• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.1
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• pp.65-73
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• 2011

The fibrous raw materials in packaging-grade paper production in Korea were mainly obtained from waste paper. The use of recycled paper has both positive and negative impacts in papermaking process. The primary positive impacts are the environmental protection and manufacturing cost reduction, and the negative impacts are the quality reduction in paper quality and the accumulation of heavy metals and other pollutants in wet- and dry-end process. This study was carried out to consider the optimum acid decomposition system with the highest recovery rate for the analysis of heavy metals in packaging-grade paper. The open digestion system using Kjeldahl apparatus and the closed digestion system using microwave oven for decomposing the organic materials in paper were compared. In both open and closed digestion method, the combination of nitric acid, hydrochloric acid and hydrogen peroxide showed higher recovery rate than using only nitric acid alone because the presence of Cl- ions in hydrochloric acid stabilizes ligand formation with metal ions. KOCC was observed to have the highest heavy metal content among the recycled paper samples. The heavy metal contents decomposed with the closed digestion system were relatively higher than with open digestion system.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.239-244
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• 1997

To develope more effective extraction methods for paraquat in soil, some modification methods were accomplished in two different types of soil. For extraction of tightly bound-paraquat, conc. HCl 70ml were added with different shaking times, and then $H_2SO_4$ reflux were performed for an hour. In this case, 60 minutes shaking were optimum and recovery were increased more $1.09{\sim}1.50$ folds(84.0% in high clay contents soil, but 96.7% in low clay contents soil) and the long-time consuming step, filtration were easily done, with decreasing filtration time were shorter 4.6 folds(ca. $11{\sim}14min.$). than general paraquat analytical method(ca. $55{\sim}65min.$). And only $H_2O_2$ digestion with different volume and refluxing time resulted in recovery increasing. Nevertheless, considering analyst's safety, 30ml of $H_2O_2$ addition and 30 minutes reflux were regarded as optimum condition. Although, Kjeldahl digestion with $H_2O_2$ showed relatively high recovery, it is not significant statistically. For extraction of loosely bound-paraquat, 0.01, 0.1, 1.0, 10.0M of $NH_4Cl$ and of $CaCl_2$ compared with $1.5{\sim}24hr$ of different shaking time. There were no loosely bound residues of paraquat.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.93-99
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• 2017

Analysis of mineral nutrients in plant is required for evaluating diagnosis of plant nutritional status. Pretreatment procedure for the analysis of plant can be varied depending on elements to be analyzed. Wet-digestion is suitable for total nitrogen, phosphate and cations, however, digestion solution including nitric acid is not suitable for nitrogen analysis. Incineration procedure is required to analyze chloride, silicate and total sulfur. After digestion, total nitrogen is analyzed by Kjeldahl method, and phosphate is detected at 470nm by colorimetric analysis with ammonium meta vanadate. Cations and micro elements are determined by titration or colorimetry, also, these elements can be measured by Atomic absorption spectrometer (AAS) or Inductively coupled plasma spectrometer (ICP).

• Korean Journal of Poultry Science
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• v.28 no.3
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• pp.215-224
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• 2001

Since nitrogen(N) is a volatile compound affected by many environmental factors, determining the N content of manure tends to be difficult. Upon arrival in the laboratory, the manure should be moist and refrigerated. Manure samples will have variable N contents due to drying temperature, and the presence of soil in the sample will affect N content. Acidification of the sample prevents ammonia volatilization and should be done before drying. It is recommended that manure samples be pretreated with a strong oxidizing agent, KMnO$_4$, followed by digestion under reduced conditions (reduced Fe-$H_{2}$ $SO_{4}$ ), which achieves a complete recovery of both $NO_{3}$ -N and $NO_{2}$ -N without a low recovery of $NH_{4}$ -N, resulting in a more accurate determination of N content. Accuracy of results for N content determined by recently developed rapid analysis techniques in the field should be tested by comparison with results obtained at laboratories using approved standard methods. Most commonly, the Kjeldahl system is used to determine manure N content. More research is needed on the effects of species, breed, age and individuals on the nutrient contents of manure. The procedures for manure sampling on the farm, shipping and handling of the sample until it reaches the laboratory, and the methods of sampling of the manure at the laboratory must be studied. Development of animal agricultural laboratories where feed, manure, soil, and water are all analyzed by appropriate specialists is needed.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.147-152
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• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.223-226
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• 2012

Liquid livestock manure (LLM) has been used as a nitrogen fertilizer source for horticulture plants. LLM contains organic nitrogen (N), ammonium, nitrate, and nitrite. The amount of nitrate and nitrite in LLM are usually small compared to the amount of ammonium in it and so they can be negligible if total nitrogen (N) concentration in LLM is higher than $1,000mg\;L^{-1}$. However, if total N concentration in LLM is less than $1,000mg\;L^{-1}$, the amount of nitrate and nitrite may affect total N concentration in LLM. Currently, Kjeldahl digestion method is mainly used for ammonium-N in LLM. Therefore, it is ineffective to analyze nitrate-N and nitrite-N. The objective of this study was to evaluate whether the total N concentrations are affected by the amount of nitrate-N and nitrite-N with diverse LLMs by Kjeldahl method (with and without Devarda's alloy after Conc. sulfuric acid digestion). Five liquid livestock manure samples were collected at swine farms in Ansung and Icheon. All LLM samples were stored at $25^{\circ}C$, subsampled at every $15^{th}$ day for 90 days, and analyzed for total N, ammonium-N, and nitrate-N. At the $90^{th}$ day, LLM samples were analyzed with and without Devarda's alloy after Conc. sulfuric acid digestion. Potassium nitrate, ammonium nitrate, and ammonium chloride were used to determine the N recovery percentages. Total N concentration ranged from 560 to $4,230mg\;L^{-1}$. Nitrate-Ns were found in all LLM samples, ranged from 21 to $164mg\;L^{-1}$. N recovery percentages with potassium nitrate were 0 % without Devarda's alloy and 100% with Devarda's alloy because adding Devarda's alloy facilitated nitrate-N into ammonium-N conversion. Total Ns were significantly different between two methods, with and without Devarda's alloy. Total N concentrations were $210mg\;L^{-1}$ at LLM 4 and $370mg\;L^{-1}$ at LLM 5 without Devarda's alloy and $290mg\;L^{-1}$ at LLM 4 and $490mg\;L^{-1}$ at LLM 5 with Devarda's alloy. These results suggest that if total N of LLM is less $1,000mg\;L^{-1}$, additional procedure such as adding Devarda's alloy can be used to estimate the total N and inorganic N better.

• Animal Bioscience
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• v.35 no.2
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• pp.260-271
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• 2022

Objective: We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations. Methods: Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3×2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by enzyme-linked immunosorbent assay kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting. Results: Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the casein (CAS) and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05). Conclusion: We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.