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What can cause HIGHER than expected Dietary Fiber results?
What can cause HIGHER 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 (TDF52) during the weighing process.
Moisture control: Moisture Stop desiccant pouches (X45) should be used to minimize the effect of moisture on the weighing process. Verify that the desiccant pouches are in good condition (no holes and the zipper is functioning) and the packets within the desiccant pouches are still working (they should be a blue color).
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 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 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 TDF Operator's Manual (IDF/SDF Analysis section) for performing the acetone rinses.
Sample size: Using sample sizes larger than the recommended size of 0.5 (+/- 0.05g) can cause higher results.
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.
Enzyme delivery: View the enzyme containers while the enzymes are being delivered. The fluid level should go down. If the enzymes are not being delivered properly, contact ANKOM at [email protected].
Temperature control: To verify that the temperature is being properly controlled, follow the procedure detailed in the TDF Operator's Manual (QC / Calibration section).
Mixing: To verify that the mixing is being properly controlled, follow the procedure detailed in the TDF Operator's Manual (QC / Calibration section).
Sample with bound fat: It is possible you have a sample which has been highly processed and has bound the fat to the extent the fat is not available to the solvent before the TDF process. In this case, after running the TDF instrument, remove the bags, place them on the rinse stand and perform the 2 standard acetone rinses. Immediately after the rinses (no air drying) remove the bags from the stand and soak the filters in fresh pet ether for 10 minutes. Place the bags back on the rinse stand and immediately perform 2 pet ether rinses (just like the acetone rinses). When the solvent has evaporated, seal the bags and dry them normally.
What can cause LOWER than expected Dietary Fiber results?
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 (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 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 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. 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.
Nitrogen - what are the specifications?
Nitrogen - what are the specifications?
Do NOT run this instrument without an adequate DRY Nitrogen Supply. The instrument is powered by pneumatics that are not compatible with moisture, commonly found in compressed air. Nitrogen is also recommended as an extra precaution when handling ethanol. For these reasons Compressed Air is NOT recommended.
Nitrogen Amount
A typical TDF run requires approx. 1400L (50cu.ft.) nitrogen gas. The nitrogen supply should be 6.9 bar (100 psi). During the run, the nitrogen is used to operate pressure cylinders and also to facilitate bag filtering. During the filtering stage, the nitrogen is regulated to .3 bar (4 psi) and flow rate is approx. 15L/min (.5cu.ft.).
Nitrogen Purity
A key issue associated with the gas used in the TDF instrument is moisture content. The TDF instrument can suffer damage if moisture is introduced through the gas line. ANKOM recommends the use of nitrogen with a 99.998% purity rating. Theoretically, less pure nitrogen should work if the impurities do NOT include moisture.
Nitrogen Source
We recommend the nitrogen source be at 80-100 psi regulated back to 50 psi at the high-pressure regulator. During rinses and filtration, the ANKOMTDF instrument uses at most 20 liters/minute. This is for a short duration. For most of the length of an assay nitrogen is used only for actuating the pneumatic pistons. We do not recommend or sell a specific nitrogen generator. However, one can be used if it meets the specifications noted in this FAQ.
How much bench space does the ANKOM TDF Dietary Fiber Analyzer require and how much does it weigh?
How much bench space does the ANKOM TDF Dietary Fiber Analyzer require and how much does it weigh?
For shipment, some parts are removed and the dimensions are: 107 cm long (42") x 51 cm deep (20") x 76 cm high (30").
The TDF instrument alone weighs about 56 Kgs (123 lbs). With the attachments and other spare parts the weight is about 60 kgs (132 lbs). A rinse stand adds 1.8 kgs (4 lbs) to the shipping weight. Including the pallet & box, when the order includes a rinse stand, the total weight for shipping purposes is 85 kgs (186 lbs).
I am getting high TDF results even after doing the de-fat procedure. How can I correct this?
I am getting high TDF results even after doing the de-fat procedure. How can I correct this?
- During the de-fat procedure, do two 10 minute soaks in petroleum ether. This is particularly helpful with high fat (> than 20%) samples.
- It is possible you have a sample which has been highly processed and has bound the fat to the extent the fat is not available to the solvent before the TDF process. In this case, after running the TDF instrument, remove the bags, place them on the rinse stand and perform the 2 standard acetone rinses. Immediately after the rinses (no air drying) remove the bags from the stand and soak the filters in fresh pet ether for 10 minutes. Place the bags back on the rinse stand and immediately perform 2 pet ether rinses (just like the acetone rinses). When the solvent has evaporated, seal the bags and dry them normally.