Determination of Neutral Urinary 17-Oxosteroids with Hydroxide of Hyamine 1O-X in the Zimmermann Reaction

1967 ◽  
Vol 13 (9) ◽  
pp. 717-733 ◽  
Author(s):  
Solveig Bjerre ◽  
Rose Kita
Keyword(s):  
Incubation Temperature ◽  
Potassium Hydroxide Solution ◽  
Correlation Coefficients ◽  
Ethylene Dichloride ◽  
Laboratory Personnel ◽  
Hydroxide Solution ◽  
Modified Method ◽  
Color Development

Abstract A modified method for 17-oxosteroid determination is described. The organic base, hydroxide of Hyamine lO-X,° which is stable in methanol, has replaced the unstable ethanolic potassium hydroxide solution in the Zimmermann reaction. Maximal color development was studied by varying incubation temperature, time, m-dinitrobenzene, and concentration of hydroxide of Hyamine 10-X. An incubation temperature of 37° for 30 min., with 1% m-dinitrobenzene in 1 M Hyamine 10-X hydroxide solution, gave close to maximal color. The major urinary 17-oxosteroids, dehydroepiandrosterone, androsterone, and etiocholanolone, gave similar chromogenic values. However, C3 and C20 oxosteroids produced some color in the Zimmermann reaction, and thus if present in large amounts, interfere. The interference in vitro of 35 drugs was tested, and several drugs were found to interfere. An essentially pigment-free urinary extract was obtained during the washing step, by addition of water to the ethylene dichloride extract containing sodium hydroxide pellets. Comparative 17-oxosteroid studies of urine specimens from laboratory personnel and from patients were performed, based on absorbance at a single wavelength (520 mµ) and at three wavelengths (Allen correction). Correlation coefficients for the laboratory personnel were .983 for females and .996 for males; for the patients, .974 and .975, respectively.

Simple Manual Procedure for Determination of Serum Triglycerides

1975 ◽  
Vol 21 (6) ◽  
pp. 768-770 ◽  
Author(s):  
Jose Mendez ◽  
Barry Franklin ◽  
Harry Gahagan
Keyword(s):  
Quality Control ◽  
Calibration Curve ◽  
Room Temperature ◽  
Extraction Procedure ◽  
Serum Triglycerides ◽  
Modified Method ◽  
Color Development ◽  
Significant Difference ◽  
Control Samples

Abstract We describe a modified method for determining serum triglycerides (triacylglycerols), which is based on the heptane extraction procedure of Gottfried and Rosenberg [Clin. Chem. 19, 1077 (1973)] with the stable saponification, oxidation, and color development reagents of Neri and Frings [Clin. Chem. 19, 1201 (1973)]. This modified method eliminates one heating step, reduces saponification time to 5 min, absorbances are read at room temperature, and the calibration curve is linear to 3.0 g/liter. A sample comparison between the proposed method and the automated Block and Jarrett [Am. J. Med. Technol. 35, 1 (1969)] procedure showed no significant difference (r = 0.98). The coefficient of variation (47 duplicate samples) for the modified method was 6.3%. Further validation was obtained from analysis of quality-control samples; the proposed method gave equivalent values.

Use of faecal organisms from sheep for the in vitro determination of digestibility

1987 ◽  
Vol 109 (2) ◽  
pp. 257-259 ◽  
Author(s):  
H. M. El Shaer ◽  
H. M. Omed ◽  
A. G. Chamberlain ◽  
R. F. E. Axford
Keyword(s):  
Modified Method ◽  
Liquid Suspension ◽  
The Relationship

SummaryA method is described in which a liquid suspension of sheep faeces is used as an inoculum in the in vitro determination of digestibility of feedingstuffs for ruminants. The modified method was applied to 21 samples of grass, ten of lucerne, and a variety of other food materials. The results correlated closely (r = 0·98) with the in vivo digestibilities, and the relationship between in vitro and in vivo digestibilities was represented by the equation: in vivo digestibility = in vitro digestibility × 1·003.

A MODIFIED METHOD FOR THE IN VITRO DETERMINATION OF DRY MATTER AND ORGANIC MATTER DIGESTIBILITY

1973 ◽  
Vol 53 (2) ◽  
pp. 251-256 ◽  
Author(s):  
R. E. LARSEN ◽  
G. M. JONES
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
In Vitro Fermentation ◽  
Modified Method ◽  
Initial Stage ◽  
Fermentation Period ◽  
Organic Matter Digestibility ◽  
Stage 1

Several modifications were made to the two-stage in vitro fermentation techniques for dry matter and organic matter digestibility (IVDMD and IVOMD) determinations developed by Tilley and Terry (J. Brit. Grassland Soc. 18: 104–111, 1963) and Alexander and McGowan (J. Brit. Grassland Soc. 21: 140–147, 1966). These modifications included: (1) changing the buffer medium, which resulted in a pH of 6.8–7.0 in the fermentation tubes during the initial (stage 1) 48-h fermentation period, and (2) shortening the acid-pepsin incubation period from 48 to 24 h, and thus reducing time for estimation of both IVDMD and IVOMD by 24 h. Modification (1) eliminated pH adjustments during fermentation and acidification at the end of the fermentation period. Acid-pepsin digestion of substrates was completed within 24 h instead of 48 h. Both IVDMD and IVOMD values were obtained on the same substrates. These modifications were evaluated using 65 samples that arose from 13 forages, comprised of corn and grass silages and their mixtures, which had been dried by five different methods. IVDMD and IVOMD were determined on all samples, comparing the modified method with the parent methods. IVDMD and IVOMD coefficients within each method were not statistically different between the Tilley and Terry method and the modified method.

Comparison of Two Methods and Improvements for Colorimetric Determination of Nitrite in Cod Roe

1979 ◽  
Vol 42 (9) ◽  
pp. 715-718 ◽  
Author(s):  
YOSHIO ITO ◽  
MICHIYO YODOSHI ◽  
JUN-ICHI TANAKA ◽  
MASAHIRO IWAIDA
Keyword(s):  
Meat Products ◽  
Reference Method ◽  
Coupling Reaction ◽  
Original Method ◽  
Colorimetric Determination ◽  
Modified Method ◽  
Color Development ◽  
Reproducible Method ◽  
Ppm Level

Attempts were made to develop a sensitive and reproducible method to determine nitrite in cod roe. Two diazotation-coupling reaction methods were considered; (a) the method defined by the Ministry of Health and Welfare of Japan (Method 1) and (b) the reference method of ISO (Method 2). Since the nitrite content in cod roe was much less than in meat products, Method 2 was modified to make it suitable for microanalysis at 1 ppm level as NO2. Modifications included reducing volumes of color-development solutions and making changes in the color development process, thus making the color intensity four times as great as before. Carrying out corrections with both reagent and water blanks made the effect of the blank on measured values negligible. Recoveries of nitrite at 20- and 2-ppm levels were 94.7 and 88.1%, respectively, reproducibility being ± 7 .9%, as the coefficient of variation. The obtained values by the modified method were, on the average, higher than those of the original method by 37.1%. Nitrite contents obtained by Method 1 were lower than those by the original Method 2. These low values might be attributed to loss of nitrite during extraction from the sample without pH adjustment, since the measured value showed a remarkable increase by addition of alkaline solution before extraction. Nitrite contents in imported cod roe were within the range 0.16–1.03 ppm expressed as NO2.

Colorimetric Determination of 2,6-Dichloro-4-Nitroaniline (Dichloran) Residues in Foods

1969 ◽  
Vol 52 (4) ◽  
pp. 797-799
Author(s):  
James A Heagy
Keyword(s):  
Colorimetric Method ◽  
Chromatographic Column ◽  
Colorimetric Determination ◽  
Modified Method ◽  
Color Development ◽  
Development Procedure

Abstract The colorimetric method of Groves and Chough for determining dichloran residues in food was modified. The modified method uses a Florisil chromatographic column cleanup and a Bratton-Marshall color development procedure. Recoveries ranged from 90 to 100% for eight crops. The method is recommended for further study.

Interference by Formaldehydogenic Drugs in the Quantitative Determination of Urinary Hydroxyindoleacetic Acid

1967 ◽  
Vol 13 (5) ◽  
pp. 397-405 ◽  
Author(s):  
Maurice E Shils
Keyword(s):  
Sulfate Ions ◽  
Color Development ◽  
Normal Individuals ◽  
Hydroxyindoleacetic Acid ◽  
Qualitative Test ◽  
Per Se ◽  
Development In Vitro

Abstract The administration of methenamine mandelate (Mandelamine) to normal individuals and patients with carcinoid resulted in a marked reduction in apparent urinary hydroxyindoleacetic acid (HIAA) as determined by the quantitative nitroso-naphthol method. Mandelamine, methenamine, and formaldehyde inhibited the normal color development in vitro. The interfering reaction is dependent on an acid pH and is not reversed by raising the pH. It is suggested that formaldehyde is the active substance and the role of mandelamine and methenamine is that of a precursor of this substance in acid solution. Chloride and sulfate ions, per se, caused a definite but limited interference with the color reaction. Under the conditions of this study, mandelamine did not prevent detection of elevated urinary HIAA by the qualitative test for HIAA.

scholarly journals Biological Safety Studies and Simultaneous Determination of Linagliptin and Synthetic Impurities by LC-PDA

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Raquel Balestri Heleno Ferreira ◽  
Jonathaline Apollo Duarte ◽  
Flávio Dias Ferreira ◽  
Luis Flávio Souza de Oliveira ◽  
Michel Mansur Machado ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Degradation Products ◽  
Correlation Coefficients ◽  
Gradient Elution ◽  
Biological Safety ◽  
Ich Guidelines ◽  
Toxicity Potential ◽  
Safety Studies

A stability-indicating LC method was developed for quantification of linagliptin (LGT) and three synthetic impurities. The method utilizes a Thermo Scientific® RP-8 column (100 mm × 4.6 mm; 5 μm) with the PDA detector for quantitation of impurities. A mixture of 0.1% formic acid with pH 3.5 (A) and acetonitrile (B) was used as the mobile phase at a flow rate of 0.6 mL·min−1 with gradient elution. The percentage of mobile phase B increases from 30% to 70% over 5 min and decreases from 70% to 30% between 5 and 8 min. The method was validated according to International Council for Harmonization (ICH) guidelines. The LOD values obtained were 0.0171 μg·mL−1 and 0.015 μg·mL−1 for LGT and impurities, respectively. The LOQ values were 0.06 μg·mL−1 for LGT and impurities. In all cases, the correlation coefficients of LGT and impurities were >0.999, showing the linearity of the method. The % recovery of the LGT and added impurity were in the range of 92.92–99.79%. The precision of the method showed values less than 1.47% for LGT and less than 4.63% for impurities. The robustness was also demonstrated by small modifications in the chromatographic conditions. The selectivity was evidenced because the degradation products formed in stress conditions did not interfere in the determination of LGT and impurities. Toxicity prediction studies suggested toxicity potential of the impurities, which was confirmed using biological safety studies in vitro.

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