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Veri-Fry® Tests In Spectrophotometer

Instructions For Using The Veri-Fry^® Tests In The Spectrophotometer

Please read carefully first before performing the test (Handle hot oil with care!)

VERI-FRY^® Supplies from Test Kit Technologies (TKT) 

• VERI FRY^® reagent gel vial 

• Oil Ladle or other transfer device (dropper pipet) 

• Disposable Syringes & high speed oil Filter Disks 

• Spectrophotometer (Turner SP-830 or comparable instrument suitable for VERI-FRY^® vial) 

• Warming Block & Heater (or comparable bath) set at 65°C (150°F) 

• VERI-FRY^® "Blank" (clear liquid) vial

PROCEDURE FOR THE VERI-FRY^® TESTS:

1. Turn the power on, and allow the SPECTROPHOTOMETER to warn up for at least 20 minutes. The display shows (□□□□). Turn on the WARMER so that the BLOCK reaches 65°C (150°F).

2. Unscrew the cap from a VERI FRY^® reagent gel Vial, and place the vial in the WARMER'S BLOCK to reach 65°C (150°F) until the vial shows a clear, colored, transparent reagent gel liquid.

3. Record the Test type, BLOCK temperature, SPECTROPHOTOMETER wavelength, and date/time on a worksheet.

4. Carefully take about 50 mL (2oz.) of warm oil from the fryer and place into a clean container. Use care not to spill or get burned by the oil. Bring the container of oil to the measurement area.

5. If the oil is crystal clear and without interfering particles or sludge, use the OIL LADLE (or dropper pipet) to transfer an aliquot of the oil from the container into the vial. Fill the vial to the molded-in fill line, so the meniscus (the round edge between the oil and the vial wall) of the oil "sits on" the fill line, or... If the oil is cloudy (contains particles or sludge that may interfere with the analysis), use a SYRINGE to draw up a sample of warm oil. (Oil should be free of fat crystals and hot enough to filter. As a rule, filtration is required.) Attach a high-speed TKT oil FILTER DISK to the syringe tip.

6. Filter the sample of warm oil carefully from the SYRINGE directly through the oil FILTER DISK into the reagent gel vial. Add enough oil so that the meniscus "sits on" the fill line of the vial.

7. Screw the cap tightly onto the vial. Shake the melted reagent gel and the oil sample vigorously to ensure complete mixing of the oil with the liquefied gel. Reheat the vial in the WARMER if the gel does not stay completely liquid and clear from the oil.

8. Allow the capped vial to stand for a few minutes in the BLOCK set at 65°C (150°F). The TPM reagent gel mixes completely with the oil. The WET and FFA reagent gels only suspend in the oil. For WET and FFA tests, a bottom layer of gel reforms and separates cleanly from the oil. In abused, or surfactant contaminated oils, an emulsion may form between the lower reagent gel liquid and the upper oil layer. If this happens, and the bottom layer does not cleanly separated in the warming bath, remix, and tap the vial to push the emulsion upward to clear the lower layer until it becomes transparent and can be evaluated in the spectrophotometer.

9. Be sure the lower liquid layer in the vial is completely clear without fat crystals or suspended matter. Agitate and re warm the vial if necessary. Allow the lower layer to again separate distinctly and become transparent. Total clarity in the lower, colored, testing area is critical for accuracy. (Special circumstances may require centrifugation or other clarification of the sampled oil before testing with the VERI-FRY^® vials - please call TKT for technical support).

10. Place the VERI-FRY® "BLANK" (clear liquid) vial in the cuvette holder in the sample compartment of the spectrophotometer, with the molded-in arrow on the VERI-FRY^® vial facing the arrow in the cell compartment or the operator. (Never heat the BLANK vial.)

11. Make sure the wavelength dial in front of the cell holder is set at 610 nm to perform the FFA-75, FFA-350, and WET tests. The stray light filter wheel (inside the sample compartment of a Turner-830) should be set at the #3 position. For the TPM test only, set the wavelength to 590 nm and the stray light filter to the #3 position. (Some spectrophotometers/colorimeters automatically change.)

12. Close, or adapt the spectrophotometer/colorimeter sample compartment lid to create a dark compartment. Make sure any sample sensing micro-switch is engaged (automatic on Turner SP-830).

13. Make sure the Absorbance mode is selected, or press the TRANS/ABS button. The ABS light will be illuminated under the display on the Turner SP-830.

14. Insert the colorless BLANK vial with molded-in arrow oriented as above, and zero instrument by pressing the 100% T/OA button. The display will show 0.000 when the absorbance mode has been correctly selected. Remove the colorless BLANK vial.

15. Immediately insert the warm (65°C = 150°F) VERI-FRY^® vial containing the sample to be analyzed into the sample compartment. The vial should be placed with the molded in arrow on the VERI-FRY^® vial facing the arrow in the sample compartment, or the operator.

16. Quickly close the sample compartment door. The absorbance of the sample solution is shown on the display. This absorbance value should not drift more than ±0.0005 if the power to the SPECTROPHOTOMETER is "noise free".

17. Record the absorbance value and remove the vial containing the sample.

18. Repeat Steps 15-17 for more samples that are to be tested with the VERI FRY^® test using the same wavelength. Multiple samples in the WARMER can be processed very quickly in this manner. If the power to the SPECTROPHOTOMETER is noise free, multiple tests can be performed without recalibration for drift with the BLANK vial. In the worst electrical supply case, determine the BLANK and sample values rapidly, and repeat use of the BLANK vial before evaluating each sample.

19. Read the concentration for the analyte from either the supplied calibration curve or your own calibration curve. Test Kit Technologies CHARTS are provided for the FFA 75, FFA 350, and WET tests. A custom curve must be produced in a laboratory for the TPM test to account for the interferences that can be encountered with that test. This is available from TKT for a nominal fee.

20. To make your own calibration curves, use oils containing known quantities of fatty acid or "soap". TKT supplies VERI-FRY^® STANDARDS (sets of five pre-made solutions) to help perform calibration on-site to counter unusual circumstances, or to have the most accurate values for research or Quality Assurance. For ordering, or help see www.libralabs.com (products menu). 

Version: 04Dec2003