• Analytical Science and Technology
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• v.33 no.3
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• pp.125-133
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• 2020

Methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT) cause allergic contact dermatitis and are banned cosmetics ingredients, except in rinse-off products. However, their presence has been detected in cosmetics. We report a UPLC-tandem MS/MS screening method for their simultaneous determination in cosmetics. To facilitate extraction from various matrices, pretreatment methods were developed for each sample type. The method was optimized through a series of assessments, including specificity, LOD, LOQ, linearity, recovery, stability, precision, and accuracy. The LODs and LOQs for MIT ranged from 0.054 and 0.163 ㎍ mL^-1 whereas those for CMIT ranged from 0.040 and 0.119 ㎍ mL^-1. The linear correlation coefficients (r²) were higher than 0.999. Relative standard deviations (RSDs) for both intra- and inter-day measurements ranged from 0.3 ~ 13.6 %. Recoveries at three different concentrations were within 87.9 ~ 118.9 %. The RSD for stability measurements of spiked samples was within 7 %. These results confirm the suitability of the developed method for the simultaneous quantitation of MIT and CMIT in cosmetics. Samples of 320 color cosmetics, including eyeshadows, solid lipsticks, liquid lipsticks, and nail polishes were analyzed using the developed method, and two of them were found to contain both MIT and CMIT and one of them was found to contain only MIT. This data and the method will aid the regulation of ingredients used in cosmetics.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5843-5846
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• 2015

Background: Detection of cervical high grade lesions in patients with atypical squamous cells of undetermined significance (ASCUS) is still a challenge. Our study tested the efficacy of the paired boxed gene 1 (PAX1) methylation analysis by methylation-sensitive high-resolution melting (MS-HRM) in the detection of high grade lesions in ASCUS and compared performance with the hybrid capture 2 (HC2) human papillomavirus (HPV) test. Materials and Methods: A total of 463 consecutive ASCUS women from primary screening were selected. Their cervical scrapings were collected and assessed by PAX1 methylation analysis (MS-HRM) and high-risk HPV-DNA test (HC2). All patients with ASCUS were admitted to colposcopy and cervical biopsies. The Chisquare test was used to test the differences of PAX1 methylation or HPV infection between groups. Results: The specificity, sensitivity, and accuracy for detecting CIN2 + lesions were: 95.6%, 82.4%, and 94.6%, respectively, for the PAX1 MS-HRM test; and 59.7%, 64.7%, and 60.0% for the HC2 HPV test. Conclusions: The PAX1 methylation analysis by MS-HRM demonstrated a better performance than the high-risk HPV-DNA test for the detection of high grade lesions (CIN2 +) in ASCUS cases. This approach could screen out the majority of low grade cases of ASCUS, and thus reduce the referral rate to colposcopy.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.368-374
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• 2020

BACKGROUND: The residual analysis of polar pesticides has remained a challenge. It is even more difficult to simultaneously analyze multiple polar pesticides. Diquat, paraquat, and chlormequat are typical examples of highly polar pesticides. The existing methods for the analysis of diquat, paraquat and chlormequat are complex and time consuming. Therefore, a simple, quick and effective method was developed in the represent study for simultaneous analysis of diquat, paraquat and chlormequat in animal products, meat and fat using UPLC-MS/MS. METHODS AND RESULTS: Sample extraction was carried out using acidified acetonitrile and water and re- extracted with acidified acetonitrile and combine the extracts followed by centrifugation. The extract was then cleaned up with a HLB cartridge after reconstitution with acidic acetonitrile and water. The method was validated in quintuplicate at three different concentrations. The limits of detection (LOD) and quantification (LOQ) were 0.0015 and 0.005 mg/L, respectively. Matrix suppression effect was observed for all of the analytes. A seven point matrix matched calibration curve was constructed for each of the compound resulted excellent linearity with determination coefficients (R2) ≥ 0.991. Accuracy and precision of the method was calculated from the recovery and repeatability and ranged from 62.4 to 119.7% with relative standard deviation less than 18.8%. CONCLUSION: The recovery and repeatability of the developed method were in the acceptable range according to the Codex Alimentarius guideline. The developed method can be applied for the routine monitoring of diquat, paraquat, and chlormequat in animal products, meat and fat.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.429-440
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• 2010

HS-SPME-GC/MS was studied and optimized for the determination of 17 orgarnophosphorous pesiticides (OPPs: chlorpyrifos, chlorpyrifos-methyl, demeton-s-methyl, diazinon, dimethoate, EPN, fenitrothion, fenthion, malathion, methidathion, monocrotophos, parathion, phenthoate, phosphamidon, sulfotep, terbufos, triazophos) in blood. Optimum SPME parameters were selected: choice of SPME fiber (85 ${\mu}m$ polyacrylate), pH effect (0.5 N HCl), salt effect ($Na_2SO_4$, 0.2 g; 20%), headspace incubation temperature ($80^{\circ}C$), headspace incubation time (1 min), headspace adsorption time (30 min) and GC desorption time (2 min). These parameters were optimized using HS-SPME autosampler coupled with gas chromatography-mass spectrometry (GC-MS). Method validation was carried out in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and recovery in blood. The assay was linear over 0.5~5.0 mg/l ($r^2$=0.955~1.000). Limit of detection (LOD) and limit of quantitation (LOQ) in blood were determined 0.03~0.3 mg/l (S/N=3) and 0.1~1.1 mg/l (S/N=10), respectively. Relative recovery with 0.5, 1 and 5 mg/l (in blood) were 90.8%, 98.5% and 94.1%, respectively. This method will be applied to the determination of the orgarnophosphorous pesticides in postmortem blood. The proposed protocol can be an attractive alternative to be used in routine toxicological analysis.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Journal of Korean Society on Water Environment
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• v.32 no.5
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• pp.410-418
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• 2016

This study was conducted to improve the analysis method used for N-nitrosamines and to investigate the occurrences of N-nitrosamines in tributaries of the Han-river, intake stations, water treatment plants and tap water used within the city of Seoul. The samples were pretreated through a solid phase extraction and analyzed using a gas chromatography tandem mass spectrometer (GC-MS/MS). The GC-MS/MS in CI mode was compared with the GC-MS/MS in EI mode by the method detection limits (MDLs). MDLs by GC-CI/MS/MS and GC-EI/MS/MS were 0.2 ~ 1.1 ng/L and 0.2 ~ 1.4 ng/L, respectively. Samples were collected from ten tributaries of the Han-river (T1 ~ T10), six intake stations (I1 ~ I6), six water treatment plants (P1 ~ P6) and 25 taps in Seoul city. The maximum levels of N-nitrosodimethylamine (NDMA) were 0.013 μg/L, 0.008 μg/L, 0.006 μg/L and 0.002 μg/L in tributary water, raw water, finished water and tap water samples, respectively. Detected levels were much lower than 0.1 μg/L corresponding to the guideline value of WHO.

• Korean Journal of Clinical Pharmacy
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• v.18 no.1
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• pp.60-67
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• 2008

This study aimed to compare a microparticle enzyme immunoassay (MEIA) with a liquid chromatography-tandem mass spectrometry (LC/MS/MS) technique for the measurement of tacrolimus concentrations in adult liver transplant recipients, to investigate how the assay choice influenced the population pharmacokinetics of tacrolimus and to identify patient characteristics that affected pharmacokinetic parameters in each assay. Tacrolimus concentrations from 29 liver (n=52 paired-samples) transplant recipients measured by both MEIA and LC/MS/MS were used to evaluate the performance of these methods in the clinical setting. Tacrolimus pharmacokinetics was studied independently using MEIA and LC/MS/MS data in 70 adult patients using a population approach performed with NONMEM. Patient characteristics which influenced pharmacokinetic parameters in each assay were compared. The relation between LC/MS/MS and MEIA measurements was best described by the regression equation MEIA=1.465*LC/MS/MS-1.336 (r=0.91). Multiple linear regression analysis showed significant inverse relationships between assay difference and hematocrit (Hct) (p<0.025) in liver graft recipients. In MEIA, the population estimate of tacrolimus CL/F and apparent volume of distribution (Vd/F) were found to be 10.1 L/h and 226 L, and in LC/MS/MS, 13 L/h and 305 L respectively. Neither patient's age, weight, gender, grafted hepatic weight, albumin concentration, nor markers of liver function influenced tacrolimus CL/F The final model of CL/F was found to be 10.1+(Hct/Hct mean)$^{12.0}$ in MEIA and 13+(1+Hct/578) in LC/MS/MS indicating that CL/F was influenced by hematocrit.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.296-313
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• 2014

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) multiresidue method was developed for the simultaneous analysis of 124 pesticides in soil by LC-MS. The procedure involved liquid extraction of soil immersed with 0.2N $NH_4Cl$ by acetonitrile with 1% acetic acid, followed by anhydrous $MgSO_4$ and sodium acetate, and dispersive SPE cleanup with $MgSO_4$, primary secondary amine (PSA) and $C_{18}$. The extracts were analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.99. Recovery studies for the validation were carried out using two type soils, loam and sandy loam, at four concentration levels (0.005, 0.01, 0.02, and 0.1 mg/kg). The recoveries of pesticides were in the range of 70-120% with < 20% RSD except 4 pesticides, Benfuracarb, Ethiofencarb, Pymetrozine, and Pyrethrin. This result indicated that the method using QuEChERS and LC-MS/MS could be applied for the simultaneous determination of pesticide residues in soils.

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.51-54
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• 2009

Myxobacteria, Gram-negative soil bacteria, are a well-known producer of bioactive secondary metabolites. Therefore, this study presents a methodological approach for the high-throughput screening of secondary metabolites from 4 wild-type Myxococcus xanthus strains. First, electrospray ionization mass spectrometry (ESI-MS) was performed using extracellular crude extracts. As a result, 22 metabolite peaks were detected, and the metabolite profiling was then conducted using the m/z value, retention time, and MS/MS fragmentation pattern analyses. Among the peaks, one unknown compound peak was identified as analogous to the myxalamid A, B, and C series. An analysis of the tandem mass spectrometric fragmentation patterns and HR-MS identified myxalamid K as a new compound derived from M. xanthus. In conclusion, LC-MS/MS-based chemical screening of diverse secondary metabolites would appear to be an effective approach for discovering unknown microbial secondary metabolites.

• Polymer Science and Technology
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• v.22 no.2
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• pp.188-193
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• 2011