• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.215-219
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• 2009

To conduct a risk assessment of $AFB_1$ intake, $AFM_1$, which is a metabolite of $AFB_1$ in the human and porcine urine, was determined by competitive direct ELISA (cdELISA). The detection limit of cdELISA using anti-$AFM_1$ antibody and $AFB_1$-HRP conjugate was 10 pg/mL. The recoveries of $AFM_1$ were 117-167% after the addition of $AFM_1$ in the human urine in a range of 3-100 pg/mL. 165 samples (95.5%) of those obtained from 172 persons evidenced measurable levels of urinary $AFM_1$. The detected $AFM_1$ ranges were 0-11.6 pg/mL and the average level of $AFM_1$ contamination was 2.74${\pm}$ 1.89 pg/mL. The estimated amount of $AFM_1$ excretion in the human urine was 3.97 ng/day and the estimated $AFB_1$ intake amount was 79.4 ng/day. The probable daily intake (PDI) of $AFB_1$ by the subjects was estimated to be 1.28 ng/kg bw/day, which was higher than the tolerable daily intake (TDI, 0.15 ng/kg bw/day). In the case of porcine urine, the $AFM_1$ ranged between 0.97-26.7 pg/mL and the average contaminated $AFM_1$ was 10.62${\pm}$4.39 pg/mL. The estimated amount of $AFM_1$ excretion in the porcine urine was 27.6 ng/day, and the estimated $AFB_1$ intake amount was 551 ng/day.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.200-205
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• 2001

In this study, occurrence of aflatoxin M$_1$(AEM$_1$) in domestic milk and milk products was determined. The level of AFM$_1$ in market milk (0.047 ppb) was lower than that in raw milk (0.083 pub) but this looks like that is due to dilution in collecting process rather than the effect of sterilization. In the case of nonfat dry milk, level of AFM$_1$appeared high by 0.24 ppb but it is thought to be not different from market milk actually because nonfat dry milk is diluted at intake. In the case of ice cream, finished products were contaminated with AFM$_1$of 0.020 ppd and also have the possibility of the contamination of AFB$_1$due to secondary raw material such as nuts and almond. On the basis of the results of this study and previous studies, Monte-Carlo simulation is conducted to estimate the contamination level of AFM$_1$in domestic market milk. To consider uncertainty and variability fitting procedure was passed through. And we used beta distribution to estimate the prevalence and triangular distribution to estimate the concentration level of AFM$_1$in milk. As a result, the 5%, 50% and 95% points of the distribution of the probability of AFM$_1$contamination level in milk is 0.0214, 0.0946 and 0.1888 ppb, respectively. Also we estimate that AFM$_1$in almost milk was low more than 0.5 ppb that is American acceptable level but 80.4% exceeded far 0.05 ppb that is European standard.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1184-1187
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• 1996

A simple and rapid detection system for $aflatoxin\;M_1\;(AFM_1)$ in cow's milk by an enzyme-linked immunosorbent assay (ELISA) was developed. Specific antibodies against $AFM_1$, conjugated to bovine serum albumin $(AFM_1-BSA)$ were raised in rabbits and purified. The cross-reactivities of the antibodies against aflatoxin analogs were less than 29.9%. When a competitive direct ELISA (cdELISA) for $AFM_1$, established by use of the antibodies was applied to the spike test of $AFM_1$ onto uncontaminated cow's milk, the assay recovery was unstable unless cow's milk was diluted to 40% (2:3) with phosphate buffered saline (PBS). In that condition of sample dilution, the mean ELISA recovery of $AFM_1$, from the cow's milk was 113% (coefficient of variation (CV) of each recovery percentage, 8.2%) in the range of $0.3{\sim}3.0\;ppb$. These results showed that the ELISA system could be a convenient tool to monitor the contamination of AFM1 more than 0.5 ppb in cow's milk (FDA allowance limit) easily.

• Journal of Life Science
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• v.23 no.2
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• pp.306-310
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• 2013

We compared the efficacy of the competitive ELISA method for measuring the level of urinary aflatoxin M1 (AFM1) with that of the HPLC-fluorescence detector (HPLC-FLD) method. The recovery rate of AFM1 with the ELISA method was 105% (73-124%), and the coefficient of variation of the analysis was 6.85%. The ELISA method showed a 0.20 pg/ml and 0.62 pg/ml limit of detection and limit of quantitation, respectively. In correlation analysis, the two methods showed a very strong and statistically significant correlation (R=0.96, p<0.01). However, in spite of the strong correlation, the ELISA method tended to overestimate the urinary AFM1 concentration compared to the HPLC-FLD method. These results suggest that the competitive ELISA method may be a useful technique for measuring the AFM1 level in high-throughput urine samples, but it needs to be corrected with a regression equation from regression analysis with the HPLC-FLD method.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.630-635
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• 1996

For a survey of the occurrence of aflatoxin M$_{1}$ (AFM$_{1}$) in domestic cow's milk, we developed an enzyme-linked immunosorbent assay (ELISA) system, and quantitated the toxin in cow's milk. In order to produce specific antibodies AFM, conjugated to bovine serum albumin (AFM$_{1}$-BSA) and Freund's adjuvant were immunized subcutaneously to rabbits. By use of the antiserum showing the highest titer and AFB$_{1}$-HRP conjugate, we established a competitive direct ELISA (cdELISA) for AFM$_{1}$, whose detection limit was 0.003 ppb. The cross-reactivities of the antiserum against aflatoxin M$_{1}$ M$_{2}$, B$_{1}$, B$_{2}$, G$_{1}$, G$_{2}$, B$_{2a}$, and G$_{2a}$, were 100, 29.9, 25.0, 2.7, 13.0, 0.65, 0, and 0%, respectively. When the cdELISA was applied to the cow's milk spiked with AFM$_{1}$ and followed by cleanup with C$_{18}$ cartridge, the mean recovery of the assay was 104% (mean of CV, 6.4%) in the final concentration of 0.01-1 ppb (10-1, 000 ppt). When cow's milk samples gathered from markets and farms were assayed by the cdELISA, the mean concentration and SD of AFM$_{1}$ was 80.4 $\pm$ 55.0 ppt (n=64; range, 5.6-280 ppt).

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.81-84
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• 2007

Ab initio periodic Hartree-Fock calculations with the full potential and minimum basis set are applied to interpretation of scanning tunneling microscope (STM) and atomic force microscope (AFM) images on 1TVTe2. Our results show that the simulated STM image shows asymmetry while the simulated AFM image shows the circular electron densities at the bright spots without asymmetry of electron density to agree with the experimental AFM image. The bright spots of both the STM and AFM images of VTe2 are associated with the surface Te atoms, while the patterns of bright spots of STM and AFM images are different.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.96-104
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• 2007

Calibration of the spring constants of atomic force microscopy (AFM) cantilevers is one of the issues in biomechanics and nanomechanies for quantified force metrology at pieo- or nano Newton level. In this paper, we present an AFM cantilever calibration system: the Nano Force Calibrator (NFC), which consists of a precision balance and a one-dimensional stage. Three types of AFM cantilevers (contact and tapping mode) with different shapes (beam and V) and spring constants (42, 1, 0.06 N $m^{-1}$) are investigated using the NFC. The calibration results show that the NFC can calibrate the micro cantilevers ranging from 0.01 ${\sim}$ 100 N $m^{-1}$ with relative uncertainties of less than 2%.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.102.1-102.1
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• 2010

대체수자원 중 막여과 기술에 대한 관심이 지속적으로 높아지고 있다. 하지만, 이러한 막여과 기술에는 fouling이 발생시 효율저감, flux저감, 소모에너지 증대 등 문제점이 발생한다. 이러한 fouling저감을 위해 막 표면특성분석을 통한 기초연구가 필요하다고 보고 이 연구를 진행하였다. AFM을 이용하여 CML입자와 막의 상호작용을 통해 초기 막오염 경향을 예측할 수 있다.

• Environmental Analysis Health and Toxicology
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• v.23 no.1
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• pp.47-51
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• 2008

The toxicity of environmental pollutants was measured between a image of the surface topography in HeLa cells using atomic force microscopy for the possibility of toxic effect measurement and environmental monitoring. A image of the surface topography by AFM were estimated as toxic endpoints. The surface topography by AFM was observed a change of the cell surface in the environmental pollutants, but the standard of the measurement requires for the dose-effect degree. The overall results indicate that the possibility of measurement using AFM were confirmed a dose-effect degree related toxic effects, but it requres correlation between more various biomarker and AFM's measurements if the possibility of the toxic effect measurement was established.

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.85-88
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• 2007

Ab initio periodic Hartree-Fock calculations with the full potential and minimum basis set are applied to interpretation of scanning tunneling microscope (STM) and atomic force microscope (AFM) images on 1TVTe2. Our results show that the simulated STM image shows asymmetry while the simulated AFM image shows the circular electron densities at the bright spots without asymmetry of electron density to agree with the experimental AFM image. The bright spots of both the STM and AFM images of VTe2 are associated with the surface Te atoms, while the patterns of bright spots of STM and AFM images are different.