Instrumental precision

Data uncertainty Data uncertainty was measured based on used instruments precision and on the uncertainty of Simapro datasets... 

Complex, expensive instrumentation. Precision sometimes poor. Inter-... 

A QC assessment was done for all samples. De-ionized water field blanks were collected on seven different days to evaluate process contamination. Site duplicates were taken at eight sites to evaluate repeatability and site variation. Instrumental precision was constrained by analysis of laboratory duplicate solutions, and is typically less than 5%. Finally, standard reference material (SRM) water standards were analyzed with sample batches, to assess instrumental accuracy. 

Precision is the reproducibility of a result. Instrument precision, also called injection precision, is the reproducibility observed when the same quantity of one sample is repeatedly introduced (>1() times) into an instrument. Variability could arise from variation in the injected quantity and variation of instrument response. 

Intra-assay precision is evaluated by analyzing aliquots of a homogeneous material several times by one person on one day with the same equipment. Each analysis is independent, so the intra-assay precision is telling us how reproducible the analytical method can be. Intraassay variability is greater than instrument variability, because more steps are involved. Examples of specifications might be that instrument precision is <1 % and intra-assay precision is 2%. 

Define the following terms instrument precision, injection precision, intra-assay precision, ruggedness, intermediate precision, and interlaboratory precision. 

A large number of experimental engine techniques have been developed in the course of investigating the knock phenomenon. Highly instrumented, precision knock-rating engines have been used in studying the knock characteristics of various hydrocarbon... 

In the 15 years since Pintozzi s study, great improvements have been made in lead isotope studies. In particular, the instruments and techniques have greatly improved. Additionally, the foundation of a standardized archaeometry database (5) has greatly increased the required instrument precision required for acceptable sourcing of artifacts using the ore source data. As interesting as Pintozzi s results are, her method was not as precise as current TIMS analysis. 

The information which is usually obtained from a ruggedization experiment is limited to the identification of the nonsignificant parameters. However, if the expected experimental precision is independently known, it is possible to determine whether the standard error of the ruggedization experiment is comparable to the expected instrumental precision. The standard error of all the 10 metals except Cr, Mo, and Pd (Table VII) is very close to the expected instrumental deviation at spiked concentration levels of 1.0 to 3.0 yg/ml in solution. This indicated that for Be, Cd, Co, Cu, Mn, Ni, and Pb analysis, the screening experiments did not introduce significant imprecision compared to repetitive analysis of synthetic standard solutions of these metals. One variable uniquely significant (99 per cent) for Cr, Mo, and Pd is the treatment with perchloric acid (variable F). An attempt to explain the... 

Instrument precision is a measure of reproducibility, i.e., how consistent an instrument is in delivering volume. This is generally measured as a coefficient of variance (CV). Reproducibility for multichannel (96- or 384-tip) pipetting instruments has two aspects. Within-plate variability measures the consistency from one channel to another in the same transfer cross-plate variation measures the consistency of the same channel through multiple transfers. A good liquid handler should be consistent in both functions. 

In our work (5,6), a fractional factorial design was used as described above. In addition, one of the experiments run early in the analysis of each compound is repeated near the end of the analysis to determine instrumental precision and to detect any decomposition of the sample. This makes a total of 17... 

With the exception of the clathrate framework model, all these hypotheses appear to be qualitatively consistent with the available X-ray diffraction data on liquid water. It is argued by some investigators, however, that there are still significant inconsistencies between the most sophisticated statistical thermodynamic models for liquid water and the most sophisticated X-ray and neutron diffraction measurements [734-736]. The interpretation of these data from different experiments, using the concept of pair-correlation functions, shows discrepancies that are considered significant in terms of the instrumental precision, and the definitive answer seems not yet available [737J. 

The development of new instrumental methods to replace the troubled Scoville procedure necessitated the design of an improved sensory method for validation of instrumental precision. A new sensory method (4) was designed which offered the following procedural improvements over the Scoville Method 1) a 20 minute aqueous extraction, (2) no ethanol used, 3) reference standard included in each test, 4) trained panelists, 5) timed tasting, rinsing and recess, 6) one dilution for all samples, and 7) use of a graphic line scale to score the heat sensation. 

Instrumental precision is determined by the stability of the analytical signal and is made up of two components—noise, appearing as a random variation, and drift, which is a systematic change in signal level. The importance of drift will depend on the frequency of standardization and... 

Specimen mix-up Incorrect volume of specimen Interfering substance present Instrument precision problem Wrong patient identification Report not posted in chart Report not legible Report delayed Transcription error Interfering substances not recognized... 

The sediment samples were sequentially leached in accordance with the method of Tessier et al. (1979) in which five fractions are experimentally defined. The extracts were analysed by atomic absorption (Perkin Elmer 3030), (Pb and Rb), and inductively coupled plasma spectrometry (ARL 35000), (Cu, Zn, Cd, Ni, Fe and Mn). Instrumental precision was better than 1 % and accuracy was ensured by analysing a range of international reference sediments. 

As palaeoceanographic reconstructions based on bulk fossil chemistry proliferate, comparability of measurements between laboratories has become an important issue. A recent calibration exercise involving thirteen laboratories by Rosenthal et al. (2004) evaluated the reproducibility of analyses of synthetic standard solutions within and between laboratories. The study found that intralaboratory instrumental precisions were generally better than 0.5% for both Mg/Ca and Sr/Ca measurements, but interlahoratory precisions (r.s.d) were significantly worse (up to 3.4% and 1.8%, respectively). This could be a result of differences between cahbration standards used by laboratories, or because the circulated standard solutions had become contaminated in the interval between their... 

Precision of a chemometric method refers to the reproducibility of the method. For quantitative chemometric methods, it is important to test both the instrument and method precision. Instrument precision is done by repeating measurements on the same sample method precision is the closeness of replicate sample measurements while intermediate precision can be evaluated by running the same samples with different analysts on different days. 

---