Determination Of Total Nitrogen Content Research Articles

Protein Determination in some Animal Products from Sulaymaniyah Markets Using Kjeldahl Procedure

In this study, the crude protein of animal product samples was measured through determination of total nitrogen content using the Kjeldahl method. Measurement of total nitrogen by Kjeldahl procedure is the universal reference method for estimation of protein content in animal and plant products and is used for both calibration and validation of alternative methods in protein determination. The animal protein sources analysed in this study were samples of veal meat, chicken meat, egg and beef hot dog. Based on the results found in this research, the sequence of protein content in the samples was: chicken breast> fresh silverside > fresh thigh > frozen silverside > egg-yolk > beef hot dog > egg-albumin. We also concluded that the health claim of protein percentage that declared on the can of beef hot dog, as well the results of egg-albumin and fresh thigh chicken showed no significance differ compared to the standards.

Determination of total nitrogen content in fresh leaves and leaf powder of Dendrobium orchids using near-infrared spectroscopy

Appropriate application of nitrogen (N) fertilizer promotes plant growth, inflorescence yield, and flower quality of orchids. In this study, we used the near-infrared spectroscopy (NIRS) technique to develop a prediction model of the N content in the leaf of Dendrobium orchid, which is an essential indicator for monitoring plant health. The Dendrobium orchid samples were foliar sprayed in rotation between 20N–20P–20K and 30N–10P–10K fertilizers at a frequency of once or twice a week to create a diverse amount of leaf N content. An application of water was used as the control treatment. After nine months of fertilizer treatments, 150 fresh orchid leaf samples, containing various N contents, were scanned using Fourier-transform near-infrared spectroscopy (FT-NIRS). Then the samples were dried and ground to a fine powder and were again scanned. The absorbance spectra were collected at the 12,000–4000 cm−1 (800–2500 nm) region. Total N content was determined by using the combustion method. The result showed a high proficiency in the estimation of N in leaf powder with the correlation coefficient of prediction (Rp), the root mean square error of prediction (RMSEP), and the ratio of standard deviation of reference data of prediction set to standard error of prediction (RPD) being 0.9882, 0.0637% dry weight (DW), and 6.53, respectively. The fresh leaf sample was successfully predicted with Rp, RMSEP, and RPD of 0.8874, 0.207% DW, and 2.13, respectively. Additionally, external validation confirmed the high reliability of using leaf powder since the correlation coefficient of external validation (rp) and RMSEP of the external validation achieved 0.9651 and 0.1405% DW, respectively, while the external validation of fresh leaf should be improved with rp = 0.7438 and RMSEP = 0.2652% DW. The overall results suggested that NIRS can be used for monitoring the N status in orchids, especially in leaf powder, with high accuracy.

Pemanfaatan Limbah Kulit Pisang Sebagai Pupuk Organik Cair dan Aplikasinya Terhadap Pertumbuhan Tanaman Kangkung Darat (Ipomea Reptans Poir)

Banana peel waste utilization as organic manure and its application has been made to the land kale plant growth (Ipomea reptans Poir). This paper aims to describe how to manufacture liquid organic fertilizer from the waste banana skin, determine the total nitrogen content of liquid organic fertilizer and the effect of liquid organic fertilizer waste banana skin on plant growth kale land (Ipomea reptans Poir). The method used was experimental at the stage of making a liquid organic fertilizer waste banana peel in fermentation, the determination of total nitrogen content and the application of the organic liquid fertilizer waste banana skin using a randomized block design (RBD) with 4 treatments include P0 (0 mL); P1 (20 mL); P2 (40 mL); and P3 (60 mL).The parameters measured were plant height (cm), the number of leaves (leaf) and wet weight (g). The growth data of the swamp cabbage land (Ipomea reptans poir) were analyzed by using the statistical test analysis of variance (ANOVA) then followed by Duncan test with significance level of 5%. The results showed that levels of total nitrogen of the organic liquid fertilizer waste was 0.032% and the application of the organic liquid fertilizer of banana peel waste on the growth of swamp cabbange land (Ipomea reptans poir) influence on plant height (cm) and wet weight (g) but have no effect on the number of leaves (leaf). Treatment P2 (40 mL) showed the best result for the average plant height (cm), the number of leaves (leaf) and wet weight (g) of the swamp cabbage land (Ipomea reptans poir).

Rapid detection of total nitrogen content in soy sauce using NIR spectroscopy

Xu J., Huang F., Li Y., Chen Z., Wang Y. (2015): Rapid detection of total nitrogen content in soy sauce using NIR spectroscopy. Czech J. Food Sci., 33: 518–522. A method for the rapid and nondestructive determination of total nitrogen content in soy sauce was explored. Pre diction models were established using near-infrared spectroscopy combined with each of the following techniques: partial least squares (PLS), interval PLS, synergy interval PLS (siPLS), and backward interval PLS. Results showed that each improved forecast model was better than the PLS model. The siPLS method exhibited the best performance. The full spectrum of light soy sauce was divided into 20 subintervals. The combination of four subintervals, namely, 6, 11, 13, and 18, showed the best effect, with a correlation coefficient of 0.9977 and an RMSECV of 0.0198. The full spectrum of dark soy sauce was divided into 20 subintervals. The combination of three subintervals, namely, 14, 17, and 19, showed the best effect, with a correlation coefficient of 0.9818 and an RMSECV of 0.0640. Therefore, the siPLS method can realise a rapid and accurate detection of total nitrogen content in soy sauce.

In house validation for the determination of total nitrogen content in fertilisers: developing criteria with uncertainty measurement evaluation and compliance assessment

In house validation using several different fertilizer types and two analytical methods for total nitrogen content determination with assessment of measurement uncertainty. Importance of decision of analytical methods and rules for compliance assessment.

Double-antibody based immunoassay for the detection of β-casein in bovine milk samples

The concentration of casein (CN) is one of the most important parameters for measuring the quality of bovine milk. Traditional approach to CN concentration determination is Kjeldahl, which is an indirect method for determination of total nitrogen content. Here, we described a double-antibody based direct immunoassay for the detection of β-CN in bovine milk samples. Monoclonal antibody (McAb) was used as capture antibody and polyclonal antibody (PcAb) labelled with horseradish peroxidase (HRP) as detection antibody. With the direct immunoassay format, the linear range of the detection was 0.1–10.0μgmL−1. The detection limit was 0.04μgmL−1. In addition, the concentration of β-CN in real bovine milk samples has been detected by the developed immunoassay. There was a good correlation between the results obtained by the developed technique and Kjeldahl method from commercial samples. Compared to the traditional approach, the advantage of the assay is no need of time-consuming sample pretreatment.

Determination of total nitrogen content by different approaches in petroleum matrices

Two analytical methods are developed and validated for determination of low total nitrogen levels (below 0.0150%) in different petroleum matrices. The experimental and the instrumental conditions are optimized during the study. The oxidative combustion method with chemiluminescence’s detection is automatic with less handling while the Kjeldahl method involves more manual handling procedures and hence, has more potential for problems rise from contamination. The oxidative combustion with chemiluminescence’s detection method is more sensitive, faster (i.e. the determination requires few minutes compared to several hours with Kjeldahl method) and lees hazardous (i.e. no handling of dangerous boiling sulfuric acid). The estimated analytical characteristics suggest that two methods are reliable: the mean values of recovery for the Kjeldahl method and the other method are respectively 91.5% and 98.6%. The relative uncertainties are less than 2.5% and 2.8% respectively for the developed methods. The detection limits, based on the triple standard deviation, are 5 and 0.03 mgN kg −1 respectively.

Use of Radial Basis Function Networks and Near-Infrared Spectroscopy for the Determination of Total Nitrogen Content in Soils from Sao Paulo State

Total nitrogen has been determined by using a model developed between the conventional chemical measurements and diffuse reflectance spectra in the near-infrared region. Samples (244) from different types of soils with total nitrogen contents ranging from 0.20 to 13.60% (m/m) were modeled by partial least-squares regression (PLS), multi-layer perceptron feed-forward networks (MLP) and radial basis function networks (RBFN). The RBFN model produced a better square error of prediction (SEP) of 0.048 and R(2) = 0.93 in a procedure that is simpler, faster and less dependent on the initial conditions.

Determination of total nitrogen content, pH, density, refractive index, and brix in Thai fish sauces and their classification by near-infrared spectroscopy with searching combination moving window partial least squares

Near-infrared (NIR) transflectance spectra in the region of 1100-2500 nm were measured for 100 Thai fish sauces. Quantitative analyses of total nitrogen (TN) content, pH, refractive index, density and brix in the Thai fish sauces and their qualitative analyses were carried out by multivariate analyses with the aid of wavelength interval selection method named searching combination moving window partial least squares (SCMWPLS). The optimized informative region for TN selected by SCMWPLS was the region of 2264-2428 nm. A PLS calibration model, which used this region, yielded the lowest root mean square error of prediction (RMSEP) of 0.100% w/v for the PLS factor of 5. This prediction result is significantly better than those obtained by using the whole spectral region or informative regions selected by moving window partial least squares regression (MWPLSR). As for pH, density, refractive index and brix, the 1698-1722, and 2222-2258 nm regions, the 1358-1438 nm region, the 1774-1846, and 2078-2114 nm regions, and the 1322-1442, and 2000-2076 nm regions were selected by SCMWPLS as the optimized regions. The best prediction results were always obtained by use of the optimized regions selected by SCMWPLS. The lowest RMSEP for pH, density, refractive index and brix were 0.170, 0.007 g cm(-3), 0.0079 and 0.435 degrees Brix, respectively. Qualitative models were developed by using four supervised pattern recognitions, linear discriminant analysis (LDA), factor analysis-linear discriminant analysis (FA-LDA), soft independent modeling of class analog (SIMCA), and K neareat neighbors (KNN) for the optimized combination of informative regions of the NIR spectra of fish sauces to classify fish sauces into three groups based on TN. All the developed models can potentially classify the fish sauces with the correct classification rate of more than 82%, and the KNN classified model has the highest correct classification rate (95%). The present study has demonstrated that NIR spectroscopy combined with SCMWPLS is powerful for both the quantitative and qualitative analyses of Thai fish sauces.

Kjeldahl Method for Determination of Total Nitrogen Content of Milk: Collaborative Study

Abstract A macro-KJeldahl procedure using a copper catalyst for determination of milk total nitrogen was developed for both traditional and block dlgestor/steam distiller equipment, and the performance was evaluated by collaborative study. In the first trial of the collaborative study, 9 pairs of blind duplicate milk samples were analyzed for total nitrogen and total nitrogen was converted to "protein" by using a factor of 6.38. Protein content of milk samples ranged from 3.086 to 3.610%. In the first trial, sR and R values for the block dlgestors were influenced significantly by protein concentration; 8R and R values were not Influenced by protein concentration for traditional equipment. It was hypothesized that total digestion time for some block dlgestors In the first trial was not sufficient for high protein milk samples. Thus, a second trial was undertaken with boiling time after clearing Increased by 0.5 h. In the second trial, none of the parameters for reproducibility with either type of equipment were Influenced by protein concentration. It was concluded that laboratory-to-laboratory differences In line voltage may require different total digestion times in different laboratories, particularly those using block dlgestors. The Kjeldahl method using a copper catalyst and either traditional or block digestor equipment for determination of milk total nitrogen has been adopted official first action by AOAC to replace method 920.105.