scholarly journals Interlaboratory Comparison for the Determination of Five Residual Organochlorine Pesticides in Ginseng Root Samples by Gas Chromatography

2007 ◽  
Vol 90 (4) ◽  
pp. 1133-1141 ◽  
Author(s):  
Mei-Fung Kong ◽  
Serena Chan ◽  
Yiu-Chung Wong ◽  
Siu-Kay Wong ◽  
Della Wai-Mei Sin
Keyword(s):  
Measurement Uncertainty ◽  
Organochlorine Pesticides ◽  
Interlaboratory Comparison ◽  
Analytical Data ◽  
Quality Criterion ◽  
Asia Pacific ◽  
Ginseng Root ◽  
Mean Values ◽  
Z Scores

Abstract An interlaboratory comparison study for the determination of 5 residual organochlorine pesticides (hexachlorobenzene and 4 hexachlorocyclohexane isomers) in ginseng root was performed. This program [Asia Pacific Laboratory Accreditation Cooperation (APLAC) T049] was the first of its kind for an herbal matrix and involved the participation of 70 laboratories from 26 countries worldwide. Consensus mean values were computed statistically from the reported results, which were eventually used to assess the performance of individual laboratories in terms of the z-scores. The distribution of analytical data was found to be widespread, with standard deviation ranging from 43.9 to 55.9%, and the result patterns obtained were similar to those residue pesticide programs using other matrixes. Although the estimation of measurement uncertainty is a crucial requirement for all quantitative tests for laboratories that meet the requirements of International Organization for Standardization/International Electrotechnical Commisssion (ISO/IEC) 17025, some laboratories in this program had difficulties and showed unfamiliarity with respect to that quality criterion. It was recommended that laboratories review and rectify the situation promptly so that they would have a better understanding of measurement uncertainty or the test service provided.

Interlaboratory comparison of dynamic olfactometry in Central Europe 2000

2001 ◽  
Vol 44 (9) ◽  
pp. 27-32 ◽  
Author(s):  
D. Mannebeck ◽  
H. Mannebeck
Keyword(s):  
Central Europe ◽  
Hydrogen Sulphide ◽  
Interlaboratory Comparison ◽  
European Standard ◽  
Mean Values ◽  
Repeatability And Reproducibility ◽  
Odour Concentration ◽  
Standard Deviations ◽  
Dynamic Olfactometry

This paper presents the results of an interlaboratory comparison (ringtest) on olfactometry with 31 participants from four countries in Central Europe. The aim was to give evidence of the performance of dynamic olfactometry on the basis of the European Standard prEN 13725 (Draft) “Determination of odour concentration with dynamic olfactometry”. The test included the analysis of three individual substances (n-butanol, hydrogen sulphide, tetrahydrothiophen) as well as a natural odour mixture (coffee flavour) to compare mean values and the standard deviations of results for the investigated samples. It was confirmed that laboratories working in compliance with the requirements of the new standard achieve a significantly better repeatability and reproducibility than those that are not compliant.

scholarly journals Proficiency Testing Program for the Determination of Total Arsenic, Cadmium, and Lead in Seawater Shrimp

2008 ◽  
Vol 91 (4) ◽  
pp. 858-864 ◽  
Author(s):  
Mei-Fung Kong ◽  
Serena Chan ◽  
Yiu-Chung Wong
Keyword(s):  
Proficiency Testing ◽  
Robust Statistics ◽  
Asia Pacific ◽  
Homogeneity Test ◽  
Total Arsenic ◽  
Mean Values ◽  
True Value ◽  
Consensus Mean ◽  
Cadmium And Lead

Abstract The proficiency testing (PT) program for 97 worldwide laboratories for determining total arsenic, cadmium, and lead in seawater shrimp under the auspices of the Asia-Pacific Laboratory Accreditation Cooperation (APLAC) is discussed. The program is one of the APLAC PT series whose primary purposes are to establish mutual agreement on the equivalence of the operation of APLAC member laboratories and to take corrective actions if testing deficiencies are identified. Pooled data for Cd and Pb were normally distributed with interlaboratory variations of 21.9 and 34.8, respectively. The corresponding consensus mean values estimated by robust statistics were in good agreement with those obtained in the homogeneity tests. However, a bimodal distribution was observed from the determination of total As, in which 14 out of 74 participants reported much smaller values (0.4826.4 mg/kg) as compared with the mean values of 60.9 mg/kg in the homogeneity test. The use of consensus mean is known to have significant deviation from the true value in bi- or multimodal distribution. Therefore, the mode value, a better estimate of central tendency, was chosen to assess participants' performance for total As. Estimates of the overall uncertainty from participants varied in this program, and some were recommended to acquire more comprehensive exposure toward important criteria as stipulated in ISO/IEC 17025.

An interlaboratory study of the determination of digoxin by immunoassay.

1980 ◽  
Vol 26 (3) ◽  
pp. 480-486
Author(s):  
D M Fast ◽  
W H Hannon ◽  
C A Burtis ◽  
D D Bayse
Keyword(s):  
Frequency Distribution ◽  
Statistical Difference ◽  
Analytical Data ◽  
Statistical Information ◽  
Mean Values ◽  
Clinical Laboratories ◽  
The Mean ◽  
Computational Procedures

Abstract We conducted a voluntary survey of laboratories and manufacturers to assess the current quality of analytical assays for serum digoxin. More than 300 clinical laboratories and 18 manufacturers responded, giving data on methods, instruments, computational procedures, and results for five survey samples. We sorted the analytical data to provide statistical information on the grand mean values separately for manufacturers and clinical laboratories, the frequency distribution of all reported values, and the mean values by method of interpolation and algorithms used for linear transformation. There was no statistical difference (alpha = 0.05) between the means for each specimen as determined by the kit manufacturers as a group and the clinical laboratories as a group.

An interlaboratory study of the determination of digoxin by immunoassay.

1980 ◽  
Vol 26 (3) ◽  
pp. 480-486 ◽  
Author(s):  
D M Fast ◽  
W H Hannon ◽  
C A Burtis ◽  
D D Bayse
Keyword(s):  
Frequency Distribution ◽  
Statistical Difference ◽  
Analytical Data ◽  
Statistical Information ◽  
Mean Values ◽  
Clinical Laboratories ◽  
The Mean ◽  
Computational Procedures

Abstract We conducted a voluntary survey of laboratories and manufacturers to assess the current quality of analytical assays for serum digoxin. More than 300 clinical laboratories and 18 manufacturers responded, giving data on methods, instruments, computational procedures, and results for five survey samples. We sorted the analytical data to provide statistical information on the grand mean values separately for manufacturers and clinical laboratories, the frequency distribution of all reported values, and the mean values by method of interpolation and algorithms used for linear transformation. There was no statistical difference (alpha = 0.05) between the means for each specimen as determined by the kit manufacturers as a group and the clinical laboratories as a group.

scholarly journals Interlaboratory comparison for determination of ochratoxin A by ELISA in maize (running title: Determination of ochratoxin A in maize)

2013 ◽  
pp. 77-84
Author(s):  
Sandra Jaksic ◽  
Igor Jajic ◽  
Ksenija Nesic ◽  
Igor Stojanov ◽  
Milica Zivkov-Balos ◽  
...  
Keyword(s):  
High Pressure ◽  
Ochratoxin A ◽  
Interlaboratory Comparison ◽  
Fluorescence Detector ◽  
Elisa Kit ◽  
Proficiency Testing Schemes ◽  
Z Scores ◽  
Layer Chromatography ◽  
Selection Of

Participation in interlaboratory comparison and proficiency testing schemes is important for laboratories to control the work quality. In this study, a sample of naturally contaminated maize was analyzed for the content of ochratoxin A (OTA) in three laboratories in Serbia. Participating laboratories used enzymatic immunoaffinity method (ELISA) for the determination of OTA and selection of the ELISA kit was free. Between-laboratory precision was acceptable as evidenced by Cochran?s C test. Moreover, z-scores for all three laboratories were z < ? 2, which is considered acceptable. Used OTA confirmation methods were thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC), with fluorescence detector. The results of different methods were comparable.

scholarly journals High-Throughput Determination of Seven Trace Elements in Food Samples by Inductively Coupled PlasmaMass Spectrometry

2006 ◽  
Vol 89 (2) ◽  
pp. 469-479 ◽  
Author(s):  
Kwok Chu Chan ◽  
Yiu Chung Yip ◽  
Hei Shing Chu ◽  
Wing Cheong Sham
Keyword(s):  
High Throughput ◽  
Interlaboratory Comparison ◽  
Certified Reference Materials ◽  
Food Samples ◽  
Inductively Coupled ◽  
Microwave Assisted ◽  
Z Scores ◽  
Sample Dilution ◽  
Microwave Assisted Digestion

Abstract A method was developed for high-throughput determinations of 7 elements in food samples, namely antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and tin (Sn). The samples were digested by closed-vessel microwave-assisted digestion using concentrated nitric acid (HNO3) as the medium, followed by microwave- assisted evaporation to concentrate the sample solutions before dilution to the desired volume. The microwave-assisted evaporation procedure effectively reduced the final acid concentration to around 8 before analysis by inductively coupled plasmamass spectrometry (ICPMS). This reduction allows determination by ICPMS to proceed without further sample dilution, which would affect the detection limit. The method was validated, and method recoveries for As, Cd, Cr, Pb, and Hg were within the certified ranges of the chosen certified reference materials. Recoveries of the 7 elements from spiked samples ranged from 93.1 to 103.6. The standard uncertainties of precision for the 7 elements were between 3.1 and 4.3. Interlaboratory comparison studies for As, Cd, and Pb gave z-scores ranging from 0.2 to 0.3.

scholarly journals A comparison of the effectiveness of QuEChERS, FaPEx and a modified QuEChERS method on the determination of organochlorine pesticides in ginseng

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0246108
Author(s):  
Pennante Bruce-Vanderpuije ◽  
David Megson ◽  
Song-Hee Ryu ◽  
Geun-Hyoung Choi ◽  
Sang-Won Park ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Organochlorine Pesticides ◽  
Extraction Methods ◽  
Ginseng Root ◽  
Quechers Method ◽  
Modified Quechers ◽  
Chromatography Tandem Mass Spectrometry ◽  
Significant Difference ◽  
Solvent Volume

This study provides a review of methods used in the determination of organochlorine pesticides (OCPs) in ginseng and compares the effectiveness of three extraction methods (Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), a modified QuEChERS and a Fast Pesticide Extraction (FaPEx)) in the analyses of 20 OCPs in ginseng root samples. For each method, sample mass, solvent volume and sorbent mass were varied to identify the optimum combination to effectively isolate analytes of interest from the complex sample matrix. Extracts were analyzed using the gas chromatography-μ-electron capture detector (GC-μ-ECD), and confirmatory analyses performed by gas chromatography-tandem-mass spectrometry (GC-MS/MS). Eighteen out of 20 OCPs spiked onto in-house prepared ginseng samples produced acceptable recoveries (51–156%) when extracted using QuEChERS and FaPEx. All 20 analytes, including dichlorodiphenyldichloroethane (p, p’- DDD) and dichlorodiphenyltrichloroethane (o, p’-DDT), produced acceptable recoveries (51–129%) with the use of a modified QuEChERS method. The applicability of the modified QuEChERS method was demonstrated through the analysis of ginseng samples grown in endosulfan-treated soil. The samples were analyzed by both GC-μ-ECD and GC-MS/MS with no significant difference identified in the results of each analytical method. This study highlights the applicability of the modified QuEChERS method, in combination with GC- μ-ECD, to determine organochlorine pesticides in ginseng. This may be especially useful for laboratories in developing countries and less advanced institutions without access to MS/MS instrumentation.

Gas-Liquid Chromatographic Determination of Technical Chlordane Residues in Food Crops: Interpretation of Analytical Data

1975 ◽  
Vol 58 (5) ◽  
pp. 1051-1061
Author(s):  
William P Cochrane ◽  
James F Lawrence ◽  
Young W Lee ◽  
Ronald B Maybury ◽  
Brian P Wilson
Keyword(s):  
Field Experiments ◽  
Stationary Phases ◽  
Analytical Data ◽  
Chromatographic Determination ◽  
Electron Capture Detection ◽  
Food Crops ◽  
Liquid Chromatographic Determination ◽  
Consistent Method ◽  
Liquid Chromatographic

Abstract An interlaboratory investigation of technical chlordane residues in food crops was carried out to determine the most practical and consistent method of reporting results. Using a technical chlordane reference standard, 8 gas chromatographic stationary phases were studied for their resolution capabilities. The best separations were obtained with SE-30 and its OV-1 equivalent. Using these columns and electron capture detection, potatoes and carrots from supervised field experiments were analyzed in duplicate and quantitated by using 4 methods of calculation. The data were statistically treated to determine the precision and bias for each method. Also, 1 sample was analyzed in duplicate on 2 different occasions by 6 laboratories to substantiate the initial conclusions. Based on the criterion of high precision it is suggested that a comparison of total area under the chromatogram of the sample with total area of a standard technical chlordane be the method of quantitation. Only peaks which are common to both standard and sample have any significance in this type of calculation.

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