| Attention deficit/hyperactivity disorder (ADHD) | | | | thousand psi over the sample which most frequently is |
| medication abuse, frequently by teens & young adults, | | | | urine. |
| has resulted in an increase in emergency room visits. | | | | Mass Spectrometry: Developments of technology and |
| A January 2006 Food and Drug Administration | | | | methodology in the field of mass spectrometry have |
| advisory panel recommended that ADHD medication | | | | been rapid over the last seven years and are providing |
| carry a warning of increased potential for cardiac | | | | highly sensitive and accurate strategies for drug |
| problems, such as hypertension, cardiac arrest and | | | | detection purposes. In this, a spectroscope is used for |
| stroke. The possibility of experiencing medical problems | | | | obtaining a mass spectrum by deflecting ions into a thin |
| may be exacerbated by using ADHD medications | | | | slit and measuring the ion current with an electrometer. |
| improperly, or in combination with other drugs. | | | | Usually, selected reaction monitoring (SRM) as well as |
| Ritalin is the ADHD prescription drug that is most | | | | an electro-spray ionization source (EIS) are used to |
| frequently abused. It is a CNS stimulant that is | | | | detect both urinary methylphenidate and the more |
| chemically known as methylphenidate, which when | | | | prevalent metabolite which is ritalinic acid in this case. |
| metabolized by the liver, forms ritalinic acid (RA) i.e. | | | | The major advantage of MS analysis is that this |
| when someone pops in a pill of Ritalin, within the liver | | | | ionization technique tolerates a reasonable amount of |
| this methylphenidate is converted or metabolized into | | | | impurities in the sample to be analyzed & many |
| ritalinic acid as a primary metabolite. Now, both | | | | different samples can be processed rapidly in an |
| methylphenidate & its metabolite ritalinic acid can be | | | | automated manner and these can be kept on the |
| used for diagnostic purposes. Various diagnostic | | | | target for several days without compromising the |
| techniques have been developed over last few | | | | quality of the analysis, allowing easy re-analysis when |
| decades for drug identification & quantification | | | | required. |
| purposes; some of the most common have been | | | | Enzyme linked immunoassays: ELISA uses antibodies |
| briefly mentioned below: | | | | that are covalently linked to a "reporter enzyme" such |
| • Liquid/Gas Chromatography | | | | as alkaline phosphatase or horseradish peroxidase, |
| • Mass Spectrometry | | | | enzymes whose products are readily detected, often |
| • Enzyme Linked Immunoassays | | | | just by a color change. The serum or urine to be |
| Liquid/Gas Chromatography: Chromatography is a | | | | tested is placed along with a solution of antibodies |
| process used for separating mixtures by virtue of | | | | covalently linked to a reporter enzyme. If |
| differences in their absorbency. Most frequently | | | | methylphenidate or ritalinic acid is present, the specific |
| employed methods for chemical compound separation | | | | antibodies will adhere to them. The presence and |
| & subsequent identification include gas | | | | quantity of bound antibody are then determined by |
| chromatography (GC) and high-performance liquid | | | | adding the substrate for reporter enzyme & |
| chromatography (HPLC). HPLC employs | | | | quantitative analysis can be done on the basis of |
| incompressible silica or alumina µ-beads as the | | | | intensity of the developed color. |
| stationary phase and pressures of up to a few | | | | |