Getting accurate and reproducible trace element analysis results

Challenge 3: preparation

In the words of the pioneering French criminologist Edmond Locard, “Every contact leaves a trace”. This is as true for sample preparation as it is for forensic science, in that everything a sample, blank or calibration solution comes into contact with risks contaminating it. The basic rule is therefore to minimise sample handling steps as much as possible to minimise the risk, as well as using pre-cleaned labware as described earlier. Since we humans are also well known sources of trace element contamination (from hair, skin cells and dust from outside the lab carried in on our clothes), as little manual sample manipulation as possible helps reduce contamination. When manual interaction is necessary, use of powder-free gloves, clean laboratory coats and safety glasses is essential.

Gallery

If your laboratory analyses medium to large numbers of samples every week and dilution of samples is a regular activity for you, the most effective way to minimise manual sample handling is to invest in a hands-free autodilution system for your ICP-MS instrument. There are a couple of major providers of such systems and a quick internet search or conversation with a local ICP-MS sales representative will highlight them. Autodilution systems not only take away the laborious task of fixed manual dilution of a set of samples (e.g. dilution by a factor of 10) using so-called prescriptive dilution, but also provide the ability to dilute intelligently by different amounts on a sample by sample basis, in accordance with rules such as ‘dilute if a result is above the calibration range’ or ‘dilute if the internal standard recovery is below an acceptable value’. With the iCAP RQ and iCAP TQ ICP-MS instruments, the common software platform that operates them, Qtegra Intelligent Scientific Data Solution (ISDS), offers both prescriptive and intelligent dilution functionality as standard, giving you flexibility for unattended and uncontaminated automatic analysis.

* Dr. S. Nelms: Thermo Fisher Scientific, Hemel Hempstead/UK, analyze.eu@thermofisher.com

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