Quantitative analysis of vitamin D using m/MALDI-TOF mass spectrometry based on a parylene matrix chip

Abstract

Vitamin D deficiency is associated with various disorders and is diagnosed based on the concentration of 25-hydroxy vitamin D3 (25(OH)D3) in serum. The parylene matrix chip was fabricated to reduce the matrix background noise, and the homogenous distribution of the matrix was retained for the quantitative analysis of 25(OH)D3. The Amplex Red assay was performed to confirm that the sample-matrix mixing zone of the parylene matrix chip was formed below the surface of the parylene-N film. The homogeneous distribution of the matrix was verified from the fluorescence image. For effective analysis using a parylene matrix chip, 25(OH)D3 was modified through the nucleophilic addition of betaine aldehyde (BA) to form a hemiacetal salt. Such modified 25(OH)D3 with a positive charge from BA could be effectively analyzed using MALDI-TOF mass spectrometry. Serum 25(OH)D3 was extracted by liquid–liquid extraction (LLE) and quantified using MALDI-TOF mass spectrometry based on the parylene matrix chip. The intensity of the mass peak of 25(OH)D3 was linearly correlated (r2 = 0.992) with the concentration of 25(OH)D3 spiked in serum, and the LOD was 0.0056 pmol/μL. Energy drinks and vitamin D3 tablets were also employed for the real sample analysis. Finally, the results of the chemiluminescence binding assay and MALDI-TOF mass spectrometry were statistically analyzed to determine the applicability of the method using the Bland–Altman test and Passing–Bablok regression.

Simultaneous analysis of acylcarnitines using MALDI-TOF mass spectrometry based on a parylene matrix chip

“…Subsequently, MALDI-TOF mass spectrometry based on the parylene matrix chip was developed for the quantitative analysis of small molecules and was capable of removing the interference from organic matrix fragments in the low m/z range. 26,31,35 As previously reported, the parylene matrix chip was fabricated by the deposition of a parylene film with a thickness of around 50 nm on a dried organic matrix spot to reduce the matrix fragmentation in the low mass range for small molecule analysis (Fig. 1(a)).…”

“…2(a)). 34,35 The nanoporous structure of the parylene film of thickness less than 70 nm was analyzed using cyclic voltammetry on a gold electrode (Fig. S1 †).…”

“…[31][32][33][34] Homogeneous crystal formation is currently confirmed by fluorescence imaging, which reveals the high reproducibility of the parylene matrix chip and its applicability for quantitative analysis. 35 In this study, acylcarnitines were analyzed quantitatively by MALDI-TOF MS using a parylene matrix chip to demonstrate the applicability of this method for the diagnosis of fatty acid oxidation and disorders related to organic acids. Then, seven acylcarnitines were analyzed simultaneously and quantitatively for a multiplex test.…”

Laser-Assisted Desorption/Ionization Mass Spectrometry Using Nanoporous SiO2 Aerogels for the Diagnosis of Colon Cancer

“…36−38 For quantitative analysis of the combi-matrix, the homogeneous and densely distributed analytes in the combi-matrix were displayed using fluorescence imaging, and the spot-to-spot, as well as the shot-to-shot reproducibility, was estimated. 39 Finally, LDI-MS based on the combi-matrix was applied to the quantitative analysis of a biomarker for colon cancer, dodecanoyl-L-carnitine (DC). 40,41 Using real samples from healthy volunteers and patients, the medical diagnosis of colon cancer was demonstrated using a combi-matrix.…”

“…As the first step, the optimal component ratio of the combi-matrix between the SiO 2 aerogel and the organic matrix was determined to eliminate the mass peaks from the organic matrix and maximize the signal-to-noise ratio (S/N ratio) of the analytes. The influence of the nanoporous structure and insulating properties of the SiO 2 aerogel on the ionization of target analytes was investigated using differential scanning calorimetry (DSC). − For quantitative analysis of the combi-matrix, the homogeneous and densely distributed analytes in the combi-matrix were displayed using fluorescence imaging, and the spot-to-spot, as well as the shot-to-shot reproducibility, was estimated . Finally, LDI-MS based on the combi-matrix was applied to the quantitative analysis of a biomarker for colon cancer, dodecanoyl- l -carnitine (DC). , Using real samples from healthy volunteers and patients, the medical diagnosis of colon cancer was demonstrated using a combi-matrix.…”