Test Procedure

Enter the nominal test information for hardness as well as a batch number via the PTB111E / 111E-500 / 111E keyboard. Select the unit to measure, KP (Kilopond), N (Newton) or Sc (Strong Cobb), now place the sample onto the sample dish and start the test. The driven jaw will run forward, touch and force the tablet until it breaks to measure the hardness (tablet breaking force). The result is immediately displayed and printed to a connected dot-matrix or suitable PCL5 type laser- or printer.

Repeat this until your series has been tested, get a full print-out including each individual result, date, time, serial number of the instrument, batch number of the product tested, mean value and deviations of the test series. The flexibility and the reproducibility of the results have made this and other models, like the PTB 311E/511E/311E-800 series become one of the most sold tablet hardness testing instruments worldwide.

Operating Principle

Even in the existing USP and EP monographs there is no standard force setting or force increase mode established, but it is recommended to use a linear force increase rate of 20N/s. Different force settings usually cause problems when comparing results received by different supplier's instruments when testing the same tablet. The hardness result is directly influenced by the contact speed and force increase rate. Faster operated test jaw means lower reproducibility and often higher results.

In order to offer the possibility to select an operating mode which will offer you similar results as the instruments you may already use, select the force mode, linear force increase or linear speed increase and select the same or similar rate. Also touch and detection force may be altered to suit the sample design specification. When the sample is touched the instrument switches to the selected mode and linear increasing rate.

Calibration and Validation
The current USP Pharmacopeia requires the force sensor of a tablet hardness testing instrument to be calibrated periodically over the complete measuring range (or the range used for measuring samples) with a precision of 1N. All Pharma Test tablet hardness testing instrument can be statically calibrated over the complete measuring range by the use of different traceable counterweights. All instruments support the checking of at least three different points during calibration to prove the linearity of the force sensor.

Furthermore, Pharma Test offers the PT-MT3 magnetic tablets to calibrate the breakpoint detection of the whole tablet hardness testing instrument (force sensor and mechanics of the instrument). All Pharma Test tablet hardness testing instruments are fully compliant to the requirements of the current USP Pharmacopeia.

PT-MT3 for dynamic hardness calibration

The PTB111E / 111E-500 / 111E offers a built-in calibration and validation program for the hardness test station. To validate the hardness test station the PT-MT3 magnetic tablet or different certified counterweights are used. Use the PT-MT3 to qualify the correct breakpoint detection, the PT-MT3 instrument works like a tablet, it withstands force and after "breaks". For the two point adjustment (zero and reference) of the load cell inside the hardness station a certified reference weight of 10 kg is used. For validation purposes the use 5 up to 30kg certified weights is recommended. All adjustment and calibration results can be printed and countersigned.

To prove the linearity of the instrument, the operator can program a print-out of the force curve recorded during a test. This will show the linear increase of the adjusted force mode. Also different counterweights, like the PTB-CAL15 and PTB-CAL30 which includes 5, 10, 15kg and also 30kg or the PTB-CAL30 using 2 additional 10kg weights for total 50kg, may be placed onto the load cell or the PT-MT3 shall be used to breakpoint detection. Using the Parallel Printer Port a Dot-Matrix or PCL5 printer can be added. The RS232 COM port is used to transmit all results to software running on a computer system.