Time, analysis, minimum

Base-metal P numberf Weld-metal analysis A numberf Material group Nominal waU thickness Minimum specified tensile strength, base metal Metal temperature range h/in, nominal wall Minimum time, b Brinell hardness, maximum... 

Laboratory economy will also require the maximum sample throughput from the equipment and, thus, the second criterion will require the analysis to be completed in the minimum time. It should be pointed out,that just a rapid separation is not the criterion. The separation must be achieved in the minimum time. In practice, the column must be designed so that, when employed with the chosen phase system and the specific apparatus, no other column will separate the mixture in less time. 

It is obvious that a record of the kind in Figure 7-1 can yield valuable information about an unknown mineral in the minimum time at little cost. The x-ray emission spectrograph may well become the most valuable single tool for the qualitative analysis of minerals. Its advantages are obvious enough to make further discussion supererogatory. 

It should be noted that at a flow rate of 2 ml/min., the mobile phase velocity will be well above that of the optimum and so the maximum efficiency will not be realized. Generally, when there are more theoretical plates available than required, the flow rate is increased until the separation required is just realized. This procedure trades efficiency for time and allows the separation to be achieved in the minimum time given the column and phase system that has been chosen. It must be emphasized that the minimum analysis time can... 

The posttrial bum period is the time for U.S. EPA to evaluate all of the data that were recorded during the incinerator s trial burn. To allow the operation of a hazardous waste incinerator following the completion of the trial bum, U.S. EPA establishes permit conditions sufficient to ensure that the unit will meet the incinerator performance standards. This posttrial burn period is limited to the minimum time required to complete the sampling, analysis, data computation of trial bum results, and the submission of these results to U.S. EPA. 

This time is considerably shorter than the galvanostatic minimum time (Eq. 15). Since a theoretical analysis of this type of unsteady-state free convection offers severe difficulties, there is no way to confirm this difference except by controlled experiments of the kind undertaken, on a limited scale, by Hickman (H3) and by Fenech (F2). 

An approach for analyzing data of a quantitative attribute that is expected to change with time is to determine the time at which the 95% one-sided confidence limit for the mean curve intersects the acceptance criterion. If analysis shows that the batch-to-batch variability is small, it is advantageous to combine the data into one overall estimate by applying appropriate statistical tests (e.g., p-values for level of significance of rejection of more than 0.25) to the slopes of the regression lines and zero-time intercepts for individual batches. If it is inappropriate to combine data from several batches, the overall shelf life should be based on the minimum time a batch can be expected to remain within the acceptance criteria. 

To find the minimum and maximum of a quantity, you will have to run the Worst Case analysis four times. To find the maximum of the quantity, you will have to run die simulation once with the jMAX model and once with the jMIN model. To find the minimum of the quantity, you will also have to run the simulation once with the jMAX model and once with the jMIN model. If you happen to know which of the two models will give you the maximum or minimum of the quantity you are looking for, you may be able to reduce the number of simulations. 

The purpose of studytng the theory of liquid chromatography columns is not merely to understand the function of the column and how a separation can be achieved, but to provtde sufficient knowledge to be able to design a column that will provide a given separation, and consequently an analysis, in the minimum time. 

The efficient laboratory manager will also require the maximum throughput of samples from the equipment and thus, the second criterion is that the analysis must be achieved in the minimum time. It should be pointed out... 

Employing the conditions defined in the three data bases and the appropriate equations derived from the Plate and Rate Theories the physical properties of the column and column packing can be determined and the correct operating conditions identified. The precise column length and particle diameter that will achieve the necessary resolution and provide the analysis in the minimum time can be calculated. It should again be emphasized that, the specifications will be such, that for the specific separation carried out, on the phase system selected and the equipment available, the minimum analysis time will be absolute No other column is possible that will allow the analysis to be carried out in less time. 

The analytical specifications must prescribe the ultimate performance of the total chromatographic system, in appropriate numerical values, to demonstrate the performance that has been achieved. The separation of the critical pair would require a minimum column efficiency and the number of theoretical plated produced by the column should be reported. The second most important requisite is that the analysis should be achieved in the minimum time and thus the analysis time should also be given. The analyst will also want to know the maximum volume of charge that can be placed on the column, the solvent consumption per analysis, the mass sensitivity and finally the total peak capacity of the chromatogram. The analytical specifications can be summarized as follows. 

LPRINF2/ The analysis must be completed in the minimum time " LPRINT"3/ The analysis must be completed with the minimum solvent" LPRINT... 

LPRINT"2/ The analysis must be completed in the minimum time ... 

In the optimisation process, resolution and elution time are the two most important dependent variables. The goal is to conduct a separation of the components of interest in the minimum time without neglecting the time it will take for the instrument to come back to its initial state and be ready for the next analysis. Chromatography corresponds to a slow type of analysis. If the resolution is excellent, optimisation can still be conducted in order to save time in the analysis. This can be done using a shorter column, knowing that resolution varies with the square root of the length of the column (cf. N in equation (1.26)). 

Analysis time, t The minimum time required for separation. 

When analyzing materials, any one of the above categories (sample, separation, measurement) may assume more importance than another. Obtaining a representative sample may be more difficult than the separation and/or measurement or the separation may be more difficult than the sampling or measurement. Two objectives should be paramount for any analysis the data must have the required accuracy and precision and be produced in the minimum time. 

ANALYSIS TIME. If possible we like to perform the chromatographic separation in a minimum time. Time is important in analysis but it is particularly important in process chromatography. Analysis time is based upon the solute component which is more readily sorbed. Using the equation for determination of retention time,... 

Qualitative Observations. As an example of multi-particle imaging SIMS analysis, equilibrium catalyst sampled from an FCC unit which had recently begun adding fresh catalyst from a different vendor has been chosen. In this situation, we have a handle on the maximum length of time which a new type catalyst particle has been in the reactor, as well as the minimum time for an old type catalyst particle. (Although mixing in the fresh catalyst feed silo adds uncertainty to the situation, as will be seen in the following analysis.)... 

The desired analysis time (fmax) was set equal to 4 min., whereas the value of the minimum time (tmin, which is irrelevant for the optimization process see section 4.4.2) was taken to be 1.5 min. 

It can be seen in the chromatogram of figure 6.11 that four peaks (the three antioxidants plus an unknown impurity) are amply resolved to the baseline. This implies that all values for the peak-valley ratio P are equal to 1 and that the criterion has become very insensitive to (minor) variations in the resolution between the different peak pairs. In the area of the parameter space in which four well-resolved peaks are observed, the only remaining aim of the optimization procedure is to approach the desired analysis time of 4 minutes. The irrelevance of the minimum time tmin is illustrated by the occurrence of the first peak in figure 4.9 well within the value of 1.5 min chosen for this parameter. 

Successful analysis of some samples require a rapid, reliable, precise method for sample preparation and cleanup to remove potential interfering components so accuracy is maximized. It follows then that the goal of sample preparation is to obtain, from the sample, the components of interest in solution in a suitable solvent, free from interfering constituents of the matrix, at a suitable concentration for detection and measurement. Naturally, this preparation needs to be done with minimum time and expense. 

---