Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NITROGEN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed1996

Aerobic treatment of a nitrogen-limited chemical process wastewater.

Nitrogen transformations and their effect on aerobic suspended growth treatment of an industrial wastewater were studied in three parallel bench-scale reactors operated at 5 degrees C at mean cell residence times (MCRT) of 15, 30, and 60 days. In normal process wastewater, the bulk of influent nitrogen was in organic form, and the fraction transformed was almost totally incorporated into synthesized biomass. Assimilative control by heterotrophs maintained ammonia-nitrogen levels below permitted effluent levels, and nitrification was not significant. Although volatile suspended solids had a nitrogen content of only 5% to 8%, effective organics removal was maintained, and total organic carbon and filtered daily average five-day biochemical oxygen demand (BOD5) were below permitted effluent levels. A marked improvement in settleability and lower effluent total suspended solids was achieved by adding ammonia-nitrogen to the wastewater in excess of stoichiometric growth requirements. During a batch production cycle of a cationic chemical, the ratio of nitrogen to chemical oxygen demand and the fraction of the total influent nitrogen in soluble form increased in the wastewater. Reactor effluent ammonia levels increased to above permit levels at all three MCRTs during treatment of wastewater containing cationic production effluents. The magnitude of ammonia increase was greater for longer MCRTs, suggesting that synthesis of cell mass was not capable of assimilating the increased ammonia supply under these non-steady conditions. The experimental results suggest several potential strategies for operating the aerobic process at the treatment facility, including adding nitrogen to improve settleability and discontinuing these additions when wastewater contains a high ratio of nitrogen to chemical oxygen demand and an elevated soluble nitrogen fraction.

Aerobiosis↗
PubMed1984

[Nutrient digestibility and nitrogen utilization in lactating cows under restricted protein supply and subsequent refeeding].

The effects of a 17% deficiency of crude protein for four weeks on nutrient digestibility and parameters of N metabolism were investigated using four pairs of monozygotic twin cows. During a period of realimentation of three weeks with slight nutrient oversupply and a further period of three weeks with nutrient supply adjusted to the lactation trend it was examined if residual effects remain. Protein restriction enhanced the excretion of fecal dry matter by 7.7%. Total fecal nitrogen was a high in the restricted group as in the control group. Apparent digestion coefficients for dry matter, organic matter and N-free extracts were lowered by 2 to 3 percent points with deficient protein nutrition. Crude fiber and nitrogen digestibilities declined by 4.5 and 9.8 percent points, respectively. The reduction of urine nitrogen excretion amounted to 47% as consequence of a drastically diminished nitrogen content of urine. Total nitrogen retention (milk-N and body-N) was lowered by 14%. The sum of the relative nitrogen losses via faeces and urine was not different between the protein-deficient and the normal diet. The utilization of feed nitrogen for milk nitrogen excretion was 28.2% in protein deficiency and 25.9% in control feeding. After realimentation no relevant residual effects of the previous protein deficiency were found neither with respect to nutrient digestibility nor to parameters of the nitrogen balance. So far the observed permanent effect in reduced milk yield by 6% of the expected performance can not be explained with changes in digestibility or nitrogen balance.

Animals↗
PubMed1982

Nitrogen economy during very low calorie reducing diets: quality and quantity of dietary protein.

Controversy exists whether protein quantity or quality affect "nitrogen sparing" or physical health while subsisting on very low calorie diets. Therefore, in 38 obese men, nitrogen economy was evaluated over 2 months periods using one of five regimens: 1) 400 kcal high quality protein: 2) 400 kcal low quality protein; 3) 500 kcal 55 g protein natural food; 4) total fasting with potassium; and 5) total fasting without potassium. Up to the 20- and 40-day intervals, mean cumulative nitrogen deficity for all three diet groups was the same but 60% lower than with total fasting. However, within groups, individual capability to conserve nitrogen varied over as much as 2.8-fold. All 10 subjects of diet groups 1 and 2 had negative nitrogen balances to day 21, and six of these subjects were still negative by day 40. The improvement in nitrogen conservation and the ability to attain nitrogen equilibrium was unrelated to the differences in protein quantity and quality. Intake of essential or branched-chain amino acids was also unrelated to the efficiency of nitrogen conservation, as were insulin, glucagon, and 3-hydroxybutyrate levels. The only indicator correlating positively with nitrogen deficit was a fall in complement C3 (r = 0.87). Despite the extent of overall nitrogen loss, no cardiac arrhythmias were observed with either the high or low quality protein diet.

Adult↗
PubMed2002

Nitrogen balance of healthy Dutch women before and during pregnancy.

BACKGROUND: Experimental studies including longitudinal nitrogen balance studies could provide insight into protein metabolism in pregnancy. OBJECTIVE: Our aim was to determine the development of nitrogen balance during pregnancy compared with nitrogen balance before pregnancy in women consuming imposed constant diets. We also tracked changes in muscle mass and lean body mass by measuring urinary 3-methylhistidine (3-MeH) and urinary creatinine. DESIGN: Nitrogen balance was determined over 8 d in 12 healthy Dutch women before pregnancy and at weeks 12, 23, and 34 of gestation. Complete daily diets were supplied during each balance period so that each subject's energy, protein, and macronutrient intakes were similar in amount and composition in all 4 balance periods. RESULTS: Throughout pregnancy there was no significant change in loss of nitrogen in feces and therefore no change in protein digestibility. The amount of nitrogen excreted in urine in late pregnancy (11.0 +/- 1.4 g/d) was significantly (P < 0.01) less than in early pregnancy (12.6 +/- 1.3 g/d). Nitrogen retention increased toward term, even though energy balance became progressively negative. The difference between the first (-0.4 +/- 1.7 g N/d) and third (1.2 +/- 1.6 g N/d) trimester was significant (P < 0.05). No differences were found in either 3-MeH or creatinine excretion between trimesters. CONCLUSIONS: These urinary nitrogen excretion and nitrogen retention data show that when the dietary supply remains constant, nitrogen balance increases toward the end of pregnancy, suggesting a more efficient use of dietary protein later in pregnancy. Urinary 3-MeH and creatinine excretion indicated no change in protein metabolism.

Adaptation, Physiological↗
PubMed1998

Production of nitrogen dioxide in a delivery system for inhalation of nitric oxide: a new equation for calculation.

We have evaluated the kinetics of nitrogen dioxide production in a system for inhalation of nitric oxide. In addition to a small fraction of contamination of nitrogen dioxide in the nitric oxide stock gas, a considerable part of the total concentration of nitrogen dioxide is formed immediately after mixing of nitric oxide and oxygen. This initial build-up of nitrogen dioxide is followed by a linear, time-dependent increase in the concentration of nitrogen dioxide. An equation describing the concentration of nitrogen dioxide in the delivery system is formulated: [NO2] = kA x [NO] + kB x [NO]2 x [O2] + kC x t x [NO]2 x [O2], where nitrogen dioxide [NO2] and nitric oxide [NO] concentrations are in parts per million (ppm), oxygen concentration [O2] is expressed as a percentage and contact time (t) is in seconds. The rate constants are kA = 5.12 x 10(-3), kB = 1.41 x 10(-6) and kC = 0.86 x 10(-6). Calculated nitrogen dioxide values correlated well with measured concentrations. This new finding of an initial build-up of nitrogen dioxide has to be taken into consideration if the conversion of nitric oxide to nitrogen dioxide is to be calculated and in the safety guidelines for the use of nitric oxide.

Administration, Inhalation↗
PubMed1976

Some factors affecting the nitrogen sparing action of methionine and threonine in rats fed a protein free diet.

It was previously reported that methionine and threonine supplementation of a protein free diet had a greater nitrogen sparing action than methionine supplementation alone. Investigated in this study were (1) effects of depletion of labile body protein on the nitrogen sparing action of methionine and threonine supplementation of a protein free diet, (2) the effects of graded levels of methionine and threonine on urinary nitrogen excretion, (3) the effect of supplementation of other amino acids to the protein free diet plus methionine and threonine on the urinary excretion of nitrogen and (4) sex differences in the nitrogen sparing action of methionine and threonine supplementation of a protein free diet. After 10 days of feeding a protein free diet to deplete the body labile proteins, nitrogen excretion in urine of female rats was significantly reduced within the first 2 days of feeding a protein free diet supplemented with methionine and threonine. After 7 days of feeding a protein free diet supplemented with methionine and threonine, nitrogen excretion was reduced when even as little as 0.0188% of each amino acid was added. The supplementation of all essential amino acids to the protein free diet did not reduce the urinary excretion of nitrogen further than the supplementation of methionine and threonine, but improved the nitrogen balance slightly. The excretion of urinary nitrogen by female rats fed the protein free diet supplemented with small amounts (0.0188%) of methionine and threonine was significantly reduced after 7 to 14 days of feeding. In males, small amounts of methionine and threonine had no significant effect at either 7 or 14 days.

Amino Acids↗
PubMed2001

Nitrogen at raised pressure interacts with the GABA(A) receptor to produce its narcotic pharmacological effect in the rat.

BACKGROUND: Strong evidence supports the concept that conventional anesthetics, including inhalational agents and inert gases, such as xenon and nitrous oxide, interact directly with ion channel neurotransmitter receptors. However, there is no evidence that nitrogen, which only exhibits narcotic potency at increased pressure, may act by a similar mechanism. METHODS: We compared the inhibitory and sedative effects of gamma-aminobutyric acid (GABA) and nitrogen pressure on locomotor activity and striatal dopamine release in freely moving rats and investigated the pharmacologic properties of the GABA-induced and nitrogen pressure-induced narcotic action using the highly selective competitive GABA(A) receptor antagonist bicuculine. RESULTS: Intracerebroventricular GABA infusion up to 60 micromol or exposure to nitrogen pressure up to 3 MPa decreased to a similar extent striatal dopamine release (r2= 0.899, df = 4, P < 0.01) and locomotor activity (r2 = 0.996, df = 28, P < 0.001). However, both agents only showed small effects on striatal dopamine release, reducing dopamine currents by only 12-13% at sedative concentrations. Pretreatment with bicuculline at 0.5, 1, and 2.5 pmol reduced the sedative action of GABA on locomotor activity by 10, 20, and 41%, respectively. Bicuculline in the nanomole range at 1, 2.5, and 5 nmol but not in the picomole range reduced the sedative action of nitrogen pressure by 5, 37, and 73%, respectively. Schild plot analysis is consistent with the fact that bicuculline is a competitive antagonist of both GABA and nitrogen at pressure. CONCLUSIONS: These results suggest (1) that the presynaptic effects of both GABA and nitrogen pressure on striatal dopamine transmission are modest and not mainly involved in their sedative action and (2) that nitrogen at increased pressure may interact directly with the GABA(A) receptor. However, because the antagonistic effect of bicuculline on nitrogen sedation only occurred at much higher bicuculline concentrations than seen with GABA, it is suggested that nitrogen does not compete for the same site as GABA.

Air Pressure↗
PubMed2001

Estimation of leaf nitrogen content from spectral characteristics of rice canopy.

Ground-based remotely sensed reflectance spectra of hyperspectral resolution were monitored during the growing period of rice under various nitrogen application rates. It was found that reflectance spectrum of rice canopy changed in both wavelength and reflectance as the plants developed. Fifteen characteristic wavebands were identified from the apparent peaks and valleys of spectral reflectance curves, in accordance with the results of the first-order differentiation, measured over the growing season of rice. The bandwidths and center wavelengths of these characteristic wavebands were different among nitrogen treatments. The simplified features by connecting these 15 characteristic wavelengths may be considered as spectral signatures of rice canopy, but spectral signatures varied with developmental age and nitrogen application rates. Among these characteristic wavebands, the changes of the wavelength in band 11 showed a positive linear relationship with application rates of nitrogen fertilizer, while it was a negative linear relationship in band 5. Mean reflectance of wavelengths in bands 1, 2, 3, 5, 11, and 15 was significantly correlated with application rates. Reflectance of these six wavelengths changed nonlinearly after transplanting and could be used in combination to distinguish rice plants subjected to different nitrogen application rates. From the correlation analyses, there are a variety of correlation coefficients for spectral reflectance to leaf nitrogen content in the range of 350-2400 nm. Reflectance of most wavelengths exhibited an inverse correlation with leaf nitrogen content, with the largest negative value (r = -0.581) located at about 1376 nm. Changes in reflectance at 1376 nm to leaf nitrogen content during the growing period were closely related and were best fitted to a nonlinear function. This relationship may be used to estimate and to monitor nitrogen content of rice leaves during rice growth. Reflectance of red light minimum and near-infrared peak and leaf nitrogen content were correlated nonlinearly.

Agriculture↗
PubMed2004

Regulation of GlnK activity: modification, membrane sequestration and proteolysis as regulatory principles in the network of nitrogen control in Corynebacterium glutamicum.

P(II)-type signal transduction proteins play a central role in nitrogen regulation in many bacteria. In response to the intracellular nitrogen status, these proteins are rendered in their function and interaction with other proteins by modification/demodification events, e.g. by phosphorylation or uridylylation. In this study, we show that GlnK, the only P(II)-type protein in Corynebacterium glutamicum, is adenylylated in response to nitrogen starvation and deadenylylated when the nitrogen supply improves again. Both processes depend on the GlnD protein. As shown by mutant analyses, the modifying activity of this enzyme is located in the N-terminal part of the enzyme, while demodification depends on its C-terminal domain. Besides its modification status, the GlnK protein changes its intracellular localization in response to changes of the cellular nitrogen supply. While it is present in the cytoplasm during nitrogen starvation, the GlnK protein is sequestered to the cytoplasmic membrane in response to an ammonium pulse following a nitrogen starvation period. About 2-5% of the GlnK pool is located at the cytoplasmic membrane after ammonium addition. GlnK binding to the cytoplasmic membrane depends on the ammonium transporter AmtB, which is encoded in the same transcriptional unit as GlnK and GlnD, the amtB-glnK-glnD operon. In contrast, the structurally related methylammonium/ammonium permease AmtA does not bind GlnK. The membrane-bound GlnK protein is stable, most likely to inactivate AmtB-dependent ammonium transport in order to prevent a detrimental futile cycle under post-starvation ammonium-rich conditions, while the majority of GlnK is degraded within 2-4 min. Proteolysis in the transition period from nitrogen starvation to nitrogen-rich growth seems to be specific for GlnK; other proteins of the nitrogen metabolism, such as glutamine synthetase, or proteins unrelated to ammonium assimilation, such as enolase and ATP synthase subunit F(1)beta, are stable under these conditions. Our analyses of different mutant strains have shown that at least three different proteases influence the degradation of GlnK, namely FtsH, the ClpCP and the ClpXP protease complex.

Amino Acid Sequence↗
PubMed2001

Ecological aspects of ntcA gene expression and its use as an indicator of the nitrogen status of marine Synechococcus spp.

Nitrogen nutrition in cyanobacteria is regulated by NtcA, a transcriptional activator that is subject to negative control by ammonium. Using Synechococcus sp. strain WH7803 as a model organism, we show that ntcA expression was induced when cells were exposed to nitrogen stress but not when they were subjected to phosphorus or iron deprivation. Transcript levels accumulated in cells grown on a variety of inorganic and organic nitrogen sources, with the sole exception of ammonium. ntcA transcription was induced when ammonium levels dropped below 1 microM and reached maximal levels within 2 h. Furthermore, the addition of more than 1 microM ammonium led to a rapid decline in ntcA mRNA. The negative effect of ammonium was prevented by the addition of L-methionine-D,L-sulfoximine (MSX) and azaserine, inhibitors of ammonium assimilation. Thus, basal ntcA transcript levels are indicative of ammonium utilization. Conversely, the highest ntcA transcript levels were found in cells lacking a nitrogen source capable of supporting growth. Therefore, maximal ntcA expression would indicate nitrogen deprivation. This state of nitrogen deprivation was induced by a 1-h incubation with MSX. The rapid response of ntcA gene expression to the addition of ammonium and MSX was used to design a protocol for assessing relative ntcA transcript levels in field populations of cyanobacteria, from which their nitrogen status can be inferred. ntcA was basally expressed in Synechococcus at a nutrient-enriched site at the northern tip of the Gulf of Aqaba, Red Sea. Therefore, these cyanobacteria were not nitrogen stressed, and their nitrogen requirements were met by regenerated nitrogen in the form of ammonium.

Bacterial Proteins↗
PubMed2006

Alanine dehydrogenase activity is required for adequate progression of phycobilisome degradation during nitrogen starvation in Synechococcus elongatus PCC 7942.

Degradation of the cyanobacterial light-harvesting antenna, the phycobilisome, is a general acclimation response that is observed under various stress conditions. In this study we identified a novel mutant of Synechococcus elongatus PCC 7942 that exhibits impaired phycobilisome degradation specifically during nitrogen starvation, unlike previously described mutants, which exhibit aberrant degradation under nitrogen, sulfur, and phosphorus starvation conditions. The phenotype of the new mutant, AldOmega, results from inactivation of ald (encoding alanine dehydrogenase). AldOmega is deficient in transcription induction of a number of genes during nitrogen starvation. These genes include the "general nutrient stress-related" genes, nblA and nblC, the products of which are essential for phycobilisome degradation. Furthermore, transcripts of several specific nitrogen-responsive genes accumulate at lower levels in AldOmega than in the wild-type strain. In contrast, ald inactivation did not decrease the accumulation of transcripts during sulfur starvation. Transcription of ald is induced upon nitrogen starvation, which is consistent with the ability of wild-type cells to maintain a low cellular content of alanine under these conditions. Unlike wild-type cells, AldOmega accumulates alanine upon nitrogen starvation. Our analyses suggest that alanine dehydrogenase activity is necessary for an adequate cellular response to nitrogen starvation. Decomposition of alanine may be required to provide a sufficient amount of ammonia. Furthermore, the accumulated alanine, or a related metabolite, may interfere with the cues that modulate acclimation during nitrogen starvation. Taken together, our results provide novel information regarding cellular responses to nitrogen starvation and suggest that mechanisms related to nitrogen-specific responses are involved in modulation of a general acclimation process.

Alanine Dehydrogenase↗
PubMed1999

Control of nitrogen catabolite repression is not affected by the tRNAGln-CUU mutation, which results in constitutive pseudohyphal growth of Saccharomyces cerevisiae.

Saccharomyces cerevisiae responds to nitrogen availability in several ways. (i) The cell is able to distinguish good nitrogen sources from poor ones through a process designated nitrogen catabolite repression (NCR). Good and poor nitrogen sources do not demonstrably affect the cell cycle other than to influence the cell's doubling time. (ii) Nitrogen starvation promotes the initiation of sporulation and pseudohyphal growth. (iii) Nitrogen starvation strongly affects the cell cycle; nitrogen-starved cells arrest in G1. A specific allele of the SUP70/CDC65 tRNAGln gene (sup70-65) has been reported to be defective in nitrogen signaling associated with pseudohyphal formation, sporulation, and NCR. Our data confirm that pseudohyphal growth occurs gratuitously in sup70-65 mutants cultured in nitrogen-rich medium at 30 degrees C. However, we find neither any defect in NCR in the sup70-65 mutant nor any alteration in the control of YVH1 expression, which has been previously shown to be specifically induced by nitrogen starvation.

Gene Expression Regulation, Fungal↗
PubMed1991

Phenylacetylglutamine may replace urea as a vehicle for waste nitrogen excretion.

Phenylacetylglutamine (PAG), the amino acid acetylation product of phenylacetate (or phenylbutyrate after beta-oxidation) was evaluated as a waste nitrogen product in patients with inborn errors of urea synthesis. A boy with carbamyl phosphate synthetase deficiency receiving a low nitrogen intake excreted 80-90% of administered phenylacetate or phenylbutyrate as PAG. The amount of PAG nitrogen excreted varied from 38-44% of his dietary nitrogen, similar to the relationship between urea nitrogen and dietary nitrogen found in normal subjects receiving low dietary nitrogen. With few exceptions, neither phenylacetate nor phenylbutyrate accumulated in plasma. Treatment with relatively high dose phenylacetate or phenylbutyrate (0.5-0.6 g/kg/d) resulted in normal daytime levels of glutamine. These data suggest that PAG may replace urea as a waste nitrogen product when phenylbutyrate is administered at a dose that yields PAG nitrogen excretion equal to 40-44% of a low nitrogen intake.

Adolescent↗
PubMed1982

Branched chain amino acids as a major source of alanine nitrogen in man.

In vitro perfusion and incubation studies and recent investigations in dogs suggest that branched chain amino acids (BCAA) may be a major source of alanine nitrogen. To determine the contribution of BCAA nitrogen to the formation of alanine in man, seven postabsorptive adults received prime-dose constant infusions of 15N-leucine, L-[6,6,6-2H3] leucine, and L-[2,3,3,3-2H4] alanine; isotopic enrichment was determined in arterialized venous plasma samples by gas chromatography-mass spectroscopy. At substrate and isotope steady state, alanine flux and the rate of 15N alanine appearance were 5.4 +/- 0.3 mumol/kg-min and 32 +/- 2 nmol/kg.min, respectively. Leucine nitrogen flux was significantly greater than that of leucine carbon flux (2.54 +/- 0.25 vs. 1.90 +/- 0.10 mumol/kg.min, respectively; P less than 0.001). The 30% greater flux of leucine nitrogen when compared with leucine carbon suggests significant recycling of the leucine carbon in vivo. The percent of circulating alanine nitrogen derived from leucine was 12.5 +/- 1.5%; however, the rate of leucine nitrogen transferred to alanine was 0.66 +/- 0.05 mumol/kg.min, and represents a minimum of 28% of leucine nitrogen going to alanine. On the basis of these data, together with the percent of alanine and leucine in body protein, only 40% of circulating plasma alanine could come from endogenous protein, whereas 60% is derived from de novo synthesis. In addition, at least 20% of the nitrogen required for alanine synthesis is derived solely from leucine following an overnight fast. Therefore, if the contribution of isoleucine and valine nitrogen is similar to that of leucine, the BCAA may contribute to a minimum of 60% of the nitrogen required for alanine synthesis in postabsorptive man.

Adult↗
PubMed1976

Metabolic acidosis, nitrogen balance and weight gain in preterm infants.

Nitrogen balance, urinary NAE and the acid base parameters in the blood of 15 male preterm infants with birth weights of 1000--2370 g (mean 1715 g) and gestational age of 29--37 weeks (mean 33.3 weeks) were determined weekly, in the first six weeks of life. The sum of NAE plus acid retention, as "total acid", was used to investigate the relationship between nitrogen balance, weight gain and acid-base homeostasis. During the first three postnatal weeks, nitrogen intake, urinary and faecal loss of nitrogen as well as the nitrogen retention were rapidly increasing. Later, urinary excretion continued to rise, the intake remained unchanged and as a result, the amount of retained nitrogen decreased slightly. Urinary NAE was steadily increasing to reach the maximum of 2.8 mEq/kg by the fourth week. Acid retention was the most pronounced in the second and third week, thereafter it fell until the end of the study. The importance of NAE relative to acid retention was continuously increasing throughout the observation period. The "total acid" increased gradually and reached its peak value in the third week of life. Subsequently a continuous fall was seen. During the first three weeks of life there was a significant positive correlation between "total acid" and nitrogen intake and urinary nitrogen extraction. Since the increase in "total acid" went parallel with the increasing nitrogen retention, the latter may be assumed to be an additional factor in producing acidosis. Calculated per 100 mg nitrogen ingested, retained or excreted with urine, "total acid" was decreasing with the increasing rate of weight gain. This indicates that the growth process -- irrespective of the postnatal development of renal H+ handling -- is also involved in the elimination of acids.

Acidosis↗
PubMed2002

[Characteristics of nitrogen loss from sloping field in red soil area under different cultivation practices].

The characteristics of nitrogen loss under six types of cultivation practices were studied in Lanxi Water and Soil Conservation Supervision Station of Zhejiang Province. The results showed that compared with the traditional cultivation practice (treatment 5, straight farming), the other cultivation practices including grass strip, contour ditch, contour farming, contour dam, and fallow decreased soil nitrogen loss significantly, and the percentages of nitrogen loss under the 5 types of cultivation practices decreased by 43.46%, 46.55%, 71.36%, 77.05%, and 87.92%, respectively. Soil nitrogen lost mainly with runoff, and it accounted for 81.9-93.4% of total soil nitrogen loss. Dissolved nitrogen was the major form of lost nitrogen and accounted for 78-87.6% of total lost nitrogen in runoff. Nitrogen loss was occurred mainly during May to August, and it accounted for 85-100% of total annual nitrogen loss.

Agriculture↗
PubMed2004

[Study on distribution of nitrogen compounds in catalytic diesel oil by gas chromatography-atomic emission detector].

The method for the separation and determination of nitrogen compounds in a typical catalytic diesel oil by gas chromatography-atomic emission detector (GC-AED) was established. Seventy-three nitrogen compounds (including aniline, alkyl anilines, quinoline, indole, alkyl indole, carbazole, alkyl carbazole) in the catalytic diesel oil were qualified based on the retention times of some pure nitrogen compounds and the retention indices of nitrogen compounds. Effects of pressures of various reagent gases on peak area of main nitrogen compounds in diesel oil were examined as well. The pressures of reagent gases were optimized. Retention indices of different nitrogen compounds under temperature programmed condition were calculated. Reproducibilities of peak areas of main nitrogen compounds in the catalytic diesel oil were no more than 8.0%. The detection limit for nitrogen was 1.0 mg/L under specific conditions. The linear range was 2.0 - 600 mg/L for each nitrogen compound and correlation coefficient was greater than 0.998. The method can be successfully applied in the determination of nitrogen compounds in different catalytic diesel oils.

Aniline Compounds↗
PubMed2005

[Investigation on the nitrogen functionality of volatile through FTIR spectroscopy equipped with a long path distance gas cell].

Nitrogen functionalities of volatile of three different rank coals, namely TONGCHUAN lean coal, SHENMO bituminite and YIBIN anthracite, were studied by using Fourier transform infrared spectroscopy (FTIR) equipped with 16 m long path distance gas cell. The detection problem of low content of nitrogen in volatile was successfully solved because of the application of the long path distance gas cell. In the long path distance gas cell, the infrared penetrates the sample more times than in a normal gas cell. Results from the analysis of spectra obtained by FTIR show that there are four functionalities of nitrogen in volatile, including pyrrole-type nitrogen, pyrindine-type nitrogen, pyridine-N-oxide nitrogen, and nitrile nitrogen. Comparison of research results of nitrogen group between coal and volatile suggests that the difference in fate of nitrogen between volatile and coal results from the macromolecular nitrogen group of coal decomposition under the effect of temperature.

Coal↗