Tray, autosampler

The Benchmate program is started. After unattended operation, the vials are removed from the EasyFill module and placed on the LC/MS/MS autosampler tray for analysis. Each Benchmate Workstation will process up to 50 samples in less than a 24-h period. 

Automated online SPE LC systems are used extensively for environmental assays. Trays of SPE cartridges and autosampler can be used in the field. Water samples are preconcentrated trays of SPE cartridges loaded with analytes are brought to the laboratory and mounted onto an online SPE LC/ MS/MS system for analysis. Prospekt and Symbiosis systems were used for monitoring herbicides and transformation products (Hogenboom et al. 1998,1999a and b Lopez-Roldan et al. 2004 Kato et al. 2003 Lacorte and Barcelo 1995 Ferrer and Barcelo 1999,2001 Riediker et al. 2002), phenols... 

A system is typically comprised of multiple instrument components. Therefore, there is usually an individual IQ for each of these instruments and for any corresponding instrument control/data-handling software. The typical instrument components making up an HPLC system include a binary or quaternary HPLC pump, an autosampler supporting multiple vials or microtiter plates (autosamplers often include cooled Peltier trays for sample stability), a column oven, and a UV-Vis or photodiode array (PDA) detector. 

To test the autosampler s performance independence of vial location, it would be recommended that standards are injected out of various locations in the autosampler tray. This is shown in the Vial colnmn for experiments 10-27 in Figure 10. It should be noted that the higher vial positions may have to be tailored to the capacity of the actual autosampler tray. 

TTie instrument is built around a commercially available autosampler designed by P.S. Analytical Ltd, Kent, UK. This has a helical tray and the probe remains static. All the analytical modules are incorporated in to the upper housing of the sampler system. The unit is compact but it is difficult to maintain and service nevertheless it has been widely accepted as a standard in the UK water industry. 

The injection temperature can be a signiflcant issne for thermally unstable samples or where samples are stored for hours in an antosampler prior to injection. For this reason, most manufacturers sell autosamplers with optional thermostated sample compartments. This can be done either by placing the sample tray in an air bath oven or by a condnctive temperature control of the sample rack. The need to keep samples cool prior to injection when conpled with elevated temperature separation increases the complexity of the flow system reqnired. For such application, a separate mobile phase pre-heater with a low volnme placed between the injector and the column is a good choice. Alternatively, the injector valve wonld need to be monnted ontside the antosampler or in the column oven to insure preheating of the mobile phase before the colnmn. 

PE Series 200 LC autosampler with 96-well plate sample tray insert. 

This simple method is used in industry for repetitive analyses. For such analyses, the chromatograph must be equipped with an autosampler, including a sample tray and an automatic injector. The single reference solution, periodically injected for control purposes, can be used to compensate for baseline drifts. It is not necessary to add an internal standard to each of the samples, as discussed below. 

Calibration is time consuming when performed correctly. It may require 1 or 2 days to perform all the necessary steps (i.e., prepare stocks, filter, measure absorbance, check purity, dilute, mix, and inject calibrants). Once the stock solutions and mixed calibration solutions have been prepared, a calibration check can be performed in -4 hr. Sample preparation, depending on the matrix, may require a few minutes or a few hours. If an autosampler is unavailable for overnight injection the extracts are typically stable overnight, refrigerated at - 20° to 4°C. It is prudent to maintain the autosampler tray temperature from 4° to 15°C to reduce sample degradation. HPLC analysis of the extracted sample requires 20 to 60 min. Typically one technician can extract 12 to 24 samples per day to be analyzed overnight or the next day. 

LC-MS/MS System Used and Analytical Conditions An LC system from Thermo Finnigan, USA was used. The system consisted of a quaternary pump (Surveyor series) and an Autosampler (Surveyor series, equipped with a temperature controlled tray and a column oven), connected to a TSQ-Quantum triple quadrupole mass spectrometer, supplied with an electrospray ion source (Thermo Finnigan, San Jose, CA, USA). 

LC-MS/MS System Used and Analytical Conditions A Shimadzu liquid chromatography system was used (Shimadzu Scientific Instruments, USA). The system consisted of a Shimadzu SCL-10A VP system controller with four LC-10AD VP pumps. A Perkin-Elmer series 200 autosampler, equipped with a cool-tray (Perkin Elmer, Norwalk, CT, USA) was used for sample injection. Moreover, a six-port switching-valve was implemented in order to switch between an extraction column and the analytical column. Samples were injected onto the extraction column (Oasis HLB column). After a short extraction/equilibration time of 0.3 min, the samples were eluted from the extraction column onto the analytical column (Symmetry C18) (Figure 1). 

Injector. This allows an introduction (injection) of the analytes mixture into the stream of the mobile phase before it enters the column most modern injectors are autosamplers, which allow programmed injections of different volumes of samples that are withdrawn from the vials in the autosampler tray. 

It should be determined if the drug substance being analyzed is stable in solution (diluent). During initial method development an autosampler tray cooler... 

Two samples of the intermediate were prepared using acetonitrile and methanol as the diluents. Each sample preparation was immediately analyzed using an autosampler-tray-cooler-equipped HPLC for the initial control time-point, and portions were also stored under ambient conditions (clear volumetric flask and ambient room lighting) and under refrigerated conditions for 50 hours. 

Products/technologies Midas autosampler with 96-tray capacity. 

Fig. 15.15 Thermostated bath mounted above a moving autosampler tray.

Samples can be injected via a sample loop using a valve (Figure 3.12). Once the sample has been introduced into the loop, the valve is switched (manually or by electric actuation) to deliver the sample plug onto the analytical column. Autosamplers allow more precise injection. In this case, a carousel or tray of sample vials can be left unattended for automatic injection (by compressed air or nitrogen) at predetermined intervals (Figure 3.13). The volumes injected are usually in the range 5-500)tL but lower and higher volumes can be injected under certain conditions if required. 

The autosampler functions as a separate IEEE-488 device, distinct from the source system. It also Incorporates its own internal microcomputer and associated memory. It allows random access of any sample In the tray at any time during the analysis. Using the autosampler for sample introduction allows the analyst to perform other analysis-related tasks while an analysis is taking piace. Including the system controller, both monochromators, the RF system and the autosampler, the instrument assembly contains five separate microprocessors. 

Autosamplers usually hold several samples contained in septum capped vials in a carousel or tray that serves as a fixed address for each sample. These samples are... 

Automation has also allowed the use of open access mass spectrometry for chemical analysis. Initially developed for single analysis of chemical samples with no prior separation, the system simply requires sample details to be logged onto a computer. A choice of positive and/or negative ion APCI (or electrospray depending on the source available) is allowed. More recently LC/MS is available with perhaps a choice of two separation systems. The user is then directed to place the sample in a particular location in an autosampler tray. 

Samples can be injected automatically with mechanical devices that are often placed on top of gas chromatographs. These autosamplers mimic the human injection process just described using syringes. After flushing with solvent, they draw up the required sample several times from a sealed vial and then inject a fixed volume into the standard GC inlet. Autosamplers consist of a tray which holds a large number of samples, standards, and wash solvents, all of which are rotated into position under the syringe as needed. They can run unattended and thus allow many samples to be run overnight. Autosamplers provide better precision than manual injection— typically 0.2% relative standard deviation (RSD). 

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