ISCO Automated Sampler

by Timothy LaBreche and Chris Williams


What is an ISCO autosampler? Why use an autosampler?
Where do you use an autosampler? How do you operate an ISCO auto sampler?

What is an ISCO autosampler?

An ISCO sampler is a programmable liquid sampler that is capable of operating in hostile environments such as sanitary sewers and heavy storms without additional protection. Atop the unit is a watertight control box that contains a microprocessor with software imbedded in a PROM (Programmable Read-Only Memory) along with other supporting electronics. The controller can be programmed to sample according to many different monitoring protocols. Aside the controller case is a peristaltic pump that pulls in the samples and purges the sample line. The sample is fed from the pump down to a filling arm beneath the control case. The filling arm rotates above the bottle case and fills each bottle, up to 24 for the 3700 standard model, as the according to the program the user has entered. A variety of bottle sizes varying from twenty four 350 mL bottles to one 4 gallon bottle can be used in the bottle case. Samples that are heat sensitive can be kept cold by addition ot ice to the water proof and insulated (R-14) bottle case.
Why use an autosampler?

Autosamplers are very useful when you need to take samples from the same site many times. When the sampling site is very difficult, expensive, or dangerous to sample manually they become essential. Autosamplers are also useful when you need to sample at specific time intervals following events like rain storms that are beyond the control of the researcher.

The flexible but repeatable sample programming also makes them useful tools to the researcher. Samples may be taken at preset time intervals such as on every hour or at irregular time intervals such as the peak flow periods in the daily cycle of wastewater flows. The sampler may be connected to a flow meter so that samples are taken only after a certain flow is reached. One research area where this feature is applied is in erosion and runoff studies. In erosion/runoff studies the researcher needs many data points during a rain event when the stream flow is changing rapidly but needs less data when the stream is not changing as dynamicly. An autosampler can be programmed to take these types of storm monitoring samples which are often inconvenient if not impractical to do manually.
Where can you use an autosampler?

You can use an autosampler just about anywhere. They are very useful for sites that are difficult, dangerous, or time consuming to sample. For example: the photo below is of the waterfall at Cascades park in Virginia. If you were working on you masters at Virginia Tech and wanted to study the water quality upstream and downstream from this waterfall you would have to drive 45 minutes then hike 2 miles one-way with all your gear up some moderately difficult trails to get one day of samples. If you were interested in daily changes you would have to to this on a daily basis. If you were interested in the quality following major rain events you would have to make the hike in heavy rain, a potentially dangerous endeavour. With an autosampler you can program the machine to sample on a daily basis or when the stream flow reaches a certain level thus saving you a great deal of time and risk.


The Cascades, January 1997, near Pembroke, Virginia.
Daily sampling at a remote (and cold) site such as this would be impractical without an autosampler.


In addition to streams autosamplers can be used in lakes, sewers, industrial waste streams, and industrial process streams. Sewers in particular are another popular deployment area for autosamplers. Entering a city sewer is a time consuming and potentially hazardous activity. OSHA regulations mandate a number of precautions be taken during any entry into a confined space such as a sewer. Add to the danger heavy traffic and any sampling becomes unattractive. Instead of entering a confined space every time a sample is required autosamplers can be placed down manholes to sample for many days between servicing. Two or more autosamplers can be coordinated to record data at identical times upstream and downstream of a sewer discharge. Such simultaneous sampling is useful for determining compliance with discharge permits in difficult to access sewers such as in a large city.

How do you operate an ISCO autosampler?
CHRIS WONDERING HOW TO WORK THE ISCO

The most difficult part of ISCO operation usually has nothing to do with the physical use of the machine but rather is the design of a statisitically valid experiment. Once an experiment design has been developed the right number of samples, the format of sampling whether one sample per bottle, multible samples per bottle, or several bottles filled at one sample period can be programmed without much difficulty. Basic operation of the ISCO is relatively simple. Time intervals and sample volumes are entered through the control panel keyboard. A simple time paced sampling program can be set up in a few minutes. More complex programs dealing with multiple and multiplexed samples and or more elaborate time controls will take longer.

The following video clips show the basic setup, operation, and features of the ISCO.

In these two movies, watch how Tim demonstrates how easy it is to set up an ISCO in the field for sampling.

After attaching a float and strainer Tim throws the collection line in to the lake to collect lake water. Now see how easy it is to recover the samples.

See how simple it is to program the ISCO to sample.

In this section you can see the inner workings of the ISCO, how it actually deposits water into the bottles. A rotating arm located inside the sampler deposits samples directly into the bottles, determined by keypad inputs.


References

  1. Instruction Manual 3700 Portable Samplers, ISCO, 1995


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Student Authors: Timothy M. C. La Breche, tlabrech@vt.edu and Chris Williams, chrisw@vt.edu
Faculty Advisor: Daniel Gallagher, dang@vt.edu
Copyright © 1997 Daniel Gallagher
Last Modified: 2-25-1997