The Trinder spot test is a diagnostic test used in medicine to determine exposure to

salicylate Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substance ...

s, particularly to

salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substance ...

. The test employs the Trinder reagent (a.k.a. Trinder solution) which is mixed with a patient's

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...

. The colour change, resulting from the Trinder reaction, is immediate, enabling rapid bedside assessment. The Trinder solution/reagent is a pre-mixed solution of 10%

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 ...

. It can be prepared by combining 40 g of

mercuric chloride Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is a ...

and 40 g of

ferric nitrate Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts. H ...

in 850 ml of type II deionized water, and then adding 10 ml of concentrated

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

to the solution and diluting to a volume of 1 litre with more type II deionized water. The test for the Trinder reaction is to mix 1 ml of urine with 1 ml of the Trinder reagent in a

test tube A test tube, also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top and closed at the bottom. Test tubes are usually placed in s ...

. The test is positive if a colour change results. The specific colour changes are: ;blue or purple:positive test ;no change:negative test ;brown:false-positive test caused by the presence of

phenothiazine Phenothiazine, abbreviated PTZ, is an organic compound that has the formula S(C6H4)2NH and is related to the thiazine-class of heterocyclic compounds. Derivatives of phenothiazine are highly bioactive and have widespread use and rich history. T ...

s The test has a sensitivity of 94% and a specificity of 74% for identifying patients whose salicylate concentrations are greater than 30 mg per decilitre (2.17 mmol/L). False positive concentrations (2.8 to 14.3 mg per decilitre) have been reported to occur in neonates with

hyperbilirubinemia 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 ...

, premature neonates, and children who are seriously ill (e.g. children who have extensive burns). The reaction between iron(III) and pharmaceuticals was first adapted for clinical use by P. Trinder (after whom the test, reaction, and reagent are now named), of the Biochemistry Department of the

Royal Infirmary Royal Infirmary may refer to a number of hospitals in the United Kingdom: *England **Blackburn Royal Infirmary **Bradford Royal Infirmary **Bolton Royal Infirmary **Bristol Royal Infirmary **Chester Royal Infirmary **Derbyshire Royal Infirmary **Do ...

Sunderland Sunderland () is a port city in Tyne and Wear, England. It is the City of Sunderland's administrative centre and in the Historic counties of England, historic county of County of Durham, Durham. The city is from Newcastle-upon-Tyne and is on t ...

, in 1954 (see the article listed in

further reading Further or Furthur may refer to: * ''Furthur'' (bus), the Merry Pranksters' psychedelic bus *Further (band), a 1990s American indie rock band *Furthur (band), a band formed in 2009 by Bob Weir and Phil Lesh * ''Further'' (The Chemical Brothers alb ...

Salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substance ...

salicylamide Salicylamide (''o''-hydroxybenzamide or amide of salicyl) is a non-prescription drug with analgesic and antipyretic properties. Its medicinal uses are similar to those of aspirin. Salicylamide is used in combination with both aspirin and caffe ...

, and

methyl salicylate Methyl salicylate (oil of wintergreen or wintergreen oil) is an organic compound with the formula C8H8O3. It is the methyl ester of salicylic acid. It is a colorless, viscous liquid with a sweet, fruity odor reminiscent of root beer, but often a ...

all react with iron(III) via the phenol group which is next to their –COOH, –CONH₂, or –COOCH₃ functional groups. The Trinder reaction has been used for the determination of the presence of

oxytetracycline Oxytetracycline is a broad-spectrum tetracycline antibiotic, the second of the group to be discovered. Oxytetracycline works by interfering with the ability of bacteria to produce essential proteins. Without these proteins, the bacteria cannot g ...

in 1991, of

ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin infec ...

in 1992, and of

norfloxacin Norfloxacin, sold under the brand name Noroxin among others, is an antibiotic that belongs to the class of fluoroquinolone antibiotics. It is used to treat urinary tract infections, gynecological infections, inflammation of the prostate gland, go ...

in 1993, in each case using a solution of iron(III) in sulphuric acid. It has also been used for the determination of the presence of

bromazepam Bromazepam, sold under many brand names, is a benzodiazepine. It is mainly an anti-anxiety agent with similar side effects to diazepam (Valium). In addition to being used to treat anxiety or panic states, bromazepam may be used as a premedicant ...

in 1992, using an iron(II) solution in a hydrochloric acid rather than an iron(III) solution.

See also

References

Further reading