scholarly journals Liquid Chromatographic Determination of Methylxanthines and Catechins in Herbal Preparations Containing Guaraná

1998 ◽  
Vol 81 (4) ◽  
pp. 691-701 ◽  
Author(s):  
Marvin Carlson ◽  
Richard D Thompson
Keyword(s):  
Phosphate Buffer ◽  
Chromatographic Determination ◽  
Nutritional Supplement ◽  
The United States ◽  
Precision Data ◽  
Herbal Preparations ◽  
Solid Dosage ◽  
System A ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract Herbal preparations derived from the dried seeds of guarana (Paullinia cupana) have become a popular nutritional supplement used for stimulatory purposes. Once considered a drug substance in the United States, guaraná currently is classified as a food additive and dietary supplement. The pharmacological activity of guaraná-containing products is primarily due to methylxanthine alkaloids. For guaraná preparations, methylxanthine levels and, more significantly, the presence of several polyphenol compounds (i.e., catechins) provide phytochemical markers of authenticity. Methylxanthines and polyphenols are extracted from sample matrix with a heated phosphate buffer-methanol solution, the cooled extract is filtered, and the extract is injected into the liquid chromatographic (LC) system. A Nova-Pak C18 column eluted with phosphate buffer-methanol mobile phase (pH = 3.50) and monitored at 272 nm gave satisfactory resolution for the methylxanthines theobromine, theophylline, caffeine and the polyphenols (+)-catechin and (−)-epicatechin. Twenty-four products including dried seeds, dried paste, seed powders, tablets, and capsule formulations were assayed and conclusions were drawn about their authenticity. The LC system responded linearly to methylxanthines over the 100-fold range in concentration from 0.043 to 4.30 μg/mL for theobromine and caffeine and from 0.041 to 4.10 μg/mL for theophylline. Precision data for the 3 methylxanthines obtained from 10 different products (n = 5) gave relative standard deviation (RSD) values of 1.18-15.52% within a concentration range of 0.01-52.28 mg/g. Recoveries of methylxanthines from fortified products varied from 87.5 to 120.0%. The response for catechins was linear over a 200-fold range in concentration of 0.05-10.0 μg/mL. Precision data from 5 products (n = 5) gave RSD values of 1.08-5.54% within a concentration range of 0.34-32.65 mg/g. Recoveries from these products ranged from 87.7 to 109.7%. Results and chromatographic profiles for 14 commercial products in solid dosage form indicate that a number of these products may not contain authentic guaraná as an active ingredient or contain less than the declared quantity of guaraná. The proposed procedure also was applied to 2 carbonated soft drinks and a sample of mate.

scholarly journals Liquid Chromatographic Determination of S-Adenosyl-L-Methionine in Dietary Supplement Tablets

2002 ◽  
Vol 85 (4) ◽  
pp. 901-905 ◽  
Author(s):  
Joseph Ziqi Zhou ◽  
Ted Waszkuc ◽  
Spiro Garbis ◽  
Felicia Mohammed
Keyword(s):  
Dietary Supplement ◽  
Phosphate Buffer ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Ion Pair ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A simple and reliable liquid chromatographic method was developed for the determination of S-adenosyl-L-methionine (SAM) in dietary supplement tablets. SAM in products was extracted with a phosphate buffer and separated from the mixture on a reversed-phase C8 column by ion-pair chromatography. A gradient mobile phase containing phosphate buffer, sodium octanesulfonate as the ion-pair reagent, and acetonitrile at a flow rate of 1.2 mL/min was used in the analysis. The UV detection wavelength was set at 257 nm. The calibration curve was linear over a range of 75–375 μg/mL for the SAM active ion with R2 = 0.9999. Replicate tests indicated good reproducibility of the method with a relative standard deviation of 0.9% (n = 8). The multiple extractions and recoveries from fortified products showed the high accuracy of the analysis. The use of the acidic buffer for SAM extraction and elution and the use of a fresh standard for each calibration to counteract the instability of the SAM compound significantly improved the accuracy of the method.

Rapid Solvent-Efficient Method for Liquid Chromatographic Determination of Ochratoxin A in Corn, Barley, and Kidney: Collaborative Study

1992 ◽  
Vol 75 (3) ◽  
pp. 481-487 ◽  
Author(s):  
Stanley Nesheim ◽  
Michael E Stack ◽  
Mary W Trucksess ◽  
Robert M Eppley ◽  
Palle Krogh
Keyword(s):  
Ochratoxin A ◽  
Collaborative Study ◽  
Kidney Tissue ◽  
Chromatographic Determination ◽  
The United States ◽  
Relative Standard ◽  
Pork Kidney ◽  
Standard Deviations ◽  
Liquid Chromatographic

Abstract A joint Interlaboratory study of a rapid, solvent-efficient liquid chromatographic method for determination of ochratoxin A (OTA) in barley, corn, and pork kidney tissue was conducted by AOAC, the International Union of Pure and Applied Chemistry, and the Nordic Committee on Food Analysis In 16 laboratories in Europe, Canada, and the United States. OTA was added to barley and corn at 10,20, and 50 ng/g and to kidney at 5,10, and 20 ng/g. Duplicate test portions were prepared at 20 ng/g for corn and barley and 10 ng/g for kidney. Mean recoveries of OTA ranged from 53 to 97%. Within-laboratory relative standard deviations were 7.9,20.1, and 15.7% for barley, corn, and kidney tissue, respectively. Between-laboratories relative standard deviations were 20.7-31.7% for all concentrations of OTA In barley and corn and 68.0,41.8, and 32.7% for OTA concentrations of 5,10, and 20 ng/g, respectively, In kidney. OTA Identity was confirmed by methyl ester derivatization followed by liquid chromatography. The method has been adopted first action by AOAC as quantitative at the levels tested for OTA determination In corn and barley.

Liquid Chromatographic Determination of Vitamin D in Milk and Infant Formula

1985 ◽  
Vol 68 (2) ◽  
pp. 177-182
Author(s):  
David C Sertl ◽  
Bruce E Molitor
Keyword(s):  
Vitamin D ◽  
Infant Formula ◽  
Vitamin D3 ◽  
Chromatographic Determination ◽  
The United States ◽  
Vitamin D2 ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Vitamin D2 or vitamin D3 is determined by liquid chromatography (LC) in milk and infant formula. Vitamin D is extracted from the saponified sample, passed through an amino-cyano LC cleanup column to remove major interferences, and quantitated using normal phase LC. Within-day precision is 4.5% relative standard deviation (RSD); the overall method RSD (reflecting technician-to-technician, day-today, and within-day variability) is 7.7%. Overspike recoveries averaged 97% for milk, 98% for milk-based infant formula, and 93% for soy-based infant formula. The performance of the method is compared with that of the official AOAC vitamin D method (rat bioassay). The method is applicable to the determination of vitamin D in milk and in the major milk- and soy-based infant formulas available in the United States. The method can quantitate (but not distinguish) either vitamin D2 or vitamin D3. The method is applicable to milk and infant formula samples containing between 100 and 1500 IU vitamin D/L. Sample throughput is between 4 and 8 replicates per da

Liquid Chromatographic Determination of Glyphosate and Aminomethylphosphonic Acid (AMPA) in Environmental Water: Collaborative Study

1991 ◽  
Vol 74 (2) ◽  
pp. 317-323 ◽  
Author(s):  
Mark E Oppenhuizen ◽  
John E Cowell
Keyword(s):  
Collaborative Study ◽  
Chromatographic Determination ◽  
Environmental Water ◽  
Aminomethylphosphonic Acid ◽  
Relative Standard ◽  
Total Variability ◽  
Liquid Chromatographic Determination ◽  
Predicted Values ◽  
Liquid Chromatographic

Abstract A new method for determination of glyphosate and amlnomethylphosphonlc acid (AMPA) residues In environmental water was collaboratively studied by 6 laboratories. The method Is simpler and shorter than previous methods. A filtered volume of water is evaporated to dryness and the residue Is dissolved In a buffered EDTA solution. Glyphosate and AMPA are determined by liquid chromatography with postcolumn reaction detection. The method was validated over the range 0.50-5000 ppb, although one of the collaborating laboratories could not reliably quantltate below 1.0 ppb. Statistical analysis of the results showed that typical reproducibility relative standard deviations (RSDR) ranged from 11 to 20% for both glyphosate and AMPA, which compares very well with predicted values for this concentration range. Total variability (as measured by sR) Increased with increasing fortification level. The method has been adopted official first action by AOAC.

scholarly journals Stability Indicating HPLC-ECD Method for the Analysis of Clarithromycin in Pharmaceutical Dosage Forms: Method Scaling versus Re-Validation

2019 ◽  
Vol 87 (4) ◽  
pp. 31 ◽  
Author(s):  
Makoni ◽  
Chikukwa ◽  
Khamanga ◽  
Walker
Keyword(s):  
High Performance ◽  
The United States ◽  
High Performance Liquid Chromatographic ◽  
Dosage Forms ◽  
Pharmaceutical Dosage Forms ◽  
Analytical Column ◽  
Ich Guidelines ◽  
Relative Standard ◽  
Run Time ◽  
Liquid Chromatographic

An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.

Liquid Chromatographic Determination of Diclazuril in Premix and Supplemented Feed: Interlaboratory Study

1994 ◽  
Vol 77 (6) ◽  
pp. 1359-1361 ◽  
Author(s):  
Andre Fontaine ◽  
Karel Haustraete
Keyword(s):  
Solid Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Peak Height ◽  
Reversed Phase ◽  
Poultry Feed ◽  
Uv Detector ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract Diclazuril, Janssen Research Compound R 64433 (Clinacox), is analyzed by liquid chromatography (LC). Compound R 062646, with a structure analogous to that of diclazuril, is used as internal standard. The drug is extracted from feed with acidified methanol. Diclazuril is then isolated by solid-phase extraction (SPE) with a cartridge containing a C18 phase. The eluate is evaporated, and the residue is redissolved in dimethylformamide. An aliquot is injected onto a reversed-phase ODS LC column, and the drug quantitated at 280 nm with a UV detector. Peak areas are obtained at the retention times corresponding to the internal standard and diclazuril. The quantity of active ingredient is determined by comparing the ratio of the peak height of diclazuril to that of internal standard in the sample with the same ratio in a single calibration solution. SPE is not necessary for the analysis of premixes. Eleven laboratories participated in the collaborative study. Laboratories were provided with 2 samples of premixes and 3 samples of feed for poultry. Feed sample K1 was sent to only 6 laboratories. The reproducibility relative standard deviations (RSDRS) were 7.38 and 7.53% for the 2 premixes and 9.67,13.65, and 18.61% for the 3 samples of supplemented feed.

scholarly journals Liquid Chromatographic Determination of Ampicillin Residues in Porcine Muscle Tissue by a Multipenicillin Analytical Method: European Collaborative Study

2002 ◽  
Vol 85 (4) ◽  
pp. 889-900 ◽  
Author(s):  
Eric Verdon ◽  
Pierric Couëdor ◽  
Pierre Maris ◽  
Michel Laurentie ◽  
P Batjoens ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Muscle Tissue ◽  
Phosphate Buffer ◽  
Collaborative Study ◽  
Porcine Muscle ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract A collaborative study involving 14 laboratories was conducted to determine residues of ampicillin in porcine muscle tissue by using a liquid chromatographic method developed for multipenicillin analysis that can quantitate 8 penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, nafcillin, oxacillin, cloxacillin, and dicloxacillin) at trace levels in muscle tissue. This method involves extraction of the penicillins with phosphate buffer, pH 9, followed cleanup and concentration on a C18 solid-phase extraction column and reaction with benzoic anhydride at 50°C and with 1,2,4-triazole and mercury(II) chloride solution, pH 9.0, at 65°C. The derivatized compounds are eluted isocratically on a C8 column with a mobile phase of acetonitrile and phosphate buffer (pH 6; 0.1M) containing sodium thiosulfate and the ion-pair reagent tetrabutylammonium hydrogen sulfate. The penicillins are detected by UV absorption at 325 nm. The limit of detection and the limit of determination (quantitation) of the method were calculated to be approximately 3–5 and 25 μg/kg, respectively, in accordance with the criteria of European Union (EU) Decision No. 93/256/EEC. In this first interlaboratory study, collaborators were instructed to monitor 4 different penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, and amoxicillin) by analyzing 8 blind samples of muscle tissue in triplicate. These samples were prepared from 2 materials containing different concentrations of incurred ampicillin (63.5 μg/kg for material No. 1 and 358.1 μg/kg for material No. 2) and 1 blank material. The repeatability relative standard deviation and the reproducibility relative standard deviation were 10.2 and 17.4%, respectively, for material No. 1 and 7.0 and 16.0%, respectively, for material No. 2. These results demonstrate that the method is suitable for the determination of ampicillin residues in muscle tissue at the EU maximum residue limit (50 μg/kg) and above. However, the identification of positives by this procedure may need additional confirmation by techniques with greater specificity, such as liquid chromatography combined with mass spectrometry, or tandem mass spectrometry. Investigations regarding the basis of interlaboratory testing studies will further demonstrate the suitability of multiresidue methodology for detecting and quantitating other compounds in the family of penicillin antibiotics.

scholarly journals Liquid Chromatographic Determination of Deoxynivalenol in Baby Food and Animal Feed: Interlaboratory Study

2006 ◽  
Vol 89 (4) ◽  
pp. 1012-1020 ◽  
Author(s):  
Joerg Stroka ◽  
Michelle Derbyshire ◽  
Carsten Mischke ◽  
Massimo Ambrosio ◽  
Katy Kroeger ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
High Performance ◽  
Animal Feed ◽  
Chromatographic Determination ◽  
Baby Food ◽  
Interlaboratory Study ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract An interlaboratory study was conducted for the determination of deoxynivalenol in baby food and animal feed by high-performance liquid chromatography with UV detection. The study included 14 participants representing a cross section of industry, official food control, and research facilities. Mean recoveries reported ranged from 89% (at 120 g/kg) to 85% (at 240 g/kg) for baby food and from 100% (at 200 g/kg) to 93% (at 400 g/kg) for animal feed. On the basis of the results for spiked samples (blind duplicates at 2 levels), as well as those for naturally contaminated samples (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) in analyses of baby food ranged from 6.4 to 14.0% and in analyses of animal feed, from 6.1 to 16.5%. The relative standard deviation for reproducibility (RSDR) in analyses of baby food ranged from 9.4 to 19.5% and in analyses of animal feed, from 10.5 to 25.2%. The HorRat values ranged from 0.4 to 1.0 and from 0.7 to 1.3, for baby food and animal feed, respectively. The method showed acceptable performance for within-laboratory and between-laboratory precision for each matrix, as required by European legislation.

Liquid Chromatographic Determination of Quinine, Hydroquinine, Saccharin, and Sodium Benzoate in Quinine Beverages

1985 ◽  
Vol 68 (4) ◽  
pp. 782-784
Author(s):  
Leonard P Valenti
Keyword(s):  
Sodium Benzoate ◽  
Direct Injection ◽  
Chromatographic Determination ◽  
Peak Height ◽  
Relative Standard ◽  
Sodium Saccharin ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
The Relationship

Abstract A liquid chromatographic (LC) method is described for the determination of quinine, hydroquinine, sodium saccharin, and sodium benzoate in soft drinks. The method involves simple sample preparation, direct injection onto an octadecylsilane column, and elution with a methanol-acetonitrile-water-acetic acid (20 + 10 + 70 + 1) mobile phase. Eluted constituents are measured spectrophotometrically at 254 nm. The relationship between peak height and concentration was linear between 20 and 120 μg/mL for quinine. A relative standard deviation of 0.82% was obtained for commercial samples spiked with quinine, and the average recovery was 100.3%. The proposed procedure is accurate and rapid and can also detect hydroquinine (a natural contaminant of quinine), sodium saccharin, and sodium benzoate. Linear responses ranged from 0.45 to 20 (xg/mL for hydroquinine, from 54.8 to 219 μg/mL for sodium saccharin, and from 10.1 to 145.1 (ig/mL for sodium benzoate. The reproducibility of the LC method was evaluated with standard solutions of hydroquinine, sodium saccharin, and sodium benzoate, which produced relative standard deviations of 0.42, 0.46, and 1.13%, respectively. The average recoveries for sodium saccharin and sodium benzoate from spiked samples were 99.4 and 100.2%, respectively.

Liquid Chromatographic Determination of Sulfentrazone in Soil

1999 ◽  
Vol 82 (5) ◽  
pp. 1214-1216 ◽  
Author(s):  
G Anthony Ohmes ◽  
Thomas C Mueller
Keyword(s):  
Chromatographic Determination ◽  
Soil Samples ◽  
Ultraviolet Detection ◽  
Liquid Chromatographic Separation ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Soluble Components

Abstract A rapid method for the determination of sulfentrazone in soils is described. The method consists of extraction of soil samples with methanol, filtration, liquid chromatographic separation of methanol-soluble components through a C18 column, and ultraviolet detection at 220 nm. Recoveries from fortified surface soils were >85% for sulfentrazone. Average relative standard deviations over the soils examined was 7.7%. A conservative lower limit of quantitation for sulfentrazone was 40 ng/g soil.

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