Figure 1a. Hardware
Figure 1b. Consumable kit
Figure 1c. Software
(PC is not included)

Rapid Onsite Toxicity Audit System is a rapid portable toxicity test based on naturally occurring bioluminescent bacteria (Vibrio fischeri). These bacteria emit visible light when in a state of metabolic health. Light emission is directly linked to the production of ATP, so the relative level of bioluminescence reflects the metabolic health of the cell; or the total toxicity of the sample which has been exposed to the bacteria. Unlike any other rapid, field-based toxicity test, Rapid Onsite Toxicity Audit System has been specifically developed and validated for the testing of solid matrices, including soil, sludge, sediments and waste.
The principle of using bioluminescent bacteria for the toxicity testing of soil and water samples has been used for over 30 years. There are over 500 papers published on the technique and the test has been used to detect over 1,300 different known environmental contaminants and toxins in soil, sludge, sediments, composts, waste material, wastewater, potable waters, leachate and groundwater samples.
Rapid Onsite Toxicity Audit System comprises: hardware (portable luminometer and accessories; Figure 1a); kits of consumables to process batches of samples (Figure 1b); and software to drive the assay procedure, and analyse and report the results (Figure 1c).

VALIDATION AND DETECTION LIMITS

Rapid Onsite Toxicity Audit System has been extensively trialled in the UK and across Europe to establish its capabilities in over 30 different projects. In summary, the system is capable of detecting chemical contamination in soil in over 80% of contaminated samples tested. The technology was spun out of the University of Surrey, UK. It took over three years to commercialise and has been available on the market since 2004.

Although detailed detection limits are available from Cybersense for a range of inorganic and organic contaminants; as a guide, Rapid Onsite Toxicity Audit System is capable of detecting metals in solution down to < 10 ppm and organics (including hydrocarbons) at < 100 ppm.

SITE INVESTIGATION AND RISK ASSESSMENT WORK

Rapid Onsite Toxicity Audit System can be used in site investigation work as a rapid screening tool to identify hotspots of contamination for further investigation. As the test measures total toxicity, it provides unique information on:

• chemical unknowns not tested for by conventional lab-based chemical analyses
• the total biological effects of contaminants present in the sample which may collectively contribute to overall risk

When used alone, the system provides limited information, but when used in concert with conventional lab-based chemical analysis, it can function as a rapid, low-cost screening tool of total contaminant burden.

Rapid Onsite Toxicity Audit System can process up to 330 samples per day and report this data in an auditable Toxicity Report as part of a dynamic sampling exercise. This is particularly suitable for screening large areas of land where data is required quickly and sampling is relatively easy.

In certain circumstances Rapid Onsite Toxicity Audit System can also be used to provide additional information to help support risk assessment decisions, particularly in the determination of environmental risk.

LIMITATIONS OF Rapid Onsite Toxicity Audit System

Whenever the system is used, the following limitations must be acknowledged:

• the test does not provide a direct measure of risk to human health
• Rapid Onsite Toxicity Audit System measures acute, not chronic toxicity (although certain carcinogenic compounds are detectable).

Notwithstanding these limitations, in situations where the possible contamination is unclear or complex, a rapid, field-based, low cost toxicity test such as Rapid Onsite Toxicity Audit System can be an ideal tool to identify and prioritise hotspots of contamination. As the system provides broad screening information on total contaminant burden, it can be used as part of a dynamic site investigation program to provide powerful additional information to more accurately and cost-effectively determine risk.

COMPONENTS

Rapid Onsite Toxicity Audit System - Hardware

Rapid Onsite Toxicity Audit System is designed for the rapid field-based assessment of toxicity using bacterial bioluminescence. The system is based on a rugged portable luminometer which measures light output from the bacterial reagent. The system can be calibrated onsite to action trigger levels for a range of compounds.

<Hardware Contents>

Luminometer, Installation CD, Power Supply Unit, PC connecting cables (RS 232 and USB cable), Pipettes, Sampling spatula, Safety spectacles,.

<Luminometer Specification>

Product code	RT01
Size (mm)	143(W) x 210(D) x 62(H)
Weight	1,240 g
Condition	15 to 27 °C
Battery	Up to 24 hours
OS	for PC Windows XP*

* PC is not included, Windows is a trademark of Microsoft.

Rapid Onsite Toxicity Audit System – Consumable kits

The most suitable test to perform depends on the nature of the samples. Measurement of maximum 22 samples is available in a test.

Kit	Leachable kit	Metal kit	Organics kit
Code	RTL22	RTM22	RTO22
Note	The Leachable test uses water as an extractant and will detect any contaminants that are leachable from the soil, for example excess metals and leachable organic compounds	The Metals test uses a mild acid extractant to assist metal solubility. Prior to use, the sample is neutralised using a buffer optimised to prevent precipitation. The Metals test allows the effective detection of metals in soil samples	The Organics test uses methanol as an extractant and will detect hydrocarbon contamination. Examples of contaminants that will be detected are poly-aromatic hydrocarbons (PAH) and total petroleum hydrocarbons (TPH)
Contents (General)	Reagent (Freeze-dried bioluminescent bacteria), Rehydration medium, Test Plates (24 wells), Pipette tips, Blank & Control, Safety gloves
Contents (Special)	Extractant (Water), pH strips	Extractant (mild acid), pH strips, Buffer	Extractant (methanol)