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1、16.4.04 AOAC Of fi cial Method 968.35 Filth and Ex tra ne ous Ma te rial in Pea nut But ter Sedimentation/Flotation Methods First Ac tion 1968 Fi nal Ac tion 1988 A. Prep a ra tion of Sam ple Examine individually at least 3, and preferably 6, jars. If jars contain 1 lb each, make 36 composites of 2
2、jars each so that composite sample will be ca 1 lb. Remove contents of each jar and mix thoroughly, preferably in evaporating dishes of convenient size, using heavy table fork or spatula. Peanut butter after warming may also be mixed in the jar by means of mixer, 945.75B(e) (see 16.1.01), equipped w
3、ith stiff paddles. If large number of jars is to be examined, make composite samples by thoroughly mixing contents of 36 jars of equal size. B. Wa ter-Insoluble In or ganic Res i due (“WIIR”) and Ex creta (Caution: See Appendix B, Distillation, Flammable Solvents, Toxic Solvents, Chloroform, Petrole
4、um Ether.) Weigh 100 g sample into 250 mL beaker (hooked-lip type), add ca 10 mL petroleum ether, and mix thoroughly. Continue to add petroleum ether, mixing thoroughly until ca 150 mL has been added. Cover, let settle 25 min, and decant 100 mL petroleum ether layer and floating light tissue without
5、 losing any coarse peanut tissue. Add ca 125 mL petroleum ether to residue and mix, let settle 15 min, and decant 100 mL as before. Repeat with third ca 125 mL addition petroleum ether, stir, wash down sides of beaker with stream of petroleum ether, let settle 10 min, and decant 100 mL. Discard all
6、decanted portions of petroleum ether. Evaporate remainder of petroleum ether from residue in beaker; gentle heat may be used. Add 150 mL CHCl3 to residue and mix thoroughly; cover beaker and let settle 20 min. Stir top layer several times during this period. Carefully decant CHCl3 and floating peanu
7、t tissue onto 15 cm paper in Bchner without disturbing heavy residue in bottom of beaker. Repeat extraction with small amounts of CHCl3, rinsing all particles from sides of beaker. At this point, watch for fragments of rodent excreta pellets on top of NaCl in bottom of beaker; do not decant them. (I
8、f sample contains considerable peanut skin, it may be necessary to use mixture of CHCl3 and just enough CCl4 to float skin particles away from heavy residue of NaCl, sand, etc.) Dry residue in air. Add 50 mL HCl (1 + 35) to residue in beaker; then add 90 mL boiling water and let stand 30 min with oc
9、casional stirring to dissolve any phosphate, carbonate, or anhydrite (CaSO4) included with the NaCl. Decant liquid through ashless filter in 60? glass funnel and finally transfer residue with hot water. Test filtrate for sulfate by adding 5 mL saturated BaCl2 solution. Wash residue on filter several
10、 times with hot water. If test for sulfate in filtrate was positive, test residue on filter by placing clean beaker or test tube under funnel and treating residue with 25 mL HCl (1 + 35), adding little at time. Test filtrate with 20 drops saturated BaCl2 solution (fine white ppt of BaSO4 indicates p
11、resence of anhydrite in residue on filter; allow 5 min for ppt to appear). Wash residue on filter with hot water until all HCl is removed. Examine residue microscopically for fragments of rodent excreta pellets (identified by presence of rodent hair fragments in mass), insect excreta pellets, and ot
12、her filth. Ignite paper in weighed crucible over medium Bunsen flame or in furnace at ca 500?C. Cool, and weigh crucible and contents to nearest 0.5 mg. If “WIIR” is excessive and application of above test indicates that all CaSO4 has not been removed, make quantitative determination of either Ca or
13、 sulfate in “WIIR” in crucible, as in 925.55(F) or (G) (see 11.2.01). Calculate this weight to CaSO4 and correct weight of “WIIR.” C. Rocks and De com posed Pea nuts (Caution: See Appendix B, Toxic Solvents, Carbon Tetrachloride.) Remove entire contents of jar to 1.5 L beaker or other suitable conta
14、iner. Add ca 700 mL CCl4 and mix thoroughly, using mixer, 945.75B(e) (see 16.1.01), if convenient. Rinse jar with CCl4 and add rinsings to beaker. Let mixture stand 15 min with occasional stirring. Decant ca 2/3 of mixture and add ca 200 mL CCl4. Let stand 5 min and decant. Wash down sides of beaker
15、 with CCl4 and repeat decantation until residue is free from peanut tissue. Save all decanted material. Dry residue in beaker and wash out salt with hot water. If large amount of sand is present, wash residue to remove, slat, phosphate, carbonate, and anhydrite as in B, 4th paragraph. Transfer resid
16、ue to ashless filter paper and examine under low-power microscope. Report number and approximate size of rocks and other extraneous material. If much sand is present, ignite filter and weigh residue, including rocks, reporting result in mg/100 g peanut butter. Pour decanted CCl4peanut mixture throug
17、h No. 14 sieve and examine residue for gross filth, stems, other extraneous material, and decomposed peanut tissue. D. Glass (Pro ce dure) Take precautions to avoid picking up glass particles when removing contents from glass container and during analysis. Use only stainless steel, Al, plastic, or o
18、ther nonglass laboratory ware. Filter reagents. Loosen jar tops and warm jars of peanut butter several hours at ca 50?C in oven. Add 10 g household detergent powder, such as alkyl aryl sulfonate, to 2 L ca 70?C water. Mix thoroughly and filter through folded filter into 34 L stainless steel beaker.
19、Place beaker in ca 70?C water bath and set beaker with bath under paddle-type stirrer, 945.75B(e) (see 16.1.01). While stirring detergent solution, add entire contents of 12 oz jars, or composite contents of two 6-oz jars, or subdivided 12 oz sample portions of larger containers. Rinse jar and top p
20、ortionwise with ca 100 mL kerosene and finally with detergent water, and washings to mixture. Continue stirring ca 3 min. Stop stirrer, scrape bottom and sides of beaker with metal spatula, and manually mix any residual peanut butter. Replace paddle and stir again ca 3 min until peanut material is c
21、ompletely dispersed. Stop stirrer, rinse paddle blades over beaker with water, and promptly begin decantation procedure. In decanting, let mixture settle full 15 s each time after beaker is refilled with 5570?C water, with beaker in upright position, or leaning up to 45?. Pour off smoothly, after in
22、dicated standing period, 80% of beaker contents. Repeat as necessary until coarser particulate matter in small amount of clear water is left. Carefully pour off as much of this clear water as possible; still leaving particulate matter in beaker. Thoroughly rinse down sides of beaker with alcohol fro
23、m plastic wash bottle, and continue decantations after standing 15 s as above, finally pouring off all possible alcohol without losing particles. Rinse sides of beaker with ca 250 mL 2006 AOAC IN TER NA TIONAL CHCl3. If plant particles tend to aggregate, add more alcohol down sides of beaker until p
24、articles are freely mobile. After 20 s standing, decant, agitating plant particles to free any mech. entrapped glass. Be careful that glass from beaker pocket is not picked up by plant material as it sweeps forward from “back” side of beaker during decantation. Remove as much plant material as pract
25、ical by CHCl3 decantations, after 20 s standing with preceding precautions. Transfer beaker contents to filter paper (preferably black) on Bchner. Invert beaker over filter and scrupulously rinse sides and bottom of beaker with jet streams of alcohol and warm water alternately from plastic wash bott
26、les. Examine microscopically at 30X for glass particles, using only water as moistening agent. Light Filth First Ac tion 1968 E. Re agent De ter gent so lu tion.Dis solve sep a rately 20 g USP so dium lauryl sul fate and 10 g tech ni cal Na2B4O7?10H2O in H2O, com bine, and di lute to 1 L. F. Determi
27、nation Weigh 100 g test por tion into 1.5 L beaker and heat on steam bath un til soft ened. Add 1 L fil tered hot de ter gent so lu tion, and stir well. Heat 10 min in steam bath. Stir well, decant onto No. 230 sieve, 945.75B(r) (see 16.1.01), and wash with forc ible stream of 5570?C tap water, us i
28、ng aer a tor, 945.75B(a) (see 16.1.01). When foam is gone, trans fer ma te rial on sieve to 2 L trap flask, 945.75B(h)(4) (see 16.1.01), with 55% al co hol (or 40% isopropanol) and bring vol ume to 1 L. Add 50 mL HCl. Lower mag netic stir ring bar into flask on stir ring rod stop per. Heat to bp and
29、 boil 10 min while slowly stir ring on mag netic stir ring hot plate, 945.75B(n) (see 16.1.01). Trans fer flask to un heated stir ring unit and im me di ately add 40 mL min eral oil, 945.75C(p) (see 16.1.01), by pour ing down stir ring rod. Stir mag net i cally 2 min. Fill with deaerated 55% al co h
30、ol (or 40% isopropanol) and gently stir 510 s with stoppered rod. Let stand 5 min. Trap off. Add 25 mL min eral oil, stir by hand gently 30 s, and let stand 5 min. Re peat trap ping. Wash flask neck thor oughly with isopropanol. Fil ter onto ruled pa per and ex am ine mi cro scop i cally. Ref er ence: JAOAC 51, 531 (1968) 2006 AOAC IN TER NA TIONAL