Studies on neurosteroidsXXIII. Analysis of tetrahydrocorticosterone isomers in the brain of rats exposed to immobilization using LC–MS

Enhancement of the capabilities of liquid chromatography–mass spectrometry with derivatization: General principles and applications

“…For the identification, tetrahydro-metabolites of corticosterone (CORT) were converted to the APCI-active derivatives (the dinitrobezoyl esters and 2-nitro-4-trifluoromethylphenyl hydrazones) and detected in the negative-ion mode. These derivatives showed 60-and 40-fold higher sensitivities, respectively, than intact steroids measured in the positive-ion APCI-MS (Higashi et al, 2007c).…”

“…For an APCI interface, the proton-transfer reaction, adduct formation, and electron-capture reaction are all involved (Covey, Thomson, & Schneider, 2009). Thus, it is believed that the introduction of proton-affinity moieties (usually contain oxygen and nitrogen atoms) to the target analyte is generally effective to increase the sensitivity in the positive-ion APCI mode (Gaboriau et al, 2003;Williams et al, 2006;You et al, 2006;Higashi et al, 2007c). On the contrary, an electron-affinity derivatization reagent will be needed for a higher detection sensitivity in the negative-ion APCI and is named as electron-capture negative-ion APCI (ECNAPCI) (Boni et al, 1994;Hayen et al, 2003;Higashi et al, 2006b;Islam et al, 2007;Kuo et al, 2008).…”

“…Acyl chlorides (R-CO-Cl) and sulfonyl chlorides (R-SO 2 -Cl) could be classified as the same type of derivative reagents that react readily with nucleophiles like alcohol (-OH), thiol (-SH), phenol (Ph-OH), and amine (-NH 2 and >NH) to produce the corresponding esters and amides. According to the differences of the organic radical group (R-) connected with the acyl and sulfonyl, this type of reagent could be divided into: (1) alkyl acetyl chloride, such as acetyl chloride (AC) (Liebisch et al, 2006); (2) benzoyl chloride, such as pentafluorobenzoyl chloride (PFBC) (Straube, Dekant, & Volkel, 2005); (3) nitrobenzoyl chloride, such as p-nitrobenzoyl chloride (NBC) (Higashi et al, 2006a,b) and 2,4-dinitrobenzoyl chloride (DNBC) (Higashi et al, 2007c); (4) nitrobenzenesulfonyl chloride, such as 4-nitrobenzenesulfonyl chloride (4-NBSC) (Higashi et al, 2006b); and (5) dansyl chloride (DNS-Cl) (Gaboriau et al, 2003;Kushnir et al, 2008). Figure 3 shows the chemical structures of the above-mentioned representative acyl chloride and sulfonyl chloride reagents.…”

A review of sample preparation methods for quantitation of small-molecule analytes in brain tissue by liquid chromatography tandem mass spectrometry (LC-MS/MS)

“…19,21,22,31,36,38,40,41,43,75,77,79,81,[84][85][86]90 However, extra attention needs to be paid to the cleanliness of the blades, otherwise contamination can be a possible issue with the traditional rotating blade homogenizer. Bead beating 15,55 and ultrasonication 8,[24][25][26]39 are both newer techniques that have the advantages of higher efficiency, higher throughput as well as lower chance of contamination when compared to the traditional grinding or rotating blade homogenization techniques, making these two new techniques more popular in recent studies. In addition, pulverization is another highly efficient homogenization method.…”

“…In addition to pure water or aqueous solutions, organic solvents are also used in brain tissue homogenization in many studies. 9,11,15,[24][25][26]28,30,32,34,38,39,42,53,68,76 To be used as homogenization media, the organic solvent needs to be miscible with water and hydrophobic enough to compromise interactions between protein molecules. Due to their abilities to disrupt protein structures and therefore precipitate proteins, the use of organic solvents as homogenization media, which is similar to the use of TCA, can be combined with homogenization.…”