Liquid-chromatographic quantification of plasma phenylalanine, tyrosine, and tryptophan.

1981 ◽  
Vol 27 (1) ◽  
pp. 146-148 ◽  
Author(s):  
L M Neckers ◽  
L E Delisi ◽  
R J Wyatt
Keyword(s):  
Amino Acids ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Plasma Phenylalanine ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Reversed Phase Column

Abstract Phenylalanine, tyrosine, and tryptophan are isolated and quantified by "high-pressure" liquid chromatography, with fluorescence detection. An isocratic mobile phase and reversed-phase column are used to provide rapid and reproducible measurement of these amino acids in as little as 1 to 2 microL of human plasma.

Simultaneous measurement of phenobarbital, phenytoin, primidone, ethosuximide, and carbamazepine in serum by high-pressure liquid chromatography.

1977 ◽  
Vol 23 (7) ◽  
pp. 1284-1288 ◽  
Author(s):  
P M Kabra ◽  
B E Stafford ◽  
L J Marton
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Mobile Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Acetonitrile Solution ◽  
Serum Samples ◽  
Column Temperature ◽  
Phase Column ◽  
Reversed Phase Column

Abstract We present a method for simultaneously determining five anticonvulsants [phenobarbital, phenytoin (diphenylhydantoin), primidone, ethosuximide, and carbamazepine] in as little as 25 microliters of serum. The proteins are precipitated with an acetonitrile solution containing hexobarbital as an internal standard. The anticonvulsants are eluted from a reversed-phase column with a mobile phase consisting of an acetonitrile/phosphate buffer (19/81 by vol) at a flow rate of 3.0 ml/min. The eluted drugs are detected by their absorption at 195 nm, and quantities estimated from their peak heights. Each analysis requires about 14 min. at an optimum column temperature of 50 degrees C. The lower unit of detection for all of these drugs is less than 10 ng. Sensitivities, for serum samples, of 1.0 mg/liter for all the drugs analyzed are attained routinely. Analytical recoveries for the five drugs varied from 97 - 107%, with good day-to-day precision (CV between 3.9 and 5.9%). Of more than 30 drugs tested for possible interference, only ethotoin interferes with the analysis of phenobarbital.

4-Nitrophenol in 4-nitrophenyl phosphate, a substrate for alkaline phosphatase, as measured by paired-ion high-performance liquid chromatography.

1977 ◽  
Vol 23 (12) ◽  
pp. 2288-2291 ◽  
Author(s):  
P H Culbreth ◽  
I W Duncan ◽  
C A Burtis
Keyword(s):  
Alkaline Phosphatase ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Flow Rate ◽  
Mobile Phase ◽  
High Performance ◽  
Reversed Phase ◽  
Nitrophenyl Phosphate ◽  
Phase Column ◽  
Reversed Phase Column

Abstract We used paired-ion high-performance liquid chromatography to determine the 4-nitrophenol content of 4-nitrophenyl phosphate, a substrate for alkaline phosphatase analysis. This was done on a reversed-phase column with a mobile phase of methanol/water, 45/55 by vol, containing 3 ml of tetrabutylammonium phosphate reagent per 200 ml of solvent. At a flow rate of 1 ml/min, 4-nitrophenol was eluted at 9 min and monitored at 404 nm; 4-nitrophenyl phosphate was eluted at 5 min and could be monitored at 311 nm. Samples of 4-nitrophenyl phosphate obtained from several sources contained 0.3 to 7.8 mole of 4-nitrophenol per mole of 4-nitrophenyl phosphate.

Liquid-chromatographic assay of urinary 5-hydroxy-3-indoleacetic acid, with electrochemical detection.

1980 ◽  
Vol 26 (7) ◽  
pp. 907-909 ◽  
Author(s):  
Z K Shihabi ◽  
J Scaro
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
High Performance ◽  
Indoleacetic Acid ◽  
Reversed Phase ◽  
Solvent Mixtures ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Reversed Phase Column

Abstract After extraction with two organic solvent mixtures, urinary 5-hydroxy-3-indoleacetic acid can be assayed by "high-performance" liquid chromatography on a reversed-phase column, with electrochemical detection. Compared to the nitrosonaphthol method (J. Biol. Chem. 216: 499, 1955), this method is more specific for detection of patients with carcinoid tumors.

Liquid-chromatographic assay of urinary 5-hydroxy-3-indoleacetic acid, with electrochemical detection.

1980 ◽  
Vol 26 (7) ◽  
pp. 907-909
Author(s):  
Z K Shihabi ◽  
J Scaro
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
High Performance ◽  
Indoleacetic Acid ◽  
Reversed Phase ◽  
Solvent Mixtures ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Reversed Phase Column

Abstract After extraction with two organic solvent mixtures, urinary 5-hydroxy-3-indoleacetic acid can be assayed by "high-performance" liquid chromatography on a reversed-phase column, with electrochemical detection. Compared to the nitrosonaphthol method (J. Biol. Chem. 216: 499, 1955), this method is more specific for detection of patients with carcinoid tumors.

Determination of bethanidine in plasma by liquid-chromatography with a microbore reversed-phase column.

1983 ◽  
Vol 29 (10) ◽  
pp. 1793-1795 ◽  
Author(s):  
J R Shipe ◽  
A F Arlinghaus ◽  
J Savory ◽  
M R Wills ◽  
J P DiMarco
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Ultraviolet Absorbance ◽  
Standard Curve ◽  
Novel Method ◽  
Phase Column ◽  
Reversed Phase Column

Abstract In this novel method for quantifying bethanidine in plasma, after a multi-step extraction of bethanidine and internal standard from 2.0 mL of plasma, the drugs are separated on a "microbore" C18 reversed-phase column and quantified by their ultraviolet absorbance at 210 nm. The isocratic chromatographic separation takes about 15 min with use of an ion-pairing regent in the mobile phase (acetate buffer/acetonitrile, 9/1 by vol) and a flow rate of 0.25 mL/min. Sensitivity is increased relative to conventional columns, and solvent consumption is reduced by 90%. The standard curve is linear to at least 5 mg/L, and the detection limit is 0.02 mg/L. The within-run precision of the method is excellent (CV 4%) at a midrange concentration of 1.25 mg/L.

Liquid-chromatographic measurement of phenylalanine and tyrosine in serum.

1982 ◽  
Vol 28 (11) ◽  
pp. 2282-2285 ◽  
Author(s):  
F W Spierto ◽  
W Whitfield ◽  
M Apetz ◽  
W H Hannon
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Phenylalanine Ammonia Lyase ◽  
Reversed Phase ◽  
Coumaric Acid ◽  
Chromatographic Measurement ◽  
Liquid Chromatographic ◽  
Detection And Quantification ◽  
Phase Column ◽  
Reversed Phase Column

Abstract With phenylalanine ammonia-lyase (EC 4.3.1.5) we converted phenylalanine (Phe) and tyrosine (Tyr) to transcinnamic acid and p-coumaric acid, respectively. These were separated by "high-performance" liquid chromatography and detected at 280 nm. We measured the Phe and Tyr content of human serum by adding 100 mU of the enzyme to a 20-microL serum aliquot, mixing for 2 h at 24 degrees C, then stopping the reaction with 1 mL of cold methanol. Precipitated proteins were removed by centrifugation and the separated clear supernates were stored at -20 degrees C. For chromatographic separation, detection, and quantification, we used a system equipped with a C-18 reversed-phase column, a variable-wavelength spectrophotometer, a printer-plotter, and a microcomputer. The mobile phase was a mixture of dilute aqueous (50 g/L) acetic acid and CH3CN (80/20, by vol). CVs for specimens containing 100 mg of Phe or Tyr per liter varied from 5 to 10%. Analytical recoveries were near 100%.

scholarly journals Determination of 4-Hexylresorcinol in Shrimp by Liquid Chromatography with Fluorescence Detection

2000 ◽  
Vol 83 (1) ◽  
pp. 241-244 ◽  
Author(s):  
Klaas M Jonker ◽  
Colinda P Dekker
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Analysis ◽  
Reversed Phase ◽  
Fluorimetric Detection ◽  
Relative Standard ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Reversed Phase Column

Abstract A method was developed to determine 4-hexylresorcinol in shrimp meat. The procedure is based on extraction of test portions with methanol followed by liquid chromatographic analysis of the extracts, using a reversed-phase column and fluorimetric detection (excitation: 280 nm, and emission: 310 nm). The confidence interval of the recovery in working range of 1.5–2.5 mg/kg was 81.6 ± 0.8%. The relative standard deviation in the working range was 2.1%. Limits of quantitation and detection were 6.59 and 1.98 ng/mL extract, respectively, corresponding to 0.26 and 0.08 mg/kg in shrimp.

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