Head-space gas-chromatographic determination of 3-hydroxybutyrate in plasma after enzymic reactions, and the relationship among the three ketone bodies.

1985 ◽  
Vol 31 (4) ◽  
pp. 596-598 ◽  
Author(s):  
M Kimura ◽  
K Kobayashi ◽  
A Matsuoka ◽  
K Hayashi ◽  
Y Kimura
Keyword(s):  
Ketone Bodies ◽  
Normal Subjects ◽  
Chromatographic Determination ◽  
Diabetic Patients ◽  
Head Space ◽  
Analytical Recovery ◽  
Acetoacetate Decarboxylase ◽  
Reproducible Method ◽  
The Relationship

Abstract In this sensitive, reproducible method for determination of D-3-hydroxybutyrate (3-OHB) in plasma, it is converted to acetone by use of 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30)/lactate dehydrogenase (EC 1.1.1.27) coupled with acetoacetate decarboxylase (EC 4.1.1.4). The resulting acetone is detected by head-space gas chromatography. The lowest concentration of 3-OHB detectable in plasma was 2 mumol/L. The calibration curve showed a linear relationship for 3-OHB concentration from 0 to 5 mmol/L (r = 0.999). Analytical recovery of 3-OHB (50 mumol/L) was 97.9 (SD 3.8)%. The method was developed for determination of the three ketone bodies in plasma. The ratio of acetone to acetoacetate was not significantly different (p greater than 0.2) between normals (n = 31) and diabetics (n = 86). In normal subjects, the ratio of 3-OHB to acetoacetate was 1.20 (SD 0.44). In diabetic patients, the ratio correlated with the logarithm of the total ketone body concentration (r = 0.828).

Gas Chromatographic Determination of Residual Hexane in Modified Hop Extract

1972 ◽  
Vol 55 (6) ◽  
pp. 1226-1227
Author(s):  
Mark A Litchman ◽  
Lewis A Turano ◽  
Ronald P Upton
Keyword(s):  
Liquid Chromatography ◽  
Quantitative Determination ◽  
Chromatographic Determination ◽  
Methanol Solution ◽  
Chromatographic Column ◽  
Gas Liquid Chromatography ◽  
Porapak Q ◽  
Residual Hexane ◽  
Head Space

Abstract A method is described for the quantitative determination of hexane in modified hop extract by head-space gas-liquid chromatography. A sample of extract is weighed into a serum vial and water-methanol solution is added. The vial is sealed tightly and heated 1 hr in a 70°C bath. A sample of the head-space gas over the solution is injected onto a Porapak Q gas chromatographic column for determination. Recovery of 2–29 ppm hexane added to potassium isohumulone was 95.5–114.8%. The method may be applicable to other hop extracts.

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.

Haemoglobin and flow-mediated vasodilation

2006 ◽  
Vol 110 (4) ◽  
pp. 467-473 ◽  
Author(s):  
Per Lav Madsen ◽  
Michaela Scheuermann Freestone ◽  
Stefan Neubauer ◽  
Keith Channon ◽  
Kieran Clarke
Keyword(s):  
Radial Artery ◽  
Vascular Endothelium ◽  
Type Ii Diabetes ◽  
Normal Subjects ◽  
Diabetic Patients ◽  
Type Ii ◽  
Peripheral Vasodilation ◽  
Hb Concentration ◽  
Flow Mediated Vasodilation ◽  
The Relationship

A low [Hb] (Hb concentration) is out-balanced by peripheral vasodilation via mechanisms that are incompletely understood. Peripheral vasodilation is influenced by NO (nitric oxide) released from vascular endothelium in response to increased vessel wall shear stress, and absorption by Hb is the main mechanism by which the bioactivity of NO is disarmed. Thus we propose that graded NO absorption is the mechanism through which a low [Hb] is related to peripheral vasodilation. In the present study, we examined the relationship between [Hb] and FMD (flow-mediated vasodilation; 5 min of cuff ischaemia) of the radial and brachial arteries in 33 normal subjects and in 13 patients with Type II diabetes, known to have impaired NO-mediated vasodilation. The smaller radial artery provided the more sensitive test, as it had a 2-fold larger FMD than the brachial artery (22±18% compared with 9±18% respectively, in normal subjects; means±S.D., P<0.05). FMD of the radial artery had a negative correlation with [Hb] (r2=−0.66, P<0.05; n=27). In subjects with [Hb] below and above the median of 14.1 g/dl, the radial artery FMD was 30±22% compared with 13±12% respectively (P<0.05). In diabetic patients, FMD was lower and a co-variation with [Hb] could not be established. Thus, in normal subjects, NO-mediated endothelium-related vasodilation at least partly out-balanced the ‘added burden’ of a low [Hb] during post-ischaemic reperfusion.

Gas chromatographic determination of residual ethylene oxide by head space analysis

1973 ◽  
Vol 45 (14) ◽  
pp. 2327-2330 ◽  
Author(s):  
S. J. Romano ◽  
J. A. Renner ◽  
P. M. Leitner
Keyword(s):  
Ethylene Oxide ◽  
Chromatographic Determination ◽  
Space Analysis ◽  
Head Space ◽  
Head Space Analysis

Gas-chromatographic determination of amantadine in human urine.

1980 ◽  
Vol 26 (2) ◽  
pp. 295-296 ◽  
Author(s):  
M J Stumph ◽  
M W Noall ◽  
V Knight
Keyword(s):  
Limit Of Detection ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Organic Layer ◽  
Liquid Chromatographic Method ◽  
Analytical Recovery ◽  
Instrument Response ◽  
Aqueous Layer ◽  
Liquid Chromatographic

Abstract We describe a gas--liquid-chromatographic method for determining the concentration of amantadine hydrochloride in urine with beta-phenylethylamine as internal standard. The urine sample is made alkaline and extracted with 0.5 mL of chloroform. After centrifugation the aqueous layer is aspirated, and an aliquot of the organic layer is injected directly into the gas chromatograph. Concentration and instrument response are linearly related between 2 and 125 mg/L. The limit of detection was 0.5 mg/L. Mean analytical recovery was calculated to be 97%.

Liquid-chromatographic determination of acetaminophen in serum.

1979 ◽  
Vol 25 (3) ◽  
pp. 409-412 ◽  
Author(s):  
C G Fletterick ◽  
T H Grove ◽  
D C Hohnadel
Keyword(s):  
Chromatographic Determination ◽  
Pharmacokinetic Studies ◽  
Structural Isomers ◽  
Internal Standards ◽  
Standard Curve ◽  
Liquid Chromatographic Method ◽  
Analytical Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a sensitive and precise "high-pressure" liquid-chromatographic method for determining acetaminophen in serum. The 2-acetaminophenol and 3-acetaminophenol structural isomers of acetaminophen are used as internal standards. The method, which involves solvent extraction and adsorption chromatography on silica, provides excellent sensitivity, accuracy, and selectivity. The standard curve is linear over the range of acetaminophen concentrations of 0.5 to 300 mg/L, which makes the method useful for both pharmacokinetic studies and overdose monitoring. Analytical recovery is 97% for acetaminophen concentrations ranging from 5 to 300 mg/L. Many commonly used drugs were tested and found not to interfere. The procedure has been successfully adapted as a microscale method requiring only 50 microL of sample. The microscale method is particularly useful for pediatric and neonatal patients for whom sample size is a major concern.

Simultaneous liquid-chromatographic determination of some bronchodilators, anticonvulsants, chloramphenicol, and hypnotic agents, with Chromosorb P columns used for sample preparation.

1989 ◽  
Vol 35 (8) ◽  
pp. 1615-1618 ◽  
Author(s):  
D A Svinarov ◽  
D C Dotchev
Keyword(s):  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Bioactive Metabolites ◽  
Therapeutic Drug ◽  
Simple Liquid ◽  
Analytical Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a simple liquid-chromatographic system for simultaneously measuring bronchodilators, anticonvulsants, hypnotics, and chloramphenicol. Use in therapeutic drug monitoring includes determination of theophylline, caffeine, chloramphenicol, ethosuximide, primidone, phenobarbital, phenacemide, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites within 13 min. In the "toxicology mode" theophylline, caffeine, barbital, butabarbital, pentobarbital, amobarbital, secobarbital, primidone, phenobarbital, methylprylon, glutethimide, methaqualone, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites are resolved within 17 min. A reversed-phase C8 column (5-microns particles) is used, with acetonitrile/water (20/80 by vol) as mobile phase. The drugs are extracted from 50 microL of serum with use of a Chromosorb P microcolumn and chloroform/isopropanol (6/1 by vol). The drugs are quantified by absorbance at 208 nm, with tolylphenobarbital as internal standard. Lower limits of detection varied from 0.05 to 0.1 mg/L, analytical recovery from 94% to 106%; CVs were less than 5.6% within run, less than 6.9% between runs.

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