LC/ESI‐MS/MS method for determination of salivary eicosapentaenoic acid concentration to arachidonic acid concentration ratio

Abstract

A simple liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for determination of the eicosapentaenoic acid (EPA) concentration to arachidonic acid (AA) concentration ratio in human saliva has been developed. The EPA/AA ratio in serum or plasma is widely recognized as a useful indicator in identifying the risk of cardiovascular disease, especially atherosclerosis. The salivary EPA/AA ratio is expected to be a convenient alternative to the serum or plasma EPA/AA ratio, because saliva offers the advantages of easy and noninvasive sampling. The saliva was deproteinized with acetonitrile, purified using an Oasis HLB cartridge, and derivatized with 1-[(4-dimethylaminophenyl)carbonyl]piperazine (DAPPZ). The derivatized EPA and AA were subjected to LC/ESI-MS/MS, and the EPA/AA ratio was determined using the selected reaction monitoring mode. The DAPPZ-derivatization increased the ESI sensitivity by 100- and 300-fold for EPA and AA, respectively, and enabled the detection of trace fatty acids in saliva using a 200 μL sample. The assay reproducibility was satisfactory (relative standard deviation, <5.0%). The method was successfully applied to the measurement of the salivary EPA/AA ratios of healthy Japanese subjects and their changes owing to the supplementation of EPA.

Quantitative analysis of endogenous compounds

“…Various approaches ( Figure 2) are followed to address the lack of blank matrices for the quantification of endogenous compounds by LC-MS/MS including, background subtraction [26-31], the standard addition method [24,25,[32][33][34][35][36][37][38][39][40][41][42][43][44], neat solutions [45][46][47][48][49][50][51][52], artificial matrices of biological fluids [23,, stripped matrices [8,10,11,[74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91], and surrogate analytes [66,[92][93][94][95][96][97]…”

“…Applications of the use of stripped matrices as surrogate matrices.Similar matrix effect between original and stripped matrix for all analytes and IS at one QC MS/MS No matrix effect in original matrix for all analytes at two QCs[87] a Validation: How similarity of recoveries/matrix effect for original and surrogate matrices were demonstrated.…”

Current trends in isotope‐coded derivatization liquid chromatographic‐mass spectrometric analyses with special emphasis on their biomedical application

“…The ratio of eicosapentaenoic acid to arachidonic acid is a useful marker to identify the potential of cardiovascular diseases. ICD with DAPPz improved the detectability of eicosapentaenoic acid and arachidonic acid by 100‐ and 300‐folds, respectively (Ogawa, Tomaru, Matsumoto, Watanabe, & Higashi, ). The same reagents were also utilized for ICD of urinary tetrahydroglucocorticoid glucuronides followed by quantification via LC–MS/MS.…”

“…This method was applied for the determination of 24 hydroxyl‐containing steroid hormones (androgens, estrogens, corticoids, and progestogens) in urine from males, females, and pregnant women and demonstrated 10 3 –10 4 ‐fold enhanced sensitivity (Dai et al, ). As mentioned previously, 2 H 4 ‐DMBA was also used as a substrate for the synthesis of other ICD reagents including 2 H 4 ‐DAPPz and 2 H 4 ‐DAPAP, which target carboxylic acids (Ogawa et al, ; Ogawa, Tadokoro, et al, ). Recently, the 2 H 0 / 2 H 3 ‐3‐ N ‐methyl‐2′‐carboxyl rhodamine 6G ( 2 H 0 / 2 H 3 ‐MCR6G) pair was used for derivatization of hydroxyl‐containing cholesterol and metabolites as indicators for Alzheimer's disease (Wang, Sun, et al, ).…”

Biomedical Chromatography 2018

“…Likewise, determination of endogenous biomarkers is also represented by three manuscripts. Tatsuya Higashi and co‐workers from Tokyo University of Science developed a novel LC–MS/MS method to detect the ratio of eicosapentaenoic acid to arachidonic acid for use as an indicator for cardiovascular disease (Ogawa, Tomaru, Matsumoto, Watanabe, & Higashi, ). Babak Basiri and co‐workers at the University of Georgia developed a method to assess changes in vitamin B1 homeostasis as a means of evaluating the role of this essential vitamin in cancer (Basiri, Sutton, Hanberry, Zastre, & Bartlett, ).…”