Reverse Phase Gradient Elution for Chemically Bonded C18 Thin Layer Chromatographic Plates

1980 ◽  
Vol 18 (3) ◽  
pp. 133-135 ◽  
Author(s):  
L. C. Sander ◽  
L. R. Field
Keyword(s):  
Thin Layer ◽  
Gradient Elution ◽  
Reverse Phase ◽  
Phase Gradient

Simultaneous Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk by Liquid Chromatography

1989 ◽  
Vol 72 (4) ◽  
pp. 564-567 ◽  
Author(s):  
Michael H Thomas
Keyword(s):  
Bovine Milk ◽  
Phosphate Buffer Solution ◽  
Gradient Elution ◽  
Buffer Solution ◽  
Reverse Phase ◽  
Phase Gradient ◽  
Simultaneous Quantification ◽  
Molecular Weight Cutoff ◽  
Tetracycline Residues

Abstract A simple, rapid procedure is described for the simultaneous quantification of 3 tetracycline drugs in bovine milk. Samples are prepared by dilution with an EDTA/phosphate buffer solution and filtration through a molecular weight cutoff filter. Analytes are concentrated on-column using a reverse-phase gradient elution system of oxalic acid, acetonitrile, and methanol. The limits of quantitation are approximately 15-50 ng/mL and the limits of detection are 10-20 ng/ mL, depending on the compound. For oxytetracycline, over the range 50-1200 ng/mL, the average recovery and intralaboratory coefficient of variation were 97% and 4.1%, respectively. Over the same range, these parameters were, respectively, 97% and 5.0% for tetracycline, and 89% and 6.4% for chlortetracycline. The applicability of this procedure is demonstrated by separation and detection of incurred tetracycline residues in milk from treated animals.

scholarly journals Novel Isocratic RP-HPLC Method Development and Validation of Rosuvastatin and Fenofibrate in Tablets

2020 ◽  
Vol 11 (03) ◽  
pp. 343-349
Author(s):  
Chandrasekhar Kudupudi ◽  
Manikandan Ayyar
Keyword(s):  
Related Compound ◽  
Method Development ◽  
Quantitative Estimation ◽  
Gradient Elution ◽  
Simultaneous Estimation ◽  
Reverse Phase ◽  
Phase Gradient ◽  
Compound A ◽  
Atorvastatin Calcium ◽  
Rp Hplc

A novel, simple, selective, precise, and accurate reverse-phase high-performance liquid chromatography (RP-HPLC) gradient method was developed for the simultaneous estimation of atorvastatin and fenofibrate in the combined formulation. The drugs atorvastatin calcium and fenofibrate were separated in the presence of their impurities atorvastatin related compound H, fenofibrate related compound A, and fenofibrate related compound B. The drugs and related compounds were separated on Kromasil C18 (250 x 4.6, 5μ) with reverse-phase gradient elution. Water adjusted pH 4.0 with phosphoric acid used as a buffer in pump A and acetonitrile used as a solvent in pump B as a mobile phase with gradient elution. The flow rate was 2.0 mL/min. 254 nm was the detection wavelength. The retention times were about 4.6 minutes for fenofibrate related compound A, 5.2 minutes for atorvastatin calcium, 5.7 minutes for fenofibrate related compound B, 8.7 minutes for atorvastatin related compound H, and 17.6 minutes for fenofibrate. The linearity ranges for atorvastatin calcium and fenofibrate were 5.00 to 15.00 and 80 to 240 mcg/mL, respectively, with correlation coefficient 0.999 for both. The proposed method validated statistically with respect to system suitability, specificity, linearity, precision, accuracy, range, robustness, and ruggedness. The method was accurate, linear, precise, specific, selective, and rapid suitable for the quantitative estimation of atorvastatin and fenofibrate in tablets.

EVIDENCE FOR BIIIARY EXCRETION OF PHENPROCOUMON AND ITS METABOLITES IN HUMANS; IDENTIFICATION BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY

1987 ◽  
Author(s):  
J X de Vries ◽  
R Raedsch ◽  
A Stiehl ◽  
U Voelker ◽  
I Walter-Sack ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Phase Gradient ◽  
Chromatography Mass Spectrometry

Recently it has been shown that in man the oral couma-rin anticoagulant phenprocoumon is eliminated up to 60-70 % in urine and 30-40 % in faeces; in urine phenprocoumon (PH) and its metabolites 7-hydroxy-(7-OH),6-hydroxy-(6-OH) and 4'-hydroxy-(4'-OH) phenprocoumon are present mainly as conjugates. No data so far were available on the biliary excretion of these compounds.We examined bile obtained from four in-patients during PH treatment; bile samples were aspirated in the duodenum at the papilla during routine diagnostic endoscopy and immediately deep frozen before analysis. Samples were extracted both untreated as well as after hydrolysis with 6-glucuronidase/aryl sulfatase and separated by reversed phase gradient elution high performance liquid chromatography (HPLC) with fluorescence detection; for confirmation, the same extracts were methylated and analysed by gas chromatography-mass spectrometry (CG-MS) (J.X.de Vries et al J Chromatogr., 338 (1985) 325). PH, 7-OH, 6-OH and 4'-OH were identified by comparison with synthetic authentic samples'''''''

Determination of retinol, alpha-tocopherol, and beta-carotene in serum by liquid chromatography with absorbance and electrochemical detection.

1987 ◽  
Vol 33 (9) ◽  
pp. 1585-1592 ◽  
Author(s):  
W A MacCrehan ◽  
E Schönberger
Keyword(s):  
Electrochemical Detection ◽  
Chromatographic Separation ◽  
Protein Denaturation ◽  
Internal Standard ◽  
Beta Carotene ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Alpha Tocopherol ◽  
Phase Gradient

Abstract We describe a method for the determination of retinol, alpha-tocopherol, and beta-carotene in serum, using a liquid-chromatographic separation with wavelength-programmed ultraviolet/visible absorbance and amperometric electrochemical detection with a glassy carbon electrode. After protein denaturation and addition of an internal standard, tocol, 250-microL samples are twice extracted with hexane. The reversed-phase, gradient-elution chromatographic separation provides baseline resolution of: the all-trans isomer of retinol from the cis isomers, alpha- from gamma-tocopherol, and all-trans-beta-carotene from alpha-carotene and from cis-beta-carotene isomers. The linearity of response and the detection limits for the two detectors for the three analytes are measured. A comparison of the values obtained for serum extracts shows good agreement between the absorbance and electrochemical detectors.

A Simple and Rapid High-Performance Liquid Chromatography—Photodiode Array Method for Quantitation of Triacetin Contents From 30 Batches Produced in China

2020 ◽  
Vol 59 (1) ◽  
pp. 23-29
Author(s):  
Ran Li ◽  
Xi Pan ◽  
Hao Wang ◽  
Guoning Guo ◽  
Long Huang ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Energy Efficient ◽  
High Performance ◽  
Preparation Method ◽  
Gradient Elution ◽  
Sample Preparation Method ◽  
Formic Acid Solution ◽  
Reverse Phase ◽  
Photodiode Array

Abstract In our present study, the standard chemicals of triacetin were purified by reverse-phase and normal-phase semi-preparative high-performance liquid chromatography (HPLC), and 1H NMR and 13C NMR were employed to determine the purity and structure of triacetin. Moreover, a simple and rapid HPLC-photodiode array (PDA) method was developed to determine the contents of triacetin in 30 batches from different suppliers. The chromatographic separation was performed on a Phenomenex Gemini-NX C18 column (250 × 4.6 mm, 5 μm) using a gradient elution system of water and acetonitrile (contained 0.1% of formic acid) solution with a flow rate of 1.0 mL/min at 30°C at 210 nm. Sample preparation method is rapid and energy efficient, and the obtained sample have a good purity. Validation shows good specificity, linearity (R2 = 0.9995), precision, stability, repeatability (% RSD < 2.80) and the average recovery (99.72%) of triacetin. The content of triacetin in most samples is concentrated in 94–97%. This developed approach is simple, rapid, accurate and can be used to quickly determine the purity and the content of triacetin in plasticizers and filter plugs.

Determination of Seven Artificial Sweeteners in Diet Food Preparations by Reverse-Phase Liquid Chromatography with Absorbance Detection

1988 ◽  
Vol 71 (5) ◽  
pp. 934-937 ◽  
Author(s):  
James F Lawrence ◽  
Claudette F Charbonneau
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Sorbic Acid ◽  
Artificial Sweeteners ◽  
Reverse Phase ◽  
Phase Gradient ◽  
Reverse Phase Liquid Chromatography ◽  
Absorbance Detection ◽  
Phase Liquid

Abstract The artificial sweeteners aspartame, saccharin, cyclamate, alitame, acesulfam-K, sucralose, and dulcin are determined in diet soft drinks and tabletop sweetener preparations. Samples are diluted, filtered, and analyzed directly by liquid chromatography on a C-18 reversephase column with a mobile phase gradient ranging from 3% acetonitrile in 0.02M KH2P04 (pH 5) to 20% acetonitrile in 0.02M KH2P04 (pH 3.5). Diet puddings and dessert toppings are extracted with ethanol, filtered, and diluted with mobile phase for analysis. The sweeteners, except sucralose and cyclamate, were detected by UV absorbance at either 200 or 210 nm. Sucralose was determined at 200 nm or by refractive index. Cyclamate was determined after post-column ion-pair extraction. The sweeteners stevioside and talin were not detected. Additives such as caffeine, sorbic acid, and benzoic acid did not interfere.

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