Salicylate testing is a category of drug testing that is focused on detecting salicylates such as acetysalicylic acid

Salicylic acid

Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin...

 for either biochemical or medical purposes.

Analytical

Salicylates can be identified by GC/MS

Gas chromatography-mass spectrometry

Gas chromatography–mass spectrometry is a method that combines the features of gas-liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation,...

, proton NMR

Proton NMR

Proton 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 structure of its molecules. In samples where natural hydrogen is used, practically all of the hydrogen consists of the...

, and IR

Infrared spectroscopy

Infrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...

.

In Vitro

One of the first in vitro tests for aspirin was through the Trinder reaction. Aqueous Ferric chloride 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, but would occur in the presence of any phenol

Phenol

Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

 or enol

Enol

Enols are alkenes with a hydroxyl group affixed to one of the carbon atoms composing the double bond. Alkenes with a hydroxyl group on both sides of the double bond are called enediols. Deprotonated anions of enols are called enolates...

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

Bilirubin

Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...

. When the level of bilirubin exceeds 1 mg/dl

Litre

pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

, a false positive could occur.

Enzyme Specific Assay

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

Immunoassay

Another identification mechanism is through immunoassay

Immunoassay

An immunoassay is a biochemical test that measures the presence or concentration of a substance in solutions that frequently contain a complex mixture of substances. Analytes in biological liquids such as serum or urine are frequently assayed using immunoassay methods...

. Abbott Labs'

Abbott Laboratories

Abbott Laboratories is an American-based global, diversified pharmaceuticals and health care products company. It has 90,000 employees and operates in over 130 countries. The company headquarters are in Abbott Park, North Chicago, Illinois. The company was founded by Chicago physician, Dr....

 AxSYM 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

Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

 labeled with fluorescein

Fluorescein

Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....

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

Antibody

An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

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

Blood serum

In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...

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