Standard blind analysis

Single-operator characteristics are determined by analyzing a sample whose concentration of analyte is known to the analyst. The second step in verifying a method is the blind analysis of standard samples where the analyte s concentration remains unknown to the analyst. The standard sample is analyzed several times, and the average concentration of the analyte is determined. This value should be within three, and preferably two standard deviations (as determined from the single-operator characteristics) of the analyte s known concentration. 

Agency. A second example of an external method of quality assessment is the voluntary participation of the laboratory in a collaborative test (Chapter 14) sponsored by a professional organization such as the Association of Official Analytical Chemists. Finally, individuals contracting with a laboratory can perform their own external quality assessment by submitting blind duplicate samples and blind standard samples to the laboratory for analysis. If the results for the quality assessment samples are unacceptable, then there is good reason to consider the results suspect for other samples provided by the laboratory. 

Several small, double-blind studies show trimipramine to be superior to placebo and at least comparable with other standard TCAs ( Table 7-5). There was a trend in one large, carefully controlled study favoring amitriptyline, but it did not supply data on percent improvement, so it was not included in our analysis ( 102). Considering all the data, we would conclude that trimipramine is equal in effect to other TCAs. 

The specifications approved for the GC/MS instrument allow the selection of an instrument with performance criteria of a standard GC/MS bench top system. The requirements specified in relation to blinding and transportability are substantial and require significant adaptations to any system currently available on the market. However, they do not limit analysis performance in terms of sensitivity or selectivity. The current system specifications do not include chemical ionization and limit analysis to electron impact spectra. 

The on-site version of AMDIS is a 16-bit Windows application running under OS2 operating system of the Dolch PC. This version of AMDIS was specially designed by NIST (National Institutes of Standards and Technology) for OPCW on-site analysis use. Its role in the postprocessing of analysis data is equivalent to the role of the blinded mode software in regard to the general control of the instrument and the acquisition of the data restrict the information on the identity of chemicals present in the sample to chemicals that are only relevant to the inspection aim. 

Standard Operating Procedure (SOP) SOP-LAB-EQP-005, Bruker EM640S Portable GC/MS with AMDIS Data Analysis Software (Blinded Mode) for Qualitative Analyses of Liquid Samples Prepared by On-site Methods, Version 3, The Technical Secretariat of the Organization for the Prohibition of Chemical Weapons, The Hague, 1999. 

Kirby RS, Andersen M, Gratzke P, Dahlstrand C, Hoye K. A combined analysis of double-blind trials of the efficacy and tolerability of doxazosin-gastrointestinal therapeutic system, doxazosin standard and placebo in patients with benign prostatic hyperplasia. BJU Int 2001 87 192-200. 

Elemental Analysis The carbon, hydrogen, and nitrogen contents of reference standards may be determined by combustion analysis. Combustion analysis thus provides an orthogonal determination of the molecular formula and the purity of the reference standard. Poor agreement between the theoretical and experimental elemental compositions is generally an indication of an impure substance or a discrepancy between the theoretical and actual molecular formulas. Elemental analysis may also identify the presence of solvates and inorganic contaminants. Elemental analysis is typically performed in specialized laboratories under blinded conditions. 

There are several concepts and terms that are essential to discussions about QA, even the concept itself. While at a very detailed level any definition can be challenged as being too narrow or too broad, the definitions presented below are useful (20). It should be noted that these terms are quite recent in definition and are not usually given in statistics books. Other terms like pollution have evolved over hundreds of years (21). Some key terms used in the field like reproducibility, standard deviation, standard error, replicate analysis, blanks, spiked samples and blind samples are self-explanatory. 

In the full review process, a modified block randomization scheme was used to confirm inclusion and to abstract information and assess the quality of each article. Each paper was randomly assigned to two of four reviewers. Reviewers were blinded to original authors names, affiliations, and journal of publication. Reviews were recorded on a standard case report form and entered into a database for analysis. Discrepancies between reviewers were arbitrated by group consensus. Reviewers first made a final check of inclusion and exclusion criteria to exclude further any nonapplicable articles. Reviewers recorded the study setting, objectives, methods, results, and any additional comments. 

For this aim, three proficiency testing (PT) campaigns were organized within the SWIFT-WFD project, mainly dedicated to the determination of the list of priority pollutants annexed to the WFD. The SWIFT-WFD PT campaigns, one per year for three years, were organized on 17 reference materials (RMs) including 5 matrix RMs at natural concentration levels, 3 at low fortified concentration levels, 4 at fortified concentration levels, and 5 multi-analyte blind standard solutions, targeting the analysis of... 

Training requirements for pharmacologists and toxicologists Definition of nomenclature project, study, indication, NCE ID, etc. Review and approval process for PK summaries and related reports Standards for PK data analysis basic parameters to be obtained Use of blinded data... 

Positive, blank, and interferent samples were prepared using standard MECHEM methods. All samples were marked by sampling personnel in a manner that made it impossible for analysts to determine the composition of the sample during analysis. Nomadics personnel and dog handlers were not given any information on sample identity until analysis of samples was completed and results were submitted for scoring (i.e., the tests were conducted in a blind fashion). 

An example of a control chart is illustrated in Figure 3.6, representing a plot of day-to-day results of the analysis of a pooled serum calcium or a control sample that is run randomly and blindly with samples each day. A useful inner control limit is two standard deviations since there is only 1 chance in 20 that an individual measurement will exceed this purely by chance. This might represent a warning limit. The outer limit might be 2.5 or 3cr, in which case there is only 1 chance in 100 or 1 chance in 500 a measurement will fall outside this range in the absence of systematic error. Usually, one control is run with each batch of samples (e.g., 20 samples), so several control points may be obtained each day. The mean of these may be plotted each day. The random scatter of this would be expected to be smaller by VA, compared to individual points. 

Work is underway to standardize the test method described here as a new ASTM standard. An Inter-Laboratory Study (ILS) is proposed to include at least nine each of gasoline and diesel Tier 2 class materials containing sulfur levels between <10 and 80 mg/kg in gasoline and between <10 and 80 mg/kg in diesels. Some blind National Institute of Standards and Technology (NIST) Standard Reference Materials (SRM) and solvent blanks are also plaimed for the cross check. The ILS will follow a protocol of an initial analysis of a set of samples and solvent blanks, and after an elapsed time of at least 12 h but no more than 72 h, a second set of measurements on the same set of samples and blanks will be completed. We expect this ILS to be completed by the end of2005. 

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