scholarly journals Colorimetric Determination of the Activity of Starch-Debranching Enzyme via Modified Tollens’ Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1291 ◽  
Author(s):  
Ke Luo ◽  
Nack-geun Kim ◽  
Sang-Mook You ◽  
Young-Rok Kim
Keyword(s):  
Colloidal Stability ◽  
Colorimetric Assay ◽  
Colorimetric Determination ◽  
Detection Range ◽  
Debranching Enzymes ◽  
Absorbance Peak ◽  
Starch Debranching Enzyme ◽  
Aldehyde Groups ◽  
Determination Of Activity

Nelson–Somogyi and 3,5-dinitrosalicylic acid (DNS) assays are the classical analytical methods for the determination of activity of starch-debranching enzymes, however, they have a narrow detection range and do not adapt to the quantitative measurement of linear polysaccharides. Herein, we developed a simple and accurate colorimetric assay for determining the activity of starch-debranching pullulanase through the modified Tollens’ reaction in combination with UV irradiation. Silver nanoparticles (AgNPs) were formed by reducing aldehyde groups in short-chain glucans (SCGs) generated by debranching of waxy maize starch using pullulanase through the modified Tollens’ reaction. In addition to providing a reducing moiety to the Tollens’ reaction, the debranching product, SCGs, also enhanced the colloidal stability of synthesized AgNPs, of which the amplitude of its surface plasmon resonance (SPR) absorbance peak was proportional to the concentration of SCGs ranging from 0.01–10 mg/mL. The detection limit of this system was 0.01 mg/mL, which was found to be 100 times higher than that of the conventional DNS assay. The purification of SCGs by recrystallization and gelatinization improved the selectivity of this colorimetric assay for debranching products, which provides a simple and accurate means of monitoring the debranching process and characterizing the activity of starch-debranching enzymes.

Rapid Colorimetric Assay of Trimethoprim and Sulfamethoxazole in Pharmaceuticals

1983 ◽  
Vol 66 (6) ◽  
pp. 1447-1449 ◽  
Author(s):  
Asis K Sanyal ◽  
Dinabandhu Laha
Keyword(s):  
Solvent Extraction ◽  
Colorimetric Assay ◽  
Pharmaceutical Preparations ◽  
Ion Pair ◽  
Pair Formation ◽  
Bromophenol Blue ◽  
Colorimetric Determination ◽  
Ion Pair Formation ◽  
Subsequent Measurement

Abstract A method is described for the direct colorimetric determination of trimethoprim and sulfamethoxazole in pharmaceutical preparations, without prior separation. Estimation of trimethoprim is based on its ion-pair formation with bromophenol blue and subsequent measurement of absorbance of the ionpair at 418 nm. Estimation of sulfamethoxazole is possible without removal of trimethoprim by solvent extraction.

Convenient and sensitive colorimetric determination of alendronate sodium with Ce4+-triggered oxidation of TMB

2020 ◽  
Vol 44 (30) ◽  
pp. 12962-12966
Author(s):  
Jing Sun ◽  
Rui Wang ◽  
Meng Xia ◽  
Shuyun Zhu ◽  
Xian-En Zhao
Keyword(s):  
Colorimetric Assay ◽  
Colorimetric Determination ◽  
Selective Detection ◽  
Alendronate Sodium ◽  
First Time

A facile colorimetric assay for the sensitive and selective detection of alendronate sodium has been developed based on Ce4+-triggered oxidation of TMB for the first time.

Colorimetric Determination of Potassium in Plasma and Serum by Reflectance Photometry with a Dry-Chemistry Reagent

1992 ◽  
Vol 38 (7) ◽  
pp. 1371-1372 ◽  
Author(s):  
R H Ng ◽  
K M Sparks ◽  
B E Statland
Keyword(s):  
Reference Material ◽  
Standard Reference Material ◽  
Colorimetric Assay ◽  
Ion Selective Electrode ◽  
Colorimetric Determination ◽  
Selective Electrode ◽  
Flame Photometer ◽  
Near Patient Testing

Abstract We evaluated a colorimetric assay of potassium in plasma and serum with the Boehringer Mannheim Reflotron reflectance photometric analyzer, which is designed for near-patient testing in hospitals and physicians' offices. This potassium method does not require calibration or instrument maintenance by the operator. Analysis of 30 microL of plasma or serum takes approximately 140 s. Within-day imprecision (CV) was 1.0-1.2%. Total CVs over a 1-month period were 1.0-1.4%. Patients' results from the Reflotron correlated well with those from the IL 643 flame photometer and the Beckman Synchron CX3 ion-selective electrode methods. The accuracy of Reflotron values was also verified with Standard Reference Material 956 from the National Institute of Standards and Technology.

Colorimetric Determination of Serum Isocitric Dehydrogenase

1960 ◽  
Vol 6 (3) ◽  
pp. 208-215 ◽  
Author(s):  
Thomas H Taylor ◽  
Michael E Friedman
Keyword(s):  
Colorimetric Assay ◽  
Colorimetric Determination ◽  
Reaction Products ◽  
Standard Unit ◽  
Isocitric Dehydrogenase

Abstract A colorimetric assay of serum isocitric dehydrogenase has been described in which the α-ketoglutaric acid formed is determined as the hydrazone. A standard unit of lCD activity is defined as millimicromoles KG-A formed per milliliter serum per hour of incubation at 37°. Analyses of KGA and TPNH as reaction products show that 1.58 moles of KGA are formed for each mole of TPNH under the conditions of this experiment.

Analyses of Fat-Soluble Vitamins, XIV. Collaborative Study of the Determination of Vitamin D in Multivitamin Preparations

1977 ◽  
Vol 60 (1) ◽  
pp. 151-154
Author(s):  
Frits J Mulder ◽  
Ellen J De Vries ◽  
Ben Borsje
Keyword(s):  
Vitamin D ◽  
Polyethylene Glycol ◽  
Vitamin A ◽  
Colorimetric Assay ◽  
Collaborative Study ◽  
Official Method ◽  
Colorimetric Determination ◽  
Trans Isomers ◽  
Decomposition Products

Abstract The colorimetric assay for the determination of vitamin D (4000—50,000 international units (IU)/g) in multivitamin preparations has been collaboratively studied. The method is based on the same principle as the official method for the determination of vitamin D in concentrates, i.e., elimination of trans-isomers of vitamin D resins. The method includes the following steps: saponification and extraction (isolation of unsaponifiable material), phosphate-treated alumina column chromatography (elimination of tocopherols and vitamin A decomposition products), partition chromatography with polyethylene glycol 600 and Celite (separation of vitamin D fraction from vitamin A alcohol), adsorption chromatography on Florex (elimination of vitamin A decomposition products and small amounts of polyethylene glycol 600), maleic anhydride addition reaction (elimination of trans-isomers of vitamin D resins), and colorimetric determination at 2 wavelengths with and without acetic anhydride (an inhibitor for the color reaction of vitamin D and antimony trichloride). The mean result of 4 laboratories for 8 different samples, expressed as per cent of the known amount of vitamin D added, was 95.8% with a coefficient of variation of 10.5%. Considering the complexity of the method, the collaborative results were reasonable. The method has been adopted as official first action.

Rapid Colorimetric Assay for Nitroglycerin, Suitable for Content Uniformity Testing

1970 ◽  
Vol 53 (3) ◽  
pp. 579-581
Author(s):  
Clyde E Wells ◽  
Harvey M Miller ◽  
Yvonne H Pfabe
Keyword(s):  
Standard Deviation ◽  
Colorimetric Assay ◽  
Content Uniformity ◽  
Colorimetric Determination ◽  
Isolation Method ◽  
Infrared Method ◽  
Content Uniformity Testing ◽  
Chromatographic Isolation ◽  
Column Chromatographic

Abstract The column chromatographic isolation method of Hohmann and Levine has been combined with a modified version of the colorimetric determination of Bell, resulting in a convenient assay for nitroglycerin in tablets. The method agrees closely with the AOAC infrared method and is sensitive enough for analysis of individual tablets (0.15 mg nitroglycerin). The standard deviation is 0.91% at the 1.2 mg level.

scholarly journals Colorimetric Determination of Hypochlorite Based on the Oxidative Leaching of Gold Nanorods

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1629 ◽  
Author(s):  
Yurong Ma ◽  
Yingyi Zhu ◽  
Benzhi Liu ◽  
Guixiang Quan ◽  
Liqiang Cui
Keyword(s):  
Gold Nanorods ◽  
Color Change ◽  
Colorimetric Assay ◽  
Tap Water ◽  
Critical Role ◽  
Colorimetric Method ◽  
Residual Chlorine ◽  
Colorimetric Determination ◽  
Oxidative Leaching

Hypochlorite plays a critical role in killing microorganisms in the water. However, it can also cause cardiovascular diseases, neuron degeneration, and cancer to humans. Although traditional methods feature excellent sensitivity and reliability in detecting hypochlorite, the expensive instruments and strict determination conditions have limited their application in environmental analysis to some extent. Thus, it is necessary and urgent to propose a cheap, facile, and quick analytical assay for hypochlorite. This paper proposes a colorimetric assay for hypochlorite utilizing gold nanorods (AuNRs) as the nanoreactor and color reader. The AuNRs were acquired via a reported seed-mediated method. NaClO with strong oxidation property can cause the etching of gold from the longitudinal tips of AuNRs, which could shorten the aspect ratio of AuNRs, decrease the absorption in the UV–Vis spectrum and also induce the solution color changing from red to pale yellow. Thus, according to the solution color change and the absorbance of longitudinal surface plasmon resonance of AuNRs, we established the calibration curve of NaClO within 0.08 μM to 125 μM (∆Abs = 0.0547 + 0.004 CNaClO, R2 = 0.9631). Compared to traditional method, we obtained the conversion formula between the concentration of residual-chlorine in tap water and the concentration of hypochlorite detected by the proposed colorimetric assay, which is Cresidual-chlorine = 0.24 CNaClO. Finally, the real application of the colorimetric assay in tap water was successfully performed, and the accuracy of the colorimetric method can reach from −6.78% to +8.53%.

A MODIFIED METHOD FOR THE COLORIMETRIC DETERMINATION OF HEPARIN

1967 ◽  
Vol 45 (5) ◽  
pp. 787-794 ◽  
Author(s):  
L. B. Jaques ◽  
A. Wollin
Keyword(s):  
Colorimetric Assay ◽  
Colorimetric Determination ◽  
Azure A ◽  
Modified Method

A sensitive accurate quantitative colorimetric assay for heparin with Azure A using the Beckman DK-2 spectrophotometer is described. Limits for the presence of impurities and precautions are given.

scholarly journals Effects of the Drug Disulphine Blue on Routine Biochemical Investigations

1983 ◽  
Vol 20 (5) ◽  
pp. 317-320 ◽  
Author(s):  
Stephen P Halloran ◽  
David J Torrens
Keyword(s):  
Binding Capacity ◽  
Total Iron ◽  
Blue Dye ◽  
Colorimetric Determination ◽  
Reaction Conditions ◽  
Successive Sampling ◽  
Absorbance Peak ◽  
Iron Binding Capacity ◽  
Significant Interference

Major interference by Disulphine Blue in the colorimetric determination of amylase, albumin, protein, iron and total iron-binding capacity is described. The drug, an intense blue dye, was administered intravenously to a patient before surgery to allow demarcation of devitalised bone. Successive sampling showed the drug to have a half-life of 30 hours, to remain visible for 150 hours in both urine and blood, and to cause significant interference with the five analytes for up to 2 1/2 days. The 640 nm absorbance peak of Disulphine Blue was shown to be pH-dependent, and therefore the reaction conditions of individual methods may influence the degree of interference.

Rapid Colorimetric Determination of Activity of Subtilisin Enzymes in Cleaning Products

1989 ◽  
Vol 72 (6) ◽  
pp. 881-882
Author(s):  
Allan E Klein ◽  
John Freiberg ◽  
Steven Same ◽  
Maryanne Carroll
Keyword(s):  
Colorimetric Method ◽  
Hydrolytic Activity ◽  
Colorimetric Determination ◽  
Cleaning Product ◽  
Cleaning Products ◽  
Spontaneous Hydrolysis ◽  
Relative Standard ◽  
Determination Of Activity ◽  
Hydrolysis Of

Abstract A new colorimetric method is described for the determination of enzymatic activity of subtilisin in cleaning products. The procedure is more rapid and precise than the casein digestion methods commonly used to assay protease activity. The principle of the colorimetric method depends on the determination rate of p-nitrophenol released on hydrolysis of N-CBZ-L-leucine-/Miitrophenyl ester at pH 8.0 by subtilisin, with correction for any nonenzymatic (spontaneous) hydrolysis of the substrate. Because of the broad range of hydrolytic activity of this enzyme, and the difficulties in predicting its proteolytic activity, this hydrolytic rate was chosen as a general indicator of subtilisin enzyme behavior. The slope for 7 replicate standard curves generated over a 6 week period exhibited a relative standard deviation of 7.5%, and 8.0% for 20 replicates with an enzyme cleaning product. Papain does not interfere with this assay.

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