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Once the empty cell has been measured the specified number of times, the unit will prompt the user to add the standard(s) to the cell; the "SPHERE_10" standards are found in the wooden box shown in Figure 23. Open the pycnometer cell and place the standard ball(s) into the cell, then close securely. Clicking "Done" will trigger the above analytical steps, including purges, for the standard ball(s). After the replicate measurements on the steel ball(s) are done, the system will prompt the user to remove the standards from the cell. Pressing done at this point shows the expansion (red circle) and analytical cell (black circle) volumes determined by the calibration experiment as shown in Figure 24.

Figure 23. Six sets of steel balls are kept in this box along with the wire tool to extract them from the cells. Do not touch the spheres with bare fingers! Fingerprints don't significantly affect the volume measurement, but will cause the spheres to begin corroding. Wipe them thoroughly off with a Kim-Wipe if it is necessary to do so.



Figure 23. Final calibration screen for the pycnometer cell.

Click the "Accept" button (blue circle) to complete the calibration process for this cell. Once a cell's calibration is completed the pycnometer measurement on unknowns can be started independently of the other cells undergoing calibration.

Frequency of Calibration/Calibration Check Standards

The pycnometer has proven to be quite stable, so the standard practice is to calibrate the instrument at the beginning of an expedition. To ensure quality, each set of five samples should be accompanied by a standard rotated through the cells. So long as the standards continue to give an acceptable value (less than 0.5% deviation), recalibration is not necessary (NOTE: As of X375 the recommendation is to Calibrate the beginning of each shift, and then +/- 0.5% deviation).
Rotation of the check standards through the cells is important, however, to ensure on a continuing basis that the system is still stable and functioning properly. An example measurement plan is given here:

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After calibration is complete, the user can begin analyzing samples and one standard per six runs as noted above. Double-click on the Volume Dry (cm³) portion of the main screen next to the sample to be studied; normally the SPHERE_10 standards are also listed for the one cell in six to be dedicated for a standard measurement. A window will appear as shown in Figure 24 prompting the user to select a cell and to set the number of replicates. It is recommended to use the same number of replicates as the calibration.

Figure 24. Pycnometer measurement window.

Ensure that the sample is correct and select the cell to be used and the number of replicate measurements to be performed.
Once the user has selected the cell and number of cycles, click the "Measure" button, which will open the pycnometer cell control window (Figure 25). Place the sample in the cell, seal it, and then click "Done" followed by clicking the "Start" button (circled in blue). Unlike the calibration measurement, the experiment will not start until the "Start" button is clicked.

Figure 25. Starting a pycnometer measurement on a sample.

The pycnometer will step through the same purge and measurement steps described in the calibration section and when it is finished, will show the screen shown in Figure 26.

Figure 26. Sample completed indicator for pycnometer.

Once the "Done" button is clicked, the volume of the sample (including the volume of the container) will appear in the "Calculated Volume" window. At this point, the user may select "Rerun," which will redo the measurement, "Cancel" to reject the measurement, or "Accept" to keep the data and transfer it to the main screen.

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The result should be in the appropriate field, but in case the user double-clicked the wrong volume measurement, MADMax provides the capability to switch the volume measurement from "wet" to "dry" and vice-versa. As shown in Figure 27, right-click the mass cell and select the "Send this result to the Volume Wet (cm³)" option. If two volumes are already present, this option will instead state "Swap Volume Wet (cm³) to Volume Dry (cm³)."

Figure 27. Right-click options for the volume measurement.

Once the user clicks the "Swap" options, a window will pop up to confirm the action, similar to that for the swap mass measurements window.

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If the user wishes, they can also look at a detail of the mass results as shown in Figure 28. This is a summary of all of the parameters used to determine the volume with the parameters labeled by their database names.

Figure 28. Review dry volume results window.

The volume_dry component is the volume of the sample. The volume_dry_container component is the volume of the sample and the container together. The pyc_stdev value is calculated from the individual measurements (in this case, three) done by the pycnometer.

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Volume determination by caliper is best used on consolidated, high-porosity samples (e.g., coral or vesicular basalt) as part of Method D. It is not likely to give accurate results when used on soft sediments (Method A).
Double-click on the "Caliper Volume (cm³)" column in the field adjacent to the sample to be analyzed. This will invoke the caliper measurement window as shown in Figure 29. The user should select cube or cylinder depending on the sample to be measured with the precision caliper.

Figure 29. Caliper measurement entry screens.

Ensure that the sample being measured is the correct one and click either the "Cube" or "Cylinder" radio button. Make the measurements using the precision caliper (Figure 30). Enter the measurements for each dimension in centimeters. Once the measurements have been entered, click "Ok" and the result will be transferred to the main screen.

Figure 30. Digital caliper used for volume measurements.

Review Results

Right-clicking the caliper result will allow the user to select "Review Results" to see details of the measurement.

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The MADMax software will calculate all of the other MAD parameters once any three of four measurements are completed: wet mass, dry mass, dry volume, and wet volume. Once the three measurements related to the chosen method (e.g., Method C: wet mass, dry mass, dry volume) are completed, double-click on the "Methods Completed" field on the line of the sample in question. This will invoke the MAD calculation window as shown in Figure 31.

Figure 31. Run MAD Calc window. Ensure the proper sample is shown.

Click on the "Run MAD Calc" button and after a brief pause, the calculated parameters for the MAD analysis will appear on the main screen for that specific sample and will be updated in the LIMS database at the same time. See the "MAD Computations" section below for more information about the various parameters determined by the software.

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After the MAD calculation is run, the user may wish to clean up the main screen list of samples. This is done by clicking in the "Done" boxes as shown in Figure 32. Once the samples to be removed are checked, click the "Refresh Sample List" button and the checked samples will disappear. (Any new samples will also appear.)
Note: Until this step is completed, two (and rarely three) lines will appear in the LIMS reports. Once this step is completed, the extra lines will be canceled.

Figure 32. Using the "Done" check boxes to clean up completed samples.

Quality Assurance/Quality Control

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The user is encouraged to treat each group of five samples as an analytical batch and to carry a QC sample through the pycnometer process as the "sixth" sample. Thus, each pycnometer batch will consist of five samples and one calibration verification sample.
For the balance and caliper, the accuracy and precision of the equipment can easily be determined by measuring standards and confirming the system is giving proper numbers.

Precision and Accuracy

Each science party must define what error is acceptable for measurements, but the JRSO has some guidelines as to what can be expected.

Balance

For repeated mass measurements, we expect the data to be reproducible within 0.005 g; this will be significantly higher if the sea state is rough, the weights on the two balance pans are not roughly equal, or the number of measurements is too low. In other words, if the masses on the reference and unknown balances are within 5 grams of one another and the number of measurements is sufficient for the sea state, then we expect measurement of a reference mass to be within 0.005 grams.

Pycnometer

On dry samples or the steel ball bearings when the sample container is nearly full, we expect 1% or better precision between measurements. Reproducibility will go down severely if the sample container is not filled, and even more so if wet samples are measured. Accuracy is expected within 1% of the indicated volume if conditions are correct (dry sample, container nearly full).

Caliper

The precision caliper is capable of measurements accurate to 0.01 mm ± 0.01 mm. However, the source of error in this measurement is largely from the quality of the sample being measured. If the rectangular prism's sides are not end parallel to one another, or if the cylinder is not a right cylinder, the error can be significant.

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The Wheaton vials are borosilicate glass and somewhat resistant to breakage. If a vial breaks, the broken glass should be gathered up immediately and placed in a sharps container. Please see a technician or the ALO if this occurs for proper disposal instructions. Do NOT place sharp trash in the regular trash bins!

Pollution Prevention

The MAD method does not generate any hazardous waste.
Remaining samples are used for further analyses after oven-drying and volume determination.

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MAD computations are performed when triggered by the user as described above in "MAD Calculations." Each time computation is triggered, the program will recalculate the results and update the database. (This may be necessary, for example, if the wet and dry mass measurements were switched.) The computations are performed for each completed submethod using the following formulas.

LIMS Components and Definitions for MAD Analysis

CONTAINER Analysis: Sample Container

MAD_MASS Analysis: Mass Determination for MAD Analysis

CALIPER Analysis: Caliper Measurements for MAD Analysis

Analysis component	Definition	Unit	Explanation
volume	Sample volume	cm3	Sample volume calculated from length, width, and height or height and diameter, depending on geometry.
geometry	Sample geometry	—	Geometry used to calculate volume: rectangular prism or cylinder.
length	Sample length	cm	Length (x) of a rectangular prism sample; measure orthogonally to the other dimensions.
width	Sample width	cm	Width (y) of a rectangular prism sample; measure orthogonally to the other dimensions.
height	Sample height	cm	Height (z) of a rectangular prism or cylindrical sample.
diameter	Sample diameter	cm	Diameter of a cylindrical sample.
container_number	Container number	—	Number inscribed on the container and logged into the LIMS.
comment	Comment	—	Comment about caliper measurement.

PYC Analysis: Pycnometry for MAD Analysis

PYC_QAQC Analysis: Pycnometry Calibration

MAD Analysis: Computed Results for MAD Analysis