Blind blank

Are spiked samples (prepared samples to assess the accuracy of the laboratory) and blind blanks (wipes with no dust sample taken, to check for any contamination in their handling) included in the dust sam-pling ... 

Blinds, blanks, figure-8s, and valves, more than 300 lb (135 kg)... 

Operational blanks shall be of the same thickness as blind flanges or may be calculated by the following formula (use consistent units) ... 

If an optimization tuns out of steps, do not blindly assume that increasing the number of steps will fix the problem. Examine the output and determine whether the optimization was making progress or not. For example this command will provide a quick summary of an optimization s progress on a UNIX system (blank lines ate added for readability) ... 

Blind-darm, m. caecum, -feuer, n. blank fire, -ganger, m. (Expl.) dud misfire, -heit, /. blindness, -kohle, /. underbumed charcoal, -leitwert, m. (Elec.) susceptance. -licht, n. flashlight. 

Blind-probe, /. blank test, -schlauch, m. flexible tube closed at one end. -strom, m. (Elec.) wattless current, -versuch, m. blank test, -wert, m. blank value, reagent value, -wlderstand, m. (Elec.) reactance. 

Blind flanges (blank flanges) are flat plates, used to blank off flange connections, and as covers for manholes and inspection ports. 

At the age of twelve or thirteen I had my first migraine aura. The aura started with a blank spot in the middle of my vision, and gradually became flickering zigzag lights that covered about half my vision by the end of the episode. They lasted half an hour and were followed by a characteristic kind of head pain. I didn t know what they were I thought I must be going blind. My mother rarely took me to doctors, and she never took me to a doctor about this, that I can recall. They may have been connected with hormones, the onset of menstruation. 

For blind flanges and blanks, T shall be % of the flange thickness. 

The primary factor which governs the detection limit, the uncertainty of the blank, can differ markedly depending upon whether it is estimated from a model (intercept, baseline), or from a direct observation, or from "blind" interlaboratory comparison. Inappropriate blank evaluation, together with inadequate reporting of data when at or below the detection limit are seen as two of the most critical sources of information loss or information distortion, with serious potential effects in environmental and regulatory areas (3 ). 

Internal QC inclndes the nse of blanks, chemical calibrants, spiked samples, blind samples, replicate analysis, and QC samples. QC samples shotrld be homogeneous and stable. They shotrld be available in sufficient quantities. The use of control charts is recommended (see chapter 13). 

Samples of potential chemical interferences were also prepared by placing samples of selected materials inside clean cardboard boxes. The potential inter-ferent items were materials commonly encountered in demining operations such as petrol. These materials were sampled in an identical fashion as the positive samples. Blank samples were also prepared by sampling empty cardboard boxes. 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). 

Two aspects are important for IQC (1) the analysis of control materials such as reference materials or spiked samples to monitor trueness and (2) replication of analysis to monitor precision. Of high value in IQC are also blank samples and blind samples. Both IQC aspects form a part of statistical control, a tool for monitoring the accuracy of an analytical system. In a control chart, such as a Shewhart control chart, measured values of repeated analyses of a reference material are plotted against the run number. Based on the data in a control chart, a method is defined either as an analytical system under control or as an analytical system out of control. This interpretation is possible by drawing horizontal lines on the chart x(mean value), x + s (SD) and x - s, x + 2s (upper warning limit) and x-2s (lower warning limit), and x + 3s (upper action or control limit) and x- 3s (lower action or control limit). An analytical system is under control if no more than 5% of the measured values exceed the warning limits [2,6, 85]. 

It is important to point out that the quality of analytical results is not immediate it can only be achieved if an extensive set of measures are adopted and complied with. Therefore, in parallel to the development of the QA concept, QC systems were introduced as an important tool supporting the QA of chemical measurements. The QC process of examination of laboratory performance in time should always follow QA. QC thus comprises a set of operational techniques and activities used to check whether the requirements for quality are fulfilled. In practice, QC in an analytical chemistry laboratory implies operations carried out daily during the collection, preparation, and analysis of samples, which are designed to ensure that the laboratory can provide accurate and precise results. QC procedures are intended to ensure the quality of results for specific samples or batches of samples and include the analysis of reference materials (RMs), blind samples, blanks, spiked samples, duplicate, and other control samples.2... 

According to OPCW procedures, all GC/MS runs of a sample or a blank involve the coinjection of an internal standard (hexachloroben-zene contained in the OPCW HCB mixture). This is a quality control measure, which is applied to assess the validity of the run, especially when operating in blinded mode. When AMDIS processes data from the internal standard run, it uses a small auxiliary Internal Standard Library (ASCII file onsite.isl). This library contains data on HCB (mass spectrum, RI, etc.). HCB is defined as detected if the net match factor for HCB is >80 (this is the threshold for identification, which is fixed in this version of AMDIS). Everything so far is done by AMDIS in the background. 

An important part of the sampling methodology relates to the use of control samples in order that the data can be quality controlled and quality assured (see Johnson et al., 2008). While it is only duplicates that are created during the sampling process, these, along with replicates, blanks (for waters) and secondary reference materials need to be assigned sample numbers so they are included as part of the routine sample submission and are blind to the analyst. Duplicate samples are collected from a... 

The G-BASE project collects samples in random number order (Plant, 1973), as this helps identify any correctable systematic errors introduced during sample preparation and analysis, processes in which the samples are handled in numeric order. For every block of one hundred numbers, five numbers are reserved for control samples so when they are submitted within a batch of samples they are blind to the analyst. The control samples inserted are one duplicate sample, two replicate samples, two blanks, and two secondary reference materials (SRM) used to monitor accuracy and precision as well as to level data between different field campaigns (see Johnson et al, 2008). Along with the original sample ofthe duplicate pair, this means 8% of samples submitted are control samples, a point not to be overlooked in setting the budget for analyses. 

To monitor the quality of the data from this program, four types of quality control samples (reference, duplicate, replicate, blank) are regularly submitted to the analysts together with routine monthly composite and weekly samples. These quality control samples are submitted blind (i.e., in such a way as to be indistinguishable from the routine samples by the analyst) insofar as this is possible. 

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