Integrated-loop autosampler

FIGURE II A schematic of an integrated-loop autosampler under various operational cycles (a) flush, (b) sample fill, (c) inject. Reprinted with permission from Reference 16. 

Figure 4.6 Filling the loop by three different autosampler designs a, pull-loop b, push-loop c, integral-loop injection. 1 = sample vial, 2 = syringe with stepper motor, 3 —loop, 4 —from pump, 5 —to column, 6 = to waste, 7 = low-pressure seal, 8 = high-pressure seal, 9 = position of the movable loop when the valve is switched and the sample transferred to the column.

A stainless steel column (4.6 mm internal diameter by 250 mm length) packed with 7 micron Zorbax ODS (Dupont) was equilibrated with 82 % Acetonitrile in water at a flow rate of 2.0 ml/min. provided by a Spectra Physics Model 87(X) pump and controller. The effluent was monitored at 230 nm using either a Tracor UV-Visible detector Model 970A or a Jasco Uvidec UV detector Model 1(X)-V. Peaks were recorded and calculated on a SpectraPhysics recording integrator. Model 4200 or Model 4270. Samples of 0.5 mg/ml in toluene were applied to the column automatically with a Micromeritics Autosampler Model 725 equipped with a 10 pi loop. 

High-performance liquid chromatograph (HPLC e.g., Waters Chromatography) equipped with column heater, solvent pump, UV detector (set at 210 nm), integrator, autosampler, and (for manual injection) a 10-pl sample loop 15 x 0.46-cm YMC-ODS-AQ analytical column (AQ12S031546WT, Waters Chromatography)... 

To introduce samples into the flow path, the easiest way is the usage of a sample loop that is connected to an HPLC valve. After loading and switching, the loop is integrated into the flow path and the sample is delivered to the separation column. Today, this task is done by autosamplers that can temper samples and provide 24 hours of fully automated and reproducible sample injection. 

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