• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.177-183
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• 1995

This study was conducted to develop the most precise NIR(near infrared spectrometric) calibration for rapid determination of chemical composition in ground samples of toasted burley tobacco using stepwise, stepup, principal component regression(PCR), partial least square(PLS) and modified partial least square(MPLS) calibration method. The number of wavelength(W) selected by stepup multiple linear regression using: second derivative spectra was as follows: total sugar(TS)-4 W, nicotine-9 W, total nitrogen(TN)-2 W, ash-8 W, total volatile base(TVB)-5 W, chlorine4 W, L of color-6 W, a of color-6 W and b of color-7 W. Comparing the calibration equations followed by each chemical components, the most precise calibration equation was MPLS for 75, a and b of color, PLS for nicotine, ash, TVB, chlorine and L of color and stepup for TN. The standard error of calibration(SEC) and standard error of performance(SEP) between result of near infrared analysis and standard laboratory analysis were 0.18, 0.40% for 75, 0.06, 0.08% for nicotine, 0.18, 0.16% for TN, 0.33, 0.46% for ash, 0.04, 0.03% for TVB, 0.08, 0.06% for chlorine, 0.54, 0.58 for L of color, 0.22, 0.22 for a of color and 0.27, 0.27 for b of color, respectively. The SEC and SEP of ash and TVB were within allowable error of standard laboratory analysis, nicotine, TN and chlorine were 1.2-2.0 times and 75 were 2.1-4.0 times larger than allowable error of standard laboratory analysis. The ratio of SEC and SEP to mean were 1.5, 1.6% for L of color, 3.7, 3.8% for a of color and 1.8, 1.8% for b of color, respectively. Key words : burley tobacco chemistry, near infrared spectroscopy.

• Analytical Science and Technology
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• v.15 no.1
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• pp.67-71
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• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Journal of Crop Science and Biotechnology
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• v.10 no.3
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• pp.185-192
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• 2007

Near-infrared spectroscopy(NIRS) was used to develop a rapid and efficient method to determine lignan glucosides in intact seeds of sesame(Sesamum indicum L.) germplasm accessions in Korea. A total of 93 samples(about 2 g of intact seeds) were scanned in the reflectance mode of a scanning monochromator, and the reference values for lignan glucosides contents were measured by high performance liquid chromatography. Calibration equations for sesaminol triglucoside, sesaminol($1{\rightarrow}2$) diglucoside, sesamolinol diglucoside, sesaminol($1{\rightarrow}6$) diglucoside, and total amount of lignan glucosides were developed using modified partial least square regression with internal cross validation(n=63), which exhibited lower SECV(standard errors of cross-validation), higher $R^2$(coefficient of determination in calibration), and higher 1-VR(ratio of unexplained variance divided by variance) values. Prediction of an external validation set(n=30) showed a significant correlation between reference values and NIRS estimated values based on the SEP(standard error of prediction), $r^2$(coefficient of determination in prediction), and the ratio of standard deviation(SD) of reference data to SEP, as factors used to evaluate the accuracy of equations. The models for each glucoside content had relatively higher values of SD/SEP(C) and $r^2$(more than 2.0 and 0.80, respectively), thereby characterizing those equations as having good quantitative information, while those of sesaminol($1{\rightarrow}2$) diglucoside showing a minor quantity had the lowest SD/SEP(C) and $r^2$ values(1.7 and 0.74, respectively), indicating a poor correlation between reference values and NIRS estimated values. The results indicated that NIRS could be used to rapidly determine lignan glucosides content in sesame seeds in the breeding programs for high quality sesame varieties.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.525-527
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• 1999

Many types of chemical data tend to be characterized by many measured variables on each of a few observations. In this situation, target concentration can be predicted using multivariate statistical modeling. However, it is necessary to use a few variables considering size and cost of instrumentation, for an example, for development of a portable biomedical instrument. This study presents, with a spectral data set of total hemoglobin in whole blood, the possibility that modeling using only a few variables can improve predictability compared to modeling using all of the variables. Predictability from the model using three wavelengths selected from all possible regression method was improved, compared to the model using whole spectra (whole spectra: SEP = 0.4 g/dL, 3-wavelengths: SEP=0.3 g/dL). It appears that the proper selection of variables can be more effective than using whole spectra for determining the hemoglobin concentration in whole blood.

• Analytical Science and Technology
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• v.16 no.2
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• pp.125-133
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• 2003

In order to determine the contents of trans-resveratrol in red wine, which was mainly consumed in Korea, both LC/MS-ESI and LC/MS-APCI methods were used after solid-phase (Sep-Pak $C_{18}$-cartridges) extraction. The contents of trans-resveratrol obtained by LC/MS-ESI were detected in the range of $0.06-4.31{\mu}g/mL$. The recoveries were ranged from 88.4 to 97.9%. The values of relative standard deviation were ranged from 0.6 to 4.6% and the detection limit was $0.001{\mu}g/mL$. The contents of trans-resveratrol obtained by LC/MS-APCI were detected in the range of $0.09-4.02{\mu}g/mL$ and the detection limit was $0.005{\mu}g/mL$.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.412-416
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• 1997

Seven brands of commercial apple juice in Korea obtained from local stores were analyzed for patulin. Sep-Pak silica cartridge purification of the extract by ethyl acetate offered a good separation of patulin from other components. Patulin was determined by reverse phase liquid chromatography using a J'sphere $4\;{\mu}m$ ODS-H80 column with an ultraviolet detector set at 274 nm. Patulin concentrations in four samples ranged from 4 to $20\;{\mu}g/L$ and the other three samples from 30 to $45\;{\mu}g/L$. The limit of detection was $3\;{\mu}g/L$, and the recovery was $80{\sim}90%$ at the contamination level of $3.78{\sim}125.9\;{\mu}g/L$.

• Journal of Sericultural and Entomological Science
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• v.42 no.1
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• pp.58-64
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• 2000

This study was designed to investigate the effects of silk fibroin powder (Mw 500) on oxidative stress and membrane fluidity in liver membranes of rats. Sprague-Dawley (SD) male rats (160$\pm$10g) were fed basic diet (control group), and experimental diets (SEP-2.5 and SFP-5.0 groups) added 2.5 and 5.0 g/kg BW/day for 6 weeks. Cholesterol levels resulted in a significant decrease (12.1% and 9.0%, respectively) in the liver mitochondria and microsomes of SEP-5.0 group compared with control group. Membrane fluidity as significantly increased (16.1% and 16.5%, 5.8% and 17.4%) in the liver mitochondria and microsomes were significantly inhibited (16.1% and 18.3%, 8.1% and 15.1%, respectively) at the SFP-2.5 and SEP-5.0 groups compared with control group. Induced oxygen radicals (BOR) in liver mitochondria and microsomes were significantly inhibited (16.1% and 18.3%, 8.1% and 15.1%, respectively) at the SFP-2.5 and SEP-5.0 groups compared with control group. Induced oxygen radicals (IOR) in liver microsomes were significantly inhibited (17.0% and 26.6%, respectively) at the SFP-2.5 and SFP-5.0 groups compared with control group, but IOR in liver mitochondria was significantly inhibited about 12.3% at the SWP-400 group only compared with control group. Lipid peroxide (LPO) levels were significantly decreased (8.3% and 18.0%, 13.4% and 18.4%, respectively) in the liver mitochondria and microsomes of SFP-2.5 and SFP-5.0 groups compared with control group. Oxidized protein (OP) levels were dose-dependently decreased (5.4% and 11.6%, 19.0% and 24.4%, respaectively) in the iver mitochondria and microsomes of SFP-2.5 and SFP-5.0 groups compared with control group. These results suggest that administration of SFP may play an effective role in attenuating an oxidative stress and increasing a membrane fluidity in liver membranes.

• Analytical Science and Technology
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• v.28 no.2
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• pp.125-131
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• 2015

A method was developed and fully validated for the determination of terbutaline, a β₂-receptor agonist, in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak silica, followed by high-performance liquid chromatography (HPLC). The terbutaline was pre-separated from the interfering components in plasma on a Luna C18 (2) column, and terbutaline and salbutamol as an internal standard were resolved and determined on a Luna Silica column. The two columns were connected by a switching valve equipped with silica pre-column. The pre-column was used to concentrate the terbutaline in the eluent from the C18 column before back-flushing onto the silica column with fluorescence detection at an excitation/emission wavelength of 276/306 nm. The method was shown to be specific by testing six different human plasma sources. Linearity was established for a concentration range of 0.4-20.0 ng/mL with a correlation coefficient of 0.9999. The lower limit of quantitation was 0.4 ng/mL with a precision of 10.1% as C.V.%.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.94-101
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• 2001

This study was intended to evaluate the relationship environmental condition and growth characteristics of seed treatment seed in direct sowing with different sowing date, and to suggest new cultivation model. The emergence percentage and hours were down as the delayed sowing date. Optimum sowing time was Sep. 10, and sowing must end before Sep. 20 for safety yield. When did sowing ended before Sep.20 in direct sowing cultivation, the seedling growth(SG) and No of roots of direct sowing seedling were larger than transplanting cultivation . At March 8 evaluated seedling, the SG of direct sowing seedling was higher than transplanting, and at Sep. 2(1 those were similar. The missing plant rate in transplanting cultivation was under 3 %, and that in direct sowing cultivation was about 13∼18%, and the extent were sever as delayed sowing date. The bulb fresh weight was decreased as delayed sowing, and those in direct sowing and transplanting cultivation were 230, 217g, respectively. The blot rate was high in direct sowing cultivation, and that was decreased as delayed sowing. The yield in direct sowing and transplanting cultivation were 5,134, 5,300kg, respectively, and those were decreased as delayed sowing. The average yield in early and medium-late maturity cultivars were 3,750, 4,908kg, respectively, and Sonic was highest yield in early maturity cultivars and Nongwoodego was highest in medium-late maturity cultivars. The emergence weed were 9 species as Loportea bulbifera Weddell and others, and Loported bulbifera Weddell, Digitaria violascens Link and Persicaria longiseta Kitagawa were dominant species in direct sowing cultivation with black hole vinyl mulching

• Analytical Science and Technology
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• v.30 no.5
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• pp.295-302
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• 2017

This study presents a method validation for extraction and quantitative analysis of levulinic acid in soy sacues using high performance liquid chromatograph-photodiode array detector (HPLC-PDA). The levulinic acid in samples were extracted with distilled water, and then purified with C18 Sep-Pak cartridge. The calibration curves showed good linearity (R > 0.999) in a relatively wide concentration range ($2.5-400{\mu}g/mL$). Mean recoveries and relative standard deviation (RSD) of levulinic acid spiked in soy sauce samples at different spiking levels ($2.5-400{\mu}g/mL$; 6 point). Recoveries were 87.58-97.26 % with RSD less than 15 %, and limit of detection (LOD) and limit of quantification (LOQ) were 0.64 and $1.64{\mu}g/mL$, respectively. According to monitoring result with the established method, levulinic acid was found in 43 of 59 domestic commercial soy sauces, soy sauce based sauces and seasoned meats. The contamination levels were 0.44-1.23 mg/mL for soy sauces, 0.03-0.83 mg/mL for soy sauce based sauces and 8.43-38.94 mg/mL for seasoned meats. The results indicated to be rapidly and accurately qualifying levulinic acid and can be used as a suitable quality control method for soy sauce and soy sauce related commodities.