scholarly journals A rapid and direct method for the quantitative determination of tryptophan in the intact protein

1970 ◽  
Vol 117 (5) ◽  
pp. 907-911 ◽  
Author(s):  
M. K. Gaitonde ◽  
T. Dovey
Keyword(s):  
Acetic Acid ◽  
Quantitative Determination ◽  
Direct Method ◽  
Intact Protein ◽  
Intact Proteins ◽  
Free Tryptophan ◽  
Acid Reagent ◽  
Tryptophan Content ◽  
Good Agreement

1. A method is given for the quantitative determination of free tryptophan or tryptophan in the intact protein by treating with ninhydrin in a mixture of formic acid and hydrochloric acid (reagent b), for 10min at 100°C. Glycyltryptophan was used as a standard for the determination of tryptophan in the intact protein. The extinction at 390nm was linear in the range 0.05–0.5μmol for free tryptophan (∈7120) and 0.05–0.30μmol for glycyltryptophan (∈15400). 2. Free tryptophan in the presence of protein may be determined by treating with ninhydrin in a mixture of acetic acid and 0.6m-phosphoric acid (reagent a) for 10min at 100°C, the extinction being linear for tryptophan in the range 0.05–0.9μmol. N-Terminal tryptophan peptides also give the typical yellow product on treatment with reagent a. 3. Tryptophan content of several pure intact proteins when treated with the above method gave values in good agreement with those reported by others. A mean tryptophan content of 11.25 (s.e.m. ±0.08) μmol/100mg of protein was found in rat brain during development from 1 to 82 days after birth.

QUANTITATIVE DETERMINATION OF CURCUMIN IN TURMERIC POWDER AND TURMERIC–HONEY BALL PILLS BY HPLC

2018 ◽  
Vol 8 (4) ◽  
pp. 42-47
Author(s):  
Tien Nguyen Huu ◽  
Tram Le Thi Bao ◽  
Ngoc Nguyen Thi Nhu ◽  
Thang Phan Phuoc ◽  
Khan Nguyen Viet
Keyword(s):  
Acetic Acid ◽  
Gastric Mucosa ◽  
Quantitative Determination ◽  
Mobile Phase ◽  
Curcuma Longa ◽  
Biological Marker ◽  
Hplc Method ◽  
Chromatography Analysis ◽  
Precision And Accuracy

Background: Curcumin is a major ingredient in turmeric (Curcuma longa L., Zingiberaceae), which has important activities such as anti-tumor, anti-inflammatory, antioxidant, anti-ischemia, protection of gastric mucosa etc,. Curcumin can be considered as a biological marker of turmeric and turmeric products. Objectives: Developing an HPLC method for quantification of curcumin in turmeric powder and turmeric - honey ball pills; applying this method for products on the market. Materials and methods: turmeric powder and turmeric - honey ball pills collected in Thua Thien Hue province. After optimization process, the method was validated and applied to evaluate the content of curcumin. Results: The chromatography analysis was performed with: Zorbaz Eclipse XDB-C18 (150 × 4.6 nm; 5 µm); Mobile phase: acetonitril: 2% acetic acid (45:55), Flow rate was kept constant at 1.0 ml/min; Detector PDA (420 nm). The method was validated for the HPLC system compatibility, specificity, linearity range, precision and accuracy; the recovery greater than 98%. Conclusion: The developed HPLC method can determine curcumin in turmeric powder and turmeric - honey ball pills. Key words: Curcumin, turmeric powder, turmeric-honey ball pills, quantitative determination, HPLC

scholarly journals New perspective in the assessment of total intracellular magnesium

2014 ◽  
Vol 87 (1) ◽  
Author(s):  
Azzurra Sargenti ◽  
Lucia Merolle ◽  
Giulia Andreani ◽  
Concettina Cappadone ◽  
Giovanna Farruggia ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Atomic Absorption Spectroscopy ◽  
Biological Processes ◽  
Intracellular Magnesium ◽  
Qualitative And Quantitative ◽  
High Affinity ◽  
New Family ◽  
New Perspective ◽  
Good Agreement

Magnesium (Mg) is essential for biological processes, but its cellular homeostasis has not been thoroughly elucidated, mainly because of the inadequacy of the available techniques to map intracellular Mg distribution. Recently, particular interest has been raised by a new family of fluorescent probes, diaza-18-crown-hydroxyquinoline (DCHQ), that shows remarkably high affinity and specificity for Mg, thus permitting the detection of the total intracellular Mg. The data obtained by fluori- metric and cytofluorimetric assays performed with DCHQ5 are in good agreement with atomic absorption spectroscopy, confirming that DCHQ5 probe allows both qualitative and quantitative determination of total intracellular Mg.

Determination of Carbaryl Residues in Honey Bees

1965 ◽  
Vol 48 (4) ◽  
pp. 771-774
Author(s):  
D P Johnson ◽  
H A Stansbury
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Quantitative Determination ◽  
Honey Bees ◽  
Methylene Chloride ◽  
Hydrolysis Product ◽  
Separate Analysis ◽  
Yellow Substance ◽  
Hydrolysis Of

Abstract A method has been developed for detecting residues of carbaryl (1-naphthyl methylcarbamate) as well as its hydrolysis product, 1-naphthol, in dead bees. The method is based on extraction of the bees with benzene, followed by a cleanup involving liquid partitioning and chromatography on Florisil. The quantitative determination involves hydrolysis of carbaryl to 1-naphthol and coupling of the latter with p-nitrobenzenediazonium fluoborate in acetic acid to form a yellow substance. For separate analysis, free 1-naphthol is separated from methylene chloride into a basic aqueous solution. The sensitivity of the method is about 0.1 ppm; recoveries averaged 85.6 ± 6.6% for 1- naphthol and 83.8 ± 2.7% for carbaryl.

Reverse Phase Liquid Chromatographic Determination of Some Food Additives

1987 ◽  
Vol 70 (3) ◽  
pp. 578-582 ◽  
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.

Partition Column for Determination of Glyceryl Trinitrate in Tablets

1964 ◽  
Vol 47 (3) ◽  
pp. 471-473
Author(s):  
John R Hohmaxn ◽  
Joseph Levine
Keyword(s):  
Acetic Acid ◽  
Glyceryl Trinitrate ◽  
Chromatographic Separation ◽  
Distillation Method ◽  
Sublingual Glyceryl Trinitrate ◽  
Acid Reagent ◽  
Quantitative Results

Abstract A method using column partition chromatographic separation has been developed for the determination of nitroglycerin in soluble, sublingual glyceryl trinitrate tablets. A mixture of the phenoldisulfonic acid reagent and acetic acid is used to extract the nitroglycerin from the eluate. Quantitative results are obtained by measuring the color of the nitrated phenoldisulfonic acid that is formed. Results by the method are in agreement with those obtained by the USP distillation method and an infrared assay.

Note on the Determination of Exchangeable Sodium in Soils

1930 ◽  
Vol 20 (3) ◽  
pp. 355-358 ◽  
Author(s):  
Rice Williams
Keyword(s):  
Acetic Acid ◽  
Ammonium Chloride ◽  
Uranyl Acetate ◽  
Exchangeable Sodium ◽  
Method Of Determination ◽  
Good Agreement

1. The application of the zinc uranyl acetate method to the determination of exchangeable sodium in soils is discussed.2. Using this method of determination, good agreement was found between the exchangeable sodium extracted by 0·5 N acetic acid and that extracted by N ammonium chloride.3. The procedure for estimating sodium in acetic acid extracts is described, and the results for a number of typical non-saline Welsh soils are given.

Determination Of Tryptophan Content In Infant Formulas And Medical Nutritionals

1992 ◽  
Vol 75 (6) ◽  
pp. 1112-1119 ◽  
Author(s):  
Saul E Garcia ◽  
Jeffrey H Baxter
Keyword(s):  
Internal Standard ◽  
Enzymatic Digestion ◽  
Reversed Phase ◽  
Infant Formulas ◽  
Free Tryptophan ◽  
Relative Standard ◽  
Wide Range ◽  
Time Requirements ◽  
Tryptophan Content

Abstract A method was developed for determination of total tryptophan content in soy- and milk-based nutritional products. The method uses enzymatic (pronase) digestion of the protein to release tryptophan, which is separated and quantitated by isocratic reversed-phase liquid chromatography with fluorescence detection. Enzymatic digestion is completed for products containing these types of proteins in less than 6 h and is accomplished under chemically mild conditions (pH 8.5,50°C), which do not significantly degrade tryptophan. Chromatographic separation is complete in about 8 min, including an internal standard. The precision of the method is 1-2% relative standard deviation. Accuracy is demonstrated by agreement with theoretical values for standard proteins (amino acid sequence known) and by quantitative recoveries of overspikes, which use either free tryptophan or a standard protein as the spiking material. The method allows determinations on samples containing a wide range of tryptophan values. Appropriate sample size selection and verification of digestion time requirements should allow the method to be applied to different protein types as well. The method allows 24 h turnaround of tryptophan analyses, and quantitative recoveries represent a significant improvement on existing techniques applied to infant formulas and other nutritional products.

scholarly journals Performance Characteristics of UV and Visible Spectrophotometry Methods for Quantitative Determination of Norfloxacin in Tablets

2014 ◽  
Vol 6 (3) ◽  
pp. 531-541 ◽  
Author(s):  
L. Chierentin ◽  
H. R. N. Salgado
Keyword(s):  
Absorption Maximum ◽  
Good Accuracy ◽  
Chloranilic Acid ◽  
Spectrophotometric Methods ◽  
Ich Guidelines ◽  
Label Claim ◽  
Acid Reagent ◽  
Development And Validation ◽  
Good Agreement

This work has proposed the development and validation of ultraviolet (UV) and visible (Vis) spectrophotometric methods for the determination of norfloxacin in the tablets. The proposed methods were applied to pharmaceutical formulation and percent amount of drug estimated (96.08% for UV method and 102.65% for Vis method) and was found in good agreement with the label claim. Using the UV method norfloxacin showed an absorption maximum at 277 nm, in 0.1 M hydrochloridric acid medium, whereas for the Vis spectrophotometric method it reacts with chloranilic acid reagent, forming a purple solution with an absorption maximum at 520 nm. The calibrations curves were linear over the working range of 2.0-7.0 ?g.mL-1 for the UV method and 90.0-120.0 ?g/mL for the Vis method. The linear regression equation for UV method was y = 0.1303x+0.0026 (r2=0.9999) and for Vis method y = 0.0037x-0.0069 (r2 = 0.9948), they proved to be linear. The methods were completely validated according to the International Conference Harmonization (ICH) guidelines, showing good accuracy, precision, selectivity, linearity and robustness. Therefore the both methods were found to be simple, rapid, sensitive, and easily contributing to the quality control of norfloxacin tablets while being interchangeable. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i3.18381 J. Sci. Res. 6 (3), 531-541 (2014)

scholarly journals Exploring peptide capture by anti-protein antibodies for LC-MS-based biomarker determination

2018 ◽  
Author(s):  
Maren Levernæs ◽  
Bassem Farhat ◽  
Inger Oulie ◽  
Sazan S. Abdullah ◽  
Elisabeth Paus ◽  
...  
Keyword(s):  
Protein Extraction ◽  
High Sensitivity ◽  
Intact Protein ◽  
Protein Biomarkers ◽  
Promising Technique ◽  
Intact Proteins ◽  
Protein Levels ◽  
Endogenous Protein ◽  
Sensitivity And Selectivity

<p>Immunocapture LC-MS/MS is a promising technique to ensure high sensitivity and selectivity of low-abundant protein biomarkers. For this purpose, the use of monoclonal antibodies (mAb) is especially attractive as they are renewable reagents that can be standardized. In this article we investigated the possibility of using mAbs developed against intact proteins (anti-protein antibodies) to capture proteotypic epitope peptides. Three mAbs were tested, and all selectively extracted proteotypic epitope peptides from a complex sample. Compared to intact protein extraction, this concept which we call peptide capture by anti-protein antibodies provided cleaner extracts, which further improved the sensitivity. Analysis of three patient samples demonstrated that p can be used for the determination of different endogenous protein levels. </p><p></p>

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