole observed as a single spot by TLC, unexpected dimer size compounds were observed by GC-MS. Dimers and trimers were observed by ESI MS. ESI tandem mass spectrometry was used to select plausible structures for the dimer. ESI MS with or without liquid chromatographic separation is useful for observing oligomeric byproducts with low volatility produced in organic reactions.