Determinations duplicate

Analytical values for the eight coals after treatment with 2 M HN03 are given in Table III. The reported values are the averages of four determinations (duplicate determinations on different days). A comparison of the dry ash values for the HNOj-extracted residues described in Table III to the dry ash values for the raw coals described in Table I reflects the reduction in mineral matter caused by extraction of the raw coals with 2 M HN03. Carbonates, sulfates, and other minerals dissolve in the acid solution used to extract pyrite. 

Information that is put into this Database is derived from published reports of crystal structure determinations. The data extracted from the scientific literature in this way include the atomic coordinates, information on the space group, chemical connectivity, and the literature reference to each structure determination. Each compound listed in the Database is identified by a six-letter code (the REFCODE), unique to each crystal structure determination. Duplicate structures and remeasurements of the same crystal structure are identified by an additional two digits after the REFCODE. Scientific journals are scanned regularly by the Database staff for reports of crystal structure determinations, and the data are then entered into this Database. Structural data are also deposited by journals, for example. Chemical Communications, that publish articles, but do not have space for atomic coordinates. All crystallographic data reported in the literature are tested by the Database staff for internal consistency, precision, and chemical reasonableness. In... 

Precision - the degree— generally expressed as a percent— to which successive determinations of the same quantity duplicate each other. Precision is sometimes further subdivided into reproducibility — which involves how closely will successive determinations duplicate each othef or repeatabihty — which involves how closely can successive determinations be made to duplicate each othef . 

Analysis of Duplicate Samples An effective method for determining the precision of an analysis is to analyze duplicate samples. In most cases the duplicate samples are taken from a single gross sample (also called a split sample), although in some cases the duplicates must be independently collected gross samples. The results from the duplicate samples, Xi and X2, are evaluated by determining the difference, d, or the relative difference, d) between the samples... 

To evaluate the precision for the determination of potassium in blood serum, duplicate analyses were performed on six samples, yielding the following results. 

In a performance-based approach to quality assurance, a laboratory is free to use its experience to determine the best way to gather and monitor quality assessment data. The quality assessment methods remain the same (duplicate samples, blanks, standards, and spike recoveries) since they provide the necessary information about precision and bias. What the laboratory can control, however, is the frequency with which quality assessment samples are analyzed, and the conditions indicating when an analytical system is no longer in a state of statistical control. Furthermore, a performance-based approach to quality assessment allows a laboratory to determine if an analytical system is in danger of drifting out of statistical control. Corrective measures are then taken before further problems develop. 

Construct a precision control chart using the following 20 ranges, each determined from a duplicate analysis of a 10-ppm calibration standard... 

Quality assessment includes the statistical tools used to determine whether an analysis is in a state of statistical control and, if possible, to suggest why an analysis has drifted out of statistical control. Among the tools included in quality assessment are the analysis of duplicate samples, the analysis of blanks, the analysis of standards, and the analysis of spike recoveries. 

Table 25 Summary of the pH values of some layer materials of precoated plates, determined as 10% aqueous suspensions (duplicate determination two different TLC/HPTLC plates from the same bateh).

The requirement is also somewhat duplicated in clause 4.1.3 on management reviews. You are required to conduct management reviews to ensure quality system effectiveness and conduct internal quality audits to determine the effectiveness of the system. It would appear that the audit collects the evidence and the review ensures that it is collected. 

Sometimes it is necessary to review the narrative in raw data records to determine whether a failure has occurred, to establish failure modes and severities, and to see if a record is a duplicate or new failure. Often, the narrative section is the only way the data analyst can determine if the document, especially a work order, is for a legitimate failure, routine maintenance, or a specified test. 

In a segmented contraction each primitive as a rule is only used in one contracted function. In some cases it may be necessary to duplicate one or two PGTOs in two adjacent CGTOs. The contraction coefficients can be determined by a variational optimization, for example from an atomic HF calculation. 

Let us take as an example some of the reaction series listed in Table IX, e.g. the oxidation of the 2-methylmercaptobenzothiazoles. The calculations are summarized in Table X, which is self-explanatory. In these calculations the deviations from regression were used as measure of error, but, when duplicate determinations are available, additional degrees of freedom for replication are obtainable, and should be used as measure of error. 

To select a turbine, there must also be geometric similarities for the type of turbine, blade width, number of blades, impeller diameter, etc. From the geometric similarity determination of the turbine diameter, the mixer speed can be established to duplicate. The Scale Ratio R, ... 

The above method is useful in determining internal combustion engine loading conditions. Failure to duplicate former readings at no load and at normal speed indicates that the engine is in poor condition. Failure to duplicate former readings... 

Once the best method of dealing with interferences has been decided upon and the most appropriate method of determination chosen, the analysis should be carried out in duplicate and preferably in triplicate. For simple classical determinations the experimental results must be recorded in the analyst s notebook. However, many modern instruments employed in instrumental methods of analysis are interfaced with computers and the analytical results may be displayed on a visual display unit, whilst a printer will provide a printout of the pertinent data which can be used as a permanent record. 

Under no circumstances should the working surface of the bench become cluttered with apparatus. All the apparatus associated with some particular operation should be grouped together on the bench this is most essential to avoid confusion when duplicate determinations are in progress. Apparatus for which no further immediate use is envisaged should be returned to the locker, but if it will be needed at a later stage, it may be placed at the back of the bench. 

It should be regarded as normal practice that all determinations are performed in duplicate. 

Procedure A with standard hydrochloric acid. Place the standardised (approx. 0.1 M) hydrochloric acid in the burette. Transfer 25 mL of the sodium hydroxide solution into a 250 mL conical flask with the aid of a pipette, dilute with a little water, add 1-2 drops of methyl orange or 3-4 drops of methyl orange-indigo carmine indicator, and titrate with the previously standardised hydrochloric acid. Repeat the titrations until duplicate determinations agree within 0.05 mL of each other. 

We run into a complication when we attempt to write an expression similar to equation (10.56) for a combination of N molecules that are not distinguishable.0 When this happens, combinations such as (ea. i + eb. ) and (ea2 + et,. i) are the same and should not be counted twice. Thus, the total number of terms in the partition function should be decreased to eliminate such duplications. To determine how to correct for this duplication, consider three gas molecules a, b, and c with energy levels we will represent as ei, e2, and e3. A total of 3 = 6 different combinations of these energy levels can be written as follows... 

In a contribution dealing with two related compound classes, space could be saved by treating them together in domains where they display close similarities. However, the only spheres where this applies to sulphones and sulphoxides are elemental sulphur determination and chromatography. The former is too unspecific to be considered for inclusion in this chapter. Chromatographic behaviour is determined by the whole molecule, but the widespread use of chromatographic methods does justify its treatment. At the risk of a very little duplication it has been deemed more suitable to provide separate accounts of the two compound classes. 

Thus, a polyester sample (1-3 g, exactly weighed) is dissolved in 25 mL of a titrated solution of acetic anhydride in dry pyridine (10% mass). The solution is heated to reflux for 1 h. After cooling, 50 mL pyridine and 10 mL water are added. The excess acetic acid present in the resulting solution is titrated by aqueous potassium hydroxide (0.5 mol/L) using a potentiometric titrator. The determination must be carried out in duplicate and a blank titration must be performed under the same conditions. The mass of polyester and the concentration of reactants should be adjusted to ensure that at least a fourfold excess of acetic anhydride is used. The final result (OH content) is expressed in mmol OH/g polyester or as the hydroxyl number, defined as the number of milligrams of KOH required to neutralize the acetic acid consumed per gram of polyester. [Hydroxyl number = (number of mmol OH/g polyester) x 56.106.]... 

Tests were performed at 75°C using a University of Texas Model 500 spinning drop tensiometer. Active surfactant concentration in the aqueous phase prior to addition of the oil phase was 0.5% wt. Interfacial tension values are the average of duplicate or triplicate determinations. 

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