Liquid Chromatographic Determination of Vitamin D in Animal Feeds and Premixes

1992 ◽  
Vol 75 (5) ◽  
pp. 812-814 ◽  
Author(s):  
Vipin K Agarwal
Keyword(s):  
Vitamin D ◽  
Mobile Phase ◽  
Potassium Hydroxide ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Ultraviolet Detection ◽  
Animal Feeds ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method has been developed for the determination of vitamin D (D2 + D3) in animal feeds and premixes. The sample is saponified with potassium hydroxide, and vitamin D is extracted with hexane and isomerized to isotachysterol with 10M HCI in 2-butanol. LC determination of isotachysterol to quantitate vitamin D is carried out on a reversed-phase column with acetonitrilemethanol (90 +10) as the mobile phase and ultraviolet detection at 301 nm. The detection limit of the method is 1 lU/g. This method can also be used for the determination of vitamin D2 and D3 separately.

Improved liquid-chromatographic determination of haloperidol in plasma.

1984 ◽  
Vol 30 (7) ◽  
pp. 1228-1230 ◽  
Author(s):  
A K Dhar ◽  
H Kutt
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Room Temperature ◽  
Internal Standard ◽  
Isoamyl Alcohol ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract This method for determination of haloperidol in plasma is based on "high-performance" isocratic liquid chromatography with the use of a C8 bonded reversed-phase column at room temperature. Haloperidol and the internal standard (chloro-substituted analog) are extracted from alkalinized plasma into isoamyl alcohol/heptane (1.5/98.5 by vol) and back-extracted into dilute H2SO4. The aqueous phase is directly injected onto the column. The mobile phase is a 30/45/25 (by vol) mixture of phosphate buffer (16.5 mmol/L, pH 7.0), acetonitrile, and methanol. Unlike other liquid-chromatographic procedures for haloperidol, commonly used psychotropic drugs do not interfere. Analysis can be completed within an hour. The procedure is extremely sensitive (1.0 microgram/L) and is well reproducible (CV 5.6% for a 2.5 micrograms/L concentration in plasma).

Improved liquid-chromatographic determination of 3-methoxy-4-hydroxyphenylethyleneglycol in urine with electrochemical detection.

1984 ◽  
Vol 30 (1) ◽  
pp. 140-143 ◽  
Author(s):  
J R Shipe ◽  
J Savory ◽  
M R Wills
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Improved Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Mean Concentration ◽  
Phase Column

Abstract In this improved method for quantifying 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in urine, after a multistep extraction of MHPG and internal standard (iso-MHPG) from 3.0 mL of urine, the compounds are separated on a C18 reversed-phase column and quantified by use of an electro-chemical detector. The isocratic chromatographic separation takes about 16 min. The mobile phase is phosphate buffer/acetonitrile (88/12 by vol), the flow rate 0.7 mL/min. Recycling the mobile phase and automating the sample injection make possible the unattended assay of more than 70 samples per day. The within-run precision of the method is excellent (CV 1.8%) at a mean concentration of 1.1 mg/L.

Liquid-chromatographic determination of pentobarbital in plasma with use of a resin column and an alkaline mobile phase.

1982 ◽  
Vol 28 (8) ◽  
pp. 1772-1774 ◽  
Author(s):  
R N Gupta ◽  
P T Smith ◽  
F Eng
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Enhanced Sensitivity ◽  
Acidic Drugs ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a liquid-chromatographic method involving a new, nonsilica column (XAD-2, Hamilton Co.) for pentobarbital in plasma. Plasma is extracted with chloroform after addition of the internal standard, 5-ethyl-5-p-tolyl-barbituric acid. Acidic drugs are back-extracted into alkali, then chromatographed on the resin-base reversed-phase column. The use of alkaline mobile phase allows enhanced sensitivity and detection of barbiturates at 240 nm. The within-run CV for 10 samples was 1.9%, the between-run CV 1.8%. Ten commonly used barbiturates are separated isocratically in less than 15 min. Other commonly prescribed acidic drugs do not interfere with determination of pentobarbital.

scholarly journals Liquid Chromatographic Determination of Scopolamine, Hyoscyamine, and Phenobarbital in Tablets

1997 ◽  
Vol 80 (2) ◽  
pp. 331-334 ◽  
Author(s):  
Susan Ting
Keyword(s):  
Mobile Phase ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Scopolamine Hydrobromide ◽  
Acid Sodium Salt ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method using a reversed- phase C18 column and octanesulfonic acid sodium salt-methanol as the mobile phase was developed for the simultaneous determination of phenobarbi- tal, scopolamine, and hyoscyamine in tablets. The mixture of the 3 drugs was resolved in <8 min. Detector responses were linear for 10 μL injections of the following: scopolamine hydrobromide, 8.25-206.3 μg/mL; hyoscyamine sulfate, 15.01-750.76 μg/mL; and phenobarbital, 250-751 μg/mL. Recoveries from tablets were 100.8% for scopolamine hydrobromide, 100.1% for hyoscyamine sulfate, and 100.3% for phenobarbital. Replicate injections of scopolamine hydrobromide, hyoscyamine sulfate, and phenobarbital gave an overall relative standard deviation of <1.0% (n = 10). The method detected as little as 3.3 ng scopolamine hydrobromide.

scholarly journals Liquid Chromatographic Determination of Histamine in Fish, Sauerkraut, and Wine: Interlaboratory Study

1998 ◽  
Vol 81 (5) ◽  
pp. 991-998 ◽  
Author(s):  
Paul R Beljaars ◽  
Remmelt Van Dijk ◽  
Klaas M Onker ◽  
Louis J Schout ◽  
◽  
...  
Keyword(s):  
Mobile Phase ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Interlaboratory Study ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Standard Deviations ◽  
Liquid Chromatographic ◽  
Postcolumn Derivatization

Abstract An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)-acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with ophthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10- 400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Average recoveries of histamine for this concentration range varied from 94 to 100%

Liquid-chromatographic determination of alpha- and gamma-tocopherols in erythrocytes, with fluorescence detection.

1983 ◽  
Vol 29 (10) ◽  
pp. 1840-1842 ◽  
Author(s):  
J Lehmann ◽  
H L Martin
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We have adapted to erythrocytes a method for the determination of alpha- and gamma-tocopherols in plasma and platelets. Erythrocytes (50 microL) were extracted with methanol containing tocol (internal standard) and pyrogallol. Tocopherols were partitioned into chloroform, washed, and injected in methanol onto a reversed-phase (C18) "high-performance" liquid-chromatographic column. The mobile phase was methanol/water (99/1 by vol) at a flow rate of 2 mL/min and detection was with a "high-performance" spectrophotofluorometer. The limit of detection for either tocopherol is 0.10 microgram/mL of packed cells. Analytical recoveries ranged from 93 to 104%. Some values for tocopherols in human erythrocytes are presented.

Liquid-chromatographic determination of total hydroxyproline in urine.

1988 ◽  
Vol 34 (8) ◽  
pp. 1572-1574 ◽  
Author(s):  
C D Dawson ◽  
S Jewell ◽  
W J Driskell
Keyword(s):  
Chromatographic Determination ◽  
Reversed Phase ◽  
Normal Range ◽  
Ultraviolet Detection ◽  
Standard Curve ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Hydroxyproline Excretion ◽  
Unrestricted Diet

Abstract In this method for quantifying 4-hydroxyproline in human urine, 50 microL of urine is hydrolyzed, derivatized with phenylisothiocyanate (PITC), and then quantified by reversed-phase HPLC with ultraviolet detection. The detection limit in urine is 373 pg of hydroxyproline per 50-microL injection. The total CVs for high- and low-concentration pools are 5.3% and 3.9%, respectively (10 runs in 10 days). The standard curve of the assay is linear over a range of 0 to 22 nmol per injection. We estimated the normal range for hydroxyproline excretion in men on an unrestricted diet to be 123-308 mumol/24 h. We also report hydroxyproline concentrations in patients with metastatic bone disease and cirrhosis of the liver.

Liquid Chromatographic Determination of Nicarbazin in Feed

1985 ◽  
Vol 68 (3) ◽  
pp. 596-598 ◽  
Author(s):  
Jeffrey A Hurlbut ◽  
Cyril T Nightengale ◽  
Roger G Burkepile
Keyword(s):  
Mobile Phase ◽  
Chromatographic Determination ◽  
Feed Additives ◽  
Alumina Column ◽  
Reverse Phase ◽  
Ultraviolet Detection ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method was developed for the determination of nicarbazin (4,4'-dinitrocarbanilide.2-hydroxy-4,6-dimethylpyrimidine) in chicken feed. Ground feed was extracted with hot dimethylformamide, filtered, and then cleaned up on an alumina column. The nicarbazin was eluted from the column with ethanol and quantitated using a reverse phase C-18 column, with a methanol-water mobile phase and ultraviolet detection at 344 nm. Recoveries at a typical use level of 100 μg/g feed averaged 98% with a standard deviation of 3%. Samples fortified at levels as low as 0.1 μg/g were analyzed with 92% recovery. The detection limit is 1 ng, and the response is linear between 4 and 1000 ng. Feed additives in combination with nicarbazin do not interfere with recovery.

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