Mass fragmentographic determination of 4-hydroxy-3-methoxyphenylglycol (HMPG) in urine, cerebrospinal fluid, plasma and tissues using a deuterium-labelled internal standard

Abstract

4-Hydroxy-3-methoxyphenylglycol (HMPG) with the three hydrogen atoms in the side-chain replaced with deuterium (HMPG-D3) was used as the internal standard in the mass fragmentographic determination of free and conjugated HMPG in human urine, cerebrospinal fluid and plasma and in rat urine, liver and brain. HMPG-D3 was added to body fluids or homogenates followed by enzymatic hydrolysis of conjugates. HMPG was extracted with ethyl acetate, converted into the trifluoroacetyl derivative and analyzed by mass fragmentography. HMPG levels were 7.4 nmoles/ml plus or minus 2.8% in human urine, 73 pmoles/ml plus or minus 8.2% in human cerebrospinal fluid, 56 pmoles/ml plus or minus 5.4% in human plasma, 24 nmoles/ml plus or minus 3.6% in rat urine, 0.26 nmoles/g plus or minus 6.2% in rat brain and 99 pmoles/g plus or minus 13% in rat liver. The method is highly specific and sensitive, permitting analysis in small samples or in plasma and in tissues for which previously no methods for HMPG analysis were available.