Liquid-chromatographic detection of thiazide diuretics in urine.

1980 ◽  
Vol 26 (6) ◽  
pp. 702-706 ◽  
Author(s):  
P A Tisdall ◽  
T P Moyer ◽  
J P Anhalt
Keyword(s):  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Spectrophotometric Method ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Analytical Recovery ◽  
Two Samples ◽  
Chromatographic Procedure ◽  
Chromatographic Detection ◽  
Liquid Chromatographic

Abstract We describe a liquid-chromatographic procedure for detection in urine of all thiazide drugs currently used clinically. Urine is treated initially with NaBH4 to convert any chlorothiazide present to hydrochlorothiazide. The urine is acidified with NaH2PO4 (1.0 mol/L, pH 5), and thiazides are extracted with ethyl acetate. Interfering substances are then removed in two washes with 0.1 mol/L Na2HPO4 at pH 8. The ethyl acetate is evaporated and the residue redissolved in mobile phase. Thiazides are assayed by reversed-phase chromatography, with detection by ultraviolet absorption. Analytical recovery of thiazides ranged from 53 to 93%. Urines from 48 patients were so studied, and the results were compared with results by the currently used spectrophotometric method. The two methods agreed for 56% of samples. Evaluation of the discrepancies by review of patients’ histories clearly showed liquid chromatography to have correctly identified seven of eight positive urines that the spectrophotometric method failed to detect. Ultraviolet scanning incorrectly identified as positive two samples, whereas liquid chromatography did not falsely identify any urines as positive. Our method was more sensitive and more specific than the spectrophotometric method.

Measurement of thiamylal and thiopental in plasma by electron capture and flame photometric gas-liquid chromatography.

1977 ◽  
Vol 23 (7) ◽  
pp. 1306-1309 ◽  
Author(s):  
R H Smith ◽  
J A MacDonald ◽  
D S Thompson ◽  
W E Flacke
Keyword(s):  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Electron Capture ◽  
Internal Standard ◽  
Chromatographic Column ◽  
Gas Liquid Chromatography ◽  
Unchanged Drug ◽  
Chromatographic Procedure ◽  
Isothermal Gas ◽  
Liquid Chromatographic

Abstract We describe an isothermal gas-liquid chromatographic procedure developed for measuring thiamylal and thiopental in plasma. The unchanged drug is extracted into ethyl acetate from acidified plasma, together with an internal standard. The solvent is removed, the residue methylated, aliquots, diluted with benzene, are injected into a 183-cm gas-liquid chromatographic column containing 3% OV-17. Sensitivity of detection is in the nanogram to picogram range.

Determination of Cymiazole Residues in Honey by Liquid Chromatography

1993 ◽  
Vol 76 (1) ◽  
pp. 92-94 ◽  
Author(s):  
Paolo Cabras ◽  
Marinella Melis ◽  
Lorenzo Spanedda
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Analysis ◽  
Mobile Phase ◽  
Chromatographic Method ◽  
Reversed Phase ◽  
Limit Of Determination ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic ◽  
Control Samples

Abstract A liquid chromatographic method is described for the determination of cymiazole residues in honey. This acaricide is determined on a reversed-phase (C18) column, with a CH3CN-O.OOIN HCI-NaCI mixture (950 mL + 50 mL + 0.3 g/L) as the mobile phase, and UV detection at 265 nm. Cymiazole is extracted with n-hexane from aqueous alkalinized (pH 9) honey solutions. No further cleanup of the honey extract was required before chromatographic analysis. Recoveries on control samples fortified with 0.01,0.10, and 1.00 ppm cymiazole ranged from 92 to 102%. The limit of determination was 0.01 ppm.

Chromatographic behaviour of some porphyrins and their complexes with Zn, Pd(II) and Cu(II)

2000 ◽  
Vol 04 (02) ◽  
pp. 209-214 ◽  
Author(s):  
M. I. UVAROVA ◽  
G. D. BRYKINA ◽  
O. A. SHPIGUN
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Mobile Phase ◽  
High Performance ◽  
Reversed Phase ◽  
Zinc Complexes ◽  
Acetate Concentration ◽  
Hydrophobic Compounds ◽  
Retention Parameters

In this work the influence of the porphyrin structure and of the nature of the mobile phase upon retention parameters is examined by means of reversed phase high-performance liquid chromatography (HPLC). Acetonitrile–ethyl acetate and other mixtures were used as eluents. An increase in the retention of azo- and benzosubstituted porphyrins as well as of those containing a large number of carbon atoms as substituents of macrocycles may be noted. A variation in the polarity of the mobile phase affects the retention of the ligands more than that of their zinc complexes. The retention of the most hydrophobic compounds may be well described in coordinates lg k'– lg M. For less hydrophobic porphyrins these dependences are close to linear only within limited intervals of mobile phase ethyl acetate concentration. The best separation of zinc complexes was achieved with acetonitrile as the eluent. The detection limit of porphyrin ligands and complexes with metals is n × 10-8 M.

Simultaneous very fast liquid-chromatographic analysis of ethosuximide, primidone, phenobarbital, phenytoin, and carbamazepine in serum.

1983 ◽  
Vol 29 (3) ◽  
pp. 473-476 ◽  
Author(s):  
P M Kabra ◽  
M A Nelson ◽  
L J Marton
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Chromatographic Analysis ◽  
Mobile Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Ultraviolet Detector ◽  
Analytical Recovery ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic

Abstract We describe a sensitive, specific, and very fast liquid-chromatographic assay for simultaneously determining five anticonvulsants (ethosuximide, primidone, phenobarbital, phenytoin, and carbamazepine) by using commercially available 5- or 3-microns particle size reversed-phase columns and a microflow-cell-equipped ultraviolet detector. The anticonvulsant drugs are extracted from 200 microL of serum containing 50 mg of cyclopal per liter as an internal standard, by elution from a Bond-Elut (Analytichem International, Harbor City, CA 90710) column with 300 microL of methanol. A 5-microL aliquot of the eluate is applied to an analytical column and eluted with a mobile phase of acetonitrile/methanol/phosphate buffer, 20 mmol/L, pH 3.7 (13.5/35/51.5 by vol), at a flow rate of 3.0 mL/min and at 50 degrees C. Detection is at 210 or 195 nm. The chromatography is complete in less than 2.5 min with the 5-microns-particle column, and in less than 1.4 min with the 3-microns-particle column. The sensitivity of the method for all drugs is less than 1 mg/L. Analytical recovery of drugs added to serum ranged from 92 to 109% for concentrations up to 200 mg/L. Between-run precision (CV) ranged from 1.3 to 4.1%.

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.

Direct determination of the linoleate/oleate ratio in serum cholesterol esters by liquid chromatography.

1982 ◽  
Vol 28 (4) ◽  
pp. 676-680 ◽  
Author(s):  
J T Bernert ◽  
J R Akins ◽  
D T Miller
Keyword(s):  
Liquid Chromatography ◽  
Serum Cholesterol ◽  
Methyl Esters ◽  
Direct Determination ◽  
Reversed Phase ◽  
Cholesterol Esters ◽  
Serum Samples ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract We describe a convenient method for the direct determination of the serum cholesterol linoleate/cholesterol oleate (L/O) ratio by reversed-phase "high-performance" liquid chromatography. After removal of phospholipids by silicic acid chromatography, a serum extract is analyzed on a 5-micrometers particle size Ultrasphere-ODS column, eluted isocratically with acetonitrile/isopropanol (30/70, by vol). Detection is at 200 nm. Cholesterol palmitoleate interferes with the measurement when the analysis is based on peak area, but not when peak height is used. The overall precision of L/O measurements by this method was very similar to that observed with a gas-liquid chromatographic procedure, in which the cholesterol esters are first isolated and transesterified to the methyl esters. In both cases, the within-run CV for six replicate analyses was less than 2%. Analysis of 53 human serum samples by both methods yielded very similar L/O ratios. A plot of the data (our method = y) vs the usual gas-liquid chromatographic procedure gave a correlation coefficient of 0.988 and a regression equation of y = 1.03x + 0.013. Furthermore, direct analysis of serum cholesterol ester L/O ratios by our liquid-chromatographic method is simpler, quicker, and more readily adaptable to automation.

Liquid-chromatographic determination of vanillylmandelic acid in urine.

1985 ◽  
Vol 31 (6) ◽  
pp. 819-821 ◽  
Author(s):  
G M Anderson ◽  
F C Feibel ◽  
D J Cohen
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Urine Samples ◽  
Vanillylmandelic Acid ◽  
Analytical Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Urinary vanillylmandelic acid (VMA) was determined by "high-performance" liquid chromatography with fluorometric (LC-F) and amperometric (LC-EC) detection. Urine samples were first purified on a small, open-bed, reversed-phase preparatory column. VMA and the internal standard (iso-VMA) were then separated by reversed-phase ion-pair liquid chromatography. Analytical recovery of VMA was high (98.3%, SD 3.3%, n = 8), and concentrations measured by LC-F and LC-EC were in excellent agreement (r = 0.996). The LC-F chromatograms of urine samples had fewer late peaks; however, detection limits were lower (15 vs 120 micrograms/L) for the LC-EC method. Typical concentrations of 1-10 mg/L in urine can be measured easily with either method.

scholarly journals Determination of Methomyl in Insecticidal Formulations by Reversed-Phase Liquid Chromatography: Collaborative Study

1996 ◽  
Vol 79 (4) ◽  
pp. 941-948
Author(s):  
James E Conaway ◽  
J B Audino ◽  
E Bane ◽  
S K Carrigan ◽  
R Glinsky ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Coefficient Of Variation ◽  
Mobile Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Reversed Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A reversed-phase liquid chromatographic (LC) method for methomyl was studied. Twelve collaborators analyzed 3 solid and 4 liquid formulations on both a Zorbax octadecylsilane (ODS) column and a similar column of their choice. Methomyl and the internal standard were separated by using a mobile phase consisting of approximately 8% acetonitrile in water, which was monitored at 254 nm. The coefficient of variation on the Zorbax column ranged from 0.70 to 5.23%, while the range on the collaborators' house columns was 1.08 to 6.01%. Results with the Zorbax ODS column fell within the 5% 2-tail limits, and 10 of 11 collaborators' results fell within these limits on house columns. The LC method for determination of methomyl in insecticidal formulations has been adopted first action by AOAC INTERNATIONAL.

Determination of urinary glyoxal and methylglyoxal by high-performance liquid chromatography

2004 ◽  
Vol 42 (2) ◽  
Author(s):  
Kazuki Akira ◽  
Yui Matsumoto ◽  
Takao Hashimoto
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Carbonyl Stress ◽  
Age Related ◽  
Highperformance Liquid Chromatography ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

AbstractCarbonyl stress compounds such as glyoxal and methylglyoxal have been recently attracting much attention because of their possible clinical significance in chronic and age-related diseases. A high-performance liquid chromatographic procedure has been developed for the simultaneous quantitation of glyoxal and methylglyoxal in human urine. The assay is based on the reaction of these compounds with 1,2-diamino-4,5-dimethoxybenzene to form fluorescent adducts, which are separated by reversed-phase highperformance liquid chromatography in a total run time of 45 minutes and quantitated fluorometrically using 2,3-pentanedione as an internal standard. Derivatization is performed for diluted urine (100–120 mOsm/kg H

Liquid-chromatographic assay of cefmenoxime in serum and urine.

1983 ◽  
Vol 29 (7) ◽  
pp. 1415-1418 ◽  
Author(s):  
D P Reitberg ◽  
J J Schentag
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Limit Of Quantification ◽  
Extraction Recovery ◽  
Anisic Acid ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic ◽  
Standard Protein ◽  
Serum And Urine

Abstract This is a simple, precise liquid-chromatographic procedure for determining cefmenoxime in patients' serum and urine. p-Anisic acid is used as the internal standard. Protein is precipitated from 0.5 mL of serum or dilute urine with 100 microL of perchloric acid. The clear supernate is injected directly onto a mu-Bondapak CN reversed-phase column. The mobile phase is acetate buffer, pH 3.8 (25 degrees C). The flow rate is 2.5 mL/min. Column effluent is monitored at 254 nm. Extraction recovery from serum averaged 74.6%. Calibration curves were linear from 0.5 mg/L, the lower limit of quantification, to 100 mg/L. We present cefmenoxime concentrations in serum from a patient being treated for pneumonia. The procedure was evaluated in the clinical setting to determine its applicability to the study of cefmenoxime pharmacokinetics in critically ill patients.

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