AOAC964_07.pdf

4.9.01AOAC Official Method 964.07Microscopy of Animal FeedBasic Microscopic ExaminationFirst Action 1964Final Action 1965A. Apparatus(a) Magnifier-fluorescent illuminator with desk base, 3, orreading glass.(b) Microscopes and illuminator.Illuminators.Illuminatorfor this purpose should have: compactness and flexibility; trans-formerorresistortovarylightintensity;focusingadjustmenttogiveuniformly lighted field of view; blue-white color from coollow-voltage source.Microscopes.(1) Compound microscope.For mold countingandotherfilthanddecompositionwork,microscopeshouldhavefol-lowing minimum specifications: binocular body with inclined ocu-lars; 4 parfocal achromatic objectives of ca 4, 10, 20, and 40;revolving 4-place nosepiece; Abbe condenser with N.A. of 1.25; 10Huygenian or wide-field eyepieces; fine adjustment; mechanicalstate. (2) Widefield stereoscopic microscope recommended for filthexamination.Microscopeshouldhavefollowingminimumspecifi-cations: binocular body with inclined oculars; sliding or revolvingnosepiece to accommodate 3 objectives; 3 parfocal objectives 1, 3,and 6 or 7.5; paired 10and paired 15widefield oculars; mountedon base and capable of illumination by transmitted or reflected light.30is ordinarily usedfor routine examination of filter papers. Verifi-cation at higher magnification may be reqired. Following are pre-ferred: (a) Widefield stereoscopic microscope.With arm rests, flatstage (remove spring holders), optional substage illumination, in-clined eyepiece, and lenses to magnify ca 730, 15optimum. (b)Compound microscope.With mechanical stage, substage con-denser, inclined binocular eyepiece, 3 position rotating nosepiece,lensestomagnifyca36400,120optimum.(c)Microscopeillumi-nator.Withirisdiaphragm;movablestandholderwithrodtopermitadjusting light source as to height and angle for substage or directover-stagelighting;abletohold2blueglassfiltersoroneblueandoneground glass; 60100 watt bulb.(c) Sieves.Nest of 5 No. 10, 20, 40, 60, 80, and bottom pan.(d) Stages.Dark Co glass plates 4 4 (Fisher Scientific Co.No. 13-735); or blue paper and microscope slides.(e) Spot plates.Black and white.(f) Forceps.Finepointed,curved.Ifnecessary,bendandgrindon emery wheel for good contact of points.(g) Dropping bottles.Amber, 30 mL, as reagent dispensers.(h) Microspatula;microstirringrodsmadebydrawingoutglassrods; spoon.B. Reagents(a) Chloroform.Technical. Recover by filtration and distil-lation.(b) Acetone.Technical.(c) Acetone, dilute.Dilute 75 mL acetone with 25 mL H2O.(d) Dilute hydrochloric acid.Dilute 1 volume HCl with 1 vol-ume H2O.(e) Dilute sulfuric acid.Dilute 1 volume H2SO4with 1 volumeH2O.(f) Iodine solution.Dissolve 0.75 g KI and 0.1 g I2in 30 mLH2O and add 0.5 mL HCl. Store in amber dropping bottle.(g) Millon reagent.Dissolve, by gently warming, one part byweight Hg in 2 parts by weight HNO3. Dilute with 2 volumes H2O.Letmixturestandovernightanddecantsupernate.SolutioncontainsHg(NO3)2, HgNO3, HNO3, and some HNO2. Store inglass-stoppered bottle. (Caution: See Appendix B, safety notes onmercury salts.)(h) Molybdatesolution.Add100mL10%NH4NO3solutionto400mLmolybdatesolution,964.06A(a)(see4.8.13).Useonlyclearsupernate to fill 30 mL amber dropping bottle. Discard and refillwhen crystallization occurs.(i) MountantI.Dissolve10gchloralhydratein10mLH2Oandadd 10 mL glycerol. Store in amber dropping bottle.(j) MountantII.Dissolve160gchloralhydratein100mLH2Oand add 10 mL HCl.(k) Silver nitrate solution.10%. Dissolve 10 g AgNO3in100 mL H2O.C. Standards(a) Feed ingredients.Collect ingredients used in grain andstockfeedsknowntoconformtodefinitionsofAssociationofAmer-ican Feed Control Officials as standards. Store in 4 oz bottles. Tocontrol insects, add ca 1 mL CS2, and stopper. Become thoroughlyfamiliar with structural appearance of standards before and aftertreatment with organic solvents.(b) Weedseeds.Collectcommonweedseedsoccurringingrains.Mostmaybefoundinforeignmaterialobtainedaftersievingcommer-cial whole grains with U.S. Grain Testing Sieve having 5/64 (2.5 mm)triangularholes.Identifyfromillustrationin“IdentificationofCropandWeedSeeds”USDAHandbook219(1963),GovernmentPrintingOf-fice,Washington,DC20402.Storeinnumberedvials.Becomefamil-iar with those weed seeds designated as prohibited and restrictednoxious under state laws of individual concern. (See “State Nox-ious-Weed Seed Requirements Recognized in the Administration ofthe Federal Seed Act” USDA, Agricultural Marketing Service, GrainDivision, Hyattsville, MD 20782.)Reference: JAOAC 47, 504(1964). 2000 AOAC INTERNATIONAL食品伙伴网http:/