Guidelines for the Notification and Testing of New Substances: Chemicals and Polymers

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APPENDIX 7 - Masking of Substance Names

1. 1.0 Substances Having a Definite Chemical Structure
   1. 1.1 Parent Masking
      1. 1.1.1 Example 1
         1. 1.1.1.1 Specific Substance Name
         2. 1.1.1.2 Acceptable Masked Names
      2. 1.1.2 Example 2
         1. 1.1.2.1 Specific Substance Name
         2. 1.1.2.2 Acceptable Masked Names
2. 2.0 Substances Not Having A Definite Chemical Structure
   1. 2.1 Example 4
      1. 2.1.1 Substance Description
      2. 2.1.2 Specific Substance Name
      3. 2.1.3 Acceptable Masked Names
   2. 2.2 Example 5
      1. 2.2.1 Substance Description
      2. 2.2.2 Specific Substance Name
      3. 2.2.3 Acceptable Masked Names
3. 3.0 Masking of Biochemicals and Biopolymers
   1. 3.1 Enzymatic Substances
4. 4.0 Justifying the Use of Additional Masking

The procedures presented below are based on guidelines developed by the USEPA for purposes of the TSCA Inventory. They have been modified for Canadian use and are included to provide guidance to notifiers submitting an NSN package in which they wish to claim the specific substance identity as confidential. For confidentiality requests, an acceptable masked name must be submitted for publication purposes on the confidential portion of the NDSL or the DSL. The intent of masking is to disguise, only to the extent necessary, the identity of the substance. Although this appendix illustrates the masking of only a single structural feature, multiple masking is permitted if the notifier can provide justification (see section 4 of this Appendix).

There are inherent differences between naming substances with a definite chemical structure and naming substances that cannot be depicted by a structural diagram. Each of these possibilities is addressed separately below.

1.0 Substances Having a Definite Chemical Structure

Substances having a definite chemical structure can be represented by a unique structure diagram. The names of substances with a distinct chemical identity normally disclose the following structural information:

1. identity of parent structure (i.e., a chain of carbon atoms, a ring system, or a coordinated metal);
2. identity, number, and position of chemical group(s) that are attached to the parent structure(s) or to other chemical groups;
3. identity and number of counter ions (for salts); and
4. stereochemical relationships.

Masked names may be created for substances with a distinct chemical identity by disguising structurally descriptive segments of the specific chemical name. Masking may be accomplished by substituting non-descriptive terms for distinctive parts of the name. Proposed masked names created by eliminating stereochemical indicators (if appropriate) from the specific chemical name and by masking one other structure detail will, in most cases, be acceptable to Environment Canada.

The structurally descriptive parts of a chemical name that could be masked when creating a proposed name are:

1. a locant that specifies the placement of a single chemical group;
2. the locant and multiplicative prefixes (e.g., di-,tri-, and tetra-) that together specify the number and placement of a given chemical group;
3. the identity (but not placement and number) of a given chemical group;
4. the identity of a given parent structure, and locants of a substituent chemical group; and
5. the identity and multiplicative prefixes (specifying the number) of a given simple cation or anion of a salt.

Table A.7.1 lists the type of chemical groups that can be masked by name and molecular formula. The groups of atoms found in Table A7.1 are common structural units; a given group may be listed under more than one name. Each group includes at least one atom other than carbon or hydrogen.

A chemical group that includes a carbon atom having more than one single free valence (e.g., carbonyl -CO) cannot be masked if the carbon is directly attached to an acyclic carbon atom or is included within a ring system; in this circumstance, only the atom or group of atoms attached to the carbon atom can be masked (see Example 2, where the oxo group is masked).

Certain chemical groups in Table A7.1 include hydrogen atoms that are often additionally substituted, e.g., an ethyl group may be substituted for hydrogen of the sulfamyl group (H₂NSO₂-) to give C₂H₅NHSO₂-. In the case of a chemical group being additionally substituted, only the chemical group listed in Table A7.1 should be masked, not the substituent.

Table A7.1 lists most of the common chemical functional groups that contain oxygen, e.g., H₂NCO-. Although not always listed, the Group VIa element (sulfur, selenium, and tellurium) analogs of these functional groups, e.g., H₂NCSe-, are considered included within Table A7.1 and, accordingly, may be used in masking.

Table A7.1 List of Common Chemical Structural Units

A:
aldo O=
amidino H₂NC(=NH)-
amino H₂N-
(aminoamidino) H₂NC(=NNH₂)- or H₂NNHC(=NH)-
(aminocarbonyl) H₂NCO-
[(aminocarbonyl)amino] H₂NCONH-
[2-(aminocarbonyl)hydrazino] H₂NCONHNH-
[(aminocarbonyl)hydrazono] H₂NCONHN=
(aminohydrazonomethyl) H₂NC(=NNH₂)-
[(aminohydroxymethylene) hydrazino] H₂NC(OH)=NNH-
(aminoiminomethyl) H₂NC(=NH)-
(aminoiminophosphoranyl) H₂NPH(=NH)-
(P-aminophosphinimyl) H₂NPH(=NH)-
(aminosulfinyl) H₂NSO-
(aminosulfonyl) H₂NSO₂-
(aminothio) H₂NS-
(aminothioxomethyl) H₂NCS-
ammonio H₃N-
antimono -Sb=Sb-
arseno -As=As-
arsenoso OAs-
arsinico HOAs(O)≡
arsinidene AsH=
arsinidyne As≡
arsinimyl AsH₂(=NH)-
arsino AsH₂-
arsinothioyl AsH₂(S)-
arsinyl AsH₂(O)-
arsinylidene AsH(O)≡
arso O₂As-
arsono (HO)₂As(O)-
(arsonooxy) (HO)₂As(O)O-
arsononitridyl AsH(=N)-
arsoranyl AsH₄-
arsoranylidyne AsH₂≡
arsylene AsH=
arsylidyne As≡
astato At-
astatoxy O₂At-
astatyl O₂At-
azi -N=N-
azido N₃-
(azidocarbonyl) N₃CO-
(azidofurmyl) N₃CO-
(azidosulfonyl) N₃SO₂-
azino =NN=
azo -N=N-
azoxy -N(O)=N-

B :
bismuthino BiH₂-
bismuthylene BiH=
bismuthylidyne Bi≡
borono (HO)₂B-
(boronooxy) (HO)₂BO-
boryl BH₂-
borylene BH=
borylidyne B≡
bromo Br-
(bromocarbonyl) BrCO-
(bromoiminomethyl) BrC(=NH)-
(bromosulfonyl) BrSO₂-

C:
carbamido H₂NCONH-
carbamoyl H₂NCO-
carbamyl H₂NCO-
carbonimidoyl -C(=NH)=
(carbonimidoylamino) H₂N=C=N-
carbonothioyl -CS-
carbonyl -CO-
(carbonylidiimino) -NHCONH-
(carbonyldioxy) -OC(O)O-
carboxy HO₂C-
chloro Cl-
(chlorocarbonyl) ClCO-
(chloroformyl) ClCO-
(chloroiminomethyl) ClC(=NH)-
(chlorosulfinyl) ClSO-
(chlorosulfonyl) ClSO₂-
chlorosyl OCl-
(chlorothio) ClS-
chloryl O₂Cl-
cyanato NCO-
cyano NC-

D:
1,2-diarsenediyl -As=As-
diarsenyl HAs=As-
diarsinetetrayl =AsAs=
diarsinyl H₂AsAsH-
1,2-diazenediyl -N=N-
diazeno HN=N-
diazo N₂=
diazoamino -NHN=N-
diazonio N₂⁺-
1,2-diborane(4)diylidene =BB=
diborane(4)tetrayl =BB=
digermanylene -GeH₂GeH₂-
digermathianyl H₃GeSGeH₂-
dioxy -OO-
1,2-diphosphenediyl -P=P-
1,2-diphosphinediyl -PHPH-
1,2-diphosphinediylidene =PP=
diphosphinetetrayl =PP=
diphosphinyl H₂PPH-
diseleno -SeSe-
1,2-disilanediyl -SiH₂SiH₂-
disilanoxy H₃SiSiH₂O-
disilanyl H₃SiSiH₂-
disilanylene -SiH₂SiH₂-
(disilanyloxy) H₃SiSiH₂O-
(disilathianyloxy) H₃SiSSiH₂O-
disilazanoxy H₃SiNHSiH₂O-
disilazanyl H₃SiNHSiH₂-
2-disilazanyl (H₃Si)₂N-
(disilazanyloxy) H₃SiNHSiH₂O-
1,3-disiloxanediyl -SiH₂OSiH₂-
1,3-disiloxanediylidene =SiHOSiH=
disiloxanoxy H₃SiOSiH₂O-
disiloxanylene -SiH₂OSiH₂-
(disiloxanyloxy) H₃SiOSiH₂O-
disilthianoxy H₃SiSSiH₂O-
1,2-distannanediyl -SnH₂SnH₂
distannanylene -SnH₂SnH₂-
1,3-distannathianediylidene =SnHSSnH=
1,2-distibenediyl -Sb=Sb-
disulfinyl -S(O)S(O)-
dithio -SS-
(dithiocarboxy) HSCS-
(dithiohydroperoxy) HSS-

E:
epidioxy -OO-
epidiseleno -SeSe-
epidithio -SS-
epioxy -O-
episeleno -Se-
epithio -S-
epoxy -O-

F:
fluoro F-
(fluorocarbonyl) FCO-
fluoryl O₂F-
formamido HCONH-
1,5-formazanidyl -N=NCH=NNH-
1-formazano H₂NN=CHN=N-
5-formazano HN=NCH=NNH-
formazanyl HN=NC(=NNH₂)-
formimidoyl HC(=NH)-
formyl HCO-
(formylamino) HCONH-

G:
germanetetrayl =Ge=
germyl H₃Ge-
germylene H₂Ge=
germylidyne HGe≡
guanyl H₂NC(=NH)-

H:
hydrazi -NHNH-
1,2-hydrazinediylidene =NN=
hydrazino H₂NNH-
(hydrazinocarbonyl) H₂NNHCO-
(hydrazinoiminomethyl) H₂NNHC(=NH)-
(hydrazinosulfinyl) H₂NNHSO-
(hydrazinosulfonyl) H₂NNHSO₂-
(hydrazinothioxomethyl) H₂NNHCS-
1-hydrazinyl-2-ylidene -NHN=
hydrazo -NHNH-
hydrazono H₂NN=
hydroperoxy HOO-
(hydroperoxycarbonyl) HOOCO-
(hydroperoxyiminomethyl) HOOC(=NH)-
(hydroperoxysulfinyl) HOOS(=O)-
(hydroperoxysulfonyl) HOOS(=O)₂-
(hydroperoxythioxomethyl) HOOCS-
hydroxy HO-
(hydroxyamino) HONH-
(hydroxyimino) HON=
(hydroxyiminomethyl) HOC(=NH)-
hydroxyl HO-
(hydroxyphosphinyl) HOPH(O)-

I:
imidocarbonyl -C(=NH)-
(imidocarbonylamino) HN=C=N-
imino HN=
(iminomercaptomethyl) HSC(=NH)-
[imino(mercaptooxy)methyl] HSOC(=NH)-
(iminomethyl) HN=CH-
(iminonitrilo) -NHN=
(iminophosphoranyl) H₂P(=NH)-
(iminosulfenomethyl) HOSC(=NH)-
iodo I-
(iodocarbonyl) ICO-
iodosyl OI-
iodyl O₂I-
isocyanato OCN-
(isocyanatocarbonyl) OCNCO-
(isocyanatosulfonyl) OCNSO₂-
isocyano CN-
(isocyanocarbonyl) CNCO-
isonitro HON(O)=
isonitroso HON=
isosemicarbazido H₂NC(OH)=NNH-
isothiocyanato SCN-
(isothiocyanatocarbonyl) SCNCO-
(isothiocyanatosulfonyl) SCNSO₂-
isothiocyano SCN-

K:
Keto O=

M:
mercapto HS-
(mercaptoamino) HSNH-
(mercaptooxy) HSO-
[(mercaptooxy)carbonyl] HSOCO-
[(mercaptooxy)sulfinyl] HSOS(=O)-
[(mercaptooxy)sulfonyl] HSOS(=O)₂-
[(mercaptooxy)thioxomethyl] HSOCS-
(mercaptotelluro) HSTe-

N:
nitramino O₂NNH-
aci-nitramino HON(O)=N-
nitrilio HN⁺≡
nitrilo N≡
(nitrilophosphoranyl) HP(=N)-
nitro O₂N-
acinitro HON(O)=
(nitroamino) O₂NNH-
(aci-nitroamino) HON(O)=N-
(nitrooxy) O₂NO-
nitroso ON-
(nitrosoamino) ONNH-
(nitrosoimino) ONN=
(nitrosooxy) ONO-
(nitrothio) O₂NS-

O:
oximido HON=
oxo O=
(oxoboryl) OB-
oxy -O-

P:
1,3-pentazadienyl H₂NN=NN=N-
perchloryl O₃Cl-
perseleno Se=Se=
perthio S=S=
phosphinico HOP(O)=
phosphinidene HO=
phosphinidyne P=
phosphinimyl H₂P(=NH)-
phosphino H₂P-
phosphinothioyl H₂P(S)-
phosphinothioylidene HP(S)=
phosphinyl H₂P(O)-
phosphinylidene HP(O)=
phosphinylidyne P(O)=
phospho O₂P-
phosphono (HO)₂P(O)-
(phosphonocarbonyl) (HO)₂P(CO)
phosphononitridyl HP(=N)-
(phosphonooxy) (HO)₂P(O)O-
phosphoranyl H₄P-
phosphoranylidene H₃P=
phosphoranylidyne H₂P≡
phosphoro -P=P-
phosphoroso OP-
plumbanetetrayl =Pb=
plumbyl H₃Pb-
plumbylene H₂Pb=
plumbylidyne HPb=

S:
seleneno HOSe-
selenino HOSe(O)-
seleninoselenoyl Se=Se=
seleninyl OSe=
seleno -Se-
selenocyanato NCSe-
selenono (HO)SeO₂-
selenonyl O₂Se=
selenoxo Se=
selenyl HSe-
semicarbazido H₂NCONHNH-
semicarbazono H₂NCONHN=
silanetetrayl =Si=
silyl H₃Si-
silylene H₂Si=
silylidyne HSi≡
(silyloxy) H₃SiO-
stannanetetrayl =Sn=
stannono HOSn(O)-
stannyl H₃Sn-
stannylene H₂Sn=
stannylidyne HSn≡
stibinico HOSb(O)=
stibino H₂Sb-
stibo O₂Sb-
stibono (HO)₂Sb(O)-
(stibonooxy) (HO)₂Sb(O)O-
stiboso OSb-
stibyl H₂Sb-
stibylene HSb=
stibylidyne Sb≡
sulfamino HOSO₂NH-
sulfamoyl H₂NSO₂-
sulfamyl H₂NSO₂-
sulfeno HOS-
(sulfenocarbonyl) HOSCO-
(sulfenosulfinyl) HOSS(=O)-
(sulfenosulfonyl) HOSS(=O)₂-
(sulfenothioxomethyl) HOSCS-
sulfhydryl HS-
sulfinimidoyl HN=S=
sulfino HOS(O)
(sulfinooxy) HOS(O)O-
sulfinothioyl S=S=
sulfinyl OS=
sulfo HO₃S-
(sulfoamino) HOSO₂NH-
sulfonimidoyl HN=S(O)=
sulfonodiimidoyl (HN=)₂S=
sulfonyl -SO₂-
(sulfooxy) HO₃SO-
sulfuryl -SO₂-

T:
telluro -Te-
telluroxo Te=
telluryl HTe-
1,4-tetraphosphinediyl -(PH)₄-
1,7-tetrasiloxanediyl -SiH₂(OSiH₂)2OSiH₂-
tetrathio -SSSS-
1,4-tetrazanediyl -(NH)₄-
1,4-tetrazanediylidene =N(NH)₂N=
1-tetrazenyl H₂NNHN=N-
thio -S-
(thioarsenoso) S=As-
(thiocarbamoyl) H₂NCS-
thiocarbamyl H₂NCS-
(thiocarbonyl) -CS-
(thiocarboxy) HOSC-
thiocyanato NCS-
thiocyano NCS-
(thioformyl) HCS-
thiohydroperoxy HOS- or HSO-
(thiohydroxy) HS-
(thionitroso) SN-
thionyl -SO-
(thioseleneno) HSSe-
(thiosulfeno) HSS-
(thiosulfo) (HO₂S₂)-
thioxo S=
(thioxoarsino) S=As-
(thioxomethyl) HCS-
thiuram H₂NCS-
triazanyl H₂NNHNH-
1-triazene-1,3-diyl -NHN=N-
1-triazenyl H₂NN=N-
triseleno -SeSeSe-
1,3-trisilanediyl -(SiH₂)₃-
1,3,5-trisiloxanetriyl -SiH(OSiH₂-)₂
trithio -SSS-

U:
uramino H₂NCONH-
ureido H₂NCONH-
ureylene -NHCONH-

1.1 Parent Masking

A parent structure that is a chain of carbon atoms or a ring system may be masked in the chemical name only by the following masked terms:

alkyl or alkane
alkenyl or alkene
alkynyl or alkyne
carbomonocyclic or carbomonocycle (e.g., benzene, cyclopentane) carbopolycyclic or carbopolycycle (e.g., naphthalene, spiroundecane) heteromonocyclic or heteromonocycle (e.g., pyrrole, p-dioxane) heteropolycyclic or heteropolycycle (e.g., indole, benzothiazole)

In the case of a coordinated metal compound, the identity of the metal atom may be masked by the term "metal" in the chemical name.

Only one such parent group or multiple occurrences of the same parent group should be masked.

The following examples show how several hypothetical compounds could be identified by names that mask only one structural detail (other than stereochemistry).

1.1.1 Example 1

CF₃CF₂CF₂CF₂CF₂CH₂N(CH₂CH₂OH)₂

1.1.1.1 Specific Substance Name

2,2,3,3,4,4,5,5,6,6,6-undecafluoro-N,N-bis(2-hydroxyethyl) hexanamide

1.1.1.2 Acceptable Masked Names

• fluorine atoms masked:
  N,N-bis(2-hydroxyethyl)-2,2,3,3,4,4,5,5,6,6,6-undecahalosubstituted hexanamide
• number of fluorine atoms masked:
  polyfluoro-N,N-bis(2-hydroxyethyl)hexanamide
• hydroxyl groups masked:
  2,2,3,3,4,4,5,5,6,6,6-undecafluoro-N,N-bis(2-substituted ethyl) hexanamide
• hexane parent (plus locants) masked:
  undecafluoro-N,N-bis(2-hydroxyethyl)alkanamide
• amide group (plus nitrogen locants) masked:
  2,2,3,3,4,4,5,5,6,6,6-undecafluorobis(2-hydroxyethyl)hexane derivative

1.1.2 Example 2

1.1.2.1 Specific Substance Name

6,7-dichloro-1-ethenyl-5,8-dihydro-5,8-dioxo-4-isoquinolinesulfonic acid

1.1.2.2 Acceptable Masked Names

• chlorine atoms masked:
  1-ethenyl-5,8-dihydro-5,8-dioxo-6,7-dihalosubstituted-4-isoquinolinesulfonic acid
• vinyl group masked:
  1-alkenyl-6,7-dichloro-5,8-dihydro-5,8-dioxo-4-isoquinolinesulfonic acid
• oxo group masked:
  6,7-dichloro-1-ethenyl-5,8-dihydro-5,8-dihalosubstituted-4-isoquinoline sulfonic acid
• sulfo group masked:
  6,7-dichloro-1-ethenyl-5,8-dihydro-5,8-dioxo-4-substituted isoquinoline
• isoquinoline ring (plus locants) masked:
  dichloroethenyldihydrodioxo heteropolycyclic sulfonic acid or dichloroethenyldihydrodioxosulfo heteropolycycle

2.0 Substances Not Having A Definite Chemical Structure

Some substances can only be represented by partial or incomplete chemical structures; in other instances the composition can only be described in terms of a complex combination of several different known or unknown components.

The method of manufacture can also identify a substance. For a substance manufactured by a chemical reaction, identification can be stated in terms of the immediate precursor substances and other reactants that participate in the final reaction sequence used to manufacture the substance, and the nature of the reaction (e.g., ethoxylation or bromination). For a substance derived from a source without chemical reaction, processing information identifies the source and method of derivation (e.g., distillation, or extraction with methylene chloride).

Although the name of substances lacking a definite chemical structure may be based on variable types of information, the procedures similar to those used for substances with a definite chemical structure may be applicable.

The composition of a substance that can be represented by a partial or incomplete chemical structure diagram can generally be described by a common chemical name that encompasses the variability or incompleteness in the structure. A masked name for such a substance will usually be acceptable if the previous guidelines for substances with a definite chemical structure have been followed.

In other instances, the preferred name may identify a predominant component or components of its composition, an immediate precursor or precursors, and other reactants by specific chemical name. A proposed masked name will usually be acceptable for such a substance if it is constructed by masking the chemical name of one such component, precursor, or reactant.

Clearly, these guideline procedures are most useful for masking the identity of substances having a distinct chemical identity, and will only be useful for some types of substances that cannot be described with a chemical structure. In some of these latter cases, the guidelines provided may have little applicability. For consistency, notifiers must base their choice of a masked name on a CAS preferred name. The NS program will consider each such proposed masked name on a case-by-case basis.

2.1 Example 4

2.1.1 Substance Description

Linseed-oil fatty acids-fumaric acid-glycerol-maleic anhydride polymer

2.1.2 Specific Substance Name

Fatty acids, linseed-oil, polymers with fumaric acid, glycerol and maleic anhydride

2.1.3 Acceptable Masked Names

• linseed-oil masked:
  Fatty acids, polymers with fumaric acid, glycerol and maleic anhydride
• fumaric acid masked:
  Fatty acids, linseed-oil, polymers with alkenedioic acid, glycerol and maleic anhydride

2.2 Example 5

2.2.1 Substance Description

Polyethylene glycol, mono-C_12-15-alkyl ethers, phosphates, potassium salts

2.2.2 Specific Substance Name

Poly(oxy-1,2-ethanediyl), α-hydro-ω-hydroxy-, mono-C_12-15-alkyl ethers, phosphates, potassium salts

2.2.3 Acceptable Masked Names

• potassium salts masked:
  Poly(oxy-1,2-ethanediyl), α-hydro-ω-hydroxy-, mono-C_12-15-alkyl ethers, phosphates, metal salts
• C_12-15-alkyl group masked:
  Poly(oxy-1,2-ethanediyl), α-hydro-ω-hydroxy-, monoalkyl ethers, phosphates, potassium salts
• 1,2-ethanediyl masked:
  Poly(oxyalkylenediyl), α-hydro-ω-hydroxy-, mono-C_12-15-alkyl ethers, phosphates, potassium salts

3.0 Masking of Biochemicals and Biopolymers

Biochemicals and biopolymers that do not have catalytic activity can be masked by disguising descriptive segments of the specific chemical name. Masking of more than one segment of the chemical name is considered multiple masking and would not be permitted without justification. Masking may be accomplished by substituting non-descriptive terms for distinctive parts of the chemical name. Please refer to sections 1 and 2 above.

3.1 Enzymatic Substances

Masked names may be created for enzymes by disguising the fourth level Enzyme Commission number description, as designated by the nomenclature committee of the IUBMB.

Example:

substance reported:
Cholestenone 5β-reductase Enzyme Commission number 1.3.1.22

Masked name that could be proposed:
NADP⁺ oxidoreductase Enzyme Commission number 1.3.1

In instances where a fourth level Enzyme Commission number only consists of one entry, the NS program will accept reverting to the second level Enzyme Commission number.

Example:

substance reported:
6-Hydroxynicotinate reductase Enzyme Commission number 1.3.7.1

Masked name that could be proposed:
Acceptor oxidoreductase Enzyme Commission number 1.3

4.0 Justifying the Use of Additional Masking

If strict application of these guideline procedures (e.g., the masking of only one single structural feature) would not adequately mask a specific substance identity, then the notifier may propose a masked name that disguises the substance identity to a greater extent. However, such additional masking must be substantiated in a written statement accompanying the notification and should be prepared in the following manner:

1. construct each reasonably applicable masked name developed following the described procedures (e.g., the masking of only a single structural feature at a time);
2. for each masked name constructed in (a), discuss the scientific rationale as to why the name is inappropriate for publication purposes. For example, the number of substances encompassed by the masked name may be very small; or, the masked name may still reveal information about the substance that in and of itself formed the basis for the confidential substance identity claim. These reasons should be clearly explained; and
3. select a suitable masked name that disguises two aspects of the substance identity. If such double masking is still perceived as inappropriate, state the reason for rejecting each reasonably applicable doubly masked name before proceeding to propose a name that masks three or more aspects of the substance name.