Dalho Kim

Comparison of separation conditions and ionization methods for the liquid chromatography-mass spectrometric determination of sulfonamides.

The effects of the type and concentration of buffer, composition of the mobile phase and the ionization mode, used for the separation and detection of sulfonamides with LC-MS, were studied. Five typical sulfonamides were selected as target compounds and beef meat was selected as a matrix sample. For the separation of sulfonamides, 0.05 M NH4Ac in 13-15% aqueous acetonitrile, APCl ionization was more effective than ESI with regard to separation efficiency and the detection sensitivity.

Application of a Polymeric Solid Phase Extraction for the Analysis of Sulfonamides in Milk by LC/MS

Abstract A simple clean up method for sulfonamides in milk, using a solvent extraction and unprecedented solid phase extraction (SPE) was studied. The effects of solid phases type, solvents type, and samples pH on the extraction of sulfonamids were compared. Sample extracts were simply cleaned up and enriched by SPE on LiChrolut EN (ethylvinylbenzene–divinylbenzene‐copolymer). Liquid chromatography/atmospheric pressure chemical ionization‐mass spectrometry (LC/APCI‐MS) was used for the determination of sulfonamides. Milk samples, spiked with 8.2 ng/mL of sulfamethazine (SMZ), were assayed with a relative standard deviation (RSD) of 2.8% using isotope labeled internal standards.

DETERMINATION OF HALOACETIC ACIDS IN TAP WATER BY CAPILLARY ELECTROPHORESIS WITH DIRECT UV DETECTION

Application of capillary zone electrophoresis with direct ultraviolet (UV) detection for determining the haloacetic acids in tap water is described. The haloacetic acids were monochloroacetic, trichloroacetic, monobromoacetic, dichloroacetic, bromochloroacetic, and dibromoacetic acids. For direct UV detection, the haloacetic acids were treated by liquid-liquid extraction and concentrated up to 2000 times. The analysis was successful with a fused-silica capillary containing 25 mM phosphate −0.5 mM cetyltrimethyl-ammonium chloride by direct UV detection at 185 nm. This technique can determine haloacetic acids at the 5 μg L−1 level in tap water within 7 min, except for trichloroacetic acid.

Evaluation of the state-of-the-art measurement capabilities for selected PBDEs and decaBB in plastic by the international intercomparison CCQM-P114.

AbstractAn international intercomparison involving eight national metrology institutes (NMIs) was conducted to establish their current measurement capabilities for determining five selected congeners from the brominated flame retardant classes polybrominated diphenyl ethers and polybrominated biphenyls. A candidate reference material consisting of polypropylene fortified with technical mixtures of penta-, octa- and decabromo diphenyl ether and decabromo biphenyl, which was thoroughly assessed for material homogeneity and stability, was used as study material. The analytical procedures applied by the participants differed with regard to sample pre-treatment, extraction, clean-up, employed calibrants and type of calibration procedure as well as regarding analytical methods used for separation, identification and quantification of the flame retardant congeners (gas chromatography coupled to an electron capture detector (GC-ECD), gas chromatography-mass spectrometry in the electron ionisation mode (GC-EI-MS), gas chromatography-mass spectrometry in the electron capture negative ionisation mode (GC-ECNI-MS), and liquid chromatography-inductive coupled plasma-mass spectrometry (LC-ICP-MS)). The laboratory means agreed well with relative standard deviations of the mean of means of 1.9%, 4.8%, 5.5% and 5.4% for brominated diphenyl ether (BDE) 47, 183 and 209 and for the brominated biphenyl (BB) congener 209, respectively. For BDE 206, a relative standard deviation of 28.5% was obtained. For all five congeners, within-laboratory relative standard deviations of six measurements obtained under intermediate precision conditions were between 1% and 10%, and reported expanded measurements uncertainties typically ranged from 4% to 10% (8% to 14% for BDE 206). Furthermore, the results are in good agreement with those obtained in the characterization exercise for determining certified values for the flame retardant congeners in the same material. The results demonstrate the state-of-the-art measurement capabilities of NMIs for quantifying representative BDE congeners and BB 209 in a polymer. The outcome of this intercomparison (pilot study) in conjunction with possible improvements for employing exclusively calibrants with thoroughly assessed purity suggests that a key comparison aiming at underpinning calibration and measurement capability (CMC) claims of NMIs can be conducted. FigureMass fraction of deca-brominated diphenyl ether (BDE 209) in the polypropylene study material analysed in the international intercomparison CCQM-P114

Analysis of Urushiols by Liquid Chromatography/Atmospheric Pressure Chemical Ionization‐Ion Trap Mass Spectrometry

Abstract Urushiol derivatives in a natural polymeric paint (urushi), obtained from Korean tapping lacquer trees were separated by reverse phase liquid chromatography and analyzed by on‐line atmospheric pressure chemical ionization ion trap mass spectrometry (LC/APCI‐ITMS). The molecular weight and molecular structure information for each peak were obtained from full scan spectrum and collision induced dissociation (CID) spectrum, respectively. Each urushiol isomer was identified, based on the pseudomolecular ion, the pattern of product ions by CID of pseudomolecular ions, and the elution order of urushiols on the C18 stationary phase. The elution order was the result of other researchers by a preparative separation and NMR. For composition analysis, the relative peak area ratios of components over total urushiol constituents were calculated from each peak area of urushiol components.

EFFECT OF SOLVENT ON EXTRACTION OF POLYCHLORINATED BIPHENYLS AND POLYCHLORINATED DIBENZODIOXINS FROM CHARCOAL

The effect of solvent on the extraction of two polychlorinated biphenyls (PCBs) and five polychlorinated dibenzodioxins (PCDDs) from charcoal is investigated and the variations in recoveries of these analytes are explained. The extraction is performed using chromatographic elution, ultrasound-assisted extraction (UAE) of probe- and bath-type, supercritical fluid extraction (SFE), and enhanced-fluidity liquid extraction (EFLE). In each of the extraction methods used, only the use of isopropanol-toluene mixtures shows higher recoveries than the use of toluene alone. Higher recoveries are obtained using EFLE, compared with other extraction methods, even though the same amount, i.e., 30mL, of extraction solvent is used, because higher temperature is applied under higher pressure. After each extraction, chromatographic interferences are removed through a multilayer silica gel column clean-up. The quantification of PCBs and PCDDs is performed using HPLC-UV.

Evaluation of the proficiency testing results for brominated flame retardants in high impact polystyrene

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs) which have taken much interest recently due to their potential hazardous effects to human body and ecosystem. Many countries and European community prohibits the usage of certain BFRs in electronics and electronic devices (e.g. RoHS). In this perspectives, Korea Research Institute of Standards and Science (KRISS) has designed and practiced proficiency testing programs based on the ISO/IEC 17043 in order to assist laboratory accreditation activities. The programs for interlaboratory comparisons include congeners of PBDE (PBDE-154, 183, 206, 209) in high impact polystyrene (HIPS). A sample bottle that contains 10 g granular HIPS was distributed to 35 participating laboratories and the test results were calculated by the statistical procedure using z-scores to evaluate performance of each laboratory. The results and the laboratory`s performance were discussed.

Evaluation of proficiency and improvement of accuracy on the analysis of brominated flame retardants (PBDEs) in ABS polymer

In order to evaluate and improve the ability of Korean testing laboratories to measure Polybrominated diphenyl ethers in acrylonitrile-butadiene-styrene (ABS), a proficiency test was organised by Korea Research Institute of Standards and Science (KRISS) based on ISO/IEC 17043. The proficiency test material used was 10 g of a granular ABS fortified with a mixture of congeners of PBDE (BDE-154, 183, 206, 209). Homogeneity and stability were investigated to assess the adequacy of the test material. The certified value established by KRISS based on the national reference was used for assigned value of each PBDE. The test materials were distributed to the 16 participating laboratories. The participating laboratories were requested to analyse the samples employing the methods used in their routine analysis. Each laboratory was given it’s own code to secure the anonymity. Participants results were evaluated with z-scores according to ISO/IEC 17043. The standard deviation for proficiency assessment was set by standard deviation of the participants results except for outlier. The results, the laboratory`s performance and improvement of accuracy were discussed.

Preparation and characterization of the primary gas standards for isoprene

Isoprene is a one of the biogenic volatile organic compounds (BVOCs) and it is known as a source of the tropospheric ozone and formaldehyde. In addition, isoprene is a trace component of the exhaled breath and it is a potential biomarker for the diagnosis of diseases such as lung cancer. In these regards, isoprene gas standards are required for the accurate measurement of isoprene in air samples. To establish a standard for isoprene gas, gravimetric preparation and characterization of primary gas standards were studied. The primary gas standards were produced independently in 4 aluminum cylinders and concentrations were examined by GC-FID. As a result, the uncertainty of the gravimetric preparations including purity of the raw material was 0.01% and reproducibility of the preparation of independent 4 cylinders was 0.08%. The primary gas standards for isoprene showed 14 months of long-term stability. The relative expended uncertainty of 2.8% (95% of confidence level, k