• Mass Spectrometry Letters
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• v.14 no.2
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• pp.36-41
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• 2023

A simple method was developed to determine residual p-arsanilic acid (ASA), an organo-arsenic compound used as a feed additive, in aquatic products (eel, halibut, and shrimp) using EDTA-assisted solvent extraction and LC-MRM. The method was successfully validated in terms of specificity, linearity (coefficient of determination ≥ 0.995), accuracy (recovery or R, 72.72-78.73%), precision (the relative standard deviation of R, 2.08-6.98%), and sensitivity (the lower limit of quantitation, 5 ppb) according to CODEX guidelines (CAC-GL 71-2009). The use of EDTA in the extraction solvent and water with a suitable pH modifier as the reconstitution solvent may be the key factors for successful results. This is the first method that can be used for monitoring residual ASA in aquatic products using LC-MRM and could contribute to establishing a better aquatic product safety management system.

• Mass Spectrometry Letters
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• v.12 no.1
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• pp.11-15
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• 2021

Nitarsone is an organoarsenic antiprotozoal drug widely used to treat blackhead disease in turkeys and chickens. However, since its biological conversion into inorganic arsenic, a carcinogen was known, its residue in foods should be regulated. Thus, here, a novel method to determine residual nitarsone in various food commodities (pork, milk, egg, halibut, eel, and shrimp) using QuEChERS and LC-MRM was developed. The developed method was successfully validated through specificity, linearity (coefficient of determination, at least 0.991), recovery (R, 63.6 - 85.6%), precision (the relative standard deviation of R, 0.5 - 10.6%), and sensitivity (the lower limit of quantitation, 5 ppb) by following the Ministry of food and drug safety (MFDS) guidelines. The present method is the first mean to quantitate nitarsone using LC-MRM, and it was designed to be conveniently merged into a new method to quantitate multiple veterinary drugs for the positive list system (PLS). Therefore, the present method could contribute to fortify the food safety system in South Korea.

• Analytical Science and Technology
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• v.16 no.6
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• pp.488-498
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• 2003

By LC/MS/MS, the analytical method of sildenafil and its analogues (homosildenafil, vardenafil and tadalafil) used as used medical treatment of impotence was established. electrosprary ionization (ESI) and atmospheric pressure chemical ionization (APCI) as a ionization method were applied. Several parameter were varied and the sensitivity and reproducibility were compared. In LC/ESI-MS method, capillary voltage, cone voltage, extractor, entrance and RF lens to create appropriate productr ions for multiple reaction monitoring (MRM) were variable parameter, but the formation of the other product ions except the precursor ion could not detect. And the value of entrance, collision energy, exit, corona voltage, cone voltage, extractor, RF lens, cone gas, and desolvation gas in APCI mode were varied, only the creation pattern of fragment ions by the change of RF lens value were detected, and the limit of detection was decreased due to the increase of S/N. Ten millimole ammonium formate (pH 4.8):acetonitrile=70:30 by isocratic elution in HPLC system was shown the maximum sensitivity in MS, the detection limit of sildenafil, homosildenafil, vardenafil and tadalafil obtained by ESI-MRM were 0.10, 0.025, 0.025, and $0.25{\mu}g/mL$ at S/N>5, respectively.

• Analytical Science and Technology
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• v.24 no.4
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• pp.237-242
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• 2011

In this study, an analytical method was developed for residual metamizol in beef and pork using LC/MS/MS. 4-methylaminoantipyrin (MAA), the main metabolite of metamizol was targeted for analysis instead of its parent compound. MAA was simply extracted from meat by acetonitrile, purified and then analyzed by multiple reaction monitoring method (MRM). Standard addition method was used for calibration. The calibration curves showed the linearity of $r^2$ > 0.99 for both matrices included. The developed method was validated by six-time intra-lab tests and inter-lab tests with two other institutes. The validation of the whole procedure for beef showed the intra-lab accuracies of 78-102% (CV 5.5-9.1%) and the inter-lab accuracy of 98% (CV 14%); the intra-lab accuracies of 95-99% (CV 3.9-5.6%) and the inter-lab accuracy of 111% (CV 13%).

• Mass Spectrometry Letters
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• v.9 no.4
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• pp.100-104
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• 2018

As a part of efforts to establish the positive list system (PLS) in South Korea, a method to determine residual emamectin benzoate (EB) in various aquatic products using QuEChERS-EDTA and LC-MRM was developed. The developed method was validated in the aspects of specificity, linearity (correlation coefficient of at least 0.996), sensitivity (the limit of detection and the lower limit of quantitation ${\leq}5ng/g$), recovery (the recovery range of 87.4 and 96.2), and precision (the relative standard deviation of recovery between 0.9 and 13.5). Additionally, the validated method was successfully applied for monitoring EB contamination in eel, halibut, and shrimp collected from local food markets. To our knowledge, the present method is the first one to determine residual EB in various aquatic products at the level satisfying the PLS and could contribute to the establishment of the PLS in South Korea.

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.65-71
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• 2019

One of the oriental medicine prescriptions, Sagunja-tang consists of four herbal medicines (Ginseng Radix, Poria Sclerotium, Atractylodis Rhizoma Alba, and Glycyrrhiziae Radix et Rhizoma) and has been used as a medicine to enhance tonify the function of spleen and stomach in Korea. In this study, we conducted simultaneous analysis of the 9 marker components, liquiritin apioside, liquiritin, ginsenoside Rg1, liquiritigenin, ginsenoside Rb1, glycyrrhizin, atractylenolide III, atractylenolide II, and atractylenolide I in Sagunja-tang using a liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). Marker compounds were separated on a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, 1.7 mm) and the column was maintained at $45^{\circ}C$. The mobile phase consists of 0.1% (v/v) aqueous formic acid and acetonitrile with gradient condition. The LC-MS analysis was performed using a Waters ACQUITY TQD LC-MS/MS system with multiple reaction monitoring (MRM) method in the positive and negative modes. The calibration curves of the nine marker components showed good linearity with coefficient of determination ${\geq}0.9984$ within tested range. The limits of detection and limits of quantification values were 0.27-2.42 ng/mL and 0.81-7.27 ng/mL, respectively. The concentrations of tested 9 analytes in the lyophilized Sagunja-tang sample using the established LC-ESI-MS/MS MRM method were detected up to 16.593 mg/g. These results can be useful as a basic data for the quality control of an oriental medicine prescriptions.

• Analytical Science and Technology
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• v.15 no.5
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• pp.410-416
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• 2002

In this study, a new quantitative analytical method has been developed for the rapid determination of vancomycin in human plasma and urine using liquid chromatography/tandem mass spectrometry (LC - MS/MS). Chromatography was carried out on a $C_{18}$ XTerra MS column ($2.1{\times}30mm$) with a particle size of $3.5{\mu}m$. The mobile phase was 0.25% formic acid in 10% acetonitrile and the flow rate was $250{\mu}L/min$. Vancomycin and caffeine (internal standard) were detected by MS/MS using multiple reaction monitoring (MRM). Vancomycin gives a predominant doubly protonated precursor molecule ($[M+2H]^{2+}$) at m/z 725.0 and a corresponding product ion of m/z 100.0. Detection of vancomycin was good, accurate and precise, with a limit of detection of 1 nM in plasma. The calibration curves for vancomycin in human plasma was linear in a concentration range of $0.01{\mu}M$ - $100{\mu}M$ for plasma. This method has been successfully applied to determine the concentration of vancomycin in human plasma and urine from pharmacokinetic study and relative studies.

• Analytical Science and Technology
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• v.22 no.4
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• pp.319-325
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• 2009

An effective and specific procedure for confirmation of neomycin, aminoglycoside antibiotic in honey was developed and validated. Honey was adjusted to pH 2 with 0.1M HCl and applied to weak cation-exchange SPE cartridge. Neomycin was eluted with basified methanol. Following separation by ion-pairing liquid chromatography, neomycin was analysed with positive electrospray ionization and MRM mode. Quantification was linear over the range of $5.0{\sim}250.0{\mu}g/kg$ ($r^2$ >0.9951). The precision (R.S.D.) and accuracy (as a bias) of quality control samples in honey ranged 11.5~18.7% and 10.9~20.9%, respectively. Established method can be applied to analysis of neomycin in honey.

• Journal of Life Science
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• v.30 no.11
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• pp.956-964
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• 2020

The radical scavenging activity measurement system linked with liquid chromatography (LC) is a useful tool for identifying the radical scavenging active compound in a sample composed of numerous compounds such as plant extracts. Using this system, DPPH and ABTS radical scavenging activity were measured on extracts of Ulmus pumila cortex, which is known as an herbal medicine with antioxidant activity. Mass spectrometry (MS) was performed on the identified radical scavenging active compounds to identify the four components estimated to be procyanidin B2, procyanidin B3, catechin-7-O-β-D-apiofuranoside, and catechin-5-O-β-D-apiofuranoside, respectively. In order to compare the relative contents between extract samples, multiple reaction monitoring (MRM) mode analysis conditions were set for the four compounds in order to examine the possibility of comparing the content of radical scavenging active compounds in Ulmus pumila cortex extract using LC-MS/MS. As a result of the relative content comparison, it was found that the higher the ethanol concentration of the extraction solvent, the higher the content of radical scavenging active compounds. As with the results of measuring the radical scavenging activity of each extract, it was confirmed that the content difference of three of the compounds (all except the compound estimated as procyanidin B3) was not significantly observed in the extracts with an ethanol concentration of 50% or more.

• Analytical Science and Technology
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• v.25 no.1
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• pp.19-24
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• 2012

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantitative determination of ertapenem in human plasma and urine. After addition of internal standard (ceftazidime), plasma and urine was diluted with methanol and analyzed by LC-MS/MS. Using MS/MS with multiple reaction monitoring (MRM) mode, ertapenem were selectively detected without severeinterference from human plasma and urine. The standard calibration curve for ertapenem was linear ($r^2$= 0.9996)over the concentration range 1~100 ${\mu}g/mL$ in human plasma. The intra- and inter-day precision over the concentration range of ertapenem was lower than 8.9% (correlation of variance, CV), and accuracy was between 97.2~106.2%. On the other hand, it was showed good relationship ($r^2$= 0.9992) and the precision (intra- and inter-day) over the concentration range of ertapenem was lower than CV 7.2%, and accuracy was between 97.9~111.6% for urine. This method has been successfully applied to the pharmacokinetic study of ertapenem in human plasma and urine.