Semiautomatic instruments

Kopriwa BM. A semiautomatic instrument for the radioautographic coating technique. J Histochem Cytochem 1966 14 923-928. 

An end point in a Karl Fischer titration can be observed visually based on the brown color of the excess reagent. More commonly, however, end points are obtained from electroanalytical measurements. Several instrument manufacturers offer automatic or semiautomatic instruments for performing Karl Fischer titrations. All of these are based on electrometric end point detection. The details of operation of Karl Fischer titrators are discussed in Chapter 22. 

Clinical instruments may also contain a feature for deproteinizing the sample. Instruments that provide only a few of these steps, primarily electronic data processing, are called semiautomatic instruments. 

The measurement of intrinsic viscosity is simple and inexpensive when compared with other measurements related to the polymer MW. However, it can be time consuming, even if modern semiautomatic instruments are used for that purpose. As mentioned in Chapter 1, measurements of intrinsic viscosity were historically important in establishing the concept of macromolecules [29]. 

The first semiautomatic instrument utilizing all advantages of the spray-on technique was the (Lino-mat 5) (Figure 2). Today s latest model is software controlled. Only the y-position of the application is set manually and the user loads the sample into the... 

Semiautomatic devices suited for preparative purposes are the CAMAG Linomat 5, the Desaga HPTLC applicator AS 30, and the Alltech TLC sample streaker. For all devices, the syringe has to be filled manually with sample solution and rinsed after sample application. Except for the Alltech TLC sample streaker, each of these instruments can be employed either as software-controlled or as a stand-alone device. The former is more convenient for creation, editing, and saving of the application pattern and instrument parameters. 

The fifth-generation systems currently available are a result of the continuing improvement in the price/performance ratio of computers. The integration of instruments for measurement with apparatus for sample preparation and transfer enables these systems to perform all of the functions required for intelHgent automation of methods. In previous generations, the tasks associated with sample preparation and transfer were performed manually, or, in a Hmited number of cases, carried out by semiautomatic devices, such as autosamplers, Hnked to an instrument. 

For the most recent LC-MS on the market, an automatic procedure is included in the software package to tune and calibrate in the ESI mode. However, older instruments and/or very specific applications still require manual or semiautomatic procedures to optimize the parameters that affect ion detection. In an LC-MS instrument, the mass spectrometer is tuned and calibrated in three steps (1) ion source and transmission optimization, (2) MS calibration, and (3) fine tuning (detection maximization of one or more particular ions). 

From these equations it can be seen that each mole of water requires one mole of I2. In a visual endpoint Karl Fischer titration, a sample is titrated with the Karl Fischer reagent until a permanent iodine color (indicating that all water has been reacted) is observed. Because of other reaction products, the color change is usually from a yellow to a brownish color, which may be difficult to detect visually. Highly colored samples may affect the visual end point as well. A much sharper end point, known as the dead stop end point, can be obtained if the titration is done electrometrically. Here, two small platinum electrodes dip into the titration cell, a small constant voltage is impressed across these electrodes, and any current that flows is measured with a galvanometer. At the end point of the titration the current either goes to a minimum or else increases suddenly from nearly zero. Commercially available Karl Fischer instruments incorporate semiautomatic microprocessors based on this principle. 

Biotech Instruments BT 7500 Boc/Fmoc 180 shaker and gas bubbling 2-10g semiautomatic... 

The first connmercially available continuous-flow synthesizers were manual instruments the PEPSYNthesiser I from Cambridge Research Biochemicals (CRB) and the Model 4175 from LKB Biochrom. In these instruments, one manual valve switches between the flow and recirculate modes and another manual valve selects the solvent, reagent or the annino acid injection port. CRB later released the semiautomatic PEPSYNthesiser II before selling the rights to the instrument to MilhGen, who ultimately released the fully automated 9050 PepSynthesizer. Pharmada-LKB Biochrom also developed an automated continuous-flow synthesizer, the Biolynx Model 4170. Several years later, the rights to this instrument were obtained by Novabiochem. Most of the automated, semiautomated, and manual continuous-flow peptide synthesizers are fisted in Table 3. 

It is customary to refer to instruments lacking the automatic functions on the above list as manual instruments. If these incorporate extensive electronic data-processing, they are called semiautomatic. 

Overview. The above description of automation as applied to clinical instruments leads to an interesting conclusion. Some of the current instruments that do not automate sample handling or processing, and which are referred to as manual or semiautomatic, may be more effective in saving skilled labor and time and reducing human error than some of the automatic instruments of the 1950s and 1960s. 

Supervisory control refers to the role a human plays in operating a semiautomatic process or system. Examples include control of large systems such as a nuclear power plant and specific instrumentation such as a robotic or assistive device. Performing supervisory control is high-level task that predominantly consists of mental components. This task is used to generically illustrate the use of analytic techniques to model a task. 

Freeman et al. (1967) have developed an instrument which uses infrared absorption for the semiautomatic analysis of mixtures of triglycerides and cholesteryl esters. The method of analysis is based on the carbonyl absorption bands of triolein and cholesteryl oleate at 1745 and 1730 cm" , respectively. Sample preparation consists of an extraction of lipids from serum in such a way as to exclude phospholipids. With adequate resolution and good precision of frequency setting, measurements at the two positions can be used successfully in a standard two-component spectrophoto-metric analysis. The nonautomatic part of the system is the handling of samples. 

Kinetic titration curves are constructed by plotting the relative analytical signal (absorbance, fluorescence, potential, or temperature) as a function of the volume of titrant added. If the two parameters are linearly related, then the titration curve will consist of two linear segments that can be extrapolated to intersect at the endpoint, as shown in Figure 4. Current instrumentation permits the use of automatic or semiautomatic devices capable of delivering the titrant and continuously monitoring the signal obtained. The time elapsed between the start of the titration and the endpoint is known as the pseudoinduction period and is proportional to the inhibitor concentration. These automated procedures are quite rapid and reproducible. 

Sample preparation for each compound is performed in 96 well plate using a semiautomatic liquid handing station. LC-MS/MS instrumentation is used for the quantification of the sample and the final raw data are stored. Further calculation is done by appropriate quantification application. From the quantification, data concentration of unknowm samples are extrated and plotted versus the sampling time points (average plasma concentration vs. time). Pharmacokinetic calculations are performed by using pharmacokinetic software WinNonlin Pharsight Corporation) ... 

The new commercially available TLC-MS Interface was first constructed as a semiautomatic (just automatic lifting and cleaning of the elution head) to keep the instrumentation affordable. However, on demand, full automatization would be possible, improving performance data and unattended operation. 

AutoAnalysis is a software which affords high flexibility in automatiDg analytical methods. Thus, with an appropriate choice of instrumental modules and the required DLLs, AutoAnalysis allows the automatic or semiautomatic implementation of a host of flow techniques including FIA, SIA, MCFIA, MPFS, MSFIA, LOV, capillary electrophoresis (CE) and high-performance hquid chromatography... 

Although of limited value in qualitative analytical TLC, a variety of automatic or semiautomatic spot and streak applicators can be purchased. These applicators are used most frequently for quantitative TLC and HPTLC, and for preparative TLC. Jaenchen (1996) has reviewed instruments for application of samples for TLC and HPTLC. 

Now that instrumentation is becoming available to measure equipment performance, it is still necessary to determine when that performance is go and when it is no go. A human must establish the threshold point, which can then be controlled by manual, semiautomatic, or automatic means. First, let s decide how the threshold is set and then discuss how to control it. 

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