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

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.

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Gas Chromatographic Determination of Histapyrrodine Hydrochloride in Pharmaceutical Preparations

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/69.4.612 ◽

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.

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Collaborative Study of a Gas Chromatographic Method for Ronnel in Feeds

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/52.3.435 ◽

1969 ◽

Vol 52 (3) ◽

pp. 435-438

Author(s):

Albert J Gehrt

Keyword(s):

Chromatographic Method ◽

Collaborative Study ◽

Flame Ionization Detector ◽

Ionization Detector ◽

Flame Ionization ◽

Coefficients Of Variation ◽

Chromatographic Measurement ◽

Cattle Feeds ◽

Gas Chromatographic Method

Abstract A GLC method (flame ionization detector) for ronnel in cattle feeds at levels of 0.038, 0.041, and 0.055% was studied by 11 collaborators. The method involves extraction of ronnel by shaking with acetone followed by direct chromatographic measurement. The method is simple and rapid (no cleanup required), measures true ronnel, and is free from interferences present in the UV methods previously studied. Agreement between laboratories was satisfactory; coefficients of variation were 11.0, 12.0, and 7.2%. Ronnel recoveries were 81.1, 93.5, and 98.0%. Low recovery from the first sample may be due to ronnel hydrolysis or binding during storage (sample was 8 months old). The Associate Keferee recommends that the method be adopted as official first action.

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/65.4.842 ◽

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.

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

Clinical Chemistry ◽

10.1093/clinchem/22.6.772 ◽

1976 ◽

Vol 22 (6) ◽

pp. 772-776 ◽

Cited By ~ 5

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.

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Qualitative and Quantitative Determination of Methaqualone in Serum by Gas Chromatography

Clinical Chemistry ◽

10.1093/clinchem/20.2.249 ◽

1974 ◽

Vol 20 (2) ◽

pp. 249-254 ◽

Cited By ~ 9

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.

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Gas Chromatographic Method for Determination of Diethylstilbestrol in Feeds

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/52.1.107 ◽

1969 ◽

Vol 52 (1) ◽

pp. 107-109 ◽

Cited By ~ 1

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.

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Gas Chromatographic Method for Determination of Cypermethrin in Pesticide Formulations: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/70.1.51 ◽

1987 ◽

Vol 70 (1) ◽

pp. 51-53

Author(s):

J F C Tyler

Keyword(s):

Chromatographic Method ◽

Collaborative Study ◽

Internal Standard ◽

Coefficients Of Variation ◽

Pesticide Formulations ◽

Glass Column ◽

Technical Material ◽

Gas Chromatographic Method ◽

Ethylhexyl Phthalate

Abstract A gas chromatographic method for determination of total cypermethrin in technical and formulated products has been developed and subjected to a collaborative study involving IS participating laboratories. Each sample was dissolved in methyl isobutyl ketone containing di(2-ethylhexyl) phthalate as internal standard and analyzed by gas chromatography on a glass column with 3% OV-101 on Chromosorb W-HP. Each collaborator was furnished with reference stdard and 4 samples of technical material, 3 emulsifiable concentrates, one wettable powder, and one ultralow volume formulation for analysis. The coefficients of variation of the results obtained ranged from 0.955 to 1.7462%. The method has been adopted as official first action by AOAC.

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Gas Chromatographic Separation and Quantitative Estimation of Barbiturate Mixtures in Solid Dosage Forms

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/51.3.619 ◽

1968 ◽

Vol 51 (3) ◽

pp. 619-621

Author(s):

John L Allen

Keyword(s):

Chromatographic Separation ◽

Chromatographic Method ◽

Quantitative Estimation ◽

Collaborative Study ◽

Internal Standard ◽

Dosage Forms ◽

Solid Dosage Forms ◽

Solid Dosage ◽

Gas Chromatographic Method ◽

Gas Chromatographic Separation

Abstract A gas chromatographic method has been described for the analysis of mixed barbiturates in solid dosage forms. Analysis on a 10% SE-30 column gave good separations for butabarbital, amobarbital, secobarbital, pentobarbital, and/or phenobarbital; amobarbital is not separated adequately from pentobarbital. An internal standard, mephobarbital, is used to minimize injection errors. The method gives both good quantitative and qualitative results on the barbiturates investigated. Two synthetic tablet mixtures were analyzed by this procedure and recoveries were 98—103%. It is recommended that the method be subjected to collaborative study.

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Single-Laboratory Validation of a Gas Chromatographic Method of Direct Determination of Volatile Compounds in Spirit Drinks: Need for an Improved Interlaboratory Study

Journal of AOAC International ◽

10.5740/jaoacint.18-0258 ◽

2019 ◽

Vol 102 (2) ◽

pp. 669-672 ◽

Cited By ~ 4

Author(s):

Siarhei V Charapitsa ◽

Svetlana N Sytova ◽

Anton L Korban ◽

Lidia N Sobolenko

Keyword(s):

Volatile Compounds ◽

Chromatographic Method ◽

Internal Standard ◽

Direct Determination ◽

Relative Bias ◽

Interlaboratory Study ◽

Detector Response ◽

Gas Chromatographic Method ◽

Single Laboratory

Abstract Background: The quality and safety control of an alcoholic drink is mainly the establishment of its chemical content, particularly the quantity of volatile compounds. Objective: A single-laboratory validation of a gas chromatographic method of direct determination of volatile compounds in spirit drinks was conducted. The discussed method applies ethanol, the major volatile component of an alcoholic beverage, as an internal standard. Possible algorithms of method validation based on interlaboratory study were proposed and described. Methods: Seven standard solutions of the following volatile compounds were prepared gravimetrically in 40% (v/v) water–ethanol solution: acetaldehyde, methyl acetate,ethyl acetate, methanol, 2-propanol, 1-propanol, isobutanol, 1-butanol, and isoamylol. Each sample wasmeasured with the proposed method 30 times in repeatability conditions. Results: Flame ionization detector response was linearly correlated with assigned concentrations at a range of 2 to5000 mg/L of absolute alcohol (AA) with coefficients of determination (R2)more than 0.995 for all analyzed components. Repeatability (RSDr ≤ 4.5%; RSDr ≤ 2.0%), reproducibility (RSDR ≤ 5.0%; RSDR ≤ 2.0%), and trueness (relative bias ≤ 2.6%; relative bias ≤ 1.4%) were obtained for low (10–25 mg/L AA for methanol and 2–10 for othervolatiles) and high (25–5000 mg/L AA for methanol and 10–5000 for other volatiles) ranges of concentrations, correspondingly. Conclusions: The method increases the reliability of measurements and eliminates manual proceduresof internal standard addition into both calibrationstandard solutions and spirit drinks.

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Gas Chromatographic Method for Determination of Permethrin in Pesticide Formulations: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/70.1.53 ◽

1987 ◽

Vol 70 (1) ◽

pp. 53-55

Author(s):

J F C Tyler

Keyword(s):

Chromatographic Method ◽

Collaborative Study ◽

Internal Standard ◽

Isobutyl Ketone ◽

Coefficients Of Variation ◽

Pesticide Formulations ◽

Glass Column ◽

Technical Material ◽

Gas Chromatographic Method

Abstract A gas chromatographic method for determination of permethrin in technical and formulated products has been developed and subjected to a collaborative study involving 19 participating laboratories. Each sample was dissolved in methyl isobutyl ketone containing n-octacosane as internal standard and analyzed by gas chromatography on a glass column with 3% OV-210 on Chromosorb W-HP. Each collaborator was furnished with reference standard and 5 samples of technical material (90-95%), 8 emulsifiable concentrates (10-50%), 2 wettable powders (20-30%), one dustable powder (1-2%), and one mter-dispersible granules (1-2%) for analysis. The coefficients of variation of the results obtained ranged from 0.79 to 4.24%. The method has been adopted as official first action by AOAC.

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