Studies directed toward labeling analysis of angiotensin II in plasma.

1985 ◽  
Vol 31 (10) ◽  
pp. 1723-1728 ◽  
Author(s):  
R L Emanuel ◽  
R Joppich-Kuhn ◽  
G H Williams ◽  
R W Giese
Keyword(s):  
Angiotensin Ii ◽  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Affinity Column ◽  
Antibody Affinity ◽  
Liquid Chromatographic ◽  
Further Development ◽  
Chemical Label

Abstract We assay a 1-mL plasma sample containing angiotensin II (103 pg by radioimmunoassay) for the hormone by the following sequence of steps: add 125I-labeled val5-angiotensin II as an internal standard, extract on a C18 Sep Pak column, extract on an antibody affinity column, label the extract with an 125I Bolton-Hunter reagent, separate on a Bio Gel P2 column, and repetitively separate on a reversed-phase "high-performance" liquid-chromatographic column, detecting the eluting compounds by counting radioactivity. The fact that we measured 46 pg of angiotensin II-like substance per milliliter in a sample of pooled plasma is encouraging for the further development of this methodology. In particular, replacing the radioisotope with a more suitable chemical label such as an electrophoric (electron-capturing) release tag should be useful.

scholarly journals Determination of Finasteride in Tablets by High Performance Liquid Chromatography

2007 ◽  
Vol 4 (1) ◽  
pp. 109-116 ◽  
Author(s):  
K. Basavaiah ◽  
B. C. Somashekar
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Calibration Graph ◽  
Official Method ◽  
Pharmaceutical Dosage Forms ◽  
Bulk Drug ◽  
Liquid Chromatographic

A rapid, highly sensitive high performance liquid chromatographic method has been developed for the determination of finasteride(FNS) in bulk drug and in tablets. FNS was eluted from a ODS C18reversed phase column at laboratory temperature (30 ± 2°C) with a mobile phase consisting of methanol and water (80+20) at a flow rate of 1 mL min-1with UV detection at 225 nm. The retention time was ∼ 6.1 min and each analysis took not more than 10 min. Quantitation was achieved by measurement of peak area without using any internal standard. Calibration graph was linear from 2.0 to 30 μg mL-1with limits of detection (LOD) and quantification (LOQ) being 0.2 and 0.6 μg mL-1, respectively. The method was validated according to the current ICH guidelines. Within-day co efficients of variation (CV) ranged from 0.31 to 0.69% and between-day CV were in the range 1.2-3.2%. Recovery of FNS from the pharmaceutical dosage forms ranged from 97.89 – 102.9 with CV of 1.41-4.13%. The developed method was compared with the official method for FNS determination in its tablet forms.

Liquid-chromatographic separation of urinary 5-hydroxy-3-indoleacetic acid, with measurement at 254 nm.

1980 ◽  
Vol 26 (7) ◽  
pp. 910-912
Author(s):  
P S Draganac ◽  
S J Steindel ◽  
W G Trawick
Keyword(s):  
High Performance ◽  
Indoleacetic Acid ◽  
Colorimetric Method ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Acetate Buffer ◽  
Nitrobenzoic Acid ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.

Liquid-chromatographic determination of 4-aminopyridine in serum, saliva, and urine.

1981 ◽  
Vol 27 (3) ◽  
pp. 437-440 ◽  
Author(s):  
D R Uges ◽  
P Bouma
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Drug Concentrations ◽  
Liquid Chromatographic Determination ◽  
High Concentrations ◽  
Liquid Chromatographic

Abstract We have developed "high-performance" liquid-chromatographic methods for determining 4-aminopyridine, an acetylcholine-releasing drug, in serum, saliva, and urine. As little as 1 microgram/L can be detected by extracting the alkalinized sample plus the internal standard (3,4-diaminopyridine) into dichloromethane, mixing the organic phase with 1-pentanol, evaporating the dichloromethane, and injecting the residue onto a reversed-phase column, where it is eluted with acetonitrile/methanol/aqueous ammonium carbonate, with detection at 245 nm. Analytical recoveries from serum averaged 86.7%. The CV at 50 micrograms/L was 2.9% (n = 8). For urine samples containing very high concentrations of 4-aminopyridine, we mixed urine and potassium carbonate in an automatic injector vial, extracted the drug into dichloromethane, centrifuged, and injected an aliquot of the extract into the chromatograph. Analytical recoveries averaged 92%, and the CV was about 2% for drug concentrations of 0.1-8 mg/L of urine.

A high-performance liquid-chromatographic method for routine simultaneous determination of nicotine and cotinine in plasma.

1988 ◽  
Vol 34 (4) ◽  
pp. 724-729 ◽  
Author(s):  
M Hariharan ◽  
T VanNoord ◽  
J F Greden
Keyword(s):  
Simultaneous Determination ◽  
Mobile Phase ◽  
High Performance ◽  
Methylene Chloride ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Standard Curve ◽  
Liquid Chromatographic

Abstract We describe a rapid, sensitive method for the routine simultaneous determination of nicotine and cotinine in 1 mL of plasma. Extraction in 10-mL screw-capped Teflon tubes with methylene chloride after deproteinization with trichloroacetic acid eliminated emulsion formation. The extract, after evaporation and reconstitution in 30 microL of mobile phase, is injected into a reversed-phase C-18 ion-pair column of an isocratic high-performance liquid-chromatographic unit. Absorbance is monitored at 256 nm. The mobile phase is a citrate-phosphate (30 mmol each per liter) buffer mixture containing 50 mL of acetonitrile and 1 mmol of sodium heptanesulfonate per liter. 2-Phenylimidazole is the internal standard. The detection limit is 1 microgram/L for nicotine and 3 micrograms/L for cotinine. The standard curve is linear from 0 to 700 micrograms/L for both compounds. The average CV for nicotine in the concentration range 0-100 micrograms/L is 6.5%, and that for cotinine in the concentration range 50-700 micrograms/L is 4%.

High-performance liquid-chromatographic determination of free nicotinic acid and its metabolite, nicotinuric acid, in plasma and urine.

1978 ◽  
Vol 24 (10) ◽  
pp. 1740-1743 ◽  
Author(s):  
N Hengen ◽  
V Seiberth ◽  
M Hengen
Keyword(s):  
Nicotinic Acid ◽  
High Performance ◽  
Isonicotinic Acid ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Related Substances ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract We report a liquid-chromatographic procedure for determining free nicotinic acid and a metabolite, nicotinuric acid, in plasma and urine. Five-tenths milliliter of urine or deproteinized plasma is evaporated and the residue analyzed isocratically by reversed-phase ion-pair chromatography, with measurement of the eluted nicotinic acid and nicotinuric acid at 254 nm. Nicotinic acid, nicotinuric acid, and the internal standard (isonicotinic acid) have retention times of 7.8, 8.4, and 6.8 min, respectively, in plasma, and 12.3, 13.1, and 10.8 min in urine, because of double column length. Day-to-day reproducibilities (CV) for nicotinic acid and nicotinuric acid within 7.5% are attainable for the concentration ranges 0.1--20 mg/liter, equivalent to 0.81--162 micromol of nicotinic acid and 0.55--11 micromol of nicotinuric acid per liter for plasma; in urine for the range 0.5--100 mg/liter, equivalent to 4--810 micromol of nicotinic acid and 2.8--555 micromol of nicotinuric acid per liter. Metabolites of nicotinic acid such as nicotinamide, N-methylnicotinamide, 2-hydroxypyridine-5-carboxylic acid, and other structurally related substances do not interfere.

Simultaneous liquid-chromatographic determination of prednisone and prednisolone in plasma.

1988 ◽  
Vol 34 (9) ◽  
pp. 1897-1899 ◽  
Author(s):  
M H Cheng ◽  
W Y Huang ◽  
A I Lipsey
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Hplc Method ◽  
Liquid Chromatographic Determination ◽  
Standard Solution ◽  
Liquid Chromatographic

Abstract This high-performance liquid-chromatographic (HPLC) method for simultaneous determination of prednisone and its metabolite, prednisolone, in plasma is a modification of the method of Frey et al. (Clin Chem 1979;25:1944-7). Heparinized plasma (1.0 mL) with 0.1 mL of internal standard solution (11-deoxy-17-hydroxycorticosterone, 2 mg/L) is extracted with 7.0 mL of dichloromethane, then washed sequentially with 0.1 mol/L HCl, 0.1 mol/L NaOH, and deionized water, 2.0 mL each. The extract is evaporated and the residue reconstituted with 75 microL of mobile phase, methanol/H2O (40/60 by vol). Thirty microliters of this is injected onto a reversed-phase C6 column, which is eluted at 1.4 mL/min. Analytical recoveries of prednisone and prednisolone were 94-98% and 102-106%, respectively. Day-to-day precision (CV) was 3.8% for prednisone, 6.1% for prednisolone. We encountered no interference from the 21 other steroids and 25 drugs tested. This method is simple, accurate, and precise.

High-performance liquid-chromatographic analysis for serotonin and tryptamine excreted in urine after oral loading with L-tryptophan.

1989 ◽  
Vol 35 (1) ◽  
pp. 43-47 ◽  
Author(s):  
H Tsuchiya ◽  
T Hayashi ◽  
M Tatsumi ◽  
Y Hoshino ◽  
S Ohtani ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
High Performance ◽  
Low Cost ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Factors Affecting ◽  
Sensitivity And Selectivity ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic

Abstract We describe a method used for determining serotonin and tryptamine in urine after oral loading with their precursor amino acid. Several factors affecting prepurification and chromatographic separation of both indoleamines were optimized, including sample extraction and mobile-phase composition. Under optimal conditions, serotonin and tryptamine are extracted from urine samples together with an internal standard, and then they are separated by reversed-phase chromatography followed by native fluorescence detection. The analytical procedure is simple enough to apply to routine analysis and performable at low cost. Sensitivity and selectivity of the method are satisfactory enough to determine urinary serotonin and tryptamine. By pursuing urinary excretion of serotonin and tryptamine after oral loading with L-tryptophan (30 mg per kilogram body weight), our method proves that urinary excretion of both indoleamines increases immediately after loading and reaches a maximum in about 45 min.

High-performance liquid-chromatographic assay of aminoglycoside antibiotics in serum.

1978 ◽  
Vol 24 (11) ◽  
pp. 1940-1947 ◽  
Author(s):  
J P Anhalt ◽  
S D Brown
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Aminoglycoside Antibiotic ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Aminoglycoside Antibiotics ◽  
Sephadex Column ◽  
Ion Pair Chromatography ◽  
Fluorescent Products ◽  
Liquid Chromatographic

Abstract We describe procedures for the high-performance liquid-chromatographic assay of gentamicin, amikacin, and tobramycin in serum. The aminoglycoside antibiotic is extracted from serum by using a CM-Sephadex column and is measured by reversed-phase, ion-pair chromatography. Continuous-flow, post-column derivatization with o-phthalaldehyde is used to form fluorescent products for detection. An internal standard is used in each assay. Synthesis of 1-N-acetylgentamicin C1, the internal standard for the gentamicin assay, is described. For each procedure, concentration and instrument response are linearly related in the range of therapeutically important concentrations. The methods are precise and results correlate well with results obtained by bioassay. The between-day CV (n = 10) for each procedure was less than 4%. No substances have been detected in clinical specimens that interfere with these chromatographic procedures. The possible use of these methods for analysis for other aminoglycoside antibiotics is discussed.

Analysis for Procainamide and N-Acetyl Procainamide in Plasma or Serum by High-Performance Liquid Chromatography

1977 ◽  
Vol 23 (4) ◽  
pp. 705-708 ◽  
Author(s):  
Richard M Rocco ◽  
Donald C Abbott ◽  
Roger W Giese ◽  
Barry L Karger
Keyword(s):  
High Performance ◽  
Colorimetric Assay ◽  
Internal Standard ◽  
Standard Addition ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Calibration Plot ◽  
Extraction And Separation ◽  
Organic Extraction ◽  
Liquid Chromatographic

Abstract A high-performance liquid chromatographic method is presented for simultaneous analysis for procainamide and N-acetyl procainamide in plasma or serum. The procedure involves internal-standard addition, organic extraction, and separation on a reversed-phase column. The detection limit for procainamide is 0.1 mg/liter and the calibration plot is linear to at least 30 mg/liter. Comparison with a colorimetric assay for procainamide gave a correlation coefficient of 0.989. We checked for interference by a large series of appropriate drugs, and found none, nor did icteric or lipemic sera present problems

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