Ultratrace Inserts

Vessel-inside-vessel technology

We introduce the best of vessel-inside-vessel solutions to ensure lower analytical blank during microwave digestion in modern laboratory. This configuration reduces the amount of acid required for digestion to near stoichiometric quantities which provides lower dilution factor and higher detection limit.

To keep blank levels as low as possible the analyst must exercise care in keeping the volume of reagents to a minimum.

T. Murphy, The role of analytical blank in accurate trace analysis.

Why maintaining a very low dilution factor

Analytical chemists are being required to measure lower and lower levels of trace metals in samples. This frequently requires the analyst to make measurements near the method detection limit which usually result in decreased accuracy and precision. Closed-vessel microwave digestion techniques require a minimum volume of 10 mL to achieve accurate temperature monitoring of the reaction conditions. Ideally, modern spectroscopic techniques require samples submitted for analysis to have acid concentration of 1 to 5% v/v. This requires samples that were digested with 10 mL of acid to be diluted by a factor of 500 to achieve the 1 to 2% acid content necessary for ICP analysis. These large dilution factors often result in some of the analytes becoming non-detectable. These large dilutions are often overcome by maximizing the sample size relative to the amount of digestion acid.

This approach works well for samples that do not contain a large amount of organic material. For samples with high organic content this is usually not an option because the reaction gases (CO2 and NOx) produced during the digestion can cause the microwave vessel to vent when larger sample sizes (greater than 0.5 grams) are used. Recent advances in understanding of microwave-assisted sample preparation have led to the development of vessel inside vessel technology as a means to improving method detection limits for high organic samples. The Vessel inside vessel technology provides better reaction control. Controlling reaction kinetics is especially important when trying to digest large quantities (0.5 to 1.0 g) of organic material because the potential for auto-catalytic decomposition increases. Moreover, it helps control these self-sustaining auto-catalytic reactions by providing a heat sink for the energy liberated during oxidization.

NO CROSS CONTAMINATION

CThree blanks were analyzed in run #1. The same blank was prepared along with two Animal Tissue samples, showing no cross contamination.

COMPLETE RECOVERY

READ OUR BOOK!

Do you know how to reduce the sample prep blank?

The book explains how a laboratory can reach full control of analytical blanks and sample preparation for obtaining accurate results. The application of instruments and strategies to control sample prep blank is often called a “Clean Chemistry” technique. This book discusses the factors impacting blank quality, in particular when microwave digestion is used, and reviews some Clean Chemistry products and technologies designed to help the analyst generate superior analytical data on their ICP-OES or ICP-MS instrumentation.