What can cause LOWER than expected Dietary Fiber results?
Static electricity during the weighting process: The largest contributor to poor results is the effect of static electricity on the weighing process. Because plastic gloves can contribute to static electricity, only use anti-static gloves. To eliminate static electricity while the bag is being weighed, you MUST use the Bag Weigh Holder (Part #: TDF52) during the weighing process.
Sample sticking to the IDF Flow-thru bags: When running a TDF assay, particles can stick to the IDF Flow-thru bag and not get rinsed down into the SDF filter. The weight of the sample stuck to the IDF Flow-thru bag is not accounted for in the TDF calculation. To avoid this problem, after the digestion processes are complete, use 78% EtOH to manually rinse any sticky particles down from the IDF Flow-thru bag into the SDF bag. If necessary, a laboratory spatula can be used to help loosen particles that are stuck to the bag.
BLANK values: BLANK values are used in the IDF, SDF, and TDF calculations. If you're not using the BLANK values provided by ANKOM, try using them in your calculation.
Chemicals: Because the MES-TRIS buffer can degrade in performance due to bacteria growth, making this solution daily is important. Clean all containers daily and refill them with fresh solutions. Make sure that each container is securely connected to the appropriate supply tube on the instrument.
Protein and Ash Determinations: Because protein and ash values are part of the IDF, SDF, and TDF calculations, verify that your protein and ash systems are working properly and providing the expected results.
Protein and Ash preparation: See the procedures detailed in the TDF Operator's Manual (Protein and Ash Determination sections) for preparing the bags for protein and ash.
Drying: Bags must be dried at 105°C to constant weight (90 minutes).
Acetone rinses: See the procedure detailed in the (IDF/SDF Analysis section) for performing the acetone rinses in the TDF Operator's Manual.
Sample loss: If any sample is spilled or left in a weigh tin during transfer to the IDF bag, the assay will produce lower values.
Filtrate transfer from IDF to SDF bag: If any liquid does not quantitatively transfer from the IDF bag to the SDF bag, SDF results will be low. Make sure that the bottom of the IDF bags remain inside the top of the SDF bags during the IDF filter process.
Diatomaceous Earth (DE) loss: If any DE is spilled or left in a weigh tin during transfer to the SDF bag, the assay will produce lower values.
Digestion times: For demonstration and diagnostic purposes, you can set the digestion times to non-standard values through the Touch Screen Display. Results will be inaccurate if the instrument is run using non-standard digestion times.
Technician variability: Confirm that all technicians are following the procedures detailed in the TDF Operator's Manual to avoid any variation in results associated with different operators.
pH: Typically, the pH reading should be between 3.5 and 6 before correction. If the pH reading is outside of these values check the acid and buffer solutions, and check that tubing is connected to the proper containers.