AOAC ERP MICRO AUGUST 2018

OMAMAN-44 A: Collaborative Study Manuscript Expert Review Panel Use Only August 2018

distilled (DI) or reverse osmosis (RO) water and adjust pH to 7.2 with 1 N NaOH and bring final volume to 122

1 liter with DI or RO water. Add 99 mL to dilution bottles and sterilize 15 min at 121°C. Store in 123

refrigerator. Or purchased, e.g. Weber Scientific, Hamilton, NJ item # 3127-14 or alternative 124

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manufacturer equivalent.

( b ) Buffered Peptone Water (BPW) .—Peptone 10 g, Sodium chloride 5 g, Disodium phosphate 3.5

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g, Mono-potassium Phosphate 1.5 g Distilled water 1 L. Add 99mL to dilution bottles and sterilize 15 min 127

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at 121°C. Store in refrigerator. Final pH 7.2 ± 0.2 .

( c ) Neutralizing Buffered Peptone Water ( n-BPW ).—buffered peptone 20.0 g, soy lecithin 7 g

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sodium thiosulfate 1 g, Microbiologically Suitable (MS) water 1 L, sodium bicarbonate 12.5g pH 7.7 ± 0.5 130

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at 25°C.

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Apparatus

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( a )

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1 mL pipet tips .

( b ) 1 mL pipettor .

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( c )

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37 ± 1°C incubator, depending on test matrix .

( d ) Light box for back illuminating and counting plates .

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( e ) Magnifying glass 2x or 4x for examining plates .

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( f )

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Stomacher- Seward 400 paddle type or equivalent ERP Use Only

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Safety Precautions

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( a ) Perform tests with clean washed and gloved hands assuming potential pathogenic bacteria.

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( b ) Microbiological cultures and reagents should be collected into biohazardous bags and

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