This is a work product of the National Organic Standards Board (NOSB). It does not represent official 

National Organic Program (NOP) positions or policy.

National Organic Standards Board

Livestock Subcommittee

Petitioned Material Proposal

Required Synthetic Amino Acids for Pet Foods

February 5, 2013

Summary of Proposed Action:

Thirteen synthetic amino acids were petitioned for use in organic pet foods. The 

Subcommittee evaluated the petition and 2012 technical report (TR), and had 

discussions with State Feed Control Officials. Based on this information, the 

Subcommittee concluded that only Taurine for cats was deemed necessary as a 

synthetic additive to meet nutritional requirements and thus should be allowed in 

organic pet food. The Subcommittee determined that the manufacturers could meet 

the required levels of Arginine, DL-Methionine, Cysteine, L-Lysine, Tryptophan, 

Threonine, Histidine, Isoleucine, Leucine, Phenylalanine, Tyrosine, and Valine to meet 

the criteria for “complete and balanced” as required by American Association of Feed 

Control Officials (AAFCO) with organic agricultural ingredients.

Evaluation Criteria 

(Applicability noted for each category; Documentation attached) Criteria 

Satisfied? 

Impact on Humans and Environment ☒ Yes ☐ No ☐ N/A 

1. Essential & Availability Criteria ☒ Yes ☐ No ☐ N/A

2. Compatibility & Consistency ☒ Yes ☐ No ☐ N/A

3. Commercial Supply is Fragile or Potentially Unavailable ☐ Yes ☐ No 

☒ N/A as Organic (only for § 205.606)

Substance Fails Criteria Category: [ ] Comments:

Proposed Annotation (if any): 205.603(d)(4) Taurine (CAS 107-35-7) for use in cat 

food only

Basis for annotation: ☒ To meet criteria above ☐ Other regulatory criteria ☐

Citation 

Notes: The other 12 petitioned Amino Acids failed to meet the necessity criteria as 

manufacturers should be able to meet the required AAFCO levels through use of 

organic agricultural ingredients.

Recommended Committee Action & Vote, including classification recommendation 

(state actual motion):

Classification Motion: Motion to classify amino acids (Arginine, Methionine, 

Cystine, Lysine, Taurine, Tryptophan, Threonine, Histidine, Isoleucine, Leucine, 

Phenylalanine, Tyrosine, and Valine) as synthetic. 
Motion by: Mac Stone Seconded by: Jean Richardson

Yes: # 9 No: # 0 Absent: # 0 Abstain: # 0 Recuse: # 0

Listing Motion: Motion to list amino acids (Arginine, Methionine, Cystine, Lysine,

Tryptophan, Threonine, Histidine, Isoleucine, Leucine, Phenylalanine, Tyrosine, 

and Valine) on section 205.603 for use in organic pet food.

Motion by: Mac Stone Seconded by: Colehour Bondera

Yes: # 0 No: # 9 Absent: # 0 Abstain: # 0 Recuse: # 0

Listing Motion: Motion to list taurine CAS (107-35-7) at 205.603(d), as a feed 

additive, for use in cat food only

Motion by: Mac Stone Seconded by: Jean Richardson

Yes: # 8 No: # 0 Absent: # 0 Abstain: # 1 Recuse: # 0

Crops ☐ Agricultural ☐ Allowed1 ☒

Livestock ☒ Non-synthetic ☐ Prohibited2 ☐

Handling ☐ Synthetic ☒ Rejected3 ☐

No restriction ☐ Commercial unavailable as 

organic

☐ Deferred4 ☐

1

Substance voted to be added as “allowed” on National List to § 205.603 with 

Annotation (if any): Taurine (CAS 107-35-7) on 206.603(d)(4) for use in cat food 

only

2

Substance to be added as “prohibited” on National List to § 205. with Annotation 

(if any): 

Describe why a prohibited substance: 

3

Substance was rejected by vote for amending National List to § 205.603 . 

Describe why material was rejected: NOTE: 12 petitioned amino acids were

rejected for lack of necessity to formulate complete and balanced feeds for cats 

and dogs. The Subcommittee determined that manufacturers should be able to 

meet the AAFCO required levels through use of agricultural ingredients. 

4

Substance was recommended to be deferred because 

 

Approved by Subcommittee Chair to Transmit to NOSB

Tracy Favre February 5, 2013

NOSB Evaluation Criteria for Substances Added To the National List
Category 1. Adverse impacts on humans or the environment?

Substance: Amino Acids for Pet Food

Question Yes No N/A1 Documentation (TAP; petition; 

regulatory agency; other)

1. Are there adverse effects on 

environment from manufacture, use, or 

disposal?

[§205.600 b.2]

x

2. Is there environmental contamination 

during manufacture, use, misuse, or 

disposal? [§6518 m.3]

x

3. Is the substance harmful to the 

environment and biodiversity?

[§6517c(1)(A)(i);6517(c)(2)(A)i] 

x

4. Does the substance contain List 1, 2 

or 3 inerts? [§6517 c (1)(B)(ii); 

205.601(m)2]

x

5. Is there potential for detrimental 

chemical interaction with other 

materials used?

[§6518 m.1]

x

6. Are there adverse biological and 

chemical interactions in agroecosystem? [§6518 m.5]

x

7. Are there detrimental physiological 

effects on soil organisms, crops, or 

livestock? [§6518 m.5]

x

8. Is there a toxic or other adverse action 

of the material or its breakdown 

products?

[§6518 m.2]

x

9. Is there undesirable persistence or 

concentration of the material or 

breakdown products in environment?

[§6518 m.2]

x

10. Are there any harmful effects on 

human health? [§6517 c (1)(A)(i); 6517 

c(2)(A)i; §6518 m.4]

x

11. Is there an adverse effect on human 

health as defined by applicable 

Federal regulations? [205.600 b.3]

x

12. Is the substance GRAS when used 

according to FDA’s good 

manufacturing practices? [§205.600 

b.5]

x

13. Does the substance contain residues 

of heavy metals or other contaminants 

in excess of FDA tolerances? 

[§205.600 b.5]

x

1

If the substance under review is for crops or livestock production, all of the questions 

from 205.600 (b) are N/A—not applicable.
NOSB Evaluation Criteria for Substances Added To the National List

Category 2. Is the Substance Essential for Organic Production?

Substance: Amino Acids for Pet Food

Question Yes No N/A1 Documentation (TAP; 

petition; regulatory agency; 

other)

1. Is the substance formulated 

or manufactured by a 

chemical process? [6502 

(21)]

x

2. Is the substance formulated 

or manufactured by a 

process that chemically 

changes a substance 

extracted from naturally 

occurring plant, animal, or 

mineral, sources? 

[6502 (21)]

x

3. Is the substance created by 

naturally occurring biological 

processes? [6502 (21)]

x

4. Is there a natural source of 

the substance? [§205.600 

b.1]

X The petition states the plant 

and animal sources of each AA.

5. Is there an organic 

substitute? [§205.600 b.1]

x From the listed sources of AA 

in the petition, some of these 

agricultural ingredients may be 

organic. 

6. Is the substance essential for 

handling of organically 

produced agricultural 

products? [§205.600 b.6]

X 

Taurine

Arginine, DLMethionine, 

Cysteine, LLysine, 

Tryptophan, 

Threonine, 

Histidine, 

Isoleucine, 

Leucine, 

Phenylalanine, 

Tyrosine, 

Valine

From the TR and petition and 

discussions with Feed Control 

Officials, only Taurine was 

determined absolutely 

necessary for cats, for diet 

formulators to meet AAFCO 

guidelines. The other twelve 

amino acids can be provided 

through use of agricultural 

ingredients. 

7. Is there a wholly natural 

substitute product?

[§6517 c (1)(A)(ii)]

X Not for taurine The TR indicates that natural 

forms of taurine are less 

available in agricultural 

products and degraded during 

commercial processing to the 

point the nutritional 
requirements of cats cannot be 

maintained.

8. Is the substance used in 

handling, not synthetic, but 

not organically produced?

[§6517 c (1)(B)(iii)]

x

9. Is there any alternative 

substances? 

[§6518 m.6]

Yes for 

other 

amino 

acids

Not for taurine The petition and TR indicate 

the non-synthetic forms of 

taurine from any source are 

degraded during processing

moreso than the other AA.

10. Is there another practice that 

would make the substance 

unnecessary? [§6518 m.6]

Yes for 

other 

amino 

acids

Not for taurine The TR describes how raw food 

diets of organ meats, bone, fat, 

and meat are a substitute, with 

risk to nutritional imbalance and 

bacterial contamination

1

If the substance under review is for crops or livestock production, all of the questions 

from 205.600 (b) are N/A—not applicable.

NOSB Evaluation Criteria for Substances Added To the National List

Category 3. Is the substance compatible with organic production practices? 

Substance: Amino Acids for Pet Food

Question Yes No N/A1 Documentation (TAP; petition; 

regulatory agency; other)

1. Is the substance compatible with 

organic handling? [§205.600 b.2]

X -

Taurine 

only

Synthetic vitamins and minerals are 

allowed in organic foods and 

livestock feeds to maintain the 

nutritional quality.

205.603(d)(2)(3)

2. Is the substance consistent with 

organic farming and handling? 

[§6517 c (1)(A)(iii); 6517 c (2)(A)(ii)]

X -

Taurine 

only

The petition describes which 

organic agricultural products and 

by-products are used in the 

production of pet foods. Taurine is 

not readily available in these 

products. Providing optimum 

nutrition to animals under our care 

is a tenant of organic farming.

3. Is the substance compatible with a 

system of sustainable agriculture? 

[§6518 m.7]

x

4. Is the nutritional quality of the food 

maintained with the substance? 

[§205.600 b.3]

X –

Taurine

Consultation with AAFCO officials 

confirm our ingredient panel 

surveys that to meet the nutritional 

requirements for cats can only be 

accomplished with synthetic form 

supplementation.

5. Is the primary use as a x
preservative? [§205.600 b.4]

6. Is the primary use to recreate or 

improve flavors, colors, textures, or 

nutritive values lost in processing 

(except when required by law, e.g., 

vitamin D in milk)? [205.600 b.4]

X

Taurine

Due to the degradation during heat 

processing and preservation 

required for pet food manufacture 

as stated in the petition and TR.

7. Is the substance used in production, 

and does it contain an active 

synthetic ingredient in the following 

categories:

a. copper and sulfur compounds;

x Numerous synthetic amino acids 

are added during processing of 

commercial pet foods is common in 

the manufacture of pet foods as 

stated in the petition and TR.

b. toxins derived from bacteria; x

c. pheromones, soaps, horticultural 

oils, fish emulsions, treated 

seed, vitamins and minerals?

x

d. livestock parasiticides and 

medicines?

x

e. production aids including netting, 

tree wraps and seals, insect 

traps, sticky barriers, row 

covers, and equipment 

cleaners?

x

1

If the substance under review is for crops or livestock production, all of the questions 

from 205.600 (b) are N/A—not applicable.

NOSB Evaluation Criteria for Substances Added To the National List

Category 4. Is the commercial supply of an agricultural substance as organic, 

fragile or potentially unavailable? [§6610, 6518, 6519, 205.2, 205.105 (d), 205.600 

(c) 205.2, 205.105 (d), 205.600 (c)] Substance: Amino Acids in Pet Food

Question Yes No N/A1 Documentation (TAP; petition; 

regulatory agency; other)

1. Is the comparative description 

provided as to why the non-organic 

form of the material /substance is 

necessary for use in organic 

handling? 

X

2. Does the current and historical 

industry information, research, or 

evidence provided explain how or 

why the material /substance cannot 

be obtained organically in the 

appropriate form to fulfill an essential 

function in a system of organic 

handling? 

X

3. Does the current and historical 

industry information, research, or 

evidence provided explain how or 

X
why the material /substance cannot 

be obtained organically in the 

appropriate quality to fulfill an 

essential function in a system of 

organic handling? 

4. Does the current and historical 

industry information, research, or 

evidence provided explain how or 

why the material /substance cannot 

be obtained organically in the 

appropriate quantity to fulfill an 

essential function in a system of 

organic handling?

X

5. Does the industry information 

provided on material / substance 

non-availability as organic, include ( 

but not limited to) the following:

a. Regions of production (including 

factors such as climate and 

number of regions);

X

b. Number of suppliers and amount 

produced;

X

c. Current and historical supplies 

related to weather events such as 

hurricanes, floods, and droughts 

that may temporarily halt 

production or destroy crops or 

supplies; 

X

d. Trade-related issues such as 

evidence of hoarding, war, trade 

barriers, or civil unrest that may 

temporarily restrict supplies; or

X

e. Are there other issues which may 

present a challenge to a 

consistent supply?

X

1

If the substance under review is for crops or livestock production, all of the questions 

from 205.600 (b) are N/A—not applicable.
National Organics Standard Board

Livestock Subcommittee

Proposal: Required Synthetic Amino Acids for Pet Foods

February 5, 2013

Introduction

The growth of the organic food sector extends into the pet food market. Consumers 

are looking for organic alternatives for their pets because they understand the strict 

policies behind the organic seal and it corresponds with their values in terms of no 

Genetically Modified Organisms (GMOs), transparent sourcing of ingredients, and 

lessened environmental impact of production. Certifiers currently certify pet food 

products by following relevant sections of the USDA organic regulations as it pertains 

to livestock feed, processed products, and associated labeling requirements. Specific 

organic pet food standards are not currently part of these regulations; however, the 

National Organic Program (NOP) is currently drafting a Proposed Rule to regulate 

organic pet food based on the 2008 NOSB recommendation.

In some cases, synthetic amino acids, like vitamins and minerals, have been allowed 

for organic pet food, if required by the U.S. Food and Drug Administration. However, 

the NOP recently reviewed the allowance for nutrients, including amino acids, for use 

in organic processed products such as organic pet food, and determined that the 

NOSB should review these nutrients through the petition process. Therefore, the Pet 

Food Institute has petitioned the NOSB to place the 13 essential synthetic amino acids 

for dogs and cats on the National List. Sourcing organic ingredients to meet the amino 

acid needs of pets and achieve “organic” or “made with organic” status is challenging 

in terms of seasonal and geographic constraints on availability of feedstuffs. Dogs, 

cats, and specialty pets that live in tanks or cages, have dietary demands that must be 

met with a sole source feed formulation specific to their species and stage of life.

Background

Meeting the nutritional needs of pets with a single source of feed requires 

manufacturers to follow strict dietary guidelines. These guidelines are regulated by a 

series of regulators and scientific communities. The Food and Drug Administration 

(FDA) regulates pet food under the Federal Food, Drug, and Cosmetic Act that 

requires all animal feeds, like human foods, to be safe to eat, produced under sanitary 

conditions, contain no harmful substances, and be truthfully labeled. The FDA Center 

for Veterinary Medicine (CVM), that manages the non-human aspect of the regulation 

for the agency, accepts the determination of an ad hoc expert nutrition committee 

under the Committee on Animal Nutrition for the National Research Council (NRC) in 

the National Academy of Sciences to establish nutrient requirements for dogs, cats, 

and all other species of animals. For dogs and cats, the required essential nutrients 

are listed and described in the NRC 2006 edition of Nutrient Requirements of Dogs 

and Cats. The 2006 edition is the standard State Feed Control Officials use when 

evaluating diet formulations and to verify labels as sufficient for use in their state. 

These State Feed Officials have formed the Association of American Feed Control 

Officials (AAFCO) to act as a forum and clearinghouse for developing an overall 

regulatory structure that is consistent across the country for continuity of interstate 

commerce. FDA officials sit on the standing committees of this organization to ensure 
compliance with the regulations. The State Feed Control Officials implement the 

regulatory process through their legislative system. 

Through this system, for a pet food to make the label claim “complete and balanced,” it 

must meet the standards in the NRC 2006 edition of Nutrient Requirements for Dogs 

and Cats.

The current AAFCO standard classifies 13 amino acids (AA) as essential for dogs and 

cats (Appendix). This means they cannot be synthesized by the body and must be 

supplied by the feed. All of these AA are naturally occurring in nature. Prior to 

domestication, these animals sought out food sources to supply these AA in the 

correct balance to meet their needs. With domestication came the need to supply the 

animals a complete and balanced diet with the correct food sources. It can be difficult 

to achieve the required balance of AA given access to ingredients and the processing 

requirements for preserving and packaging them for market. These AA are also 

manufactured by chemical synthesis, fermentation, and enzymatic synthesis to 

supplement diets that may be deficient in one or more of them. The AA produced from 

each of these processes would be considered synthetic under the working definition of 

the NOSB. The fermentation process could use excluded methods. 

Some pet foods on the market are certified organic without the use of synthetic AA 

and meet the complete and balanced claim, albeit a very small segment of the market. 

Some are certified with the understanding that synthetic nutrients, including synthetic 

AA are allowed, along with vitamins and minerals, without regard to source and “other 

ingredients” under the livestock feed standards. Certifiers, to date, are using the 

livestock feed standards at 7 CFR 205.237 for processing and handling; and label 

standards at section 205.301 to certify these products. 

In 2012, the NOP notified the industry that these amino acids must be petitioned 

individually, as they do not fall under the current allowance for vitamins and minerals 

on the National List. In 2005, a Pet Food Task Force (PFTF) was formed by the NOSB 

and NOP to advise the NOSB on future recommendations to implement pet food 

standards. This led to the NOSB making recommendations to the NOP in fall 2008 on 

numerous changes to regulate pet foods in the USDA organic regulations. These 

recommendations included the use of mammalian and poultry products and byproducts as allowed since pets are not part of the food chain. This point is the 

fundamental reason pet foods must be distinguished from livestock feeds. It also 

clarified labeling requirements, and the need for additions to the National List. 

Currently the NOP intends to announce proposed rulemaking on this topic in 2013. 

When the rulemaking process is complete, only approved synthetic AA will be allowed 

in organic pet foods. 

Discussion 

The Pet Food Institute has petitioned the NOSB to place Arginine, Methionine, 

Cystine, Lysine, Taurine, Tryptophan, Threonine, Histidine, Isoleucine, Leucine, 

Phenylalanine, Tyrosine, and Valine, as synthetic AA, on the National List. These AA, 

must be supplied by the feed, in some form, at minimum levels, for the feed to meet 

the AAFCO standards of complete and balanced. However, the petition states that
Threonine, Histidine, Isoleucine, Leucine, Phenylalinine, and Valine are available in 

agricultural products used as feedstuffs and will not need to be utilized in synthetic 

form. Therefore, the committee focused its work on Arginine, Methionine, Cystine, 

Lysine, Taurine, and Tryptophan, the AA listed on the 2008 NOSB pet food 

recommendation as potentially necessary in synthetic form. Carnitine was also on the 

2008 recommendation however, it is not part of this petition.

Dog foods must be at least 22% protein, however, some go much higher to mimic 

natural diets. The higher protein (meat based) diets may require less AA 

supplementation, yet be more expensive to produce. Many commercial dog food 

formulations have synthetic Taurine, DL-Methionine, L-Lysine and Carnitine listed on 

the ingredient panel. In addition, there are many dog foods on the market with no 

added synthetic AA.

Virtually all cat foods have synthetic Taurine because of the relatively high 

requirement for cats, and degradation during processing no matter the protein 

percentage. Many cat foods also list synthetic Methionine and Lysine on their labels. 

The Technical Report states several pet food brands are on the market as complete 

and balanced without the use of synthetic AA. 

There is no mention of “other ingredients” such as anti-oxidants, carriers, etc. 

associated with these AA. The committee would like to know more about other 

ingredients associated with these products. Those derived from fermentation would 

have to document no excluded methods are used in the process. It is reported that 

Taurine is particularly sensitive to heating and is severely degraded in the 

manufacturing process. 

The use of synthetic AA in pet foods is based on the ability of the manufacturer to 

formulate a diet that supplies the correct balance of AA to meet AAFCO standards of 

“complete and balanced”. In the case of organic pet foods, manufacturers have limited 

access to organic ingredients, thus the petitioner’s stated need to utilize synthetic 

nutrients to balance the formulations. It is unclear from the information at hand that the 

allowance of synthetic AA will foster the expanded use of organic by-products and 

other organic inputs because manufacturers will be have these limiting AA at their 

disposal. It is also unclear that if these synthetic AA are available to manufacturers, if it 

will allow the use of lower quality ingredients, supplemented with these AA, to be more 

competitive in the market place.

Relevant Areas of the Rule

The 2008 NOSB recommendation proposed a change to the organic regulations to 

support labeling of organic pet food and provide clarity where any conflicts may have 

existed between organic labeling claims and the existing state requirements for pet 

food labeling. The intent of the proposed regulation was to create a pet food label that 

is consistent with labeling for human food. 
Appendix 

AAFCO Dog Food Nutrient 

Profiles

Units Growth & Adu

1000 Reproduct Maintenan

M Minimum Minimum Maximum

Arginine g 1.77 1.46

Histidine g 0.63 0.51

Isoleucine g 1.29 1.06

Leucine g 2.06 1.69

Lysine g 2.20 1.80

Methionine- ti g 1.51 1.23

Phenlyalanine- t i g 2.54 2.09

Threonine g 1.66 1.37

Tryptophan g 0.57 0.46

Valine g 1.37 1.11

AAFCO Cat Food Nutrient 

Profiles

Growth & Adu

Units Reproduct Maintenan

Basis Minimum Minimum Maximu

Arginine % 1.25 1.04

Histidine % 0.31 0.31

Isoleucine % 0.52 0.52

Leucine % 1.25 1.25

Lysine % 1.20 0.83

Methionine- ti% 1.10 1.10

AAFCO Dog Food Nutrient 

Profiles

Growth Adult

Unit

s

D

Reproduct Maintena

Basis Minimu Minimu Maximum

Arginine % 0.62 0.51

Histidine % 0.22 0.18

Isoleucine % 0.45 0.37

Leucine % 0.72 0.59

Lysine % 0.77 0.63

Methionine- ti% 0.53 0.43

Phenlyalanine- t i% 0.89 0.73

Threonine % 0.58 0.48

Tryptophan % 0.20 0.16

Valine % 0.48 0.39
Methionine % 0.62 0.62 1.50

Phenlyalanine- tryosine% 0.88 0.88

Phenylalanine % 0.42 0.42

Threonine % 0.73 0.73

Tryptophan % 0.25 0.16

Valine % 0.62 0.62

Taurine (Dry % 0.10 0.10

Taurine (Wet

F d)

% 0.20 0.20

AAFCO Cat Food Nutrient 

Profiles

Units Growth & Adu

1000 Reproduct Maintenan

M Minimum Minimum Maximum

Arginine g 3.10 2.60

Histidine g 0.78 0.78

Isoleucine g 1.30 1.30

Leucine g 3.10 3.10

Lysine g 3.00 2.08

Methionine- ti g 2.75 2.75

Methionine g 1.55 1.55 3.75

Phenlyalanine- g 2.20 2.20

Phenylalanine g 1.05 1.05

Threonine g 1.83 1.83

Tryptophan g 0.63 0.40

Valine g 1.55 1.55

Taurine (Dry F d) g 0.25 0.25

Taurine (Wet

Food) g 0.50 0.50
Livestock:PetFoodAminoAcids

Common 

Name Chemical Name CAS Number Trade Names Other Codes

Arginine (S)-2-Amino-5-

guanidinopentanoic acid

74-79-3 Arginine (L-) EINECS: 

230-571-

3

Methionine 2-amino-4-

(methylthio)butanoic 

acid

63-68-3 (L-); 

59-51-8 (DL-)

Mepron®; Alimet® EINECS: 

200-432-

1

Cysteine 2-amino-3-

sulfanylpropanoic acid

52-90-4; 3374-

22-9 (DL-)

L-Cysteine; LCysteine 

Hydrochloride 

Monohydrate

EINECS: 

222-160-

2

Lysine 2,6-diaminohexanoic 

acid

56-87-1 (L-); 

70-54-2 (DL-)

VitaLys®; LLysine Premium®EINECS: 

200-740-

6

Taurine 2-aminoethane sulfonic 

acid

107-35-7 Taurine: AI3-

18307; O-Due; 

Taurina; Taukard

EINECS: 

203-483-

8

Tryptophan (2S)-2-amino-3-(1Hindol-3-yl)propanoic acid73-22-3 (L-); 

54-12-6 (DL-)

TryptoPure®; LTryptophanEINECS: 

200-194-

9

Threonine 2-Amino-3-

hydroxybutanoic acid

72-19-5 (L-); 

80-68-2 (DL-)

L-Threonine; DLThreonine; EINECS: 

201-300-

6

Histidine 2-Amino-3-(1H-imidazol4-yl)propanoic acid71-00-1 (L-); 

4998-57-6 (DL-

)

L-Histidine EINECS: 

225-660-

9

Isoleucine 2-Amino-3-

methylpentanoic acid

73-32-5 (L-); 

328-39-2 (DL-)

L-Isoleucine EINECS: 

207-139-

8

Leucine 2-Amino-4-

methylpentanoic acid

61-90-5 (L-); 

328-39-2 (DL-)

L-Leucine EINECS: 

206-328-

2

Valine 2-Amino-3-

phenylpropanoic acid

72-18-4 (L-); 

516-06-3 (DL-)

L-Valine EINECS: 

208-220-

0

Phenylalanine 2-Amino-3-

phenylpropanoic acid

63-91-2 (L-); 

150-30-1 (DL-)

L- Phenylalanine EINECS: 

205-756-

7

Tyrosine L-2-Amino-3-(4-

hydroxyphenyl)propanoi

c acid

60-18-4 (L-); 

556-03-6 (DL-)

L-Tyrosine EINECS: 

209-113-

1