Coal Rheology — The Effect of Rank and Sample Preparation on Test Results

2020 ◽  
Author(s):  
L. Giroux ◽  
T. Todoschuk
Keyword(s):  
Sample Preparation ◽  
Test Results

High-Throughput Analytical Techniques for Determination of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea, Part II: Comparative Study of Extraction Efficiencies of Three Sample Preparation Techniques

2013 ◽  
Vol 96 (2) ◽  
pp. 432-440 ◽  
Author(s):  
Chun-Lin Fan ◽  
Qiao-Ying Chang ◽  
Guo-Fang Pang ◽  
Zeng-Yin Li ◽  
Jian Kang ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Green Tea ◽  
High Speed ◽  
Extraction Efficiency ◽  
Preparation Technique ◽  
Test Results ◽  
Chemical Pollutants ◽  
Chemical Pollutant ◽  
Three Stages

Abstract This paper reports a study of the extraction efficiency for the multiresidue pesticides and chemical pollutants in tea with three methods over three stages. Method 1 adopts the Pang et al. approach: the targets were extracted with 1% acetic acid in acetonitrile and cleaned up with a Cleanert TPT SPE cartridge; Method 2 adopts the QuEChERS approach: the targets were cleaned up dispersively with graphitized carbon and primary-secondary amine (PSA) sorbent; Method 3 adopts the relatively commonly used approach of hydration for solid samples, with tea hydrated before being extracted through salting out with acetonitrile and the cleanup procedures identical to those of Method 1. The three stages comprised two phases of comparative tests on spike recoveries of 201 pesticides and chemical pollutants from different teas and a third phase on determination of the content of the 201 pesticides and chemical pollutants from aged tea samples. In stages I and II, test results of the spike recoveries of 201 pesticides and chemical pollutants demonstrated that 91.4% of the pesticide and chemical pollutant recoveries fell within the range of 70–110%, and 93.2% of the pesticides and chemical pollutants had RSD < 15%, with no marked difference obtained by Method 1 and Method 2 regardless of whether it was green tea or woolong tea, or GC/MS or GC/MS/MS was used for analysis. For pigment removal, Method 1 was superior to Method 2; in terms of easy operation, Method 2 outweighed Method 1. However, Method 3 obtained relatively low recoveries, with 94% of pesticide and chemical pollutant recoveries less than 70%, which proved that Method 3 was not applicable to the determination of multiresidue pesticides and chemical pollutants in tea. Stage III made a comparison of Method 1 and Method 2 for the extraction efficiency of pesticides and chemical pollutants in 165-day-aged samples of green and woolong tea. Test results showed that 94% of the pesticide and chemical pollutant content in the aged tea samples was recovered with Method 1, more than 10% higher than with Method 2 (30–50% higher on average). For green tea, 193 (GC/MS/MS) and 197 (GC/MS) pesticides and chemical pollutants accounted for 96.5% (GC/MS/MS) and 98.0% (GC/MS) with Method 1 higher than with Method 2. For woolong tea, 191 (GC/MS/MS) and 194 (GC/MS) pesticides and chemical pollutants accounted for 95% (GC/MS/MS) and 96% (GC/MS/MS) with Method 1, higher than with Method 2, respectively. In other words, there were definite differences in the test results for aged tea samples between Method 1 and Method 2, which suggests that Method 1 was capable of extracting more residual pesticides and chemical pollutants from the precipitated 165-day-aged tea samples. The reason can be traced to the possibility that Method 1 (high-speed homogenizing) has better extraction efficiency than Method 2 (vortex and oscillation). Therefore, Method 1 was chosen as the sample preparation technique for multiresidue pesticide and chemical pollutant analysis in tea.

Determination of Slake Durability Index with Spherical Samples

2013 ◽  
Vol 548 ◽  
pp. 247-252 ◽  
Author(s):  
Hüseyin Ankara ◽  
Mehmet Aksoy ◽  
Suheyla Yerel ◽  
Yasar Keser
Keyword(s):  
Sample Preparation ◽  
Preparation Method ◽  
Index Test ◽  
Test Results ◽  
Sample Preparation Method ◽  
Slake Durability Index ◽  
Slake Durability ◽  
Durability Index ◽  
Preparation Stage

In this study, the preparation method of the equivalent sized spherical samples which is called as Pasha Method is applied to slake durability index test. In order to apply this sample preparation method, white and pink tuff samples were collected at the tuff quarries located at the Eskisehir region in Turkey. After sample preparation stage, these tuff samples were subjected to the Slake Durability Index test in the laboratory. According to the test results presented in this paper, the highest slake durability index values were obtained from equal-sized spherical test samples that are prepared according to the new method, Pasha Method, when compared to the other two types of samples.

Revisiting the sampling, sample preparation, and analytical variability associated with testing wheat for deoxynivalenol

2019 ◽  
Vol 12 (4) ◽  
pp. 319-332
Author(s):  
S.A. Tittlemier ◽  
J. Chan ◽  
D. Gaba ◽  
K. Pleskach ◽  
J. Osborne ◽  
...  
Keyword(s):  
Experimental Design ◽  
Sample Preparation ◽  
Normal Distribution ◽  
Total Variance ◽  
Design Parameters ◽  
Test Results ◽  
Operating Characteristics ◽  
Test Portion ◽  
Decision Limit ◽  
Sample Test

Fifteen lots of wheat were sampled to characterise the total variance and distribution among sample test results associated with measuring deoxynivalenol (DON) in bulk wheat lots. An unbalanced nested experimental design based on past research was used to determine contributions to the total variance from sampling, sample preparation, and analysis. The wheat lots used in the study contained average DON concentrations that ranged from 0.17 to 24.5 mg/kg. Sampling was determined to be the largest contributor to the total variance of measuring DON at low mg/kg concentrations, which are relevant to existing maximum levels. With the experimental design parameters of 1 kg laboratory samples, sub-division of whole and ground grain using rotary sample division, sample comminution using a commercial-grade coffee grinder, extraction of 100 g test portions, and making one measurement of DON in the test portion by gas chromatography-mass spectrometry, the total variance of DON measurement at 2 mg/kg was 0.046 mg2/kg2 (coefficient of variation=10.7%). At this concentration, sampling contributed 67% to the total variance, followed by sample preparation (18%) and analysis (15%). The DON distribution among sample test results was accurately described by the normal distribution. The mathematical model of variance was used with the normal distribution of DON measurement results to construct operating characteristics curves to model the likelihood of mischaracterising a wheat lot as (non) compliant with a certain decision limit. With realistic laboratory sample and test portion sizes, as well as a practicable decision limit of 1.5 mg/kg, the estimated probability of mischaracterising a wheat lot containing 2 mg/kg DON as less than this concentration was reduced to 1%.

Variability and distribution among sample test results when sampling unprocessed wheat lots for ochratoxin A

2016 ◽  
Vol 9 (2) ◽  
pp. 163-178 ◽  
Author(s):  
T.B. Whitaker ◽  
A.B. Slate ◽  
T.W. Nowicki ◽  
F.G. Giesbrecht
Keyword(s):  
Liquid Chromatography ◽  
Sample Preparation ◽  
Ochratoxin A ◽  
Test Procedure ◽  
Test Results ◽  
Laboratory Sample ◽  
Sampling Step ◽  
Test Portion ◽  
Sample Test ◽  
Sampling Statistics

In 2008, Health Canada announced it was considering the establishment of maximum levels for ochratoxin A (OTA) in unprocessed wheat, oats, and their products. The Canada Grains Council and Canadian National Millers Association initiated two studies to measure the variability and distribution among sample test results for unprocessed wheat and oats so that scientifically based OTA sampling plans could be designed to meet regulatory and industry requirements. Sampling statistics related to detecting OTA in oats has been published. 54 OTA contaminated wheat lots representing three wheat classes were identified for the sampling study. Each lot was sampled according to a nested experimental protocol where sixteen 2-kg laboratory samples were taken from each lot, multiple 5-g test portions were taken from each comminuted 2-kg laboratory sample, and multiple OTA measurements were made on each test portion using liquid chromatography. The sampling, sample preparation, and analytical variances associated with each step of the OTA test procedure were found to be a function of OTA concentration and regression equations were developed to predict the functional relationships between variance and OTA concentration. When sampling a wheat lot containing 5 µg/kg OTA with an OTA test procedure consisting of a sampling step employing a single 2-kg laboratory sample, sample preparation step employing a single 100-g test portion, and an analytical step that used liquid chromatography to quantify OTA, the sampling step accounted for 95.3% of the total variability. The observed OTA distribution among the 16 OTA sample results was found to be positively skewed and the negative binomial distribution was selected to model the OTA distribution among sample test results. The sampling statistics were incorporated into the FAO Mycotoxin Sampling Tool and the chances of rejecting good lots and accepting bad lots were calculated for various sampling plan designs.

scholarly journals A Procedure to Prepare Sand–Clay Mixture Samples for Soil–Structure Interface Direct Shear Tests

2021 ◽  
Vol 11 (12) ◽  
pp. 5337
Author(s):  
Kexin Yin ◽  
Jiangxin Liu ◽  
Andreea-Roxana Vasilescu ◽  
Eugenia Di Filippo ◽  
Khaoula Othmani
Keyword(s):  
Sample Preparation ◽  
Soil Structure ◽  
Preparation Procedure ◽  
Preparation Technique ◽  
Direct Shear ◽  
Test Results ◽  
Shear Tests ◽  
Kaolinite Clay ◽  
Direct Shear Tests ◽  
Sample Preparation Procedure

A large number of experimental studies on sand–clay mixtures are well documented in the literature; however, the preparation protocol is rarely clearly detailed or varies a lot according to the authors. Variations in the preparation technique obviously increases the challenge of comparing different test results. As a consequence, sample preparation for sand–clay mixtures should be kept as constant as possible to ensure homogeneity and uniformity of samples and limit result variability. This paper develops a detailed procedure on how to prepare sand–clay samples for interface direct shear tests. Sand–clay mixtures are prepared with Fontainebleau sand, kaolinite clay and distilled water by the S1 (sand–water–clay) protocol. The uniformity of the reconstituted specimens is assessed by measuring the water content and density on three slices from the top to the bottom across the specimens. The repeatability of the samples is checked with oedometer and interface direct shear tests. This sample preparation procedure can be used for preparing sand–clay mixture for interface direct shear tests to investigate the influence of clay content or other effects (e.g., temperature) on the mechanical behavior of soil–structure interface. It has demonstrated great performance in preparing samples with good homogeneity and shape, compared to other traditional reconstitution techniques. With the sample preparation procedure, we can obtain repeatable test results as well.

Impact of Sample Preparation Procedure on the Test Results of Four US ITER TF Conductors

2010 ◽  
Vol 20 (3) ◽  
pp. 508-511 ◽  
Author(s):  
B Stepanov ◽  
P Bruzzone ◽  
R Wesche ◽  
N Martovetsky ◽  
D Hatfield ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Preparation Procedure ◽  
Test Results ◽  
Sample Preparation Procedure

Sampling Uncertainties for the Detection of Chemical Agents in Complex Food Matrices†‡

2005 ◽  
Vol 68 (6) ◽  
pp. 1306-1313 ◽  
Author(s):  
THOMAS B. WHITAKER ◽  
ANDERS S. JOHANSSON
Keyword(s):  
Sample Preparation ◽  
Coefficient Of Variation ◽  
Test Procedure ◽  
Total Variance ◽  
Test Results ◽  
Total Uncertainty ◽  
Chemical Agents ◽  
Relative Standard ◽  
Low Levels ◽  
Repeated Test

Using uncertainty associated with detection of aflatoxin in shelled corn as a model, the uncertainty associated with detecting chemical agents intentionally added to food products was evaluated. Accuracy and precision are two types of uncertainties generally associated with sampling plans. Sources of variability that affect precision were the primary focus of this investigation. Test procedures used to detect chemical agents generally include sampling, sample preparation, and analytical steps. The uncertainty of each step contributes to the total uncertainty of the test procedure. Using variance as a statistical measure of uncertainty, the variance associated with each step of the test procedure used to detect aflatoxin in shelled corn was determined for both low and high levels of contamination. For example, when using a 1-kg sample, Romer mill, 50-g subsample, and high-performance liquid chromatography to test a lot of shelled corn contaminated with aflatoxin at 10 ng/g, the total variance associated with the test procedure was 149.2 (coefficient of variation of 122.1%). The sampling, sample preparation, and analytical steps accounted for 83.0, 15.6, and 1.4% of the total variance, respectively. A variance of 149.2 suggests that repeated test results will vary from 0 to 33.9 ng/g. Using the same test procedure to detect aflatoxin at 10,000 ng/g, the total variance was 264,719 (coefficient of variation of 5.1%). The sampling, sample preparation, and analytical steps accounted for 41, 57, and 2% of the total variance, respectively. A variance of 264,719 suggests that repeated test results will vary from 8,992 to 11,008 ng/g. Foods contaminated at low levels reflect a situation in which a small percentage of particles is contaminated and sampling becomes the largest source of uncertainty. Large samples are required to overcome the “needle-in-the-haystack” problem. Aflatoxin is easier to detect and identify in foods intentionally contaminated at high levels than in foods with low levels of contamination because the relative standard deviation (coefficient of variation) decreases and the percentage of contaminated kernels increases with an increase in concentration.

Sign in / Sign up

Export Citation Format

Share Document