Phosphorus-32 for research

• Molecular biology

  DNA probes and blots^{2, 3, 4, 5}

  Random priming makes ³²P DNA probes of more than 10⁹ dpm per microgram that find single sequences on blots.

  More: DNA probes and blots

  Random-primed labeling builds [α-³²P]dCTP into new DNA; more than 70 percent of the labeled nucleotide is incorporated.

  On the first Northern blots, ³²P probes still detected ribosomal RNA bands from 300 pg of RNA after a 16 hour exposure.

  Polynucleotide kinase moves ³²P from [γ-³²P]ATP onto 5′ ends, the labeling behind Maxam-Gilbert sequencing.

• Biochemistry

  Protein kinase assays^{6, 7, 8}

  Kinase activity is measured directly as ³²P moved from [γ-³²P]ATP onto a substrate.

  More: Protein kinase assays

  The substrate peptide is caught on phosphocellulose paper, washed in phosphoric acid and counted. One unit of kinase incorporates 1 nmol of phosphate per minute.

  Reactions run for 5 minutes to an hour at 30 °C. Twice the kinase should give twice the activity while the assay stays linear.

• Cell signaling

  Labeling phosphoproteins in cells⁹

  Cells grown with [³²P]orthophosphate show which of their proteins carry phosphate.

  More: Labeling phosphoproteins in cells

  Chicken cells labeled for 18 hours had 7- to 8-fold more phosphotyrosine after transformation by Rous sarcoma virus. It was the first report of tyrosine phosphorylation.

• Gene regulation

  Gel shift assays^{10, 11}

  A ³²P-labeled DNA or RNA shows protein binding as a slower band in a gel.

  More: Gel shift assays

  The label is detectable at 0.1 nM or less, so the probe can stay at least 10-fold below the dissociation constant, where half-binding marks the constant itself.

  In one protein-RNA study, a ³²P-labeled RNA at 2 to 18 pM gave a dissociation constant of 120 pM.

• Detection

  Phosphor imaging^{12, 13, 14}

  Storage phosphor screens detect ³²P at about 1 disintegration per mm², 15 to 250 times more sensitive than film.

  More: Phosphor imaging

  Phosphor screens respond linearly over four to five orders of magnitude. Film on a ³²P dot blot was linear over only a 16-fold range.

• Radioactivity counting

  Scintillation and Cerenkov counting^{15, 16, 17}

  Phosphorus-32 counts at 85 percent or more in scintillation cocktail, and quench barely changes it.

  More: Scintillation and Cerenkov counting

  Its betas also make Cerenkov light in water, so samples can be counted without cocktail: about 56 percent efficiency in solution and 25 percent dried on a filter.

• [γ-³²P]ATP

  Labeled nucleotide in aqueous solution

  Kinase assays and 5′ end labeling

  Feasibility review
• [α-³²P]dCTP and other nucleotides

  Labeled nucleotide in aqueous solution

  Random-primed probes and other labeling

  Feasibility review
• [³²P]orthophosphate

  Phosphate in aqueous solution

  Metabolic labeling of cells

  Feasibility review

Activity, certificate and lead time are set with the manufacturer at quote.

Source: IAEA LiveChart of Nuclides, ENSDF evaluation by CHRISTIAN OUELLET and BALRAJ SINGH (literature cutoff 24 August 2011), retrieved 25 September 2026 [1]. Reference values; a manufacturer's certificate states the activity of a specific lot.

• ¹⁴C

  Carbon-14 for research

  C-14 · Half-life 5,700 years

  The label that sits in a molecule's carbon backbone, for following carbon through cells, animals, plants and soil.

• ³H

  Tritium (H-3) for research

  H-3 · Half-life 12.32 years

  A low-energy beta label that leaves a molecule almost unchanged, for binding, cell and metabolism studies.

• ¹²⁵I

  Iodine-125 for research

  I-125 · Half-life 59.41 days

  A high specific activity label for proteins, peptides and receptor ligands, counted in a gamma counter.

• ³⁵S

  Sulfur-35 for research

  S-35 · Half-life 87.37 days

  The label for newly made proteins, G protein activation and sharp autoradiographs.

• ²⁴¹Am

  Americium-241 for research

  Am-241 · Half-life 432.6 years

  Alpha particles near 5.49 MeV and a 59.5 keV gamma ray, from one long-lived source.

• ¹³³Ba

  Barium-133 for research

  Ba-133 · Half-life 10.55 years

  Gamma lines from 81 to 384 keV and cesium X-rays near 31 keV: a standard for low- and mid-energy calibration.

1. IAEA Nuclear Data Section. LiveChart of Nuclides, P-32 decay data (ENSDF evaluation). Retrieved 25 September 2026. www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
2. Feinberg AP, Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983;132(1):6-13. doi.org/10.1016/0003-2697(83)90418-9
3. Vogt SH, Weyens G, Lefèbvre M, et al. The FLC-like gene BvFL1 is not a major regulator of vernalization response in biennial beets. Front Plant Sci. 2014;5:146. doi.org/10.3389/fpls.2014.00146
4. Alwine JC, Kemp DJ, Stark GR. Method for detection of specific RNAs in agarose gels by transfer to diazobenzyloxymethyl-paper and hybridization with DNA probes. Proc Natl Acad Sci U S A. 1977;74(12):5350-5354. doi.org/10.1073/pnas.74.12.5350
5. Maxam AM, Gilbert W. A new method for sequencing DNA. Proc Natl Acad Sci U S A. 1977;74(2):560-564. doi.org/10.1073/pnas.74.2.560
6. Hastie CJ, McLauchlan HJ, Cohen P. Assay of protein kinases using radiolabeled ATP: a protocol. Nat Protoc. 2006;1(2):968-971. doi.org/10.1038/nprot.2006.149
7. Zagórska A, Pozo-Guisado E, Boudeau J, et al. Regulation of activity and localization of the WNK1 protein kinase by hyperosmotic stress. J Cell Biol. 2007;176(1):89-100. doi.org/10.1083/jcb.200605093
8. Karra AS, Stippec S, Cobb MH. Assaying protein kinase activity with radiolabeled ATP. J Vis Exp. 2017;(123):55504. doi.org/10.3791/55504
9. Hunter T, Sefton BM. Transforming gene product of Rous sarcoma virus phosphorylates tyrosine. Proc Natl Acad Sci U S A. 1980;77(3):1311-1315. doi.org/10.1073/pnas.77.3.1311
10. Hellman LM, Fried MG. Electrophoretic mobility shift assay (EMSA) for detecting protein-nucleic acid interactions. Nat Protoc. 2007;2(8):1849-1861. doi.org/10.1038/nprot.2007.249
11. Jarmoskaite I, AlSadhan I, Vaidyanathan PP, Herschlag D. How to measure and evaluate binding affinities. eLife. 2020;9:e57264. doi.org/10.7554/eLife.57264
12. Johnston RF, Pickett SC, Barker DL. Autoradiography using storage phosphor technology. Electrophoresis. 1990;11(5):355-360. doi.org/10.1002/elps.1150110503
13. Kanekal S, Sahai A, Jones RE, Brown D. Storage-phosphor autoradiography: a rapid and highly sensitive method for spatial imaging and quantitation of radioisotopes. J Pharmacol Toxicol Methods. 1995;33(3):171-178. doi.org/10.1016/1056-8719(94)00089-M
14. Malek AM, Izumo S, Alper SL. Quantitative densitometric analysis using a commercially available handheld CCD digital camera. Biotechniques. 1997;22(6):1150-1153. pubmed.ncbi.nlm.nih.gov/9187767/
15. University of Michigan Environment, Health and Safety. Phosphorus-32 radiological safety guidance. 2018. ehs.umich.edu/wp-content/uploads/2016/04/Phosphorus-32.pdf
16. Zimmerman BE, Collé R. Standardization of 63Ni by 4πβ liquid scintillation spectrometry with 3H-standard efficiency tracing. J Res Natl Inst Stand Technol. 1997;102(4):455-477. doi.org/10.6028/jres.102.031
17. Berger SL. The use of Cerenkov radiation for monitoring reactions performed in minute volumes: examples from molecular biology. Anal Biochem. 1984;136(2):515-519. doi.org/10.1016/0003-2697(84)90254-9
18. U.S. Nuclear Regulatory Commission. 10 CFR 30.71, Schedule B (exempt quantities). eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-30.71
19. U.S. Nuclear Regulatory Commission. 10 CFR 30.18, Exempt quantities. eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-30.18
20. Emory University Environmental Health and Safety Office. Nuclide safety data sheet: phosphorus-32. ehso.emory.edu/sso/documents/content-guidelines/nuclide-data-safety-sheets.pdf

Technical review by ConductScience, 25 September 2026. Next review 25 September 2027.