Serum quinidine concentrations: comparison of fluorescence, gas-chromatographic, and gas-chromatographic/mass-spectrometric methods.

1976 ◽  
Vol 22 (6) ◽  
pp. 810-812 ◽  
Author(s):  
D H Huffman ◽  
C E Hignite
Keyword(s):  
Extraction Method ◽  
Mass Spectra ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Fluorescence Method ◽  
Substantial Correlation ◽  
Gas Chromatographic Method ◽  
Therapeutic Doses ◽  
Serum Quinidine ◽  
Chromatographic Mass

Abstract Serum quinidine concentrations were determined in patients on chronic therapeutic doses. Although results were higher by a protein precipitate-fluorescence method as compared to a specific extraction fluorescence method, there was substantial correlation between results by the two methods (r = 0.945, P less than 0.001). We established the specificity of the extraction method by a methylation gas-chromatographic method in which the base peak in the mass spectra of the methylated products of both quinidine and cinchonidine, the internal standard, was monitored. We conclude that the protein precipitate method should be discarded.

Gas-chromatographic analysis for chlorpromazine and some of its metabolites in human serum, with use of a nitrogen detector.

1979 ◽  
Vol 25 (7) ◽  
pp. 1211-1215 ◽  
Author(s):  
D N Bailey ◽  
J J Guba
Keyword(s):  
Human Serum ◽  
Chromatographic Analysis ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Parent Drug ◽  
Isoamyl Alcohol ◽  
Gas Chromatographic Analysis ◽  
Coefficients Of Variation ◽  
Gas Chromatographic Method ◽  
Therapeutic Doses

Abstract We describe a gas-chromatographic method for measuring chlorpromazine and its metabolites chlorpromazine sulfoxide, mono-N-desmethylchlorpromazine, and di-N-desmethylchlorpromazine at therapeutic concentrations in human serum, with use of a nitrogen detector. The compounds are extracted from serum at pH 10.5 into hexane/isoamyl alcohol, re-extracted into dilute HCl, and then extracted into hexane after alkalinization of the HCl. The N-desmethylated metabolites are measured as their respective N-trifuloracetyl derivatives; the parent drug and its sulfoxide are measured as the unchanged bases. Promazine is the internal standard. As little as 5 micrograms of chlorpromazine, 20 micrograms of chlorpromazine sulfoxide, 20 micrograms of mono-N-desmethylchlorpromazine, and 10 micrograms of di-N-desmethylchlorpromazine per liter can be measured in 2-mL samples of serum. The within-run coefficients of variation for assays of these drugs at 100 micrograms/L are 2.7%, 5.6%, 5.1%, and 5.3%, respectively. The procedure was applied to patients receiving therapeutic doses of chlorpromazine and to patients who had ingested an overdose of chlorpromazine.

scholarly journals Validation of a Method for Determining Cholesterol in Egg Yolks/ Walidacja metody oznaczania cholesterolu w żółtkach jaj

2013 ◽  
Vol 13 (1) ◽  
pp. 143-153 ◽  
Author(s):  
Robert Gąsior ◽  
Mariusz P. Pietras
Keyword(s):  
Sample Preparation ◽  
Measurement Errors ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Limit Of Quantification ◽  
Egg Yolks ◽  
Chromatographic Measurement ◽  
Preparation Errors ◽  
Gas Chromatographic Method ◽  
Lower Uncertainty

Abstract The aim of the study was to validate a gas chromatographic method for determining cholesterol in egg yolks according to the EN ISO/IEC 17025 standard. Of the two methods, with and without internal standard, the former was characterized by lower uncertainty, with a repeatability of 4% and within-laboratory reproducibility of 6%. The method’s uncertainty (n = 2, P≤0.05), which included sample preparation errors and chromatographic measurement errors, was 10.6%. Mean recovery was 99.9% and limit of quantification was 0.16 mg/g. The coefficient of variation for repeatability, which is calculated during routine analyses, should not exceed the 8% limit of repeatability. The method is reliable, as confirmed by the results of validation, and the procedure is relatively rapid and simple.

scholarly journals Quantitative Identification of Pesticides as Target Compounds and Unknowns by Spectral Deconvolution of Gas Chromatographic/Mass Spectrometric Data

2008 ◽  
Vol 91 (6) ◽  
pp. 1467-1477 ◽  
Author(s):  
Albert Robbat ◽  
Andreas Hoffmann ◽  
Kevin Mac Namara ◽  
Yongli Huang
Keyword(s):  
Mass Spectra ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
False Negatives ◽  
Orange Oil ◽  
Complex Samples ◽  
Spectrometric Data ◽  
Lemon Oil ◽  
Quantitative Identification ◽  
Chromatographic Mass

Abstract The results of gas chromatography/mass spectrometry (MS), with Ion Signature Technology, Inc. (North Smithfield, RI) quantitative deconvolution software, are discussed for pesticides identified both as target compounds by using retention and MS data and as unknowns by using only mass spectra. Target compound analysis of 32 pesticides, surrogates, and an internal standard added to lemon oil over a wide concentration range produced precision and accuracy that are well within the acceptable criteria of 25 and 50 for complex samples. When 112 pesticides were added to orange oil and searched as unknowns, 110 of the 112 compounds were correctly identified, with an average pesticide recovery of 101 19. The injection volume of the orange oil fortified with pesticides was selected so that 4 ng per compound was injected on column. No false negatives were found, because ion signals for the 2 unidentified pesticides were not acquired by the instrument in either the standard mixture or the oil. No false positives were detected, although >750 widely different compounds were included in the library search.

Gas Chromatographic Determination of Histapyrrodine Hydrochloride in Pharmaceutical Preparations

1986 ◽  
Vol 69 (4) ◽  
pp. 612-613
Author(s):  
Ramesh T Sane ◽  
Vipul J Doshi ◽  
Sanjay K Joshi ◽  
Vijay K Shastri ◽  
Dhananjay S Sapre ◽  
...  
Keyword(s):  
Chromatographic Method ◽  
Internal Standard ◽  
Pharmaceutical Preparations ◽  
Chromatographic Determination ◽  
Chlorpheniramine Maleate ◽  
Accuracy And Precision ◽  
Label Claim ◽  
Gas Chromatographic Method

Abstract A simple gas chromatographic method is described for the determination of histapyrrodine HC1 in marketed formulations. Chlorpheniramine maleate is used as the internal standard. The amount of histapyrrodine HC1 found by the proposed method averaged 19.91 mg/tablet, compared with the label claim of 20 mg/tablet. The method was statistically evaluated for accuracy and precision.

Modification of the AOAC Gas-Liquid Chromatographic Method for Indole in Shrimp: Collaborative Study

1982 ◽  
Vol 65 (4) ◽  
pp. 842-845
Author(s):  
Theodore L Chambers ◽  
◽  
E C Netz ◽  
K Ogger
Keyword(s):  
Silica Gel ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Current Method ◽  
Peak Height ◽  
Modified Method ◽  
Liquid Chromatographic Method ◽  
Gas Chromatographic Method ◽  
Liquid Chromatographic

Abstract Several changes were suggested for standardization of the AOAC official final action gas chromatographic method for the determination of indole in shrimp. In a collaborative study, 3 FDA laboratories compared the modified method with the current method. At a 95% confidence level, the same results were obtained for each respective sample by the AOAC or the modified method, which had the following changes. The cleanup column was standardized by drying the silica gel for 2 h at 125°C and equilibrating with 3 g of water/25 g of silica gel. Concentrated ethyl acetate shrimp extracts were treated with anhydrous sodium sulfate before column cleanup and indole was eluted from the column with 15% ethyl ether/hexane. A reduced amount of the internal standard, 2-methylindole, was used to improve peak height measurements at the 25 μg% indole level. The modified method has been adopted official first action to replace method 18.075.

scholarly journals Planar Chromatographic and Liquid Chromatographic Analysis of Thiamphenicol in Bovine and Human Plasma

1997 ◽  
Vol 80 (4) ◽  
pp. 746-750 ◽  
Author(s):  
Elena Dreassi ◽  
Gianfranco Corbini ◽  
Vittoria Ginanneschi ◽  
Piero Corti ◽  
Sandra Furlanetto
Keyword(s):  
Human Plasma ◽  
Chromatographic Analysis ◽  
Extraction Method ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Bovine Plasma ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic ◽  
Pc Method

Abstract A planar chromatographic (PC) method was developed to determine thiamphenicol in human and bovine plasma with florphenicol as internal standard. The performance of the method was compared with that of a liquid chromatographic method. Recovery of extraction method developed for plasma was 81.51 ± 2.85%. Reproducibilities of the PC assay performed with various PC plates were also good.

Gas-chromatographic determination of 5-fluorocytosine in human serum.

1976 ◽  
Vol 22 (6) ◽  
pp. 772-776 ◽  
Author(s):  
S A Harding ◽  
G F Johnson ◽  
H M Solomon
Keyword(s):  
Chromatographic Method ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Mean Value ◽  
Normal Serum ◽  
Trimethylsilyl Derivative ◽  
Serum Samples ◽  
Gas Chromatographic Method

Abstract We describe a sensitive and precise gas-chromatographic method, in which cytosine is used as the internal standard, for determination of an antifungal agent, 5-fluorocytosine, in serum. The trimethylsilyl derivative of this drug is well separated from the internal standard and from normal serum constituents. Amphotericin B does not interfere with the determination of 5-fluorocytosine. The lower limit of detection for 5-fluorocytosine is 1 mg/liter when 200 mul of serum is analyzed. Within-run precision (CV), established by analysis of 10 replicates, was 4.5% at a concentration of 19.9 mg/liter. Twenty-five serum samples were analyzed for 5-fluorocytosine by a microbiological assay and by the gas-chromatographic method. Mean value observed with the bioassay was 78.5 mg/liter and with our procedure was 69.4 mg/liter. When values for our assay were regressed against values for the bioassay, slope of the least-squares line was 0.85, intercept was 2.7 mg/liter, and r was 0.93.

Qualitative and Quantitative Determination of Methaqualone in Serum by Gas Chromatography

1974 ◽  
Vol 20 (2) ◽  
pp. 249-254 ◽  
Author(s):  
M A Evenson ◽  
G L Lensmeyer
Keyword(s):  
Gas Chromatography ◽  
Quantitative Determination ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Serum Concentrations ◽  
Single Extraction ◽  
Qualitative And Quantitative ◽  
Gas Chromatographic Method ◽  
Isothermal Gas

Abstract A rapid, simple, accurate, and precise isothermal gas-chromatographic method is introduced for determination of methaqualone (2-methyl-3-o-tolyl-4(3H)-quinazolinone) in serum. A single extraction of 2 ml of serum, without derivative formation, will give adequate sensitivity for quantitation of therapeutic serum concentrations of the drug within 15 min. The method is free of interferences from biological substances, as well as from commonly used drugs. A non-drug internal standard compensates for variables in extraction, injection, and instrumental changes during analysis. The coefficient of variation, day-to-day, is 5.6%. Mean recovery of added methaqualone was 80%. To compensate for the nonquantitative yield and ensure accurate results, we prepared all analytical methaqualone standards in serum.

Gas Chromatographic Method for Determination of Diethylstilbestrol in Feeds

1969 ◽  
Vol 52 (1) ◽  
pp. 107-109 ◽  
Author(s):  
I E Smiley ◽  
E D Schall
Keyword(s):  
Chromatographic Method ◽  
Internal Standard ◽  
Commercial Feed ◽  
Gas Chromatographic Method ◽  
Feed Samples

Abstract A GLC method was developed for the determination of diethylstilbestrol in feeds within the 0.0011–0.0022% range, using dienestrol diacetate as an internal standard. A 10 g sample was extracted with 7% ethanol in chloroform and subjected to a modified alkaline cleanup. The bis-(trimethylsilyl) acetamide derivative was then prepared and determined by GLC. No interference was encountered with commercial feed samples.

Impurity Problems in Chromatographic Method Studies for Fenthion Formulations

1985 ◽  
Vol 68 (5) ◽  
pp. 925-929
Author(s):  
Willard G Boyd
Keyword(s):  
Mobile Phase ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Flame Ionization Detection ◽  
Private Communication ◽  
Flame Ionization ◽  
Glass Column ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract Several gas chromatographic (GC) methods for analyzing fenthion were studied, and flame ionization detection, a glass column packed with SE-52 on Chromosorb GHP, and on-column injection were selected as parameters. No suitable internal standard was found because of coeluting, bias-producing impurities in fenthion. Several liquid chromatographic (LC) methods were also studied, and UV detection, a Zorbax ODS column, and a methanol-water-H3P04 mobile phase were finally selected as parameters. Dipentyl phthalate was selected as internal standard. After testing, this LC method was submitted for collaborative study. During the collaborative study, the manufacturer found an impurity, 3-methyl-4-(methylthio)anisole, co-eluting with fenthion in the collaborative method. The manufacturer's method was then evaluated as an alternative for collaborative study, but a significant unidentified impurity from the formulation blank, used for formulating emulsifiable concentrates, was also found co-eluting with fenthion. The anisole impurity was verified by LC, and the presence of the S-isomer and bis-methylthio-fenthion impurities was found by gas chromatographic- mass spectrometric (GC-MS) analyses. An anisole material obtained from Mobay was also verified by GC-MS analysis. Several other impurities were identified from literature references and from private communication with the manufacturer.

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