Highest precision in tablet hardness testing

01. June 2011

With more than 15’000 tablet hardness testers in the market, Dr. Schleuniger® Pharmatron has driven tablet hardness measuring technology for almost 40 years and has continuously set new industry standards by combining reliable precision mechanics with state-of-the-art electronics. Especially in the last 20 years, technological advances in electronics and software have continuously opened up new possibilities – allowing for a new level of precision measuring technology. The MultiTest 50 is the latest advancement in tablet hardness measuring technology and incorporates modern electronics that can process data at a rate that would have been impossible just a few years ago.

To understand why the MultiTest 50 is more precise than any other tester on the market, it is important to know that measured hardness (break force) mainly depends on 4 tester-specific factors:

• Mechanical construction of tester
• Precision & linearity of load cell
• Sampling rate of tester
• Measuring principle used

Standard-setting since 1972

A solid and torsion-free mechanical construction has been the trademark of all Dr. Schleuniger® Pharmatron tablet hardness testers since 1972. The MultiTest 50 is no exception and absorbs forces without any torsion displacement and bending. Like all Dr. Schleuniger® Pharmatron tablet hardness testers, the MultiTest 50 incorporates a precision S-beam load cell with multiple transducers, which guarantees a very high linearity. From the 6D to the new MultiTest 50 and automatic systems such as the AutoTest 4 – all use the same type of load cell.

This load cell provides an analog signal, that is electronically sampled (= measured) in small time intervals by the tester. In simple terms, the main difference between the electronics of a conventional tablet hardness tester and a MultiTest 50 is the time between each sampling point (= frequency at which the analog signal is sampled). Within the same time interval, the new MultiTest 50 takes up to 30 times more measurement points than other tablet hardness testers on the market.

Why does the sampling rate influence the measured result?

As a general rule, the simple equation “more measuring points = higher precision” applies. The more measuring points are taken per time interval (= sampling rate), the more accurately the actual peak of a break force curve can be detected. If the peak (= highest point of the curve) is relatively flat, a high sampling rate is less important. If the peak is steep, the time interval becomes crucial to accurately detecting the highest point.

Modern electronics & measuring principle

Next to very user-friendly touch screen operation, the advanced electronics of the MultiTest 50 allow to select and program different measuring principles for each product if needed. Especially when testing the hardness of tablets using the “linear force increase” principle (= constant force), the MultiTest 50 electronics are capable to very quickly adjust the speed of jaw movement based on the currently measured force, thus avoiding force variations during testing known from other tablet hardness testers.

Only the combination of all factors guarantees precision results

It is important to understand, that only the combination of all main influencing factors guarantees precision results. A high sampling rate will not help to improve accuracy if e.g. the load cell doesn’t have a high linearity or the mechanical construction of the tester doesn’t absorb forces well.

The innovative design of the MultiTest 50 combines precision mechanics and proven Dr. Schleuniger® hardness measuring technology with state-of-the-art electronics. The main benefits are:

• Highest precision and repeatability
• Extremely reliable results
• Flexible programming with different measuring principles (if needed)
• Fast and easy-to-understand touch screen operation
• Efficient data handling with network integration

More about the new MultiTest 50 tablet hardness tester