scholarly journals A NEW METHOD FOR THE DIRECT DETERMINATION OF ALUMINA IN PRESENCE OF IRON, MANGANESE, CALCIUM, AND MAGNESIUM.

1899 ◽  
Vol 21 (9) ◽  
pp. 776-780 ◽  
Author(s):  
William H. Hess ◽  
E. D. Campbell
Keyword(s):  
Direct Determination ◽  
New Method ◽  
Calcium And Magnesium ◽  
Iron Manganese

New Method for the Direct Determination of Dissolved Fe(III) Concentration in Acid Mine Waters

1999 ◽  
Vol 33 (5) ◽  
pp. 807-813 ◽  
Author(s):  
Tanya Bangthanh To ◽  
D. Kirk Nordstrom ◽  
Kirkwood M. Cunningham ◽  
James W. Ball ◽  
R. Blaine McCleskey
Keyword(s):  
Direct Determination ◽  
New Method ◽  
Mine Waters ◽  
Acid Mine ◽  
Acid Mine Waters

scholarly journals A new spectrofluorimetric method for the determination of ascorbic acid with bromocresol purple in pharmaceutical samples

2021 ◽  
Vol 3 (11) ◽  
Author(s):  
L. Klepo ◽  
M. Ascalic ◽  
D. Medunjanin ◽  
A. Copra-Janicijevic
Keyword(s):  
Ascorbic Acid ◽  
Folic Acid ◽  
Citric Acid ◽  
Magnesium Carbonate ◽  
New Method ◽  
Bromocresol Purple ◽  
Pharmaceutical Samples ◽  
Spectrofluorimetric Method ◽  
Calcium And Magnesium

Abstract Based on the interaction between ascorbic acid and bromocresol purple, a new simple, straightforward, and quick method for the quantification of ascorbic acid is proposed. The procedure is based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of bromocresol purple in the reaction between ascorbic acid and bromocresol purple in phosphate buffer solution (pH 6). The reduction of bromocresol purple fluorescence intensity is detected at 641 nm, while excitation occurs at 318 nm. The linear relationship between the reduced fluorescence intensity of bromocresol purple and the concentration of ascorbic acid is in the range 4.65 × 10–5 to 4.65 × 10–6 mol L−1 (R2 = 0.9964), with the detection limit of 8.77 × 10–7 mol L−1 and quantification limit of 2.35 × 10–5 mol L−1. The findings in this study further show that the new method provides good precision and repeatability, as well as satisfactory recovery values in terms of accuracy. The new method is tested on fifteen samples with different amounts of ascorbic acid and additional components. The effects of interfering components such as citrus bioflavonoids, citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The effects of interfering components such as citrus bioflavonoids (routine and hesperidin), citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The results of iodometric titration point out that the new method is effective for the determination of ascorbic acid in pharmaceutical samples. Article Highlights A new spectrofluorimetric method for determination of ascorbic acid in pharmaceutical samples using bromocresol purple. Determination of optimal parameters for ascorbic acid determination in a variety of pharmaceutical samples. Examination of the influence of additional substances in the pharmaceutical samples on the analysis.

scholarly journals Leptin Binding and Binding Capacity in Serum

2000 ◽  
Vol 46 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Michael Landt
Keyword(s):  
Adipose Tissue ◽  
Molecular Mass ◽  
Binding Capacity ◽  
Direct Determination ◽  
New Method ◽  
Degree Of Saturation ◽  
Free Form ◽  
Hplc Separation ◽  
Serum Leptin

Abstract Background: Leptin, a hormone produced primarily by adipose tissue, is known to be present in serum as both monomeric (free) and higher molecular mass (bound) forms, but little is known about the nature of the bound forms or physiological variation in binding capacity. Methods: A new method to quantify the free and bound forms was developed, based on HPLC separation and RIA quantification in chromatography fractions. Reanalysis of specimens after addition of exogenous leptin allowed direct determination of leptin-binding capacity and the degree of saturation of leptin-binding capacity. Results: HPLC chromatography fractionated serum leptin into both the free form and as a broad peak of 59–130 kDa. Several experiments were conducted to validate the new method. The concentrations of bound leptin in serum were 0.45–3.94 μg/L, and they increased as total leptin (reflecting adiposity) increased in 24 lean and obese volunteers. Leptin was readily dissociated from the bound fraction by competition from exogenous leptin. Rechromatography of the bound fraction led to dissociation of leptin, which was promoted by warming the sera before chromatography. Leptin-binding capacity was 1.8–5.3 μg/L; binding capacity was nearly constant over a range of total leptin concentrations of 2–10 μg/L, and slowly increased at higher total leptin concentrations. Saturation of binding capacity was low (15%) at very low total leptin concentrations (<5 μg/L), but rose quickly to a plateau near 80% at higher total leptin concentrations. Conclusions: The new method facilitates measurement of free and bound fractions of serum leptin, and is the first method measuring leptin-binding capacity. These experiments demonstrate that the concentration of bound leptin and leptin-binding capacity vary physiologically, with binding/binding capacity increasing with adiposity. Except in very lean individuals, binding capacity is nearly completely saturated.

New Method for Direct Determination of "True" Creatinine

1974 ◽  
Vol 20 (9) ◽  
pp. 1131-1134 ◽  
Author(s):  
Hippocrates Yatzidis
Keyword(s):  
Ion Exchange ◽  
Serum Creatinine ◽  
Direct Determination ◽  
Direct Analysis ◽  
Color Reaction ◽  
New Method ◽  
Exchange Method ◽  
Ion Exchange Method ◽  
Serum And Urine

Abstract Determination of serum creatinine by the Jaffé reaction may give erroneous results because of interfering noncreatinine chromogens. Studies of the Jaffé reaction in alkaline picrate media of various pH demonstrated that creatinine, proteins, and certain chromogens have characteristic properties as regards the appearance and intensity of the color reaction. Thus a method for determining "true" creatinine has been developed in which simple spectrophotometric measurements are made at 500 nm in two alkaline picrate reagents, buffered at pH 9.65 and 11.50. Results agree well with those obtained by the use of an ion-exchange method. The proposed method is easy and rapid and offers the advantages of increased specificity and direct analysis of serum and urine.

Sign in / Sign up

Export Citation Format

Share Document