| Maleic acid,
    [1-14C]- | MC 2028 | 
  
    | Maleic anhydride, 
	[1-14C]-    
    Discontinued | MC 1411 | 
    
    | Maleic anhydride,
    [2-14C1]- | MC 2801 | 
  
    | Maleic anhydride,
    [2,3-14C2]- | MC 2205 | 
    
    | Maleic anhydride,
    [3-14C1]- | MC 2802 | 
	
    | Maleic anhydride,
    [3,4-14C2]- | MC 2803 | 
  
    | Malonic acid,
	
    [2-14C]- | MC 312 | 
  
    | Malonic acid diethyl ester,
	 [2-14C]- | MC 154 | 
  
    | Malonyl Coenzyme A,  [malonyl-2-14C]-      
	Discontinued | MC 413 | 
  
    | Maltose,
	 [14C(U)]- | MC 258 | 
  
    | D-Mannitol, 
    [1-14C]-      in Ethanol:water (9:1) | MC 203 | 
  
    | D-Mannitol, 
    [1-14C]-      in Ethanol:water (2:98) | MC 203W | 
  
    | D-Mannosamine 
    hydrochloride, [1-14C]- | MC 2063 | 
  
    | D-Mannose, 
    [14C(U)]-   
    
    Discontinued | MC 259 | 
  
    | D-Mannose, 
    [1-14C]- | MC 202 | 
  
    | D-Mannose, [2-3H(N)]-   
    
    Discontinued | MT 804 | 
  
    | Maraviroc, [3H]- | MT 1997 | 
  
    | Maribavir, 
    [14C]- | MC 2735 | 
  
    | Mavacamten, 
	[pyrimidine-5-14C]- | MC 2788 | 
  
    | MC3, [carbonyl-14C]- | MC 2806 | 
  
    | Meclizine, [3H]- | MT 2108 | 
  
    | Medroxyprogesterone acetate, [6-methyl-14C]- | MC 2614 | 
  
    | Melphalan, 
	[chloroethyl-1,2-14C]-   
    
    Discontinued | MC 248 | 
  
    | Menadione, sodium bisulfite, [3H]-   
	 
    (Vitamin K3, [3H]-) | MT 664 | 
  
    | Meperidine hydrochloride,
	 [3H]- | MT 503 | 
  
    | Mequitazine, [2-14C]- | MC 2025 | 
  
    | 2-Mercaptobenzimidazole,
	
    [2-14C]- | MC 2009 | 
  
    | 6-Mercaptopurine, [8-14C]-    
    Discontinued | MC 1447 | 
    
    | 6-Mercaptopurine, [3H]- | MT 2178 | 
  
    | Mesotrione, [nitrobenzoyl carbonyl-14C]- | MC 2494 | 
  
    | Metalaxyl-M, [phenyl 
	ring-14C(U)]- | MC 2713 | 
  
    | Metformin, 
    hydrochloride salt, 
    [biguanidine-14C]- | MC 2043 | 
  
    | Metformin, hydrochloride salt, [methyl-3H]- | MT 1958 | 
  
    | Methamidophos, 
	[14CH3O]- | MC 2563 | 
  
    | Methane, [14C]- | MC 2646 | 
  
    | Methanol,
	 [14C]- | MC 1111 | 
  
    | Methanol,
	 
    [14C]- | MC 1111H | 
  
    | Methazolamide, [methyl-3H]- | MT 2004 | 
  
    | D-Methionine, [1-14C]-    
    Discontinued | MC 458 | 
  
    | L-Methionine, [1-14C]-   
    Discontinued | MC 457 | 
  
    | L-Methionine, [methyl-14C]-   
    
    Discontinued | MC 351 | 
  
    | L-Methionine, [35S]- 
    Translation grade      
    Discontinued | MS 102 | 
  
    | Met-[35S]-label      
    Discontinued | MS 103 | 
  
    | Methotrexate | M 701 | 
  
    | Methotrexate 
	glutamate4, ammonium salt | M 1941 | 
  
    | Methotrexate glutamate 
	x, [3H] (x=2,3,4 or 5) | MT 815 | 
  
    | Methotrexate, disodium salt, [3',5',7-3H(N)]- | MT 701 | 
  
    | 2-Methoxy-4-acetamino-3-chloromethylbenzoate, 
    [carbonyl-14C]- | MC 2121 | 
  
    | Methoxyacetic acid, 
    [carboxy-14C]-   
    
    Discontinued | MC 2171 | 
  
    | 2-Methoxy-4-amino-5-chlorobenzoic 
    acid, [carboxy-14C]- | MC 2078 | 
  
    | Methoxyamine hydrochloride, [14C]-   
    
    Discontinued | MC 1162 | 
  
    | Methoxychlor,
    [ring-14C(U)]- | MC 2097 | 
  
    | Methoxydextran, 
	[methyl-14C]- | MC 2002 | 
  
    | 2-Methoxyestradiol, [4-3H]-   
    
    Discontinued | MT 949 | 
  
    | 2-Methoxyethanol, 
    [1-14C]- | MC 2149 | 
  
    | 6-(4-((2-Methoxyethoxy)methyl)phenyl)-5-methyl-3-phenylisoxazolo[4,5-c]pyridin-4(5H)-one, 
    [methyl-3H]- | MT 1779 | 
  
    | 2'-Methoxyethyl-5-methylpyrimidine, 
    [methyl-3H]- | MT 1709 | 
  
    | Methoxyfenoterol, [resorcinol-3H]- | MT 2035 | 
  
    | 4-Methoxyindol-3-yl-methanol, [3H]- | MT 2067 | 
  
    | 5-Methoxy-1-methyl-1H-indole-3-carbonitrile, 
    [nitrile-14C]- | MC 2165 | 
  
    | 2-Methoxy-4-nitroaniline, [ring-14C(U)]- | MC 2544 | 
  
    | 2-Methoxy-4-nitrobenzoic 
    acid, [carboxy-14C]- | MC 2119 | 
  
    | 2-Methoxy-4-nitrobenzoic 
    acid methyl ester, [carboxy-14C]- | MC 2118 | 
  
    | 4-Methoxyphenol, 
    [methyl-14C]- | MC 1375 | 
  
    | N-(4-Methoxyphenyl)-1-phenyl-1H-pyrazol-3-amine, 
	[phenyl-14C(U)]- | MC 2795 | 
  
    | 4-Methoxyphenyl acetic acid, 
	
	[carbonyl-14C]- | MC 2311 | 
  
    | 3-[2-(4-Methoxyphenyl)-ethylamino]-propionic 
    acid methyl ester, [aminoethyl-14C]- | MC 2092 | 
  
    | 9-Methyl-9H-fluorene-9-carbonyl 
	chloride, [14C]- | MC 2787 | 
  
    | N1-Methyladenosine, 
    [3H]- | MT 2184 | 
  
    | N6-Methyladenosine, 
    [3H]- | MT 1744 | 
  
    | 2'-(O-Methyl)adenosine | M 1812 | 
  
    | 2'-(O-Methyl)adenosine, 
    [8-3H(N)]- | MT 1833 | 
  
    | 3'-(O-Methyl)adenosine | M 1741 | 
  
    | 3'-(O-Methyl)adenosine, 
    [8-3H(N)]- | MT 1792 | 
  
    | Methylamine hydrochloride,
	 [14C]- | MC 465 | 
  
    | Methylamine hydrochloride, [methyl-3H]- | MT 545 | 
  
    | 2-[4-(Methylamino)phenyl]-1,3-benzothiazol-6-ol, 
	[methyl-3H]- | MT 2085 | 
  
    | p-Methylanisole, [benzyl-14C]- | MC 2472 | 
  
    | 2-Methyl-D,L-aspartic 
    acid, disodium salt,  
	[3H]- | MT 1747 | 
  
    | 4-Methylbenzaldehyde, 
	
	[carbonyl-14C]- | MC 2293 | 
  
    | 2-Methyl-1,2-benzisothiazol-3(2H)-one, 
	[phenyl-14C(U)]- | MC 2577 | 
  
    | (R)-Methylbenzylamine 
	hydrochloride, [methyl-14C]- | MC 2245 | 
  
    | Methylbenzylamine, [methyl-3H]-   
    
    Discontinued | MT 1557 | 
  
    | Methyl-t-butyl ether, [14C(U)]- | MC 2307 | 
  
    | Methyl 
	((S)-1-((S)-6-(5-(9,9-difluoro-7-(2-((1R,3S,4S)-2-((methoxycarbonyl)-L-valyl)-2-azabicyclo[2.2.1]heptan-3-yl)-1H- 
	benzo[d]imidazol-6-yl)-9H-fluoren-2-yl)-1H-imidazol-2-yl)-5-azaspiro[2.4]heptan-5-yl)-3-methyl-1-oxobutan-2-yl)carbamate, 
	[valine-1-14C]- | MC 2773 | 
  
    | Methylcholanthrene,
    [3H]- | MT 1614 | 
  
    | 2'-Methylcytidine | M 1864 | 
  
    | 2'-Methylcytidine, [3H]- | MT 1852 | 
  
    | 5-Methylcytidine | M 1784 | 
  
    | 5-Methylcytidine, 
    [3H]- | MT 1815 | 
  
    | N3-Methylcytidine | M 1803 | 
  
    | N3-Methylcytidine, 
    [3H]- | MT 1826 | 
  
    | 2'-(O-Methyl)cytidine | M 1813 | 
  
    | 2'-(O-Methyl)cytidine, 
    [3H]- | MT 1834 | 
  
    | 3'-(O-Methyl)cytidine | M 1742 | 
  
    | 3'-(O-Methyl)cytidine, 
    [3H]- | MT 1793 | 
  
    | 2'-Methylcytidine-5'-monophosphate, 
    diammonium salt | M 1738 | 
  
    | 2'-Methylcytidine-5'-triphosphate, 
    tetraammonium salt | M 1739 | 
  
    | 5-Methylcytosine, [methyl-3H(N)]- | MT 1897 | 
  
    | N1-Methyl-2'-deoxyadenosine | M 1764 | 
  
    | N1-Methyl-2'-deoxyadenosine, 
    [8-3H(N)]- | MT 1802 | 
  
    | 5-Methyl-2'-deoxycytidine | M 1767 | 
  
    | 5-Methyl 
    2'-deoxycytidine, 
    [methyl-3H]-   
    
    Discontinued | MT 1543 | 
  
    | N3-Methyl-2'-deoxycytidine | M 1763 | 
  
    | N3-Methyl-2'-deoxycytidine, 
    [3H]- | MT 1801 | 
  
    | 5-Methyl 2'-deoxycytidine 5'-monophosphate, diammonium salt,
    
    [methyl-3H]- | MT 1537 | 
  
    | N1-Methyl-2'-deoxyguanosine | M 1766 | 
  
    | N1-Methyl-2'-deoxyguanosine, 
    [8-3H(N)]- | MT 1804 | 
  
    | N3-Methyl-2'-deoxyuridine | M 1765 | 
  
    | N3-Methyl-2'-deoxyuridine, 
    [3H]- | MT 1803 | 
  
    | N6-Methyl 2',3'-dideoxyadenosine, [2',3'-3H(N)]- | MT 767 | 
  
    | α,β-Methylene adenosine 
    5'-triphosphate, tetralithium salt, [2,8-3H]- | MT 1789 | 
  
    | α,β-Methylene adenosine 
    5'-triphosphate, tetralithium salt, [2,8-3H]- | MT 1789M | 
  
    | Methylene blue, [3H]- | MT 2024 | 
  
    | 3-Methylfluoranthene, 
    [3H]- | MT 1553 | 
  
    | Methyl formanilide,
	 [formyl-14C]- | MC 454 | 
  
    | Methyl-alpha-D-glucopyranoside,  
	[methyl-14C]- | MC 1426 | 
  
    | 3-O-Methyl-D-glucose,
	[methyl-3H]- | MT 1518 | 
  
    | 2'-C-Methylguanosine, 
	[guanine-8-14C]- | MC2753 | 
  
    | 2'-(O-Methyl)guanosine | M 1814 | 
  
    | 2'-(O-Methyl)guanosine, 
    [8-3H(N)]- | MT 1835 | 
  
    | 3'-(O-Methyl)guanosine | M 1743 | 
  
    | 3'-(O-Methyl)guanosine, 
    [8-3H(N)]- | MT 1794 | 
  
    | 7-Methylguanosine 
    5'-triphosphate, [7-methyl-3H]- | MT 1703 | 
  
    | 7-Methylguanosine 5'-triphosphate, [7-methyl,8-3H]- | MT 1892 | 
  
    | 7-Methylguanosine 
	5'-triphosphate, [8-3H(N)]- | MT 1918 | 
  
    | 4-Methylimidazole, [4-14C]- | MC 2498 | 
  
    | 2'-(O-Methyl)inosine | M 1816 | 
  
    | 2'-(O-Methyl)inosine, 
    [8-3H(N)]- | MT 1837 | 
  
    | 3'-(O-Methyl)inosine | M 1745 | 
  
    | 3'-(O-Methyl)inosine, 
    [8-3H(N)]- | MT 1796 | 
  
    | Methyl 
    iodide, [14C]- | MC 1321 | 
  
    | Methyl 
    iodide, [14C]- | MC 1321L | 
  
    | 2'-(O-Methyl)-5-iodouridine | M 1818 | 
  
    | 2-Methyl-3(2H)-isothiazolone, 
	[4,5-14C]- | MC 2598 | 
  
    | Methyl 
    Isothiocyanate,  
	[isothiocyanate-14C]- | MC 2138 | 
  
    | Methylmalonic acid, [14C(U)]- | MC 2549 | 
  
    | 2'-(O-Methyl)-5-methylcytidine | M 1817 | 
  
    | 2'-(O-Methyl)-5-methylcytidine, 
    [3H]- | MT 1838 | 
  
    | 3'-(O-Methyl)-5-methylcytidine | M 1746 | 
  
    | 3'-(O-Methyl)-5-methylcytidine, 
    [3H]- | MT 1797 | 
  
    | 5-(5-Methyl-1-(3-(4-(methylsulfonyl)piperidin-1-yl)benzyl)-1H-1,2,4-triazol-3-yl)-3-(4-(trifluoromethoxy)phenyl)-1,2,4-oxadiazole, 
    [triazole ring-5-14C]- | MC2732 | 
  
    | Methylnaltrexone 
	bromide, [14C]- | MC 2677 | 
  
    | 4 -(Methylnitrosamine)-1-(3-pyridyl)-1-butanone, 
    [pyridyl-5-3H]- | MT 1621 | 
  
    | (S)-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, 
    [5-3H]- | MT 1773 | 
  
    | N-Methyl-N-nitrosourea, [methyl-3H]- | MT 813 | 
  
    | N-Methyl-N-pentylamine 
    hydrochloride, [3H]- | MT 1698 | 
  
    | 4-Methylphenoxyacetaldehyde, [14C=O]- | MC 2447 | 
  
    | 4-Methylphosphinico-butanoic acid | M 1943 | 
  
    | Methylprednisolone, [3H]- | MT 1945 | 
  
    | N-Methyl-β-psuedothymidine, [3H]- | MT 1876 | 
  
    | 6-Methylpurine 
    deoxyriboside, [2,8-3H]- | MT 1707 | 
  
    | (6S)-5-Methyltetrahydrofolic acid, [3',5',7,9-3H]- | MT 816 | 
  
    | (6S)-5-Methyltetrahydrofolic acid, 
	[3H]- | MT 2171 | 
  
    | 5-Methyltetrahydrofolic acid, [methyl-14C]-
    Discontinued | MC 2354 | 
  
    | 4-Methyl-5-thiazoleethanol, 
    [2-14C]- | MC 2112 | 
  
    | 2-Methylthioadenosine, 
	
	[adenine-8-14C]- | MC 2243 | 
  
    | 2-Methylthioadenosine,
	 [8-3H]- | MT 874 | 
  
    | 2-Methylthioadenosine 
    5'-diphosphate, triammonium salt,
	 [8-3H]- | MT 850 | 
  
    | Methyl-β-D-thiogalactopyranoside, [3H]- | MT 1748 | 
  
    | N3-Methylthymidine | M 1762 | 
  
    | N3-Methylthymidine, 
    [3H]- | MT 1799 | 
  
    | Methyltriphenylphosphonium iodide,
	 [methyl-14C]- | MC 234 | 
  
    | alpha-Methyl-L-tryptophan,
    [methyl-14C]- | MC 1396 | 
  
    | 2-Methyltyrosine, [ring-5-3H]- | MT 2029 | 
  
    | O-Methyl-L-tyrosine, [ring-3H]- | MT 1705 | 
  
    | 2'-(O-Methyl)uridine | M 1815 | 
  
    | 2'-O-Methyluridine, 
	[4-14C]- | MC 2623 | 
  
    | 2'-(O-Methyl)uridine, 
    [3H]- | MT 1836 | 
  
    | (2'R)-2'-Deoxy-2'-fluoro-2'-methyluridine, 
	[14C]- | MC 2771 | 
  
    | 3'-(O-Methyl)uridine | M 1744 | 
  
    | 3'-(O-Methyl)uridine, 
    [3H]- | MT 1795 | 
  
    | N3-Methyluridine | M 1804 | 
  
    | N3-Methyluridine, 
    [3H]- | MT 1827 | 
  
    | Metoclopramide, [3H]- | MT 1964 | 
  
    | Metolachlor, [ring-14C]- | MC 2215 | 
  
    | Metoprolol,  
	 [3H] | MT 1639 | 
  
    | Metribuzin, 
	[triazine-6-13C]- | MG 149 | 
  
    | Metribuzin, [triazine-6-14C]- | MC 2374 | 
  
    | (R,S)-Mevalonic acid, DBED salt, [2-14C]- | MC 411 | 
  
    | Mifepristone, [phenyl-14C(U)]- | MC 2690 | 
  
    | Minodronic acid, [1-14C]- | MC 2496 | 
  
    | Mitragynine, 
    [3H]- | MT 2168 | 
  
    | Mitomycin F, 
	[N-methyl-3H]- | MT 1889 | 
  
    | Mitoxantrone,
	
    [3H]- | MT 543 | 
  
    | ML 
	604086,
	
    [3H]- | MT 2147 | 
  
    | Molinate, [hexahydroazepine-2-14C]- | MC 2376 | 
  
    | 2R,4R-Monatin, sodium salt, [phenyl-14C(U)]- | MC 2534 | 
  
    | Monuron, [carbonyl-14C]- | MC 2658 | 
  
    | Motesanib, 
	[phenyl-14C(U)]- | MC 2757 | 
  
    | Motesanib, 
	[pyridyl-2-14C]- | MC 2756 | 
  
    | trans,trans-Muconaldehyde, [2,5-14C]- | MC 301 | 
  
    | Mycotoxin T-2, 
	 [3H]-   
    
    Discontinued | MT 777 | 
  
    | Myosmine,
	
    [pyridyl-5-3H]- | MT 1623 | 
  
    | Myristic 
    acid, [1-14C]- | MC 1118 | 
  
    | Myristic 
    acid,  
	[9,10-3H]- | MT 918 | 
  
    | Myristoyl Coenzyme A,
    [myristoyl-1-14C]- | MC 1467 |