Assay ofmyo-inositol in cerebrospinal fluid and plasma by chemical ionization mass spectrometry of the hexaacetate derivative

Abstract

The paper describes a capillary gas chromatographic/mass spectrometric technique to quantitate myo-inositol in cerebrospinal fluid (CSF) and plasma. A highly abundant fragment ion, m/z 373, for the hexaacetate derivative of myo-inositol was generated by chemical ionization (CI). This ion and the analogous ion of hexadeuterated myo-inositol (the internal standard), m/z 379, were both monitored in the assay. CI was performed with acetonitrile vapor in an ion trap mass spectrometer. Microliter quantities of CSF or plasma were mixed with the internal standard, dried and acetylated. After a post-derivatization clean-up, samples were analyzed on a capillary gas chromatograph interfaced with a Finnigan ion trap. Standard curves constructed for both CSF and plasma were linear and reproducible. Absence of matrix effects and good precision in the results indicate the suitability of the technique for critical assays. Results from the determination of myo-inositol in the CSF and plasma of healthy subjects and those with neurological deficits are reported.

Acetonitrile Chemical Ionization Tandem Mass Spectrometry To Locate Double Bonds in Polyunsaturated Fatty Acid Methyl Esters

“…Acetonitrile (CH 3 CN, molecular weight (MW) = 41) is an unconventional liquid CI reagent first reported by Yinon and Cohen . It has been reported recently as a proton-transfer CI reagent for several environmental , and biological − applications. With a proton affinity of 788 kJ/mol, acetonitrile is a slightly less energetic reagent than isobutane (proton affinity = 683 kJ/mol) .…”

Quantification of plasma myo-inositol using gas chromatography–mass spectrometry

“…In the present study, the mean MI level in plasma of normal pregnant women was 2.58 mg/l. In the previous study, the mean MI level was 3.99 mg/l [20] detected by GC-MS in six healthy subjects (age 59 ± 7 y) and 4.41 mg/l [31] in 42 healthy students and medical-center personnel (age 43.3 ± 15.2). These results were approximately 1.5 fold of the present study.…”

“…Due to the complexity of the biological matrix, sample should undergo complex and time-consuming pretreatment process [17], which makes the method unsuitable for the large-scale clinical application. The methods of GC or GC/MS have been reported for biological MI detection, and showed good accuracy and sensitivity [18][19][20]. However, none of these methods could be operated using the low volume samples (<100 μl) available from patients, especially infants.…”

Quantitative mass spectrometric analysis of glycoproteins combined with enrichment methods

“…Porous graphite carbon is attractive to capture and separate hydrophilic glycans that are released from glycoproteins but not retained by reverse phase chromatography (Davies et al, ; Wada et al, ; Grass et al, ; Lam et al, ). Glycans separated can be analyzed by mass spectrometry, in their free glycans or in their derivative forms labeled by various tagging techniques, such as permethylation (Ciucanu & Kerek, ; Costello, Contado‐Miller, & Cipollo, ), peracylation (Shetty & Holloway, ), derivatization with amine tag (Kotani & Takasaki, ; Gil, Kim, & Kim, ; Nakano et al, ; Walker et al, ), or active methylene tag (Ahn & Yoo, ; Markely et al, ), for high sensitive detection or improved chromatographic separation of the glycans to be analyzed. Unfortunately this glycan‐targeting approach has disadvantage such that information for glycoprotein or glycosylation site generating a specific glycan component of interest disappears inevitably during glycan‐preparing process via deglycosylation reaction by enzymatic or chemical method (Maley et al, ; Wells et al, ; Miura et al, ).…”