ASTM E640-78(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E640–78 (Reapproved 1998)
Standard Test Method for
Preservatives in Water-Containing Cosmetics
This standard is issued under the fixed designation E 640; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2.1.3 Candida albicans ATCC 10231.
4.2.1.4 Enterobacter aerogenes ATCC 13048.
1.1 This method covers the determination of the suitability
4.2.1.5 Aspergillus niger ATCC 16404.
of preservatives for use in cosmetic formulations. It sets
4.2.1.6 Penicillium levitum ATCC 10464.
minimal requirements for preservative performance in model
4.2.2 Spoilage microorganisms obtained from cosmetics
formulations.
shall be used in addition to the microorganisms described in
1.2 This standard does not purport to address all of the
4.2.1, if available.
safety concerns, if any, associated with its use. It is the
4.3 Culture Preparation—The microorganisms listed in
responsibility of the user of this standard to establish appro-
4.2.1 shall be maintained as follows:
priate safety and health practices and determine the applica-
4.3.1 Bacteria—Nutrient agar (BBL, Difco or equivalent).
bility of regulatory limitations prior to use.
4.3.2 Yeasts and Fungi—Mycophil agar, pH 4.7 (BBL or
2. Summary of Method equivalent).
4.3.3 Transfer monthly. Incubate bacteria at 32°C and fungi
2.1 This method involves a microbiological challenge test
and yeast at 25°C.
of preservatives incorporated into formulations at recom-
4.4 Media:
mended efficacy levels. Routine microbiological procedures
4.4.1 Nutrient Agar (BBL or equivalent).
are used to determine the antimicrobial activity of preserva-
4.4.2 Letheen Agar (Difco or equivalent).
tives in formulations. This method requires the knowledge of
4.4.3 Mycophil Agar, pH 4.7 (BBL or equivalent).
standard microbiological techniques.
4.4.4 Letheen Broth (Difco or equivalent).
3. Significance
5. Procedures
3.1 This method should be used to determine if a preserva-
5.1 Preparation of Challenge Inocula—Grow bacterial cul-
tive has application as a cosmetic preservative.
tures at 37°C for 18 to 24 h on slants of the appropriate solid
4. Materials
media. Grow yeast cultures at 25°C for 48 h. Grow fungal
cultures on the appropriate media at 25°C for 7 to 14 days or
4.1 Test Formulations—Formulations that the submitter
until full sporulation is achieved.
feels are appropriate for demonstration of preservative activity
5.1.1 Harvesting Bacterial Cultures—Using a sterile inocu-
shallbeincludedinthetest.Nonpreserved(control)samplesof
lating loop, transfer the growth from each culture into tubes of
these formulas shall also be included. Incompatibility of the
sterile distilled water. Adjust to an optical density of 0.45 in.
presevative with any of the formulations or formulation com-
⁄2-in. (12.7-mm) diameter optical quality test tubes using a
ponents shall be noted.
B&L Spectronic 20 Spectrophotometer (or equivalent) set at
4.2 Test Microorganisms (Minimal Panel):
425 nm. This should give approximately 1.0 3 10 bacteria/
4.2.1 Other test microorganisms shall be included where
mL.
appropriate and if standardized cultures from cosmetic isolates
5.1.2 Harvesting Yeast Cultures—Harvest and adjust yeast
become available. The primary function of these cultures is to
cultures as described in 5.1.1. This should give approximately
provide a common basis for comparison of different preserva-
1.0 3 10 yeasts/mL.
tives.
5.1.3 Harvesting Fungal Cultures and Dislodging Spores—
4.2.1.1 Pseudomonas aeruginosa ATCC 9027.
Harvest fungal cultures and dislodge spores by rubbing the
4.2.1.2 Staphylococcus aureus ATCC 6538.
growth gently with a sterile inoculating loop or removing it
with a sterile glass impinger. Filter through sterile nonabsor-
1 7
This method is under the jurisdiction ofASTM Committee E–35 on Pesticides
bentcotton.Harvestandadjustthesporelevelto1.0 3 10 /mL
and Alternative Control Agents and is the direct responsibility of Subcommittee
using a hemocytometer.
E35.15 on Antibacterial and Antiviral Agents.
5.1.4 Preparation of Inocula:
Current edition approved March 31, 1978. Published May 1978.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E640–78 (1998)
5.1.4.1 Mixed Culture Method: 5.4.3 Read plates at 72 h and calculate the number of
(1) Gram-Positive Bacteria and Yeasts—Mix equal por- surviving microorganisms per gram of test lotion. Verify the
tions of gram-positive bacteria and yeast thoroughly and label identity of the microorganisms by gram staining where appro-
“Gram-Positive Bacteria and Yeast #1.” priate.
(2)Gram-NegativeBacteria—Mix equal portions of gram- 5.5 Testing for Neutralization of Preservatives—The pres-
negative bacteria and label “Gram-Negative Bacteria #2.” ence of an active preservative carried over from the test
(3) Fungi—Mix equal parts of fungi suspensions thor- formulasintothemediamayinhibitviablemicroorganismsand
oughly and label “Fungi #3.” resultinfalsenegativereadings.Testforpreservativecarryover
5.1.4.2 Pure Culture Method—Optionally
...