Injection automated system

Immunosensors promise to become principal players ia chemical, diagnostic, and environmental analyses by the latter 1990s. Given the practical limits of immunosensors (low ppb or ng/mL to mid-pptr or pg/mL) and their portabiUty, the primary appHcation is expected to be as rapid screening devices ia noncentralized clinical laboratories, ia iatensive care faciUties, and as bedside monitors, ia physicians offices, and ia environmental and iadustrial settings (49—52). Industrial appHcations for immunosensors will also include use as the basis for automated on-line or flow-injection analysis systems to analyze and control pharmaceutical, food, and chemical processing lines (53). Immunosensors are not expected to replace laboratory-based immunoassays, but to open up new appHcations for immunoassay-based technology. 

The Gilson Aspec automatic sample preparation system is a fully automated system for solid-phase extraction on disposable columns and online HPLC analysis. The Aspec system offers total automation and total control of the entire sample preparation process including clean-up and concentration. In addition, Aspec can automatically inject prepared samples into on-line HPLC systems. 

Fig. 12.2 Diagram of a fully automated system for acquiring H/D exchange MS data starting with a stock solution of the nondeuterated protein. In this system [8], the liquid handler mixes a small amount of concentrated protein solution with a selected deuterated buffer and the mixture is incubated for a programmed period of time. The exchange reaction is conducted in a temperature-controlled chamber held at 25 °C. The mixture is then transferred to an acidic quench solution held at 1 °C. After quenching the exchange reaction, the entire sample is injected onto an LC-MS system...

The majority of commercial developments which relate to the automation of GC and HPLC pay little attention to sample preparation. There are few examples where pretreatment is not required. A fully automated system was developed by Stockwell and Sawyer [23] for the determination of the ethanol content of tinctures and essences to estimate the tax payable on them. An instrument was designed and patented which coupled the sample pre-treatment modules, based on conventional AutoAnalyzer modules, to a GC incorporating data-processing facihties. A unique sample-injection interface is used to transfer samples from the manifold onto the GC column. The pretreated samples are directed to the interface vessel hy a simple hi directional valve. An ahquot (of the order of 1 ml) can then he injected on to the GC column through the capillary tube using a time-over pressure system. 

Analyses were done on a Dionex Model 14 Ion Chromatograph (IC), equipped with a Waters WISP 7 autosampler, Linear recorder, and interfaced with a Hewlett-Packard 3354 Laboratory Automated System. The principal components of the IC, shown in Figure 2, are (A) eluent reservoir, (B) pump, (C) injection valve, (D) separator column, (E) suppressor column, (F) conductivity cell, and (G) conductance meter with a recorder (integrator). 

In 1990, Bushey and Jorgenson developed the first automated system that coupled HPLC with CZE (19). This orthogonal separation technique used differences in hydrophobicity in the first dimension and molecular charge in the second dimension for the analysis of peptide mixtures. The LC separation employed a gradient at 20 (xL/min volumetric flow rate, with a column of 1.0 mm ID. The effluent from the chromatographic column filled a 10 pU loop on a computer-controlled, six-port micro valve. At fixed intervals, the loop material was flushed over the anode end of the CZE capillary, allowing electrokinetic injections to be made into the second dimension from the first. 

Figure 13 Schematic of an automated system for producing nanoparticles with desired properties. The set up is an adaptation of the system shown in Figure 8. The emission spectra of the emergent nanoparticles recorded by the CCD are passed to an intelligent control algorithm that repeatedly updates the reaction temperature and the injection rates of the two reagents until particles with the desired properties are obtained.

The observed precision is comparable to the values we previously reported for biosynthetic human insulin (16). It also is similar to independent results obtained using a totally automated system (2.9% RSD) and much better than that reported for manual injection (11.8% RSD), both using a hydrodynamic injection technique (21). Finally, the observed precision for the percent desamido, which is really an area ratio similar to what would be obtained by comparison to an internal standard, is excellent for the 10-nL or larger injections. Although the data are insufficient to make a definitive conclusion, it suggests that the observed error is comparable to that obtained from many chromatographic techniques. It also suggests that one of the predominant sources of error is imprecision in the injection volume. The error in injection volume was recently characterized (19). They also reported approximately 1-3% RSD in peak areas for vacuum injection of various compounds. 

Procedure Inject an appropriate volume (0.1 p-L to 1.0 pL) of sample into the chromatograph. If an automated system is used, follow the manufacturer s instmctions if calculations are to be done manually, proceed as follows ... 

HPLC itself is now considered to be a fuUy automated system. Once the solutions are placed in vials and sample sequence is programmed into the software, the auto-injector injects as stated in the sample sequence and it runs as specified in the instrument method. Many types of software, once programmed, also allow integration, processing, and reporting of an entire HPLC run to be performed automatically once the run is completed. 

In Hamilton s early work, the sample was placed on the ion-exchange resin by removal of liquid at the top of the column and injection of the sample directly onto the top of the resin bed while the eluent flow was stopped. This is an adequate means of sample introduction, although an automated system can probably also be used. The chromatogram was developed with the stepwise elution by sodium citrate buffers of varying concentrations and pH from a typical sample of 0.5 ml of the body fluid (Fig. 15). 

The aeration is produced by diffusion through the pipes that transport the air to four horizontal mbes submerged in the reactor. Three blowers of between 75 and 110 kW inject the air into the sludge or mixture when this is being recycled, just before it returns to the bioreactor. To obtain correct aeration, the bioreactor has an automated system for recording and controlling the quantity of dissolved oxygen that is present in the mixmre at each moment. The bioreactor is also equipped with meters to continuously monitor the level and pH. 

Despite the potential for direct aqueous injection of water samples into reverse phase systems, there are very few cases where this is possible due to the low detection levels normally required for environmental analysis. Using direct aqueous injection and coulometric electrochemical detection, the analysis of phenol and chlorophenols and 2-mercaptobenzothiazole have been achieved at trace levels (methods with limits of detection for phenol 0.034 ngp and 0.8 pgl for mercaptobenzothiazole have been achieved). There is a potential for the use of direct aqueous injection for the analysis of phenol in effluents using fluorescence detection which would be expected to detect down to low mg T. Direct aqueous injection has been used in an automated system similar to that shown in Figure 11.1. The trace enrichment cartridge was replaced by a large sample loop (50 pi) and a coulometric electrochemical detector used instead of the UV detector. 

The capillary rheometer is a valuable tool for predicting the processability of thermoplastic resins. This is done by measuring melt viscosities at shear rates and temperatures commonly encountered in extrusion and injection molding. This procedure is difficult and time consuming due to the complex nature of rheological measurements and analyses. An automated system for acquisition and analyses of capillary rheometer data has been developed to speed up and simplify this important analytical technique. 

Liquid-liquid extraction is carried out in a 10 mL centrifuge tube, where 1 g of sodium chloride, 0.1 mL of 2-octanol solution as internal standard (230 ppm in 50% v/v hydroalcoholic solution) and 50 xL of Freon 113 are added to 5 mL of the wine sample (Rapp et al., 1994). The solution is stirred for 15 min and then centrifuged. A volume of 2 p,L of the Freon 113 extract is analysed by GC. An exhaustive presentation of this method, applying also a fully automated system with a large volume injection, was performed by Rapp et al. (1996). 

In order to avoid problems with sample inhomogeneity, the entire oil sample from each sample of shale was dissolved in 1.5 to 2.5 mL of CS2 (about 1 g oil to 1.5 mL solvent). One pL of this solution was injected into a Hewlett-Packard Model 5880 Gas Chromatograph equipped with capillary inlet and a 50 m x 0.25 mm Quadrex "007" methyl silicone column. Injection on the column is made with a split ratio of approximately 1 to 100. The column temperature started at 60°C and increased at 4°C/min to 280°C where it remained for a total run time of 90 min. The carrier gas was helium at a pressure of 0.27 MPa flowing at a rate of 1 cm /min. The injector temperature was 325°C and the flame ionization detector (FID) temperature was 350°C. Data reduction was done using a Hewlett-Packard Model 3354 Laboratory Automation System with a standard loop interface. Identification of various components was based on GC/MS interpretation described previously (4). For multiple runs on the same shale, the relative standard deviations of the biomarker ratios were about 10%. 

Automated Flow Injection Analysis System for Formaldehyde Determination... 

An automated and microprocessor-controlled flow injection analysis system was developed for formaldehyde emission measurements. This system was based on the modified pararosaniline method and a sampling rate of about 40 samples/hour was obtained. 

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