49  US 6,503,413 B2  50  tryptophan, tyrosine, tyrosineamide, valine, acetic acid,  acetoacetic acid, acrylic acid, adipamic acid, adipic acid,  d-alinine, allantoin acid, alloxanic acid, a-aminoacetic acid,  a-aminobenzoic acid, p-aminobenzoic acid,  m-aminobenzosulfonic acid, p-aminobenzosulfonic acid,  anisic acid, o-~-anisylpropionic acid, m-~-propionic acid,  p-~-propionic acid, ascorbic acid, DL-aspartic acid, barbi› turic acid, benzoic acid, m-bromobenzoic acid, n-butyric  acid, iso-butyric acid, cacodylic acid, n-caproic acid, iso- caproic acid, m-chlorobenzoic acid, p-chlorobenzoic acid,  ~-chlorobutyric acid, y-chlorobutyric acid,  o-chlorocinnamic acid, m-chlorocinnamic acid,  p-chlorocinnamic acid, o-chlorophenylacetic acid,  m-chlorophenylacetic acid, p-chlorophenylacetic acid, ~-( o- chlorophenyl)propionic acid, ~-(m-chlorophenyl)propionic  acid, ~-(p-chlorophenyl)propionic acid, ~-chloropropionic  acid, cis-cinnamic acid, trans-cinnamic acid, citric acid,  o-cresol, m-cresol, p-cresol, trans-crotonic acid,  cyclohexane-1: 1-dicarboxylic acid, cyclopropane-1: l- dicarboxylic acid, DL-cysteine, L-cysteine, deuteroacetic  acid, 2,3-dichlorophenol, 3,4-dihydroxybenzoic acid, 3,5- dihydroxybenzoic acid, dimethylglycine, dimethylmalic  acid, 2,4-dintirophenol, 3,6-dinitrophenol, diphenylacetic  acid, ethylbenzoic acid, formic acid, trans-fumaric acid,  gallic acid, glutaramic acid, glutaric acid, glycine, glycolic  acid, heptanoic acid, hexahydrobenzoic acid, hexanoic acid,  hippuric acid, histidine, hydroquinone, m-hydroxybenzoic  acid, p-hyroxybenzoic acid, ~-hyroxybutyric acid,  y-hydroxybutyric acid, ~-hydroxypropionic acid,  y-hydroxyquinoline, iodoacetic acid, m-iodobenzoic acid,  itaconic acid, lysine, maleic acid, malic acid, malonic acid,  DL-mandelic acid, mesaconic acid, mesitylenic acid,  methyl-a-aminobenzoic acid, methyl-m-aminobenzoic acid,  methyl-p-aminobenzoic acid, o-methylcinnamic acid,  m-methylcinnamic acid, p-methylcinnamic acid,  ~-methylglutaric acid, n-methylglycine, methylsuccinic  acid, o-monochlorophenol, m-monochlorophenol,  p-monochlorophenol, a-naphthoic acid, ~-naphthoic acid,  a-naphthol, ~-naphthol, nitrobenzene, m-nitrobenzoic acid,  p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol,  p-nitrophenol,  o-nitrophenylacetic  acid,  m-nitrophenylacetic acid, p-nitrophenylacetic acid, o-~› nitrophenylpropionic acid, m-~-nitrophenylpropionic acid,  p-~-nitrophenylpropionic acid, nonanic acid, octanoic acid,  oxalic acid, phenol, phenylacetic acid, o-phenylbenzoic  acid, y-phenylbutyric acid, a-phenylpropionic acid,  ~-phenylpropionic acid, o-phthalic, m-phthalic, p-phthalic,  pimelic acid, propionic acid, iso-propylbenzoic acid,  2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid,  4-pyridinecarboxylic acid, pyrocatecchol, resorcinol,  saccharin, suberic acid, succinic acid, a-tartaric acid, meso› tartaric acid, theobromine, terephthalic acid, thioacetic acid,  thiophenecarboxylic acid, o-toluic acid, m-toluic acid,  p-toluic acid, trichlorophenol, trimethylacetic acid,  tryptophan, tyrosine, uric acid, n-valeric, iso-valeric, veronal  acid, vinylacetic acid, xanthine, arsenic acid, arsenious acid,  a-boric acid, carbonic acid, chromic acid, germanic acid,  hyrocyanic acid, hydrofluoric acid, hydrogen sulfide, hypo› bromous acid, nitrous acid, a-phosphoric acid, phosphorous  acid, pyrophosphoric acid, selenious acid, m-silicic acid,  o-silicic acid, sulfurous acid, telluric acid, tellureous acid,  tetraboric acid, and mixtures thereof.  5.  The composition of claim  1,  wherein said buffering  agent is selected from the group consisting of 3chloropro- panoic acid, citric acid, ethylenedinitriloletraacetic acid,  alanine, aminobenzene, sulfanilic acid, 2-aminoberzoic acid,  2-aminophenol. ammonia, arginine, asparagine, aspartic  2.  The composition of claim  1,  wherein said buffering  agent has a pKa of from about 5 to about 9.5 and said  composition has a  pH  of from about 5 to about 9.5.  3.  The composition of claim  2,  wherein said buffering  agent has a pKa of from about 6 to about 9 and said  composition has a  pH  of from about 6 to about 9.  4.  The composition of claim  1,  wherein said buffering  agent is selected from the group consisting of acridine,  phenylalanine, allothreonine, n-amylamine, aniline,  n-allylaniline, 4-bromoaniline, 4-bromo-N,N› dimethylaniline, m-chloroaniline, p-chloroaniline, 3-chloro› N ,N-dimethylaniline, 3,5-dibromoaniline,  N ,N› diethylaniline, N,N-dimethy laniline, N-ethy laniline,  4-fluoroaniline, N-methylaniline, 4-methylthioaniline,  3-sulfonic acid aniline, 4-sulfonic acid aniline, p-anisidine,  arginine, asparagine, glycyl asparagine, DL-aspartic acid,  aziridine, 2-aminoethylbenzene, benzidine, benzimidazole,  2-ethylbenzimidazole, 2-methylbenzimidazole,  2-phenylbenzimidazole, 2-aminobenzoic acid,  4-aminobenzoic acid, benzylamine, 2-aminobiphenyl,  brucine, 1,4-diaminobutane, t-butylamine 4-aminobutyric  acid, glycyl-2-amino-n-butyric acid, cacodylic acid,  a-chlortriethylammonium-n-butyric acid, codeine,  cyclohexylamine, cystine, n-decylamine, diethylamine,  n-dodecaneamine, 1-ephedrine, l-amino-3-methoxyethane,  1,2-bisme thylaminoe thane, 2-aminoe thano 1,  ethylenediamine, ethylenediaminetetraacetic acid,  1-glutamic acid, a-monoethylglutamic acid, 1-glutamine,  1-glutathione, glycine, n-acetylglycine, dimethylglycine,  glycylglycylglycine, leucylglycine, methylglycine,  phenylglycine, N-n-propylglycine, tetraglycylglycine,  glycylserine, dexadecaneamine, 1-aminoheptane,  2-aminoheptane, 2-aminohexanoic acid, DL-histidine,  ~-alanylhistidine, imidazol, 1-aminoindane,  2-aminoisobutyric acid, isoquinoline, 1-aminoisoquinoline,  7-hydroxyisoquinoline, 1-leucine, glycylleucine,  methionine, methylamine, morphine, morpholine, l-amino- 6-h ydroxyna p h thalene, dime thy laminonaphthalene,  a-naphthylamine, ~-naphthylamine, n-methyl-a› naphthylamine, cis-neobornylamine, nicotine,  n-nonylamine, octadecaneamine, octylamine, omithine,  papaverine, 3-aminopentane, valeric acid, permidine,  phenanthridine, 1,10-phenanthroline, 2-ethoxyaniline,  3-ethoxyaniline, 4-ethoxyaniline, a-picoline, ~-picoline,  y-picoline, pilocarpine, piperazine, trans-2,5- dimethylpiperazine, 1-n-butylpiperidine, 1,2- dimethylpiperidine, 1-ethylpiperidine, 1-methylpiperidine,  praline, hydroxyproline, l-amino-2,2-dimethylpropane, 1,2- d i am in op ro pane, 1,3-diaminopropane, 1,2,3- triaminopropane, 3-aminopropanoic acid, pteridine,  2- amino -4, 6-dih ydro xyp te ridine, 2- amino -4- hydroxypteridine, 6-chloropteridine, 6-hydroxy-4- me th ylp teridine,  purine,  6-aminopurine,  2-dim ethyl am inopurine,  8-h ydro xypurine,  2-methylpyrazine, 2-amino-4,6-dimethylpyrimidine,  pyridine, 2-aldoximepyridine, 2-aminopyridine,  4-aminopyridine, 2-benzylpyridine, 2,5-diaminopyridine,  2,3-dimethylpyridine, 2,4-dimethylpyridine, 3,5- dimethylpyridine, 2-ethylpyridine, methyoxypyridine,  4-methylaminopyridine, 2,4,6-trimethylpyridine, 1,2- d i me th ylp yrro lidine,  n-me th ylp yrro lidine,  5-hydroxyquinazoline, quinine, 3-quinolinol, 8-quinolinol,  8-hydroxy-5-sulfoquinoline, 6-me thoxyquinoline,  2-methylquinoline, 4-methylquinoline, 5-methylquinoline,  serine, strychnine, taurine, myristilamine, 2-aminothiazole,  threonine, o-toluidine, m-toluidine, p-toluidine, 2,4,6- triamino-1,2,3-triazine, tridecaneamine, trimethylamine, 