A false positive for clozapine using high-pressure liquid chromatography with ultraviolet detection

2012 ◽  
Vol 24 (4) ◽  
pp. 245-246 ◽  
Author(s):  
Unax Lertxundi ◽  
Margarita H. Manrique ◽  
Saioa D. Echaburu ◽  
Manuel Martinez
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
False Positive ◽  
Detection Method ◽  
Serum Levels ◽  
Specific Method ◽  
Ultraviolet Detection ◽  
Test Request ◽  
Made In

Background:We report a case of a false positive for clozapine, when analysing serum levels using a high-pressure liquid chromatography with ultraviolet (HPLC-UV) detection method.Methods:A patient not taking clozapine tested positive for clozapine three times in two different samples. This false positive was discovered by chance, because of an administrative error made in the first analytic test request.Results:The analysis of the first sample with a more specific method [HPLC-tandem mass spectrometry (LC-MS/MS)] showed that no clozapine was present.Conclusions:It is important to acknowledge that depending on the method employed, a false positive should not be ruled out as a possibility. Moreover, and even more worryingly, it should also be taken into account that clozapine serum levels could be tested erroneously high if the unknown interference is present and the HPLC-UV method is used. Although the interfering compound could not be identified, the possibility of a cross-reaction when analysing serum clozapine levels with the HPLC-UV method warrants urgent attention.

Enhanced Detectability and Chromatography of Some Amines by High Pressure Liquid Chromatography

1980 ◽  
Vol 63 (4) ◽  
pp. 702-706
Author(s):  
F Taylor Noggle
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Secondary Amines ◽  
High Pressure Liquid Chromatographic ◽  
Ultraviolet Detection ◽  
Primary And Secondary Amines ◽  
Liquid Chromatographic ◽  
Derivatives Of

Abstract The high pressure liquid chromatographic properties of 13 phenylisothiocyanate derivatives of primary and secondary amines were examined with ultraviolet detection at 254 nm. Urine extracts of subjects who were taking ephedrine, phenylpropanolamine, and phentermine were also examined. The method described improves the chromatographic properties of the amines and also enhances their detectability.

Detection of Low-Level Carbadox Residues in Animal Feeds by High Pressure Liquid Chromatography

1977 ◽  
Vol 60 (2) ◽  
pp. 279-283
Author(s):  
Ronald G Luchtefeld
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
False Positive ◽  
Active Drug ◽  
Hplc Method ◽  
High Pressure Liquid Chromatographic ◽  
Low Level ◽  
Liquid Chromatographic ◽  
Positive Results

Abstract The high pressure liquid chromatographic (HPLC) method is capable of detecting from 1 to 0.024 ppm methyl 3-(2-quinoxalinyl-methylene) carhazate-Nl,N4-dioxido (carbadox). Carbadox is extracted from the feed with 2% NH4OH in acetone, passed through a liquid-liquid partition, subjected to HPLC, and detected by using a 365 nm detector. No feed materials or other active drug ingredients produced false positive results.

Variations in serum levels of dolichol and its occurrence in human atherosclerotic plaques

1994 ◽  
Vol 72 (1-2) ◽  
pp. 62-65 ◽  
Author(s):  
Ravi Kothapalli ◽  
Najla Guthrie ◽  
Milton D. S. Haines ◽  
Kenneth K. Carroll
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Blood Serum ◽  
High Pressure Liquid Chromatography ◽  
Normal Subjects ◽  
Serum Levels ◽  
Lipoprotein Cholesterol ◽  
Aortic Tissue ◽  
Atherosclerotic Plaques ◽  
Wet Weight

Nonsaponifiable lipids of human atherosclerotic plaques obtained at autopsy from patients ranging in age from 45 to 85 years were analyzed by high pressure liquid chromatography. All plaques contained dolichol, ranging from 125 to 460 μg/g wet weight. Dolichol was also present in normal aortic tissue, but the amounts were generally less than in plaques. To investigate the source of the dolichol in plaques, blood serum was analyzed from both volunteer subjects and hypercholesterolemic patients. The levels of dolichol were generally higher in hypercholesterolemic compared with normal subjects, but were not correlated with levels of total or lipoprotein cholesterol. The homologue pattern of dolichol in atherosclerotic plaques differed from that of aorta and blood. The source of dolichol in plaques and its significance remains to be established.Key words: dolichol, polyprenols, cholesterol, atherosclerosis, blood, plaques.

Urinary free norepinephrine and dopamine determined by reverse-phase high-pressure liquid chromatography.

1977 ◽  
Vol 23 (3) ◽  
pp. 473-476 ◽  
Author(s):  
L D Mell ◽  
A B Gustafson
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Fluorometric Method ◽  
Reverse Phase ◽  
Ultraviolet Detection ◽  
Coefficients Of Variation ◽  
Chromatographic Procedure ◽  
Reproducible Method ◽  
Liquid Chromatographic

Abstract We used reverse-phase high-pressure liquid chromatography to measure free norepinephrine and dopamine simultaneously in human urine. Samples were treated with alumina, and the catecholamine(s) then eluted from it were directly injected onto a reverse-phase column (octadecyl-silica stationary phase), with 0.17 mol/liter acetic acid as the mobile phase and ultraviolet detection at 280 nm. The assay detects concentrations in urine as low as 5 mug/liter. Assay of 24-h urines (n = 10) gave within-run and day-to-day coefficients of variation of 3.7 and 4.7% for norepinephrine, and 2.6 and 3.5% for dopamine, respectively. Comparison studies with the traditional trihydroxyindole fluorometric method showed the liquid-chromatographic procedure to be more precise and subject to less interference. This relatively rapid procedure for urinary free norepinephrine and dopamine provides an efficient, reproducible method, readily adaptable to routine clinical use.

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