QUALITY ASSURANCE WITH MICROTRACERS™ FS - ITEM OO

 
PRINCIPLES

Microtracers™ FS(colored uniformly sized stainless steel particles) are easily identifiable "harmless markers" used to assure the quality of animal feeds. When included in premixes, they serve as internal labels for critical micro-ingredients.

Completed feeds then contain both the micro-ingredients and the Microtracer™, and samples of completed feed or of the premix can be assayed for the Microtracer™ in less than a minute.

Microtracers™ allow confirmation of mixing adequacy as well as a ready answer to the question of whether or not a vitamin or medication was properly formulated in a feed. Stainless steel based Microtracers™ FS are similar to iron based Microtracers™ F. The principal advantage of Microtracers™ FS is improved stability in premixes containing dry choline chloride or other ingredients that may degrade Microtracers™ F.

Microtracers™ FS are separated magnetically from feed samples. The sample is not destroyed. Samples as large as 500 grams can be assayed, although 50-100 gram samples are more convenient for routine use.

SPECIFICATION

Microtracers FS consist of stainless steel particulates (principally iron and not more than 15% chromium, 95% passing 35 mesh but retained on 100 mesh), coated with one or more of several certified food colors stabilized with sodium carbonate. Colors include Blue, Red, Orange, Green, and various combinations. Each is distinguishable in the presence of the others; neither natural plant pigments nor colored additives interfere with the detection of Microtracers FS.

Microtracers FS withstand pelleting and generally remain stable in mash and pellets for six months or longer. These Microtracers are much more stable in premixes containing high concentrations of propylene glycol or choline hydrochloride. In all cases, Microtracers should be pre-tested to confirm stability in specific applications.


Microtracers FS contain 50,000 discrete particles per gram, subject to a coefficient of variation of 10%. Microtracers FS are designed to avoid loss to magnetic separators in feed mills, although in practice such magnets may remove 10 to 15%. Tracer recoveries average 80% of specification in mash feeds and 65% in pellets.

APPLICATIONS AND AMOUNT TO USE

1. Routine Quality Control of Finished Feeds.

Premixes should be formulated to yield not less than 3-1/2 grams of Microtracer FS per ton of finished feed at a cost of approximately 7 cents per ton. Detection by the MASON JAR procedure using a 65 gram sample (2-1/2 oz.) of finished feed will yield a theoretical count of 14 particles per assay.

One may use the Microtracer ROTARY DETECTOR to analyze as much as 500 grams of feed (17-1/2 oz.) in less than one minute. This procedure may be useful in detecting "feed carryover" or in certain instances it may permit the use of less Microtracer.

See Note 1. For Qualitative Control.
See Note 2. For Quantitative Control.

11. Mixer Efficiency.

Two different Microtracers FS formulated each at 35 grams per ton should be added at opposite ends of horizontal mixers. After mixing, 1/2-lb.samples should then be taken from the same locations where the Microtracers were added. Additional 1/2-lb. "grab" samples (8 to 12) may be taken from the discharge of the mixer as near the mixer in the production system as possible. Fifty or seventy-five gram sub-samples from each sample should then be analyzed by the ROTARY DETECTOR Demagnetizer Procedure outlined in Microtracer Literature Item I. Counts may be interpreted as outlined in Literature Item P,"The Use of Tracers To Determine Feed Uniformity".

111. Product Identification.

"Exclusive" Microtracer FS colors or color combinations may be available to code premixes and/or feeds as proprietary. Detection of these Microtracers may be as described in this paper, or it may require specific procedures provided by Micro Tracers, Inc.


DETECTION PROCEDURE - MASON JAR TECHNIQUE

A. Materials

1) A scale suitable for weighing 65 grams (24 oz) of feed.

2) Whatman# 1 filter paper, 7.0 cm. circles

3) For pelleted feeds: an osterizer or coffee mill such as the Model RCM Kitchen Aid.

4) A dropper bottle containing 70% ethanol

5) A pint mason jar

6) A special annular magnetic cap for the Mason jar

B . Method

1. Prepare pellets for assay by grinding them to a mash-like consistency.

2. Transfer 65 grams of completed feed (or a proportionately smaller sample of premix to the Mason jar

3. Insert filter paper into a magnetic cap and close the jar with the cap.

4. Shake jar so that all of sample has opportunity of touching the paper within the cap. Shaking, rolling and, inverting for one minute is generally sufficient.

5. Remove the cap; invert it with the paper uppermost and horizontal. Depress the paper at its center so that it hugs the magnet, and blow it free from non-magnetic debris if necessary. Transfer 10 drops of alcohol to the center of the paper so that the alcohol diffuses outward through the ring of entrapped iron particles. Dye will be stripped from the Microtracer to leave distinctive radiating streaks of color.

6. Remove the paper as soon as the alcohol has diffused completely. A small spatula or knife will serve to lift the edge of the paper so that it can be removed near horizontally. Dry the paper on a hot plate. Brush the paper clean. Observe the color for qualitative identification. Count the spots and/or streaks for statistical quantitative control.

Total Elapsed Time: Less than 2 minutes

Maximum Sample Size: 75 grams


DETECTION PROCEDURE - ROTARY DETECTOR TECHNIQUE

A. Materials

1) A scale suitable for weighing 65 to 500 grams

2) Whatman# 1 filter paper, 9.0 gm circles, with 3/16" hole at center

3) For pelleted feeds: an osterizer or coffee mill such as the Model KCM Kitchen Aid.

4) A dropper bottle containing 70% ethanol

5) A Microtracer Rotary Detector

B . Method

1. Prepare pellets for assay by grinding to a mash-like consistency.

2. Remove the top from detector by lifting it straight up.

3. Place a filter paper on the spindle of rotary magnet, then replace the detector top.

4. Turn on the Rotary Detector.

5. Transfer a sample of size sufficient to give a particle count no greater than 16. Slowly pour the sample into the top of the detector.

6. Turn off the power as soon as sample has passed through the detector. Remove the Top. Transfer 10 drops of alcohol to the center of the paper so that the alcohol diffuses outward through the ring of entrapped iron particles. The detector may be turned on for a moment to improve solvent dispersion, although speed must be limited to insure the magnet does not fly from the platen. Dye will be stripped from the Microtracer to leave distinctive radiating streaks of color.

7. Remove the paper as soon as alcohol has diffused completely, and place it on a cookie sheet on a hot plate to dry. Brush the paper clean. Observe color for qualitative identification. Count spots and/or streaks for statistical quantitative control.

Total Elapsed Time: Less than 2 minutes

Maximum Sample Size: 500 grams


NOTES

1. One assay of a finished feed sample yielding an average count of 9 particles will serve to answer the yes-no question "Is the specified premix present?” The chance of finding no Microtracer particles is less than two in one hundred tests. The chance of findings no Microtracer in two tests is less than four in 10,000 assays.

2. Analysis of 50-gram samples of finished feed containing 35
grams of Microtracer FS per ton (2,000-lbs.) using the ROTARY
DETECTOR-Demagnetizer Procedure will yield a theoretical count of
particles. This value will be subject to a standard deviation
equal to the square root of 96, or roughly 10. The count will thus
be defined +/- 20 % with 95% confidence. We note the "Recommended
Analytical Variation" for most drug analyses as specified by AAFCO
American Association of Feed Control Officials) is not less than
25% for most all drugs when tested in feeds.

*This derives from Poisson’s Rule. Please note Microtracer counts may vary +/- 10% from their specified count and that Microtracers may not behave identically to coded micr0-ingredients in feeds. In practice, Microtracer counts will indicate quantitatively the level of a coded micro-ingredient in feeds +/- 40% with 95% confidence if they are used with care.

May 1985