Mass Spectrometry (MS) is replacing radio-immunoassay (RIA) in Clinical biochemistry analysis thus removing the need to use radioactive reagents. One of the Steroid assays performed by Hospital clinical labs is for Vitamin D analysis where there is a need to identify the relative abundance of vitamin D2 and D3. Samples are typically extracted into Hexane, concentrated (e.g. using a miVac
) and analysed by MS, which avoids ion suppression problems seen with RIA.
miVac concentrators have also been used by the Australian Sports Drug Testing Laboratory to improve the testing for synthetic insulin analogues
in athletes' blood samples. Using the miVac's ability to control of condition during the concentration step the analyist has more confidence that they are seeing the true blood concentration of potential drugs of abuse in the athlete's sample. Another method of use can be hair analysis
, as this can provide evidence over time of drug or alcohol abuse, or program / treatment compliance.
Tandem MS is used to identify metabolic disorders which include aminoacidemias, urea cycle disorders, organic acidurias, and fatty acid oxidation disorders. Samples can be presented as plasma, urine, blood spots or urine on filter paper. Sample preparation techniques can include solvent extraction, acid derivitisation and evaporation prior to reconstitution in a suitable medium for injection to MS. Evaporation of butanolic HCl used for derivatisation using blowdown techniques results in corrosion of the system especially pins/needles/jets which can lead to contamination of samples and erroneous results. The EZ-2
with HCl resistance
commonly used for these sample preparation stages. One example would be the test for CAT (carnitine acyl carnitine translocase deficiency) in neonates, an inborn error of metabolism
. Lack of this enzyme prevents the body from converting fats into energy. Labs do the initial test on Guthrie cards (dried blood spots). The cards are punched and extracted with 200ul of Methanol. The supernatant is placed into microtitre plates and then dried, typically using Nitrogen blowdown. Samples are then derivatised using approx 100ul 3N HCl in anhydrous Butanol and dried. Finally, samples are resuspended in Water & acetonitrile for analysis by MS.