scholarly journals Quenching-Chemiluminescence Determination of Trace Amounts ofl-Tyrosine Contained in Dietary Supplement by Chemiluminescence Reaction of an Iron-Phthalocyanine Complex

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Takao Ohtomo ◽  
Shukuro Igarashi ◽  
Yoshitaka Takagai ◽  
Osamu Ohno
Keyword(s):  
Dietary Supplement ◽  
Iron Phthalocyanine ◽  
Phthalocyanine Complex

scholarly journals Single-Laboratory Validation Study of a Proton NMR Method for the Determination of L-Arginine, L-Citrulline, and Taurine Contents in Dietary Supplements

2020 ◽  
Vol 103 (4) ◽  
pp. 1140-1147
Author(s):  
Isaac Lee ◽  
Jennie Vo ◽  
Quanyin Gao ◽  
Piyush Purohit ◽  
Veronica Zarraga ◽  
...  
Keyword(s):  
Quality Control ◽  
Dietary Supplement ◽  
Proton Nmr ◽  
Hplc Method ◽  
Rapid Analysis ◽  
Test Method ◽  
Method Performance ◽  
Single Laboratory ◽  
Concentration Levels

Abstract Background A quantitative NMR (qNMR) method can provide rapid analysis compared to chromatographic methods. Sample preparation steps are relatively simpler and run time is shorter. Rapid analysis methods for release tests in quality control laboratories are very important for laboratory efficiency. Here, we describe a single-laboratory validation study for a rapid qNMR analysis of L-arginine, L-citrulline, and taurine in powdered and tablet dietary supplement products. Objectives This validation work is to provide documented evidence for the qNMR method validity as well as method performance. Methods The method used Bruker 400 MHz high-resolution proton NMR spectroscopy for simultaneous determination of L-arginine, L-citrulline, and taurine contents in dietary supplement product 1 (powder) and dietary supplement product 2 (tablet). The absolute NMR quantitation is based on a principle of universal proton response intensity correlation with the number of protons in each target analyte (amino acids) vs. that of a reference standard (maleic acid). Results The test method performance was validated with dietary supplement-1 (powder) and dietary supplement-2 (tablet). The linearity of the method was studied from about 360 mg/g to about 675 mg/g of L-arginine; from about 15 mg/g to about 30 mg/g of L-citrulline; and from about 20 mg/g to about 40 mg/g of taurine in dietary supplement-1, and from about 15 mg/g to about 30 mg/g of taurine in dietary supplement-2. The coefficients of determination (R2) are 1.0000 for L-arginine, 0.9967 for L-citrulline, and 0.9995 for taurine in dietary supplement-1 and 0.9903 for taurine in dietary supplement-2. The accuracies measured from the sample matrices are 102%, 101%, and 100% average recoveries for 80%, 100%, and 120% concentration levels of L-arginine, 105%, 105%, and 103% average recoveries for 80%, 100%, and 120% concentration level of L-citrulline, and 101%, 102%, and 100% average recoveries of taurine for 80%, 100%, 120% concentration levels in dietary supplement-1; and 95, 98%, and 93% average recoveries of taurine for 80%, 100%, 120% concentration levels in dietary supplement-2, respectively. The precisions (RSD) are 1% for L-arginine, 5% for L-citrulline, and 2% for taurine in dietary supplement -1, respectively; and 4% for taurine in dietary supplement-2. The ruggedness of the test method is within 2%, 4%, and 2% for L-arginine, L-citrulline, and taurine for dietary supplement -1, respectively, and within 4% for dietary supplement-2. The method is specific for the quantitation of each nutrient with no background interference from the matrix for the proton peaks of L-arginine, L-citrulline, taurine, and maleic acid (standard). Conclusions The test method is proven to be specific, precise, accurate, rugged, and suitable for intended quantitative analysis of L-arginine, L-citrulline, and taurine in powdered and tablet finished products. Highlights The simultaneous determination of all three nutrients of L-arginine, L-citrulline, and taurine using proton NMR provides rapid analysis for quality control release tests that is more efficient versus that of two HPLC methods. Previously, our laboratory was using one HPLC method to analyze L-arginine and L-citrulline while using a second HPLC method to analyze taurine. That approach required two HPLC instruments and two analysts for parallel analysis that takes 2 days using volatile and flammable solvents for extraction and chemical derivatization. This rapid NMR method can analyze the sample “as is” with results obtained in less than 4 h, and is efficient, safe, and environmentally friendly. The initial higher NMR instrument investment versus two HPLC instruments is rewarded with high returns for continued quality control tests.

scholarly journals Determination of St. John's Wort Components in Dietary Supplements and Functional Foods by Liquid Chromatography

2002 ◽  
Vol 85 (6) ◽  
pp. 1360-1369 ◽  
Author(s):  
Catharina Y W Ang ◽  
Yanyan Cui ◽  
Hebron C Chang ◽  
Wenhong Luo ◽  
Thomas M Heinze ◽  
...  
Keyword(s):  
Dietary Supplements ◽  
Dietary Supplement ◽  
Functional Foods ◽  
Reversed Phase ◽  
Laboratory Method ◽  
St John’S Wort ◽  
St John's Wort ◽  
Photodiode Array ◽  
Liquid Chromatographic

Abstract St. John's wort ( Hypericum perforatum L.) preparations, a top-selling botanical dietary supplement used primarily as an antidepressant, has recently been used as an ingredient in some food products sold as functional foods. A rapid extraction technique followed by a liquid chromatographic (LC) method was developed to determine 4 characteristic bioactive compounds (pseudohypericin, hypericin, hyperforin, and adhyperforin) from St. John's wort in dietary supplements and functional foods to which it was added. Solid samples, including including dried leaf/flower mixture, dietary supplement capsules, tea bags, puff and snack bar, were extracted with methanol by sonication.Noncarbonated, fruit-flavored drinks were centrifuged and mixed with methanol. Compounds were then determined by isocratic, reversed-phase LC with UV detection at 2 wavelengths and further identified or confirmed by photodiode array spectra and LC/mass spectrometry. Within-laboratory method variations (% RSD) were satisfactory. Very low amounts, if any, of the 4 components were found in drink and puff samples, and none was found in the snack bar. The methods developed provide a useful means for the determination of St. John's wort components in dietary supplements and functional foods.

Preparation of iron phthalocyanine complex bearing four tetraazamacrocycles as a precursor for oxidation catalyst with two catalytic sites

2009 ◽  
Vol 13 (06) ◽  
pp. 747-752
Author(s):  
Ümit İşci ◽  
Ayşe Gül Gürek ◽  
Vefa Ahsen ◽  
Alexander B. Sorokin
Keyword(s):  
Oxidation Catalyst ◽  
Iron Phthalocyanine ◽  
Reaction Conditions ◽  
Phthalocyanine Complex ◽  
Catalytic Sites

The synthesis of the iron phthalocyanine bearing four fused tetraazamacrocycles starting from N,N',N″,N‴-tetrakis(p-tolylsulfonyl)triethylenetetraamine and 1,2-dibromo-4,5-bis(bromomethyl)benzene is reported. The exchange of protecting tosyl groups by acetyl groups was necessary to obtain iron phthalocyanine. The efficiency of iron phthalocyanine as oxidation catalyst was tested for the practically important oxidation of 2,3,6-trimethylphenol (TMP) at different reaction conditions.

scholarly journals Determination of Ephedrine Alkaloids in Dietary Supplement Standard Reference Materials

2005 ◽  
Vol 77 (10) ◽  
pp. 3101-3112 ◽  
Author(s):  
Lane C. Sander ◽  
Katherine E. Sharpless ◽  
Mary B. Satterfield ◽  
Toshihide Ihara ◽  
Karen W. Phinney ◽  
...  
Keyword(s):  
Dietary Supplement ◽  
Reference Materials ◽  
Standard Reference Materials
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