A Novel Direct Method for Determination of Riboflavin in Alcoholic Fermented Beverages

The heats of dissociation of chlorine, bromine, and iodine have been determined by thermal methods and estimated to be 58·9, 45·2 and 35·2 kilo-cals. respectively. But no data are yet known concerning the heat of dissociation of fluorine. It is very difficult to subject fluorine to the same treatment as Cl 2 , Br 2 and I 2 ( i. e ., heating to a high temperature in a sealed quartz bulb) owing to its extreme chemical reactivity, and hence no direct method of determining the heat of dissociation of fluorine has yet been devised. In the present paper I have determined it indirectly by interpretation of the absorption spectra of alkali fluorides (for the present only NaF and KF). A short theory of the experiment is given below.

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Simultaneous determination of procaine hydrochloride, procainamide hydrochloride and lidocaine by molecular absorption spectrometry

SIMI 2019, Abstract Book - International Symposium "The Environmental and The Industry" ◽

10.21698/simi.2019.fp40 ◽

2019 ◽

pp. 318-324

Author(s):

Nicoleta Mirela Marin ◽

Gheorghe Batrinescu ◽

Mihai Nita-Lazar ◽

Luoana Florentina Pascu ◽

Carol Blaziu Lehr

Keyword(s):

Simultaneous Determination ◽

Direct Method ◽

Absorption Spectrometry ◽

Procaine Hydrochloride ◽

Zero Crossing ◽

Multicomponent Analysis ◽

First Derivative ◽

Cramer’S Rule ◽

Derivative Spectrometry

Two spectrometric methods have been developed for quantitative simultaneous determination of procaine hydrochloride (PH·HCl), procainamide hydrochloride (PHA·HCl) and lidocaine (Lid) from synthetic mixture. The methods employed are first derivative spectrometry, using zero crossing method and multicomponent analysis which is based on the additivity law. Using first derivative spectrometry, the wavelength selected for the quantitative determination of PH·HCl was 237 nm for Lid was 242 nm and for PHA·HCl was 290 nm in mixture. The method is linear when the concentration ranged between 6.62-9.93 μg/mL for PH·HCl, 6.43-9.64 for PHA·HCl and 5.56-8.35 for Lid. The multicomponent analysis is a direct method and involves the absorbance measurements of at three different wavelengths. The molar absorption coefficients values were calculated at each wavelength and the concentration of PH·HCl, PHA·HCl and Lid from mixture was determined by solving matrix using Cramer's rule. The recovery of each compound in mixture was calculated and it is 101.4 % for PH·HCl, 100.4 % for PHA·HCl and 98.4 % for Lid.

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Short routine direct method for the fluorimetric determination of uranium in phosphate rocks

10.3133/tei134 ◽

1950 ◽

Keyword(s):

Direct Method ◽

Phosphate Rocks ◽

Fluorimetric Determination

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Determination of probabilistic characteristics of random values of estimates of the Lyapunov function when describing a physical process

Metrologiya ◽

10.32446/0132-4713.2021-4-53-67 ◽

2021 ◽

pp. 53-67

Author(s):

Yu. M. Veshkurtsev ◽

D. A. Titov

Keyword(s):

Lyapunov Function ◽

Characteristic Function ◽

Direct Method ◽

Special Device ◽

Transmission Errors ◽

Matlab Package ◽

Normal Law ◽

First Time ◽

A Direct Method

The applied application of the Lyapunov characteristic function is determined by the properties of its estimates. Probabilistic characteristics of estimates of the Lyapunov characteristic function are described for the first time. The probabilistic characteristics of random values of estimates of the Lyapunov function are empirically estimated using statistical methods. The Matlab package has developed a model of a special device for obtaining estimates of the characteristic function by a direct method. A quasi-deterministic signal is fed to the input of the model, the instantaneous values of which are distributed according to the arcsine law, and an array of values of estimates of the Lyapunov function is obtained at the output, which is used to estimate the probabilistic characteristics of these estimates. Statistical estimation was performed by an indirect method. It is established that the values of the estimates of the Lyapunov characteristic function are distributed according to the normal law. The results of the research will be useful in engineering calculations, for example, when detecting message transmission errors in modems with a modulated characteristic function.

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A novel direct method for determination of L,D amino acid configuration in peptides bound to solid support

Peptides 1994 ◽

10.1007/978-94-011-1468-4_188 ◽

1995 ◽

pp. 418-419

Author(s):

M. Pavlík ◽

Z. Voburka ◽

T. Vanek ◽

M. Rinnová ◽

I. Bláha ◽

...

Keyword(s):

Amino Acid ◽

Direct Method ◽

Solid Support

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Determination of melatonin by a whole cell bioassay in fermented beverages

Scientific Reports ◽

10.1038/s41598-019-45645-7 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

María Ángeles Morcillo-Parra ◽

Gemma Beltran ◽

Albert Mas ◽

María-Jesús Torija

Keyword(s):

Whole Cell ◽

Fermented Beverages

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Direct determination of selenium in serum by graphite-furnace atomic absorption spectrometry with deuterium background correction and a reduced palladium modifier: age-specific reference ranges.

Clinical Chemistry ◽

10.1093/clinchem/34.4.709 ◽

1988 ◽

Vol 34 (4) ◽

pp. 709-714 ◽

Cited By ~ 93

Author(s):

B E Jacobson ◽

G Lockitch

Keyword(s):

Atomic Absorption ◽

Direct Method ◽

Graphite Furnace ◽

Direct Determination ◽

Background Correction ◽

Specific Reference ◽

Reference Ranges ◽

Term Infants ◽

Graphite Furnace Atomic Absorption

Abstract We describe the development of a direct method for determination of selenium in serum by graphite-furnace atomic absorption spectrophotometry with deuterium background correction. We include palladium modifier to stabilize selenium in the presence of a strong reducing agent. Spectral interferences from iron are not evident in this system. Because an analysis requires only 20 microL of serum or plasma, the method is applicable to neonatal populations. At a selenium concentration of 0.75 mumol/L (approximately the mean found in our pre-term infants), the within-run CV is 5.3%. For a concentration of 1.83 mumol/L, which approximates our normal adult mean, within-run and between-run CVs are 2.7% and 3.4%. Accuracy is demonstrated by analytical recoveries ranging from 96% to 102%. We present reference values for pre-term and term infants, and age-specific ranges for infants to adults.

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Reverse Phase Liquid Chromatographic Determination of Some Food Additives

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/70.3.578 ◽

1987 ◽

Vol 70 (3) ◽

pp. 578-582 ◽

Cited By ~ 2

Author(s):

Madduri Veerabhadrarao ◽

Mandayam S Narayan ◽

Omprakash Kapur ◽

Chilukuri Suryaprakasa Sastry

Keyword(s):

Acetic Acid ◽

Benzoic Acid ◽

Mobile Phase ◽

Direct Method ◽

Food Additives ◽

Acid Water ◽

Relative Standard ◽

Acetic Acid Water ◽

Liquid Chromatographic

Abstract Liquid chromatographic methods are described for the separation and determination of non-nutritive sweeteners, namely, acesulfame, aspartame, saccharin, and dulcin; preservatives such as benzoic acid and p-hydroxybenzoic acid; and caffeine and vanillin in ready-toserve beverages, ice candy, ice cream, squash beverage, tomato sauce, and dry beverage mix samples. These additives are separated on a ^Bondapak C18 column using methanol-acetic acid-water (20 + 5 + 75) as mobile phase and detected by UV absorption at 254 nm. Caffeine, vanillin, dulcin, and benzoic acid can be analyzed quickly by using a mobile phase of methanol-acetic acid-water (35 + 5 + 60). Aspartame can be separated in the presence of caffeine and vanillin by using the mobile phase pH 3 acetate buffer-methanol (95 + 5). Retention factors and minimum detectable limits are described. The percentage error and the percent relative standard deviation for 6 replicate samples ranged from 0.3 to 2.8 and from 1.64 to 3.60, respectively. Recovery of additives added to the foods named and analyzed by the direct method and by extraction ranged from 98.0 to 100.6% and from 91.6 to 101.8%, respectively. The proposed LC techniques are simple, rapid, and advantageous because all the additives can be detected in a single step, which makes it useful for the routine analysis of various food products.

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