Autosamplers for Purge and Trap: The Best Ones

An autosampler automates the loading of laboratory samples into the sample injector of a chromatograph hplc autosampler. In combination, the autosampler and the sample injector are known as the autosampler injection system - a system that separates compounds from the sample so the chromatograph can detect them. There are five main types of autosampler injection systems:

S/SL (split/splitless) injection systems

On-column inlet systems

PTV injector systems

Gas source inlet systems

Purge and trapsystems

With its dynamic ability to trap low level compounds, the purge and trap system is used for samples whose compounds occur at low-ppb (parts per billion) levels. When they choose an autosampler for purge and trap, many laboratories narrow their choices to the Centurion WS Autosampler and the Archon/OI Model 4552 Autosampler. If you are evaluating these autosamplers, the comparisons below will aid your evaluation.

Centurion WS Autosampler vs. Archon Autosampler

Comparing the Centurion WS to the Archon/OI Model 4552 should be done using criteria that determine the overall value of an autosampler to the user. These criteria are:

Analytical superiority

Mechanical robustness

Productivity

Ease of use

Ease of maintenance

Analytical Superiority

The Centurion WS features electronic, three-position delivery, a programmable 1ul-100ul delivery, and does not require priming. These features give it one of the most versatile, reliable, consistent, and economical IS/Surr delivery systems on the market. By using a fast hot water rinse in a fixed volume loop that keeps water in the pathway hot, and flushing the minimizer parameter soil needle and transfer line with P&T's Bake gas, it also features excellent carryover reduction.

The Archon/OI Model 4552 features mechanical, two-position delivery, a 1ul delivery, and requires priming. These features make it less versatile, reliable, consistent, and cost effective than the Centurion WS. Its slow hot water rinse with a syringe also offers less carryover protection.

Mechanical Robustness The Centurion WS displays a high level of mechanical robustness due to the following

specs:

A fully supported X-Y-Z arm

Water vial sampling that occurs in the tray

A fiber optic vial sensor

Vial sensing during transport only for soil samples

An elevator mechanism that only carries soil

Modular electronic design

A P&T concentrator that manages flow control

Elimination of the syringe mechanism found in most autosamplers

In comparison, the specs for the Archon/OI Model 4552 are that it:

Has an arm whose left side is unsupported

Does not sample water vials in the tray

Features a mechanical switch (not a fiber optic sensor) that must be manipulated during vial transport

Has an elevator that moves both water and soil samples

Contains an all-in-one printed circuit board instead of modular electronic design

Features separate pressure and flow control

Uses a syringe mechanism, which can lead to syringe errors.

Productivity

The Centurian WS achieves high productivity due to its dual concentrator mode for liquid and soil samples, and its generous sample positioning of 100 water samples and 90 soil samples. These features create cost savings for the GC/MC process and increase unattended autosampler operation. The Archon/OI Model 4552 lacks a dual concentrator mode and only features positioning for 51 samples.

Ease of Use Featuring remote control and intuitive Windows XP Software that is displayed on a 15" smart monitor, the Centurion WS is one of the easiest autosamplers to use. In contrast, the Archon/OI Model 4552 cannot be controlled remotely, and features an interface that is manipulated via a small keypad.

Ease of Maintenance The Centurion WS possesses three features that make it easy to maintain: an error tracking and sample log, on-board real-time flow diagrams, and complete on-board diagnostic checks. The Archon/OI Model 4552 does not possess these features.

Conclusion An autosampler for purge and trap is an important investment for independent researchers and laboratories that analyze solids and liquids using the GC/MC process. Although many laboratories use the Archon/OI Model 4552, it does not offer the same analytical superiority, mechanical robustness, productivity, ease of use, and ease of maintenance as the Centurion WS. For large laboratories and independent researchers whose funding depends on research cost and quality, the Centurion WS the best autosampler for purge and trap.