Standing measurement procedure

The complete traceability chain as presented here is valid only for those measurable quantities, which can have a value, expressed in SI units. When primary or secondary calibrators are not available the traceability chain for many measurands in laboratory medicine ends at a lower level, e.g. at the manufacturer s standing measurement procedure. In a situation where a manufacturer detects a new diagnostic marker and defines the measurable quantity by establishing a measurement procedure for this marker, the manufacturer s measurement procedure will form the top of the traceability chain. Nevertheless even in this simple situation the principles of the traceability concept are applicable. 

In an experiment lasting several years, six brand new cars were tested at the test stand for 40 days. For 8 hours each day the inside air was heated up to 65 °C (artificial ageing). At the beginning and after 20 and 40 days the air was characterized by means of the standardized measurement procedures described above (TUV NORD, 1996). 

The adopted mean value X, averaged over many measured values X, is claimed to have a certain accuracy, which is a measme of the reliability of this value, expressed by its prob le viation AX from the unknown true value X. A stated accuracy o X/AX means a certain confidence that the true value X is within X AX. Since the accuracy is determined not only by statistical errors but, particularly, by systematic errors of the apparatus and measuring procedure, it is always lower than the precision. It is also influenced by the precision with which the reference stand can be measured and by the accuracy of its comparison with the value X. Although the attainable accuracy depends on the experimental efforts and expenditures, the skill, imagination, and critical judgement of the experimentalist always have a major influence on the ultimate achieved and stated accimacy. 

The experimental system for measuring the sonoluminescence spectrum of alkali-metal atom emission from an aqueous solution is similar to that for measuring the MBSL spectrum from water. Degassing the solution is an important procedure because the presence of dissolved air affects the emission intensity. In an air-saturated solution, no observation of alkali-metal atom emission has been reported, whereas continuum emission can be observed. A typical experimental apparatus using ultrasonic standing waves is shown in Fig. 13.3 [8]. The cylindrical sample container is made of stainless steel, and its size is 46 mm in diameter and 150 mm in... 

A sample of melezitose was dissolved in an excess of water and filtered into a small beaker, which was covered with filter paper and allowed to stand at ordinary temperature for several days. The crystals which separated attained a diameter of a millimeter but were crowded together to such an extent as to make them unsuitable for crystallographic measurements. A few minute simple ones were picked out and the balance redissolved by addition of a little water and warming. The liquid was then allowed to cool and the crystals previously picked out were Tntroduced, the vessel being allowed to stand in a room kept at a constant temperature of 20° for several days. The same procedure was followed, using 50% alcohol as the solvent. 

This procedure (based on sample variance and covariance) is referred to as the direct method of estimation of the covariance matrix of the measurement errors. As it stands, it makes no use of the inherent information content of the constraint equations, which has proved to be very useful in process data reconciliation. One shortcoming of this approach is that these r samples should be under steady-state operation, in order to meet the independent sampling condition otherwise, the direct method could give incorrect estimates. 

Procedure Transfer an accurately measured volume of about 30.0 ml of 0.1 N potassium bromate solution into a 250 ml iodine flask. Add to it 3.0 g potassium iodide, followed by 3.0 ml of potassium iodide, followed by 3.0 ml of hydrochloric acid. Mix the contents thoroughly and allow it to stand for 5 minutes with its stopper in position. Titrate the liberated iodine with previously standardized 0.1 N sodium thiosulphate, using 3.0 ml of freshly prepared starch solution as an indicator at the end-point. Carry out a blank run using the same quantities of the reagents and incorporate the necessary corrections, if any. Each ml of 0.1 N sodium thiosulphate is equivalent to 0.002784 g of KBr03. 

Procedure Dissolve a quantity equivalent of 0.2 g of the dried substance and 5 g of hexamine in 10 ml of 1 M hydrochloric acid, add sufficient 1 M HC1 to produce 25 ml and allow to stand for 3 hours, protected from light. The optical rotation is measured by a previously calibrated polarimeter. 

Procedure Weigh accurately about 0.17 g of amoxycillin trihydrate and dissolve in sufficient DW to produce 500 ml. Now, transfer 10 ml of this solution into a 100 ml volumetric flask, add 10 ml of buffer solution pH 9.0 followed by 1 ml of acetic anhydride-dioxan solution, allow to stand for 5 minutes, and add sufficient water to produce 100 ml. Pipette 2 ml of the resulting solution into each of the two stoppered tubes. To tube 1 add 10 ml of imidazole-mercury reagent, mix, stopper the tube and immerse it in a water-bath previously maintained at 60 °C for exactly 25 minutes, with occasional swirling. Remove the tube from the water-bath and cool rapidly to 20 °C (Solution-1). To tube 2 add 10 ml of DW and mix thoroughly (Solution-2). Immediately, measure the extinctions of Solutions 1 and 2 at the maximum at about 325 nm, as detailed above, employing as the blank a mixture of 2 ml of DW and 10 ml of imidazole-mercury reagent for Solution-1 and simply DW for Solution-2. 

As described in the following chapter, there are many biopharmaceutical applications of protein assays. Assigning the protein concentration for the drug substance, drug product, or in-process sample is often the first task for subsequent analytical procedures because assays for purity, potency, or identity require that the protein concentration be known. Hence it is typical for several different methods to be employed under the umbrella of protein concentration measurement, depending on the requirements of speed, selectivity, or throughput. The protein concentration is valuable as a stand-alone measurement for QC and stability of a protein. However, protein concentration methods provide no valuable... 

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