Case Study: Guilty Or Not Guilty: Justice Is Served With XP205 Semi-Microbalance

The independent Forensic Scientific Service (FND) of the State Police in St. Gallen, Switzerland conducts analytical and forensic tests with the aim of detecting proof of suspected crimes such as the illegal possession of drugs. As samples are generally available in powder form and in rather small quantities, an XP205 semi-microbalance was the customer's solution to assist in their delicate weighing tasks.

Handle with Care

A balance in a forensic laboratory has to satisfy high demands as sample material is scarce and the quality of the investigation results depends considerably on the evidence found and the condition of the sample. Drug materials such as heroin, cocaine or amphetamine are often found in very small quantities and the forensic scientific service is forced to examine the sample with great care. Therefore, it was vital to find a balance solution that guarantees the weighing-in of small sample quantities down to 10 mg, avoids influences caused by electrostatic charges on powdery substances and facilitates the error-free positioning of up to 5 different flasks with volumes up to 200 ml.

Small Quantity, Big Impact

"On average, we weigh-in approximately 25 mg of sample, sometimes even smaller amounts down to 10 mg. In this low weighing range, the measurement accuracy of the balance lies within 1% taking a safety factor of 5 into account. Additionally, we need a balance, whose measuring accuracy is traceable and meets the requirements of ISO/IEC17025", quality manager, Mr. Daniel Eugster, explains.

The XP205 semi-microbalance fulfills this easily with a weighing capacity of 220 g and a readability of 0.01 mg. Performance of the balance was confirmed during installation by issuing a calibration certificate and minimum weight determination (according to DKD; German calibration service). In addition, a service technician from METTLER TOLEDO maintains and calibrates the balance annually.