• Mass Spectrometry Letters
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• v.2 no.2
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• pp.45-48
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• 2011

The authors describe a method for monitoring dicyclanil levels in lamb and chicken muscle tissues. The devised procedure involves dicyclanyl extraction by SPE and its detection HPLC-UV/Vis and LC/MS/MS. The method was found to have LOD and LOQ values of $0.02\;mg\;kg^{-1}$ and $0.05\sim0.06\;mg\;kg^{-1}$, respectively. The intraday precision and an accuracy of spiked samples were found to have 2.3~10.4 RSD% and 80.9~105.7%, respectively.

• Mass Spectrometry Letters
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• v.10 no.4
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• pp.112-116
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• 2019

In this study, a chloroform consumer chemical product (CCP) reference material (RM) is successfully developed, with potential to be used in the proficiency testing of hazardous compounds in CCPs for analysis and testing agencies. Validation experiments are rigorously conducted to evaluate whether the RM meets the requirements set by the ISO 13528 and ISO Guide 35, using a reliable GC/MS method for the analysis of chloroform. The obtained calibration plot linearity, limit of detection (LOD), and limit of quantitation (LOQ) are excellent. The developed RM meets the homogeneity and stability requirements; the between-unit (s_bb) and within-unit (s_wb) standard deviations are less than 2.5%, and the stability is found to be guaranteed for 50 days.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.379-383
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• 2009

For an accurate risk assessment of furan, a potential human carcinogen, levels must be determined in human blood plasma using a simple and robust assay. In this study, solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) was used to analyze blood plasma levels of furan in 100 healthy individuals who consumed a normal diet. The subjects were 30 to 70 years of age and 51% were women. Ultimately, an analytical method was established for analyzing furan in human blood. The limit of quantification (LOQ) and furan recovery rate in blood were 1.0 ppb and 104%, respectively. Finally, furan was detected in 21 individuals (13 males, 8 females) with levels ranging up to 17.86 ppb (ng furan/g food).

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3971-3976
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• 2012

A simple method was developed for the analysis of seven stilbene-type fluorescent whitening agents (FWAs) in paper materials by ion-pair reversed-phase high-performance liquid chromatography with fluorescence detection. These stilbene-type FWAs included two disulfonate, two tetrasulfonate, and three hexasulfonate compounds. After optimization of chromatographic conditions, the FWAs were satisfactorily separated using a reversed-phase column (RP-18) with the following isocratic mobile phase: methanol-water (60:40) containing 17.5 mM TBABr and 10 mM citrate buffer (pH = 7.0). The calibration plot was linear in the range from 5 to 500 ng/mL for two disulfo-FWAs and from 1 to 500 ng/mL for the other five FWAs. Precision levels of the calibration curve as indicated by RSD of response factors were 1.2 and 8.1%. Limits of quantitation (LOQ) ranged from 1.2 to 11 ng/mL.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.396.1-396.1
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• 2002

HPTLC(High Performance Thin Layer Choromatography) method was developed for rapid and precise analysis of Sildenafil and modified Sildenafils(Vardenafil. Homosildenafil, Tadanafil). Chromatographic conditions were Optimized for simultaneous analysis of them and each specific UV spectra were obtained. The calibration curve of Sildenafil and modified Sildenafils had a linearity in the range of 1.0 ~ 56.5 $\mu$/ml at 254nm. The Limit of Detection(LOD) and the limit of Quantification(LOQ) of Sildenafil and modified Sildenafils were 0.8$\mu$/ml and 1.0$\mu$g/ml. (omitted)

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.245.1-245.1
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• 2003

DA-8159 is a new PDEV (Phosphodiesterase V) inhibitor, synthesized by Dong-A Pharm., as an oral agent to treat male erectile dysfunction. To make a selection of the dosage of oral administration in carcinogenic studies, we studied preliminarily the pharmacokinetics of DA-8159 after single (at the 1$\^$st/ day) and 1-week (at the 7$\^$th/ day) oral administrations of the drug at doses of 15, 50 and 150 mg/kg/day, to male ICR mice. In 15mg/kg single and 1-week repeated oral administration groups, the concentrations of DA-8159 and DA-8164(the main metabolite of DA-8159) were below the limit of quantitation(LOQ:50ng/ml). (omitted)

• Analytical Science and Technology
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• v.35 no.1
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• pp.24-31
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• 2022

Herein, we present a simple, precise, accurate, and ultra-sensitive spectrofluorimetric method for estimation of clozapine (CLZ) in tablets and human plasma was developed and then validated. A highly fluorescent brown-yellowish fluorophore was formed (λ_ex=469 nm, λ_emi=540 nm) as a nucleophilic substitution reaction occurred between CLZ and 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in alkaline mcllavine buffer (pH 9.0). Optimum values of experimental parameters were carefully determined and optimized. The calibration curve was rectilinear over the concentration range of 80-900 ng mL^-1 with a linear correlation coefficient (r=0.9984). The LOD and LOQ were determined to be 14 ng mL^-1 and 42 ng mL^-1, respectively. The proposed approach has been used successfully to quantification of Clozapine in its commercial formulations and human plasma.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.662-667
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• 2023

Allantoin is an abundant component of yams and has been known as a skin protectant due to its pharmacological activities. In previous methods for allantoin determination using high-performance liquid chromatography (HPLC), the separation was unsatisfactory. We herein developed a ¹H quantitative nuclear magnetic resonance (qNMR) method for quantification of allantoin in the flesh and peel of yams. The method was carried out based on the relative ratio of signals integration of allantoin to a certain amount of the internal standard dimethyl sulfone (DMSO₂) and validated in terms of specificity, linearity (range 62.5-2000 ㎍/ml), sensitivity (limit of detection (LOD) and quantification (LOQ) 4.63 and 14.03 ㎍/ml, respectively), precision (RSD% 0.02-0.26), and recovery (86.35-92.11%). The method was then applied for the evaluation of allantoin in flesh and peel extracts of four different yams cultivated in Korea.

• Analytical Science and Technology
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• v.36 no.1
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• pp.1-11
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• 2023

A new, sensitive, and reliable flow injection methodology was investigated for the determination of lead ion (II) in vegetables' samples using a laboratory-prepared reagent 2-[(6-methoxy-2-benzothiazoly)azo]-4-methoxy phenol (6-MBTAMP). Infrared spectroscopy, UV-visible spectrophotometry, Energy dispersive X-ray spectroscopy (EDX), Elemental Analysis (CHN), nuclear magnetic resonance spectroscopy ¹HNMR, and ¹³CNMR techniques were used to characterize the reagent and lead (II) complex. The method is based on lead ion (II) reacting with the reagent (6-MBTAMP) in a neutral solution to produce a green-red complex with a maximum absorbance at 670 nm. The optimum conditions, such as flow rate, lead ion (II) volume, reagent volume, medium pH, reagent concentration, and reaction coil length were thoroughly examined. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.621 mg·L^-1 and 2.069 mg·L^-1 , respectively, while Sandell's sensitivity was determined to be 0.345 ㎍·cm^-2.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.124-134
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• 2019

An analytical method was developed for the determination of broflanilide and its metabolites in agricultural products. Sample preparation was conducted using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method and LC-MS/MS (liquid chromatograph-tandem mass spectrometer). The analytes were extracted with acetonitrile and cleaned up using d-SPE (dispersive solid phase extraction) sorbents such as anhydrous magnesium sulfate, primary secondary amine (PSA) and octadecyl ($C_{18}$). The limit of detection (LOD) and quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. The recovery results for broflanilide, DM-8007 and S(PFP-OH)-8007 ranged between 90.7 to 113.7%, 88.2 to 109.7% and 79.8 to 97.8% at different concentration levels (LOQ, 10LOQ, 50LOQ) with relative standard deviation (RSD) less than 8.8%. The inter-laboratory study recovery results for broflanilide and DM-8007 and S (PFP-OH)-8007 ranged between 86.3 to 109.1%, 87.8 to 109.7% and 78.8 to 102.1%, and RSD values were also below 21%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food and Drug Safety Evaluation guidelines (2016). Therefore, the proposed analytical method was accurate, effective and sensitive for broflanilide determination in agricultural commodities.