• Korean Journal of Food Science and Technology
• /
• v.43 no.2
• /
• pp.224-229
• /
• 2011

Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced by Fusarium graminerum, a species which colonizes a wide variety of cereals, including wheat, barley and processed products. A survey of ZEA contamination was conducted on 141 dried confectioneries, 59 breads and rice cakes, 135 noodles and 101 other products, for a total of 432 commercial samples. Samples were analyzed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) after immunoaffinity clean-up and was confirmed by liquid chromatography tandem mass spectrometry (LCMS/MS). The limits of detection and quantification were 2.0 and $6.0{\mu}g/kg$, respectively. The recovery ranged from 80.2% to 98.4% in the cereal based product. ZEA was detected in 38 samples (8.8% incidence), including 3 snack, 2 biscuit and 33 other cereal products. The ZEA contamination levels were in the range of $5.38-53.76{\mu}g/kg$. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected ZEA, and all 38 samples showing ZEA by HPLC-FLD were confirmed by LC-MS/MS.

• Korean Journal of Food Science and Technology
• /
• v.40 no.3
• /
• pp.354-359
• /
• 2008

A survey for zearalenone contamination was conducted on 27 soy bean samples, 27 red bean samples, 16 black bean samples, 19 seoritae samples, 14 seomoktae samples, for a total of 127 commercial Korean samples. Zearalenone was quantified by the immunoaffinity column clean-up method with high performance liquid chromatography-fluorescence detection (HPLC-FLD), and was confirmed by liquid chromatography tandem mass spectrometry(LC-MS/MS). The limits of detection and quantification were $2.0{\mu}g/kg$ and $6.0{\mu}g/kg$, respectively. The recovery in the beans ranged from 82.2 to 98.4%. According to HPLC-FLD, zearalenone was detected in 13 samples (10.2% incidence), including 1 soybean and 12 red bean samples. The zearalenone contamination levels were in the range of 8.01${\sim}38.98{\mu}g/kg$. Finally, LC-MS/MS analysis was conducted in the contaminated samples to verify the results of HPLC-FLD. The LC-MS/MS results confirmed the presence of zearalenone in all 13 samples. The contamination level was lower than that of EU, which is below $100{\mu}g/kg$ for raw grains.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2006.11a
• /
• pp.65-74
• /
• 2006

Modem drug discovery requires rapid pharmacokinetic evaluation of chemically diverse compounds for early candidate selection. This demands the development of analytical methods that offer high-throughput of samples. Naturally, liquid chromatography / tandem mass spectrometry (LC-MS/MS) is choice of the analytical method because of its superior sensitivity and selectivity. As a result of the short analysis time(typically 3-5min) by LC-MS/MS, sample preparation has become the rate- determining step in the whole analytical cycle. Consequently tremendous efforts are being made to speed up and automate this step. In a typical automated 96-well SPE(solid-phase extraction) procedure, plasma samples are transferred to the 96-well SPE plate, internal standard and aqueous buffer solutions are added and then vacuum is applied using the robotic liquid handling system. It takes only 20-90 min to process 96 samples by automated SPE and the analyst is physically occupied for only approximately 10 min. Recently, the ultra-high flow rate liquid chromatography (turbulent-flow chromatography)has sparked a huge interest for rapid and direct quantitation of drugs in plasma. There is no sample preparation except for sample aliquotting, internal standard addition and centrifugation. This type of analysis is achieved by using a small diameter column with a large particle size(30-5O ${\mu}$m) and a high flow rate, typically between 3-5 ml/min. Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of pcrous silica. The main advantage of such a network is decreased backpressure due to macropores (2 ${\mu}$m) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns. The reduction of particle diameter in HPLC results in increased column efficiency. use of small particles (<2 urn), however, requires p.essu.es beyond the traditional 6,000 psi of conventional pumping devices. Instrumental development in recent years has resulted in pumping devices capable of handling the requirements of columns packed with small particles. The staggered parallel HPLC system consists of four fully independent binary HPLC pumps, a modified auto sampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Sample throughput can be increased nearly four-fold without requiring significant changes in current analytical procedures. The process of Bioanalytical Method Validation is required by the FDA to assess and verify the performance of a chronlatographic method prior to its application in sample analysis. The validation should address the selectivity, linearity, accuracy, precision and stability of the method. This presentation will provide all overview of the work required to accomplish a full validation and show how a chromatographic method is suitable for toxirokinetic sample analysis. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method developed to quantitate drug levels in dog plasma will be used as an example of tile process.

• Journal of Food Hygiene and Safety
• /
• v.35 no.4
• /
• pp.326-333
• /
• 2020

In this work, we developed an analytical method for determining 11 illicit compounds in dietary supplements using high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry. Eleven target compounds, including those meant for weight loss (7-keto-dihydroepiandrosterone, buformin, metformin, phenformin, salbutamol, and tolbutamide), sexual enhancement (dihydroepiandrosterone), and relaxation (asarone, kavain, magnoflorine, and picamilon) were screened and confirmed in dietary supplements. Method validation was performed by evaluating the selectivity, linearity, limit of quantification (LOQ), accuracy, and precision according to the Association of Official Analytical Chemists guidelines. The linearity was > 0.993 for all analytes. The LOQs were ranged in 2.1-9.9 ㎍/mL (HPLC-DAD) and 0.002-0.008 ㎍/mL (LC-MS/MS). The accuracies (expressed as recovery) were 90.0-106% (HPLC-DAD) and 83.0-114% (LC-MS/MS). The precision (expressed as the relative standard deviation) was below 10% using HPLC and LC-MS/MS. The proposed method can be used for the surveillance of illicit compounds in dietary supplements.

• BMB Reports
• /
• v.43 no.7
• /
• pp.506-511
• /
• 2010

The levels of salivary cortisol and cortisone in Korean adults were measured for the first time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The salivary cortisol and cortisone were separated within 10 min. The regression coefficients (r) of the calibration curves were greater than 0.999 for the two steroids. The limits of quantitation (LOQ) were 0.2 ng/ml for cortisol and 1 ng/ml for cortisone. The intra-day precisions of the assay were <3.9% and 8.6% for cortisol and cortisone respectively, and the inter-day precisions were <1.9% and 4.3% for cortisol and cortisone, respectively. The salivary cortisone concentrations were approximately 4-9 times higher than those of salivary cortisol during the daytime. Diurnal rhythms, during which the cortisol and cortisone concentrations were higher in the morning than in the afternoon, were also observed. The present assay may be useful for the diagnosis of several adrenal dysfunctions in clinical biochemistry.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2005.09a
• /
• pp.91-95
• /
• 2005

In the multidimensional protein identification technology of high-throughput proteomics, we use one-dimensional gel electrophoresis and after the separation by two-dimensional liquid chromatography, the sample is analyzed by tandem mass spectrometry. In this study, we have analyzed the Pseudomonas Putida KT2440 protein. From the protein identification, the protein database was combined with its reversed sequence database. From the peptide selection whose error rate is less than 1%, the SEQUEST database search for the tandem mass spectral data identified 2,045 proteins. For each protein, we compared the molecular weight calibrated from 1D-gel band position with the theoretical molecular weight computed from the amino acid sequence, by defining a variable MW$_{corr}$ Since the bacterial proteome is simpler than human proteome considering the complexity and modifications, the proteome analysis result for the Pseudomonas Putida KT2440 could suggest a guideline to build the protocol to analyze human proteome data.

• Safety and Health at Work
• /
• v.10 no.2
• /
• pp.196-204
• /
• 2019

Background: Liquid chromatography-tandem mass spectrometry (LC-MSMS) for simultaneous analysis of multiple microbial secondary metabolites (MSMs) is potentially subject to interference by matrix components. Methods: We examined potential matrix effects (MEs) in analyses of 31 MSMs using ultraperformance LC-MSMS. Twenty-one dust aliquots from three buildings (seven aliquots/building) were spiked with seven concentrations of each of the MSMs ($6.2pg/{\mu}l-900pg/{\mu}l$) and then extracted. Another set of 21 aliquots were first extracted and then, the extract was spiked with the same concentrations. We added deepoxy-deoxynivalenol (DOM) to all aliquots as a universal internal standard. Ten microliters of the extract was injected into the ultraperformance LC-MSMS. ME was calculated by subtracting the percentage of the response of analyte in spiked extract to that in neat standard from 100. Spiked extract results were used to create a matrix-matched calibration (MMC) curve for estimating MSM concentration in dust spiked before extraction. Results: Analysis of variance was used to examine effects of compound (MSM), building and concentration on response. MEs (range: 63.4%-99.97%) significantly differed by MSM (p < 0.01) and building (p < 0.05). Mean percent recoveries adjusted with DOM and the MMC method were 246.3% (SD = 226.0) and 86.3% (SD = 70.7), respectively. Conclusion: We found that dust MEs resulted in substantial underestimation in quantifying MSMs and that DOM was not an optimal universal internal standard for the adjustment but that the MMC method resulted in more accurate and precise recovery compared with DOM. More research on adjustment methods for dust MEs in the simultaneous analyses of multiple MSMs using LC-MSMS is warranted.

• Mycobiology
• /
• v.41 no.3
• /
• pp.149-154
• /
• 2013

An ${\alpha}$-glucosidase inhibitor was developed from Aspergillus oryzae N159-1, which was screened from traditional fermented Korean foods. The intracellular concentration of the inhibitor reached its highest level when the fungus was cultured in tryptic soy broth medium at $27^{\circ}C$ for five days. The inhibitor was purified using a series of purification steps involving ultrafiltration, Sephadex G-25 gel permeation chromatography, strong cation exchange solid phase extraction, reverse-phase high performance liquid chromatography, and size exclusion chromatography. The final yield of the purification was 1.9%. Results of the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis indicated that the purified ${\alpha}$-glucosidase inhibitor was a tri-peptide, Pro-Phe-Pro, with the molecular weight of 360.1 Da. The IC50 value of the peptide against ${\alpha}$-glucosidase activity was 3.1 mg/mL. Using Lineweaver-Burk plot analysis, the inhibition pattern indicated that the inhibitor acts as a mixed type inhibitor.

• Analytical Science and Technology
• /
• v.21 no.5
• /
• pp.424-431
• /
• 2008

Streptomycin, which is one of aminoglycoside antibiotics, has been widely used in the rearing of food-producing animals to prevent and treat diseases in cattle, pigs and poultry. Although not licensed in South Korea, streptomycin has also been used for the treatment of bacterial honeybee disease, such as European foulbrood in Third World countries. A reliable and effective method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of streptomycin in honey. A established method was optimized the clean-up and extraction procedure for the trace determination, good precision and accuracy. And the chromatographic and tandem mass spectrometric parameters were also optimized. The precision (RSD) and accuracy (bias) in the concentration range of 5.0~50.0 ug/kg were 5.5~14% and -10.0~8.0%, respectively. Limit of detection was 0.75 ug/kg and recovery of streptomycin spiked at level of 10 ug/kg in honey was 74%. The established and validated method was applied to determine streptomycin in honey which was on the market.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.3
• /
• pp.230-237
• /
• 2015

BACKGROUND: To identify the sources of inaccuracy in LC/MS/MS methods used in the routine quantitation of small molecules are described and discussed. METHODS AND RESULTS: Various UPLC coupled to triple quadrupole mass spectrometer and time of flight (TOF) were used to identify the potential sources of inaccuracy and inducing the pitfalls of qualification and quntitation during the veterinary drug residue analysis. Some of stable isotope labelled veterinary drugs, which were used as internal standards, presented "cross-talk", regardless of manufactures of mass spectrometer and types of spectrometer. Group of sulfonamides also presented inaccuracy qualification and quantitation due to the multi-residue analytical method with the same fragment ions at the close retention times. CONCLUSION: The phenomena of "cross-talk" occurring between subsequently monitored transition from stable isotope labelled and isotope non-labelled authentic chemical were identified. To prevent errors and achieve more accurate data during the analysis of small molecules by LC/MS/MS SRM method, Followings should be taken care of and kept checking; purity and concentration of stable isotope as an internal standard, prevention of carry-over during the separation in column, minimizing the ion suppression by matrix effect, identification of retention time, precursor ion and product ion, and full knowledge of data processing including smoothing and peak integration.