Variation In Total Content Research Articles

Heavy metal pollution status, spatial distribution and associated ecological risks within sediments of Yundang Lagoon catchment in Xiamen, China, after 30 years continuous ecological rehabilitation and management

This study aims to assess the pollution status and spatial distribution of heavy metals, including Chromium (Cr), Manganese (Mn), Nickel (Ni), Copper (Cu), Zinc (Zn), Arsenic (As), Cadmium (Cd), and Lead (Pb), in sediments from the Yundang Lagoon catchment, and to determine the risk from such metals and associated possible sources. Results show considerable spatial variations in total concentrations of heavy metals within sediment samples. The Geo-accumulation index indicates that sediment is not contaminated with Cr, Mn, Ni, and As, but moderate to high levels of Cu, Zn, Cd, and Pb are present. The potential ecological risk is low for Cr, Mn, Ni, Cu, Zn, As, and Pb, but Cd in lagoon sediments poses a considerable ecological risk to biota. A high positive correlation was found between Zn, Cu, and Cd (r > 0.8), while Zn, Cd, and Cu (r > 0.7) were positively correlated with total organic carbon. Principal component analysis indicated that Cr, Ni, Mn, and As was mainly from the lithogenic origin and Zn, Cu, Cd, and Pb were influenced by anthropogenic contamination. We identified evidence of point source and runoff are the main contributors to enhanced heavy metals levels.

Characteristics of Vertical Distributions of Fatty Acids in Surface Sediments of the Yellow Sea and East China Sea

Fatty acids (FAs) in sediment collected from three different stations in the Yellow Sea and the East China Sea were analyzed for their distributions and to determine evidence of harmful algal blooms in the sediment core. Less diverse FAs were found in the Yellow Sea (YS) station, whereas in the two stations of the East China Sea (ECS) the FAs were more diverse. Concentrations of some FA species in the two ECS stations displayed an occasional surge in their vertical profile. The highest concentration of FAs was found in the surface layer of station QT3 (43.28 μg g−1). Monounsaturated FAs were more susceptible to degradation compared to their saturated counterparts, and changes of 16:0, 18:2 and 20:5 accounted for the most variability in total concentrations of FAs as those species made up most of the quantified FAs. The origins of the major fraction of FAs were attributed to autotrophic sources, and bacterial FAs accounted for only a small fraction of the total FAs in the region. Nutrient availability was a possible regulating factor controlling bacteria abundances in marine sediments in the ECS and the YS. A principal component analysis (PCA) was applied to analyze the FA dataset and to reveal the principal environmental factors that control the composition of FAs in the sediments. PC2, which explains 15% of the variance, was estimated to reflect the diagenetic effects on the FA compositional changes in sediments influenced by bacterial degradation.

Composition and leaching of construction and demolition waste: Inorganic elements and organic compounds

Thirty-three samples of construction and demolition waste collected at 11 recycling facilities in Denmark were characterised in terms of total content and leaching of inorganic elements and presence of the persistent organic pollutants PCBs and PAHs. Samples included (i) “clean” (i.e. unmixed) concrete waste, (ii) mixed masonry and concrete, (iii) asphalt and (iv) freshly cast concrete cores; both old and newly generated construction and demolition waste was included. PCBs and PAHs were detected in all samples, generally in non-critical concentrations. Overall, PAHs were comparable to background levels in urban environments. “Old” and “new” concrete samples indicated different PCB congener profiles and the presence of PCB even in new concrete suggested that background levels in raw materials may be an issue. Significant variability in total content of trace elements, even more pronounced for leaching, was observed indicating that the number of analysed samples may be critical in relation to decisions regarding management and utilisation of the materials. Higher leaching of chromium, sulphate and chloride were observed for masonry-containing and partly carbonated samples, indicating that source segregation and management practices may be important. Generally, leaching was in compliance with available leaching limits, except for selenium, and in some cases chromium, sulphate and antimony.

Seasonal ecophysiology of an endangered coastal species, the yellow-horned poppy (Glaucium flavum Crantz)

Glaucium flavum Crantz. is a short-lived perennial herb distributed in coastal zones from the Black Sea to southern, western and north-western Europe. Despite its diminishing area of distribution and potential pharmacological value, little is known about the ecophysiological features of this coastal species. We investigated the photosynthetic performance of G. flavum by measuring gas exchange, chlorophyll fluorescence, photosynthetic pigment concentration and leaf water content over the space of a year in a coastal habitat of SW Spain. We also measured the variation in total concentrations of nitrogen, phosphorus, sulphur, potassium, calcium and magnesium, in the leaves and soil, throughout the study period. G. flavum showed a high resistance to summer drought conditions which appeared to be due to the high degree of stomatal control. The potential photochemical efficiency of photosystem II showed minimum values during the winter, indicating that low temperatures can produce negative effects within the photosynthetic apparatus. However, the marked decline in net photosynthesis during the winter seems to be mainly related to a loss of metabolic activity. Although leaf nutrient concentrations were, in general, within the normal ranges, phosphorus availability seems to be limited by the high calcium concentrations detected in the soil of the study site. Our study points out the efficiency of the different physiological adaptations of this rare and endangered coastal species in coping with the strong seasonal variability of the Mediterranean climate.

Diversity and Relationships in Key Traits for Functional and Apparent Quality in a Collection of Eggplant: Fruit Phenolics Content, Antioxidant Activity, Polyphenol Oxidase Activity, and Browning

Eggplant (Solanum melongena) varieties with increased levels of phenolics in the fruit present enhanced functional quality, but may display greater fruit flesh browning. We evaluated 18 eggplant accessions for fruit total phenolics content, chlorogenic acid content, DPPH scavenging activity, polyphenol oxidase (PPO) activity, liquid extract browning, and fruit flesh browning. For all the traits we found a high diversity, with differences among accessions of up to 3.36-fold for fruit flesh browning. Variation in total content in phenolics and in chlorogenic acid content accounted only for 18.9% and 6.0% in the variation in fruit flesh browning, and PPO activity was not significantly correlated with fruit flesh browning. Liquid extract browning was highly correlated with chlorogenic acid content (r = 0.852). Principal components analysis (PCA) identified four groups of accessions with different profiles for the traits studied. Results suggest that it is possible to develop new eggplant varieties with improved functional and apparent quality.

Sucrose as chiral selector for determining enantiomeric composition of metalaxyl by UV–vis spectroscopy and PLS regression

This study revealed that it was possible to determine the enantiomeric composition of with multivariate regression models of spectral data obtained by ordinary UV–vis spectrophotometry of enantiomeric guest–host complexes. The total 60samples involving three concentration levels of metalaxyl as low, medium and high were prepared for spectral collecting. Four methods of modeling were subsequently proposed and compared including two common ways and two compensating ways for variations in total analyte concentration. Firstly, without normalization robust modeling was failed to achieve while employing the medium concentration levels as calibration and the other two levels as a validation. The same case occurred when full-cross validation was conducted. Besides, two enhanced methods were developed to account for the systematic variation. One of which normalized the spectra with respect to the total concentration of enantiomeric, along with spectral data, as a variable in the statistical analysis. The other one ignored variations in total concentration, relying on the specific band normalization to sort out any variations due to total concentration differences. The results clearly demonstrated that the spectra according to concentration provided the acceptable predictive ability in determining enantiomeric composition.

Sucrose as chiral selector for determining enantiomeric composition of phenylalanine by UV–vis spectroscopy and chemometrics

Abstract The determination of enantiomeric composition by partial least squares (PLS) modeling of UV–vis spectral data was investigated for samples of phenylalanine (phe) using sucrose as a chiral auxiliary. And a new data preprocess method, reference band normalization, was introduced to eliminate the spectral variations due to the changes of total concentration of phe. The determination coefficient ( R 2 ) and the standard error of calibration set (SEC) of 13 standard samples are 0.9987 and 0.0128 respectively. The standard error of validation set (SECV) of 7 validation samples is 0.0049. The standard error of predict (SEP) of 6 blind samples for evaluating the robustness of the model is 0.0366. The regression model is robust to determine enantiomeric composition when total concentration varied. It is demonstrated that the reference band normalization is a convenient method of compensating for variations in total concentrations without knowing that in advance.

Variation in Glucosinolate and Tocopherol Concentrations in a Germplasm Collection of Brassica juncea (L.) Czern. + Coss.

Detailed analysis of the leaves and seeds of 97 individual plants of a RIL population derived from the cross of NUDH-YJ-04, a tall and late flowering European juncea having low glucosinolates and RL-1359, a semi dwarf and early flowering Indian juncea having high glucosinolates, grown at a field site revealed a wide variation in total concentrations of seed glucosinolates, leaf glucosinolates, tocopherols and oil. Their contents lied in the ranges of 28.85 to 115.88 μmole/g seed, 0.82-102.30 μmole/g leaf, 32.29 to 1250 ppm and 34.96-45.00% respectively. Such variation studies are imperative for map based cloning and QTL mapping of key genes associated with the studied traits which in turn can help us in exploring the genetic view of these biochemicals.

Relação entre óxidos de ferro e de manganês e a sorção de fósforo em solos no Rio Grande do Sul

Os solos utilizados para a cultura de arroz irrigado por alagamento no Estado do Rio Grande do Sul são oriundos de diferentes materiais de origem e estão sujeitos às variações temporais das condições de oxidação e redução. Essas condições contribuem para as variações nos teores totais e na crista-linidade de óxidos de Fe e de Mn, as quais estão relacionadas aos processos de sorção e dessorção, afetando a disponibilidade de P para a cultura de arroz irrigado. Com o objetivo de verificar a sorção de P e a sua disponibilidade para o arroz em solos oriundos de diferentes materiais de origem, foram desenvolvidos dois estudos: o primeiro para determinar os teores totais de Fe e de Mn e a capacidade máxima de adsorção de P (CMAP) pelas isotermas de Langmuir; além disso, foram associados a CMAP e os teores totais de Fe e de Mn, na razão FeOx6/Fe dit, razão MnOx6/Mn dit argila e da matéria orgânica. O segundo estudo foi para quantificar a sorção de P durante quatro períodos de alagamento do solo. Os solos oriundos de sedimento de basalto (Luvissolo, Vertissolo e Chernossolo) apresentaram maior CMAP do que os oriundos de sedimento de granito e arenito (Planossolos e Gleissolos), devido aos maiores teores totais de Fe e também às razões de Fe extraído por oxalato de amônio a pH 6 (Fe ox6)/ferro extraído por ditionito (Fe dit) e Mn extraído por oxalato de amônio a pH 6 (Mn ox6)/Mn dit. A razão Fe ox6/Fe dit apresentou a maior associação com a CMAP em todos os solos utilizados. O Planossolo teve menor sorção de P do que os solos oriundos de sedimento de basalto em todos os períodos de alagamento.

Assessment of Bacterial and Fungal Aerosol in Different Residential Settings

The concentration and size distribution of bacterial and fungal aerosol was studied in 15 houses. The houses were categorized into three types, based on occupant density and number of rooms: single room in shared accommodation (type I), single bedroom flat in three storey buildings (type II) and two or three bedroomed houses (type III). Sampling was undertaken with an Anderson six-stage impactor during the summer of 2007 in the living rooms of all the residential settings. The maximum mean geometric concentration of bacterial (5,036 CFU/m3, ± 2.5, n = 5) and fungal (2,124 CFU/m3, ± 1.38, n = 5) aerosol were in housing type III. The minimum levels of indoor culturable bacteria (1,557 CFU/m3, ±1.5, n = 5) and fungal (925 CFU/m3, ±2.9, n = 5) spores were observed in housing type I. The differences in terms of total bacterial and fungal concentration were less obvious between housing types I and II as compared to type III. With reference to size distribution, the dominant stages for culturable bacteria in housing types I, II and III were stage 3 (3.3–4.7 μm), stage 1 (7 μm and above) and stage 5 (1.1–2.1 μm), respectively. Whereas the maximum numbers of culturable fungal spores were recovered from stage 2 (4.7–7 µm), in housing type I, and from stage 4 (2.1–3.3 μm) in both type II and III houses. The average geometric mean diameter of bacterial aerosol was largest in type I (4.7 μm), followed by type II (3.89 μm) and III (1.96 μm). Similarly, for fungal spores, type I houses had the highest average mean geometric diameter (4.5 μm), while in types II and III the mean geometric diameter was 3.57 and 3.92 μm, respectively. The results indicate a wide variation in total concentration and size of bioaerosols among different residential settings. The observed differences in the size distributions and concentrations reflect their variable airborne behaviour and, as a result, different risks of respiratory exposure of the occupants to bioaerosols in various residential settings.

SUBSTANCE OR SPACE? THE RELATIVE IMPORTANCE OF SUBSTANCE PROPERTIES AND ENVIRONMENTAL CHARACTERISTICS IN MODELING THE FATE OF CHEMICALS IN EUROPE

The relative influence of substance properties and of environmental characteristics on the variation in the environmental fate of chemicals was studied systematically and comprehensively. This was done by modeling environmental concentrations for 200 sets of substance properties, representative of organic chemicals used, and 137 sets of environmental characteristics, representative of regions in Europe of 250 x 250 km. Since it was expected that the model scale has an influence on the predicted concentration variations, the calculations were repeated for regions with a 100 x 100 km and 50 x 50 km area. Stepwise multiple regression analysis was performed to determine the contribution of each of the individual input parameters on the total concentration variation. Depending on the scenario, the range in predicted environmental concentrations spreads from two up to nine orders of magnitude. In accord with earlier studies, variation in the fate of chemicals in the environment appeared to depend mainly on substance-specific partition coefficients and degradation rates. For the estimation of soil and water concentrations with direct emissions to these compartments, however, the influence of spatial variation in environmental characteristics can mount up to two orders of magnitude, a range that can be significant to account for in certain model applications. Concentration differences in water and soil are predicted to be larger if a smaller region is applied in the model calculations, and the relative influence of environmental characteristics on the total variation increases on a more detailed spatial scale. It is argued that the influence of environmental characteristics as predictors of exposure concentrations of chemicals deserves better attention in comparative risk assessment with conventional nonspatial multimedia box models.

Relative amino acid concentrations as a signature for parent body processes of carbonaceous chondrites.

Most meteorites are thought to have originated from objects in the asteroid belt. Carbonaceous chondrites, which contain significant amounts of organic carbon including complex organic compounds, have also been suggested to be derived from comets. The current model for the synthesis of organic compounds found in carbonaceous chondrites includes the survival of interstellar organic compounds and the processing of some of these compounds on the meteoritic parent body. The amino acid composition of five CM carbonaceous chondrites, two CIs, one CR, and one CV3 have been measured using hot water extraction-vapor hydrolysis, OPA/NAC derivatization and high-performance liquid chromatography (HPLC). Total amino acid abundances in the bulk meteorites as well as the amino acid concentrations relative to glycine = 1.0 for beta-alanine, alpha-aminoisobutyric acid and D-alanine were determined. Additional data for three Antarctic CM meteorites were obtained from the literature. All CM meteorites analyzed in this study show a complex distribution of amino acids and a high variability in total concentration ranging from approximately 15,300 to approximately 5800 parts per billion (ppb), while the CIs show a total amino acid abundance of approximately 4300 ppb. The relatively (compared to glycine) high AIB content found in all the CMs is a strong indicator that Strecker-cyanohydrin synthesis is the dominant pathway for the formation of amino acids found in these meteorites. The data from the Antarctic CM carbonaceous chondrites are inconsistent with the results from the other CMs, perhaps due to influences from the Antarctic ice that were effective during their residence time. In contrast to CMs, the data from the CI carbonaceous chondrites indicate that the Strecker synthesis was not active on their parent bodies.

Phosphorus in rainwater: Partitioning inputs and impact on the surface coastal ocean

Phosphate concentrations in rainwater were measured at a Ligurian coastal sampling site (Cap Ferrat, France) from February 1997 to February 1998 to study the impact of wet atmospheric phosphorus (P) input on the surface ocean. Soluble and particulate fractions were differentiated to evaluate the atmospheric supply of bioavailable P. Complexed and reactive phases within the dissolved fraction were also separated. Preliminary results showed a high temporal variability in total concentration (0.05–4.3 μmol liter−1). The factors controlling the partitioning between reactive and complexed components are not clear. However, the partitioning between dissolved and particulate fractions is linked to emission sources. Soil‐derived dust from the Sahara was identified as an important source of atmospheric P, mainly insoluble. Conversely, anthropogenic emissions are sources of soluble P (i.e., basically bioavailable). A significant part of these emissions could originate from incinerators and/or biomass burning. The different wet fluxes are calculated to total 165 μmol m−2 yr−1, and the dissolved and particulate inputs are 95 and 70 umol m−2 yr−1, respectively. Taking into account the respective sol ubility of such inputs, anthropogenic emissions appear to be responsible for relatively high amounts of bioavailable P. Even if the atmosphere is globally a minor source of nutrients (compared with riverine inputs and marine vertical mixing), it might be the only source of P in oligotrophic conditions. For example, assuming that P is a limiting factor in the Mediterranean Sea, the rain event of 19 June 1997 (17 μmol m−2 of bioavailable P) potentially induced a new production of 0.02 g C m−2, which is a significant value in such conditions. Converted into biomass and integrated over a 5‐‐thick water layer, such an atmospheric input represents 0.35–0.45 mg chlorophyll a m−2, an appreciable portion of the total biomass during this period. This observation underlines the major role of the atmosphere during oligotrophic periods in the western Mediterranean.

Creatine kinase, energy-rich phosphates and energy metabolism in heart muscle of different vertebrates.

Maximal activities of creatine kinase, pyruvate kinase and cytochrome oxidase and total concentrations of creatine and phosphorylated adenylates were measured in cardiac muscle of hagfish, eight teleost species, frog, turtle, pigeon and rat. The ratio of creatine kinase to cytochrome oxidase with cytochrome oxidase as a rough estimate of aerobic capacity and cellular "energy turnover", was increased in myocardia of hagfish, turtle and crucian carp. These myocardia are likely to be frequently exposed to oxygen deficiency. In agreement with this, they possess a high relative glycolytic capacity as indicated by a high pyruvate kinase/cytochrome oxidase ratio. The creatine kinase/cytochrome oxidase ratio for the other myocardia varied within a factor of 2, except the value for cod myocardium which was below the others. Total creatine varied among species and was high in active species such as herring, pigeon and rat but also high in crucian carp. The variation in total concentration of phosphorylated adenylates was considerably less than the variation in total creatine. The high creatine kinase/cytochrome oxidase ratio in myocardia likely to be challenged by hypoxia may represent an enhanced efficiency for both "spatial" and "temporal" buffering of phosphorylated adenylates to attenuate the impact of a depressed energy liberation. As to the differences in total creatine, this factor influences not only the cellular energy distribution but possibly also contractility via an effect on the free phosphate level.

Nutrient content and ionic pattern in beech (Fagus sylvatica L.) from natural stands in Eastern Austria and ecological implications

Macro and Micro cation content, concentration of water soluble cations and anions, as well as nitrogen content in beech leaves from a variety of forest stands in the eastern part of Austria have been determined. Special attention has been focused on the highly air polluted Vienna Woods. A broad natural variability in total content of minerals, as well as in nitrogen content could be observed. In general, cation nourishment has been found to be adequate on all stands. The pattern of water soluble i.e. physiologically active cations, especially with regard to divalent cations, varies broadly among beeches from different provenances: Mg/Mn ratios differ within three orders of magnitude between dolomite and highly acidic, nutrient poor stands over silicate rock. The term ‘mineral deficiency limit’ should, therefore, be used very carefully with respect to single nutrients. Organic anions (quinate, malate, citrate) clearly dominate over inorganic anions. The relative amount of the latter increased from NO3, Cl, inorganic phosphate to SO4. A concentration of SO4 is markedly in leaves within the direct reach of SO2 sources, its level, however, remaining well below the organic anions. Slight evidence of an antagonistic behavior between SO4 and organic acids could be found. Total nitrogen as well as the ratio insoluble:soluble nitrogen were tendencially higher in Vienna Wood beeches, indicating an additional use of the airborne nitrogen. The high flexibility of beech with respect to mineral content and ionic balance is discussed with regard to the ecological distribution of beech and the susceptibility to air pollution.

Variation in tissue element concentration in mire plants over a range of sites

Elements in surface peat and ground water were estimated on seven mire sites in central and north Sweden. The variation in tissue clement concentration was studied in eleven plants occurring on the studied sites. The elements estimated were: N, P, K. Ca, Mg, Fe, Mn, Zn, Al, Cu, Mo, Na, S, B, and Si. The species studied were; Carex diandra, Carex limosa, Carex rostrata, Epilobium palustre, Menyanthes trifoliate, Pedicularis palustris, Rumex acetosa, Saxifraga hirculus, Scirpus hudsonianus, Stellaria crassifolia and Tofteldia pusilla. In surface peat over the range of sites, the variation in total concentrations of nitrogen and phosphorus was six and tenfold, respectively. The variation in total concentration of potassium was four‐fold. Extractable concentrations of these three elements showed an even greater variation between sites. Over the range of sites, the variation in tissue element concentration was larger in roots than in above‐ground parls. In above‐ground parts, floral parts varied less in tissue element concentration than did stems and leaves. The largest variation in tissue element concentration was found in Carex rostrata and Menyanthes trifoliata. The smallest variation was found in Saxifraga hirculus. Tissues of the rich fen species Saxifraga hirculus and Stellaria crassifolia had the lowest concentrations of heavy metals. The correlation between substrate element concentration and tissue concentration differed both between tissues and species. Concentrations of N, P and K in tissues of the Carex species were highly correlated with the concentrations of these elements in the substrate, while N, P and K concentrations in tissues of the herbaceous species, especially Saxifraga hirculus. correlated less well.

Uptake and internal distribution of exogenously supplied amino acids in the Pacific oyster, Crassostrea gigas (Thunberg)

A technique is described in which irrigation of the mantle cavity of oysters, Crassostrea gigas, induces pumping at steady rates. Simultaneous net influx of 10 amino acids (asp, glu, asn, ser, gly, tau, ala, val, phe, lys) is observed by high-performance liquid chromatography (HPLC). Individual amino acids exhibit first-order exponential depletion from an initial medium concentration of 2.0 μM. Influx of radiolabeled alanine corresponds very closely to net entry of alanine as estimated by HPLC. Therefore, net entry of alanine from dilute solution (5 μM) occurs. The entry of alanine is well described by Michaelis-Menten kinetics with a maximum influx ( J max) of 1.76 μmol g −1 h −1 ±0.028 (SD) and a half-saturation constant ( K t) of 33.70 μM ±1.15 (SD). Amino acids taken up from solution are distributed rapidly to the internal tissues of the animal. This is demonstrated for alanine and glutamate and for the amino acid analogues, cycloleucine and α-amino- n-butyric acid (ABA). HPLC analysis of the free amino acid pools of mantle, gill, adductor muscle and hemolymph of C. gigas demonstrates variability in total concentration and in details of FAA composition.

Effect of total drug concentration on the free fraction in uremic sera.

The effect of total drug concentration on the free fraction was studied in vitro using sera of uremic and nonuremic subjects. Both therapeutic and toxic concentrations of radiolabeled phenytoin, diazepam, and propranolol were used. The free fraction was separated by a pressure ultrafiltration method at 37 degrees C and determined from 200-microliters aliquots of serum and the ultrafiltrate. Sera from 11 acutely uremic and 10 chronically uremic patients and from 10 healthy control subjects were used. Only slight increases in the free fraction were found over the concentration range studied in both nonuremic and uremic subjects. The concentration-dependent increases in the unbound fraction of phenytoin and diazepam were quite negligible compared with the two- to threefold increases caused by uremia itself. Thus, variation in total concentrations of phenytoin, diazepam, and propranolol does not change the free fractions to a clinically significant degree even in uremic patients with a compromised binding capacity.

Antidepressive effect and pharmacokinetics of amitriptyline with consideration of unbound drug and 10-hydroxynortriptyline plasma levels.

In 27 inpatients with primary affective disorder the urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) was measured prior to a 4-week treatment with 150 mg amitriptyline (AT)/day. Ratings according to the Hamilton depression scale were performed before therapy and repeated after 2 and 4 weeks. Plasma levels of AT, nortriptyline (NT), and E-10-hydroxynortriptyline (OHNT) were assayed weekly, and binding of AT to plasma proteins was determined in one sample. Better therapeutic results were obtained at intermediate, as compared to low and high concentrations of AT or AT plus NT. Independent evaluation of AT and metabolite levels revealed that patients with AT of 50--125 ng/ml responded particularly well when NT did not exceed 95 ng/ml or when NT plus OHNT was below 150 ng/ml. Outside this "therapeutic window' the outcome was markedly poorer. Interindividual variation of AT binding was much smaller than variation of total concentrations. Evaluation of free, instead of total levels did not help to clarify the relationship between clinical and pharmacokinetic variables. Plasma levels within the optimal ranges were found in more patients with high than with low MHPG excretion. The free fraction of OHNT in plasma of healthy subjects was about 35%.

Infrared measurement of total fatty acids in blood serum

AbstractQuantitative determination of total fatty acids in rabbit blood serum is achieved using the infrared absorption band, associated with the C=0 stretching vibration at 1713 cm−1 (5.84 μm). Different tests are described to show the validity of this method for a wide range of variation in total concentration and in individual percentages of any one fatty acid. The results are treated by statistical methods, and it is found that infrared analysis is five times more sensitive than methods described previously. This accurate technique, which can be applied to other serums has, for example, been applied to disclose a systematic error in the preparation of total fatty acid samples when nitrogen flushing is not used.