Ultramicro Quantities Research Articles

Catecholamine Quantification in Body Fluids Using Isocratic, Reverse Phase HPLC‐CoulArray Multi‐electrode Chemical Detector System: Investigation of Sensitivity, Stability, and Reproducibility

Catecholamines (CATs) neurotransmitters regulate a number of physiological and behavioral functions. These amines are released from the nerve endings and are present in ultramicro quantities in plasma and other body fluids. For meaningful evaluation of their concentration, it is essential that the technology used for their measurement is highly sensitive, efficient, and stable. Among various methods used for their measurement, recently developed high performance liquid chromatography (HPLC‐ECD), combined with a CoulArray multielectrode detector system, is found to be the most suitable for detecting picogram concentrations of CATs in small samples of human plasma and other body fluids, as well as tissues. In this paper, we describe systematic investigations of various factors involved in contributing to the reliability and reproducibility of CATs measurement. These factors include sensitivity of detection, limits of linear relationship between concentration and the response factor, stability of the system and extracts, as well as, other factors that need to be controlled in order to achieve reliable results.

Application of infrared spectroscopy in vacuum

This paper describes the application of infrared spectroscopy in precise measurements of residual substances and oil contamination in a vacuum system, such as the measurement of ultralow backstreaming rate of diffusion pump and the measurement of ultramicro quantities of oil contamination in vacuum systems and equipment. We will also discuss the possibility of other applications of infrared spectroscopy in a vacuum system.

Electronic structures of solids by electron-energy-loss spectroscopy carried out using and electron microscope: oxygen-K and metal-L edges of transition metal oxides

Electron-energy-loss spectra, recorded from ultramicro quantities (<10–12 g), reveal L2,3 edges the energy and intensity of which vary systematically with oxidation state in a series of transition metal oxides; the first ever evidence for structure-sensitive features in oxygen K-edges is reported.

A kinetic determination of ultramicro quantities of serotonin, 5-hydroxyindolacetic acid, L-dopa, methyl-dopa and carbidopa

A kinetic method is presented for the determination of the biologically important substances serotonin, 5-hydroxyindolacetic acid, L-dopa, methyldopa and carbidopa. The method is based on the reaction between hydrogen peroxide, molybdenum(VI) and the substance to be determined, in carbonate buffer solution, the reaction rate being followed photometrically. In order to find optimum experimental conditions for these determinations the kinetics of the reactions were examined. The substances investigated were determined at concentrations ranging from 0.40 to 17.4 μg/ml, with relative standard deviations ranging from 0.6 to 6.1%. The effect of some foreign species usually present in biological material has also been examined.

A kinetic determination of ultramicro quantities of manganese(II), molybdenum(VI) and tungsten(VI) on the basis of their catalytic action on the oxidation of Azorubin S by hydrogen peroxide

A study has been made of the kinetics of catalytic oxidation of Azorubin S by hydrogen peroxide in the presence of Mn(II), Mo(VI) and W(VI) in order to find optimal conditions for the kinetic catalytic determination of these elements. Manganese(II), molybdenum(VI) and tungsten(VI) were determined in the concentration ranges 5.5–33.0×10−3, 1.3–8.1 and 5.9–44.1μg/ml, respectively. Standard deviations were less than 11%. The effect of some foreign ions on these determinations was also investigated.

Determination of the activity product of compounds based on microquantities of radioactive elements

Possibility of the determination of activity product (AP) of the compounds of the transuranium element, unavailable in weighable quantities or with high specific activity has been considered based on studying the cocrystallization of their ultramicro quantities with isomorphous microcomponents. Conditions of applicability of cocrystallization technique for this purpose have been discussed. Good coincidence of the values for APNaAmEDTA, calculated from the data on cocrystallization of ultramicro quantities of (AmEDTA)− with isomorphous microcomponent, NaEuEDTA, and APNaAmEDTA obtained directly from the data on dissolution of weighable quantities of NaAmEDTA has been shown.

The kinetic catalytic ultramicro determination of some 8-hydroxyquinoline derivatives

A kinetic catalytic method for the determination of ultramicro quantities of some 8-hydroxyquinoline derivatives is proposed, and consideration is given to the effect of noncatalytic reactions on this type of determination. The oxidation of alizarin S by hydrogen peroxide in the presence of ammonium carbonate, with manganese as a catalyst, is applied as the indicator reaction for the determination of 8-hydroxyquinoline sulphate, 5,7-diiodo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline and 7-iodo-8-hydroxyquinoline-5-sulphonic acid by the tangent method; the reaction rate is followed spectrophotometrically. The concentrations determined range from 2.85 · 10 -8 M to 11.3 · 10 -8 M, with standard deviations of 3.4–10.0 %.

Fluorometric assay of ultramicro quantities of glucose with somogyi filtrate and hexokinase

A procedure is described for the determination of glucose in 3 μl of serum or plasma. It is based on the phosphorylation of glucose with ATP mediated by hexokinase. The TPNH generated with glucose-6-phosphate dehydrogenase is measured fluorometrically. Sensitivity is greatly improved over the corresponding procedure using UV absorption for the determination of NADPH. Bilirubin does not interfere. Interference from hemolysis is eliminated by precipitation with Zn(OH) 2 Blood taken with fluoride can be utilized. Fluoride interference is removed with the Zn(OH) 2 and with excess Mg in the substrate. Positive interference by fructose is negligible with some enzyme preparations but is appreciable with others. The results correlate well with those obtained with an ortho toluidine method, after protein precipitation with trichloroacetic acid. The method is especially useful in the Pediatric Laboratory.

New kinetic method for determination of ultramicro quantities of organic substances. Determination of amino acids (glycine, DL-serine, DL-phenylalanine, DL-glutamic acid, and L-arginine

New kinetic method for determination of ultramicro quantities of organic substances. Determination of amino acids (glycine, DL-serine, DL-phenylalanine, DL-glutamic acid, and L-arginine

Determination of ultramicro quantities of manganese by catalytic oxidation of alizarin S by hydrogen peroxide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of ultramicro quantities of manganese by catalytic oxidation of alizarin S by hydrogen peroxideTomislav J. Janjic, G. A. Milovanovic, and M. B. CelapCite this: Anal. Chem. 1970, 42, 1, 27–29Publication Date (Print):January 1, 1970Publication History Published online1 May 2002Published inissue 1 January 1970https://doi.org/10.1021/ac60283a020RIGHTS & PERMISSIONSArticle Views66Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (295 KB) Get e-Alerts Get e-Alerts

Microdetermination of Inorganic Phosphate, Phospholipids, and Total Phosphate in Biologic Materials

Abstract A rapid, reproducible, and sensitive procedure for the determination of phosphate in several biologic materials is described Organic phosphate is rapidly converted to orthophosphate by digestion with a nitric acid-calcium ion mixture. The acid destroys the organic material while the calcium ion prevents loss of phosphate or its conversion to an unmeasurable form. Inorganic phosphate can be determined in the presence of labile organic phosphates since phosphate liberated after the color reaction has been initiated cannot interfere by forming further color. Even if phosphate were deliberately added after the color reaction had started, it could not react in the described system. The method may be applied to the determination of phosphate present in ultramicro quantities. It is unnecessary to extract the heteropoly acid complex either to increase sensitivity or to protect the color complex formed from interference of phosphate hydrolyzed during the process of color formation.

A simplified quantitative enzymatic procedure for glucose in urine.

A simplified resin treatment for removal from urine of substances which inhibit the glucose oxidase peroxidase system of analysis of glucose is described. The original technic designed for AutoAnalyzer use has been modified for a manual procedure. The cost of enzyme reagents and resin has been minimized by use of micro proportions. The enzymatic principle for determination of glucose in blood, serum and plasma is well established. Application of the glucose oxidase procedure to urine has been more limited, mainly due to the necessity of removing inhibitory substances from urine. Removal of these substances by adsorption, using a mixture of activated charcoal and Lloyd's reagent (hydrated aluminum silicate), has been found more satisfactory than the use of either component singly. The ingredients must be carefully adjusted because it is known that charcoal itself adsorbs glucose. Treatment of urine with resin has been described by Salomon and Johnson, and has been simplified for use with the enzymatic procedure on the AutoAnalyzer in our laboratory. Although automated procedures are becoming more widespread in use, there is still, and undoubtedly always will be, a need for simplified manual methods. Consequently the technic for the removal of inhibitory substances by means of a mixed bed resin has been investigated for adaptation to a manual glucose oxidase method. In this investigation we have found that the proportion of specimen to enzyme reagent may be adjusted so that ultramicro quantities of specimen may be assayed efficiently and conveniently. Precalibrated capillary tubes, 20 lambda volume, were extremely convenient to use and gave reproducible results. An economical amount of enzyme reagent (1 ml.) gave satisfactory photometric sensitivity. This simplification of the enzymatic procedure should help to make more practicable a method specific for urinary glucose.

A method for the determination of free plasma amino acids in ultra-micro quantities

A method is described in detail for the estimation of the individual free amino acids of plasma and urine using high-voltage electrophoresis and evaluating the separated components with the “Chromoscan”.

The fluorometric analysis of ultramicro quantities of hydrogen peroxide

A fluorometric method has been described for the analysis of hydrogen peroxide in the range of 10 −11 mole/ml. The method is based on the oxidation of nonfluorescent diacetyldichlorofluorescin to a fluorescent compound by hydrogen peroxide and peroxidase.

Co-crystallization of ultramicro quantities of cobalt with α-nitroso-β-naphthol

The co-crystallization of ultramicro quantities of cobalt with α-nitroso-β-naphthol, was investigated by radio-tracer techniques. More than 99% cobalt, even when carrier-free, could be recovered. The distribution was studied and appeared to follow the logarithmic distribution law. The interference of a large excess of zinc was almost negligible. The method was applied to tlie carrier-free separation of cobalt isotopes ( 55Co, 56Co, 57Co, 58Co) produced by deuteron bombardment of an iron target. Contamination by manganese ( 54Mn, 52Mn) and iron ( 59Fe) was, even in the absence of manganese carrier, almost negligible.

Cocrystallization of ultramicro quantities of elements with 2-mercaptobenzimidazole. Determination of gold in sea water : Weiss, H. V., and M. -G. Lai, 1963. Analyt. Chim. Acta, 28 (3): 242–248.

Cocrystallization of ultramicro quantities of elements with 2-mercaptobenzimidazole. Determination of gold in sea water : Weiss, H. V., and M. -G. Lai, 1963. Analyt. Chim. Acta, 28 (3): 242–248.

Spectrophotometric Determination of Ultramicro Quantities of Calcium in KCl

AbstractThe calcium content of various KCl products was determined, using glyoxal‐bis(2‐hydroxyanil) as a specific colouring reagent. Some preliminary results of purification by crystallization are also reported.

FREEZING-POINT DEPRESSION: NEW METHOD FOR MEASURING ULTRAMICRO QUANTITIES OF FLUIDS.

Accurate determination of the solute content of millimicroliter samples of biological fluids can conveniently be made with an instrument consisting of a thermoelectric cooler controlled by an electronic proportional servo system. Accuracies to within less than 2 percent have been achieved in determining the osmolarity of body fluids.

The Electron Capture Spectrometry of Haloacetates: A Means of Detecting Ultramicro Quantities of Sterols by Gas Chromatography.

The Electron Capture Spectrometry of Haloacetates: A Means of Detecting Ultramicro Quantities of Sterols by Gas Chromatography.

Cocrystallization of ultramicro quantities of elements with 2-mercaptobenzimidazole: Determination of gold in seawater

The cocrystallization of ultramicro quantities of 25 diverse elements with 2-mercaptobenzimidazole was investigated with the aid of radiotracers. Under optimum conditions Sn, Hg, Ag, Ta and Au were recovered in high yield. Distribution coefficients between mother liquor and solid phase were calculated for gold and were found to vary inversely with the degree of crystallization and the hydrogen ion concentration. The cocrystallization process was applied to the isolation and subsequent determination of the natural gold abundance in seawater. After radiometric correction for chemical yield, the concentration of gold was calculated to be 0.068 ± 0.003 μg 1 .