Salicylate testing is a category of

drug testing A drug test is a technical analysis of a biological specimen, for example urine, hair, blood, breath, sweat, or oral fluid/saliva—to determine the presence or absence of specified parent drugs or their metabolites. Major applications of dru ...

that is focused on detecting salicylates such as acetysalicylic acid for either biochemical or medical purposes.

Analytical

Salicylates can be identified by GC/MS,

proton NMR Proton nuclear magnetic resonance (proton NMR, hydrogen-1 NMR, or 1H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of a substance, in order to determine the str ...

, and IR.

In vitro

One of the first ''in vitro'' tests for aspirin was through the

Trinder reaction The Trinder spot test is a diagnostic test used in medicine to determine exposure to salicylates, particularly to salicylic acid. The test employs the Trinder reagent (a.k.a. Trinder solution) which is mixed with a patient's urine. The colour ch ...

Aqueous An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would ...

ferric chloride Iron(III) chloride is the inorganic compound with the formula . Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The colo ...

was added to a urine sample, and the formation of the iron complex turned the solution purple. This test was not specific to

acetylsalicylic acid Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat in ...

but would occur in the presence of any

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

enol In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene (olefin) with a hydroxyl group attached to one end of the alkene double bond (). The te ...

. The downfall of this test occurs in the presence of hyperbilirubinemia or elevated

bilirubin Bilirubin (BR) (Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the ...

. When the level of bilirubin exceeds 1 mg/ dl, a

false positive A false positive is an error in binary classification in which a test result incorrectly indicates the presence of a condition (such as a disease when the disease is not present), while a false negative is the opposite error, where the test resul ...

could occur.

Enzyme Specific Assay

The current ''in vitro'' testing utilizes molecule specific methods of detecting salicylates.

Immunoassay

Another identification mechanism is through

immunoassay An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoass ...

. Abbott Labs'

AxSYM The Abbott AxSYM is an immunochemical automated analyzer made by Abbott Laboratories. It is used for serology tests and therapeutic drug monitoring, and uses antibodies to alter the deflection of polarized light. It can also be used to monitor ho ...

is an immunoassay device utilizing Fluorescence Polarization Immunoassay (FPIA) technology that can determine the presence and quantify salicylates. The introduction of a salicylate specific

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

labeled with

fluorescein Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely use ...

into the sample will mark the sample. Upon irradiation with 490 nm light, some of that light will be reflected back to a detector at 520 nm. Polarization allows the machine to detect the difference between

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and Viral disease, viruses. The antibody recognizes a unique m ...

bound, and unbound fluorescein. It is therefore possible to quantify the

serum Serum may refer to: *Serum (blood), plasma from which the clotting proteins have been removed **Antiserum, blood serum with specific antibodies for passive immunity * Serous fluid, any clear bodily fluid * Truth serum, a drug that is likely to mak ...

salicylate level through the signal strength—the amount of reflected light received.

References

{{reflist Chemical tests Serology Drug testing