Weighing procedure

Filter Weighing Procedure-. The step-by-step procedure for weighing filters depends on the make and model of the balance. Consult the manufacturer s instruction book for directions. In addition, follow these guidelines ... 

It is not formulated on the basis of groups with equal numbers (as one of Duncan s procedures is), and if A) N2 there is no separate weighing procedure. 

Diagrams for a synthetic chemical, single reaction step process (Fig. 3) and a typical single product fermentation (Fig. 4) are taken from Wintner s excellent article [ Environmental Controls in the Pharm. Industry. Pharm Eng (April 1993)]. Both flow diagrams feature about the same number of unit operations and start with raw material weighing procedures. The essential difference between the two figures is that the fermentation process features sterilization, inactivation, and preservation unit operations. 

All the sources of uncertainty, both Type A and B which occur during the complete preparation process are itemised and quantified. These are then combined in a square-root-sum-of-squares manner to produce a combined uncertainty, which is then used to produce an expanded uncertainty with the use of an appropriate k factor. The value of this uncertainty will depend on a number of factors including the purity of the component gases, the weighing procedure and the uncertainties arising from the relative molar masses. 

The uncertainty in the accuracy of any given gravimetric standard is obtained from the uncertainties associated with the weighing procedure used to produce the standard, those which arise from the purity of the gases... 

The sources of uncertainties arising in the weighing procedure have been grouped together into the following categories ... 

Remove the receiving vessel from the inert gas system and place on a balance pan under a stream of argon, provided by the simple set-up shown in Fig, 6.20. Caution argon is the preferred inert gas for this procedure, but because it is heavier than air, make sure the flask remains filled through-out the weighing procedure. 

The precision of weighing the samples is a random error, which can be minimized by exercising care in the weighing procedure. 

Trace amounts of catalysts, e.g., tin catalysts, are conveniently added by means of a pipette. The weight of one drop of catalyst can be determined in advance. Small amounts of catalyst can also be added by using an anal)rtical balance. However, the use of such a balance is not recommended because of disadvantages, including time-consuming weighing procedures and risks of over charge. 

In older mechanical balances we simultaneously compared the weight of the object we were weighing with the weight of standard masses under the same gravitational conditions. So adjustment to local conditions was made automatically in the weighing procedure. 

Salts are the products of the acid-base neutralisation reaction. The salts used most in textile wet processes are common salt (NaCl, sodium chloride) and Glauber s salt (Na SO, sodium sulphate). The content analysis of salts is usually conducted by using a precipitation titration method which may be followed by fdtering and weighing procedures to obtain the final results. 

Preparation Weighing procedure +/- Non calibrated balance Inaccurate masses Calibrate balance, contact balance supplier or metrology services... 

There is no consensus yet on how to proceed, and different parts of society may use different ranking procedures. Therefore, the study has taken great care to show the influence of different weighing procedures and could show that the basic results are valid under all circumstances. 

Weighing procedures are normally associated with very small random errors. In routine laboratory work a four-place balance is commonly used, and the random error involved should not be greater than ca. 0.0002 g (the next chapter describes in detail the statistical terms used to express random errors). If the quantity being weighed is normally ca. 1 g or more, it is evident that the random error, expressed as a percentage of the weight involved, is not more than 0.02%. A good standard... 

Finally, health and safety precautions at weighing procedures generally brings with it the wearing of gloves... 

Compatibility with the receiver should be checked especially with fluids. Spatulas and spoons made of stainless steel may interact with substances such as chloral hydrate or iodine. But for the short contact time involved in the weighing procedure these interactions don t appear to be relevant. Plastic spatulas may cause a problem with electrostatic charge. Also with some substances discolouration of the plastic occurs so disposable spoons are increasingly used. 

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