Sampler automated

Modern transducers and microprocessors have been used successfully to automate particulate sampling trains in order to eliminate the operating curves and manual adjustments (7). The automated samplers adjust continuously to maintain isokinetic conditions. In addition, the microprocessor continuously calculates and displays both instantaneous sampling conditions and the total sample volume collected at any given moment. The use of the automated system with the microprocessor, therefore, eliminates both operator and calculation errors. 

FIGURE 5.14 CAMAG automatic TLC sampler 4 (ATS4, fully automated). 

A second fully automated device, the HPTLC applicator AS 30 (described earlier), can be employed in connection with a sampling device. Automated refilling of the syringe is performed by editing a volume factor, e.g., 10 for application of 10 times 100 pi. This device can be recommended if loss of sample is not relevant (e.g., owing to automatic rinsing operations that afford at least 70 pi dead volume for a minimal 20-cm tube connection). However, the fully automatic mode is not recommended for valuable samples. Sample volume still present in the Teflon tube between the sampler and AS 30 syringe will be wasted and lost because this operation cannot be circumvented by the user. 

The above so-called automated titrations still require manual sample introduction directly into the measuring cell60 in order to avoid this in series analysis, a few manufacturers added automatic samplers, which in laboratory practice require only the previous introduction of samples into a series of cups... 

A second strategy relies on parallel experimentation. In this case, the same experimental step is performed over n samples in n separated vessels at the same time. Robotic equipment such as automated liquid-handlers, multi-well reactors and auto-samplers for the analysis are used to perform the repetitive tasks in parallel. This automated equipment often works in a serial fashion as, for example, a liquid handler with a single dispensing syringe filling the wells of a microtiter plate, one after another. However, the chemical formation of the catalyst or the catalytic reaction are run at the same time, assuming that their rate is slow compared to the time needed to add all the components. The whole process appears parallel for the human user whose intervention is reduced. 

Automated injectors are often used when large numbers of samples are to be run. Most designs involve the use of the loop injector coupled to a robotic needle that draws the samples from vials arranged in a carousel-type auto-sampler. Some designs even allow sample preparation schemes such as extraction and derivatization (chemical reactions) to occur prior to injection. 

Figure 3.22 Two realizations of cross-stream cutter solutions to process sampling involving significantly heterogeneous aggregate materials (broken ore, raw material, powders, intermediates, cement, waste, soil, other). The gravity-driven, rotating cross cutter [left] does not comply with TOS requirements (highly detrimental IDE and lEE), while the automated cross-stream cutter implemented at the terminal end of a conveyor belt [right] can be easily optimized to eliminate all ISEs. See [3,14] for a broad discussion of all issues related to process industry cross-stream sampler principles, and [11,21] for particular details.

Even complex procedures can be automated, such as dialysis to clean up dirty samplers, solvent extraction, automatic distillation and on-hne UV digestion. Unhke the earlier AutoAnalyzer systems which use a purely step-wise autosampler, the TRAACS is fitted with a random-access sampler as standard. 

The random-access sampler can go to any sample cup position, any number of times, at any time during a run. This abihty to sample cups in any order and to return to sample cups more than once, allows system automation to be greatly extended. It saves time and work by allowing automatic re-run of sample(s) following off-scale peaks and also the automatic dilution and re-analysis of off-scale samples. The sampler also saves cup positions, allowing more samples and longer unattended runs. For example, one set of standards provides initial cahbration, drift correction, carry-over correction and periodic quality control. In addition, samples or standards can be sampled in repHcate form from a single cup. The random-access sampler can be controlled and either the operator or the computer can make the decision as to which cup the sampler must go to. 

Burns [27] described a fully automated approach for HPLC analysis of vitamin tablets. A sample valve provides the injection interface in this apphcation. Tablets direct from the production plant are dispensed into the sample cups on a Technicon Sohd Prep sampler, they are dissolved, and the fat-soluble vitamins are extracted. The solution is concentrated... 

In 1995 Hewlett Packard introduced the HP 6890 series of instruments which are designed to fulfil a broad range of analytical requirements. TTiis series includes a specific automatic fiquid sampler for increased throughput and automation, a series of options for data-handhng/control for the gas chromatograph and samples, as well as an integrator that supports the fuU range of features provided. 

A comparison of automated pipetting with manual pipetting, by Weltz [16]. demonstrates a difference of approximately one order of magnitude 0.4% RSD for automatic sample introduction versus 3.2% RSD for manual sample introduction. To achieve optimum results for trace elements in biological materials, the use of dedicated automated samplers is recommended. The Hquid-handhng capabihties of a pipetter/diluter workstation have been evaluated at Ortho Pharmaceutical (Haller et al. [17]). Four different volumes of each of three solvents were dispensed 20 times. Actual volumes... 

The apphcations described here illustrate the wide range of uses for robotic systems. This chapter is not intended to he exhaustive there are many other examples of successful applications, some of which are referenced below. For instance, Brodach et al. [34] have described the use of a single robot to automate the production of several positron-emitting radiopharmaceuticals and TTiompson et al. [3S] have reported on a robotic sampler in operation in a radiochemical laboratory. Both of these apphcations have safety imphcations. CHnical apphcations are also important, and Castellani et al. [36] have described the use of robotic sample preparation for the immunochemical determination of cardiac isoenzymes. Lochmuller et al. [37], on the other hand, have used a robotic system to study reaction kinetics of esterification. 

An Ion Chromatograph has been successfully automated by interfacing it to an automatic sampler (7). Continuous unattended analysis was possible, the actual number of samples analyzed being limited by the ionic capacity of the suppressor column. The automated Ion Chromatograph was used to analyze soluble sulfates, ammonia and alkyl amines in stack and automobile exhqust samples. Excellent agreement between IC and automated barium chloroanilate titration for sulfate was obtained with a relative standard deviation less than 5%. 

St. Louis Sample Collection. Ambient aerosols were collected in St. Louis in 6-h Intervals with a TWOMASS automated sequential tape sampler. This sampler fractionated the aerosol into two size classes, fine particles having aerodynamic diameters less than 3pm, and coarse particles with diameters greater than 3pm. It was equipped with a beta-attenuation mass monitor to determine fine-particle mass (11). Only the fine particle filter was examined in this study. Pallflex E70 glass-fiber filter tape with a detachable cellulose backing (Pallflex Inc. Putnam, CT) was used with this sampler. An aerosol sampler operating from the same inlet manifold as the... 

Analytical. Samples were chromatographed on a Hewlett-Packard 5880A gas chromatograph which was fitted with a 30M fused silica capillary column (DBS) and an automatic sampler. The GC was interfaced to a Hewlett-Packard 3354 Laboratory Automation System (LAS). Raw data was automatically transferred to the LAS where peaks were selected by retention time, integrated and stored in a processed file. Processed data was then transferred... 

Interesting are attempts to design dynamic hardness testers with a higher level of automation. Among these, we should mention the Equotip hardness tester manufactured by Proceq of Switzerland and the Sonodur A probe manufactured by Branson-Krautkramer. In the former, the sampler in the shape of a ball of sintered carbide is mounted in a beater weighing 5.5 g, which is also fitted out with a permanent magnet. This enables measurement of the speed of impulse and rebound by proportional current induction in the measuring coil. The quotient of rebound and impulse speed multiplied by 1000 is defined as hardness L (after the name of the method s author—Leeb). The hardness measurement result L can be converted to HKC, Hb or Hv with the aid of tables. 

This method is automated and the autoanalyser manifold used is shown in Fig. 7.4. A Technicon sampler plate and proportioning pump were used in conjunction with a Cecil CE 212 ultraviolet monitor and a Servoscribe RE 511 recorder. Glass tubing must be used to make connections from the double... 

Composite samples are typically collected for soil stockpile or surface area characterization. Twenty-four-hour composite samples of water may be collected with automated composite samplers from streams or process piping composite samples may be made of several grab samples collected from different depths in a soil boring. 

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