Imidacloprid is widely used for exterminating harmful insects; however, information regarding its distribution in insects is limited. Herein, we developed a visualization method for imidacloprid in Drosophila melanogaster, by using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). IMS requires sample cryosections; however, certain challenges prevail in retaining fly morphology in sections owing to their small size and heterogeneous components. Therefore, the section preparation method was optimized first, followed by imidacloprid distribution visualized using MALDI-IMS. Using 10% gelatin as an embedding material and 70% ethanol for pretreatment, the gaps between embedding material and D. melanogaster body surface were reduced. The tight adhesion between embedding media and D. melanogaster retains fly morphology in sections. Furthermore, the imidacloprid standard was analyzed separately via MALDI and electrospray ionization (ESI), and imidacloprid was converted to guanidine-imidacloprid via laser irradiation. Consequently, the imidacloprid distribution in D. melanogaster was successfully visualized using guanidine-imidacloprid as the target peak.

Asparaptine, an inhibitor of angiotensin-converting enzyme (ACE), is a newly discovered compound in asparagus. Asparaptine is a conjugate of arginine and asparagusic acid; this compound is suggested to be effective for preventing high blood pressure. For this reason, asparaptine has attracted remarkable attention in recent years, and it was therefore necessary to carry out further research. No studies to date have investigated the localization of asparaptine in asparagus. In this study, the localization of asparaptine in asparagus was clarified using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS), a powerful method to visualize molecules.

The determination of urinary tetrahydroglucocorticoid (THGC) glucuronides might prove helpful in the diagnosis, pathophysiological analysis and assessment of the therapeutic efficacy of the diseases caused by abnormal cortisol secretion. We developed and validated a method for the determination of the THGC glucuronides in human urine using liquid chromatography/electrospray ionization (ESI)–tandem mass spectrometry not requiring enzymatic hydrolysis. The method employed a derivatization using an ESI-enhancing reagent for carboxylic acids, 1-[(4-dimethylaminophenyl)carbonyl]piperazine (DAPPZ), and its isotopologue, ²H₄-DAPPZ. The deproteinized urine samples were derivatized with DAPPZ. The ²H₄-DAPPZ-derivatized standards of known amounts were then added to the DAPPZ-derivatized urine samples and served as the internal standards. The DAPPZ-derivatization enhanced the assay sensitivity and reduced the sample volume, and the use of ²H₄-DAPPZ significantly improved the assay accuracy. The developed method enabled the separate quantification and profiling of the urinary THGC glucuronides and had a satisfactory application for the real sample analysis.

A sensitive analytical method was developed for the simultaneous detection of 11 chiral pharmaceuticals and their hepatic metabolites by liquid chromatography–tandem mass spectrometry (LC-MS/MS) using an ovomucoid chiral column. After optimization of the LC conditions, all pharmaceuticals examined were enantio-separated with R_s of >0.82 in LC-MS/MS analysis. The limit of detections of all pharmaceuticals by MS/MS detection ranged from 1.2 to 92.3 nM, which is approximately 1000 – 25000 times lower than those obtained by UV detection. From hepatic metabolite analyses in P450-expressing cells, metabolites of three pharmaceuticals were detected and enantio-separated. By using the proposed method, changes in the optical isomer ratio of the hepatic metabolites chlorpheniramine and verapamil caused by differential cytochrome P450 enzyme expression for each isomer, could be successfully traced.

In this study, proton affinitive derivatization using picolinic acid and its analogs (3- and 6-methylpicolinic acid and 5-butylpicolinic acid) with proton affinitive moieties was performed for the highly sensitive determination of testosterone (T) and 5α-dihydrotestosterone (DHT) in saliva by LC-ESI-MS/MS. T and DHT were converted to their corresponding picolinate esters and their chromatographic behavior was investigated with a reversed phase column. The picolinate ester of each steroid exhibited a clear single peak and elution occurred in the following order: picolinate, 3/6-methylpicolinate, and 5-butylpicolinate. Estimation and understanding of the separation and retention time of each picolinate ester was made simple using the develop method. Although the peaks of picolinate and 3/6-methylpicolinate esters were suppressed by interference from the saliva background (matrix effect), the 5-butylpicolinate esters were only marginally affected.

In this study, a highly sensitive analysis method for the rapid detection of histamine (HA), imidazole-4-acetic acid (IAA) and 1-methylhistamine (MHA) in pregnant women’s fingernails was developed using the ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS). HA and MHA were connected with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) as the derivation reagent for the first time. IAA was derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) successfully. The derivative mixtures were simultaneously separated within 8 min on an ACQUITY UPLC^TM BEH C18 column (1.7 μm, 100 × 2.1 mm i.d.) by isocratic elution using a mixture of 20 mM HCOONH₄ and CH₃CN (82:18) as the mobile phase, and sensitively detected by selected reaction monitoring (SRM). The quantitative analysis of HA, IAA, and MHA are performed by SRM using the fragmentation transitions of m/z 337.2 → 292.1, 420.6 → 375.1 and 351.2 → 306.0 under the positive ESI mode. The calibration curves for HA, IAA and MHA are presented herein, and their correlation coefficient were found to be above 0.9998, the measured detection limit for derivatized histamine and metabolites ranged from 0.06 to 0.15 fmol, and the relative standard derivation of intra-day and inter-day assays was 6.3%. Furthermore, the mean recoveries (%) of the standards added to human fingernails were in the range of 90.2 – 100.5%. The validated method was successfully applied to analyze human fingernail samples from three pregnant women and three healthy non-pregnant women. To the best of our knowledge, this report about the detection of histamine and metabolites in the fingernails of pregnant women’s fingernails is the first published.

We present a sensitive and selective method for the simultaneous determination of short-chain fatty acids (SCFAs), such as acetic acid (AA), propionic acid, butyric acid (BA), isobutyric acid, valeric acid, isovaleric acid, hydroangelic acid, caproic acid, 4-methylvaleric acid and succinic acid (SA) in feces samples using a ultra-high performance liquid-chromatography tandem mass spectrometry (UHPLC-MS/MS) with simple derivatization of 2-picolylamine. The main SFCAs were derivatized in the same condition, and showed the specific product ion (m/z 109) in the electrospray positive mode regarding to 2-picolylamine. The derivatized SA showed a different pattern of the product ion (m/z 191). The derivatized analytes showed LOD < 75 nM, LOQ < 100 nM and r² in the calibration curve > 0.991. The QuEChERS was used for sample preparation of feces samples. In the recovery test, the recovery values appeared from 89.7 to 100.2% (RSD: 2.1 to 9.2%, n = 6). This developed method was applied to evaluate obese diabetes model mice. In the result, the branched-chain SCFAs levels in feces from model mice of spontaneous obese type II diabetes were on a declining trend compared with normal. The AA levels from model mice with high-calorie/fat diet are owed a declining trend for 3 to 9 months. The BA levels showed that normal mice were increasing, and model mice had decreased tendency for breeding months. High-calorie/fat diet showed that the SA levels increased.

Protein phosphorylation is one of the most ubiquitous post-translational modifications in humans, and trypsin-digested phosphorylated peptides have been analyzed by reversed phase LC/MS using C18-silica columns under acidic conditions to profile human phosphoproteomes. Here, we report that phosphopeptides generally exhibit stronger retention than their unphosphorylated counterparts when C18-silica columns are used with acetic acid or formic acid as an ion-pairing reagent, whereas the retention order is reversed when less hydrophobic stationary phases such as C4-silica columns are employed. Similarly the retention reversal is observed when more hydrophobic ion-pairing reagents such as trifluoroacetic acid are used with C18-silica columns. These phenomena could be explained by the smaller S-values of phosphopeptides in linear solvation strength theory, based on the reduced net charge caused by intramolecular interaction between phosphate and basic groups.

25-Hydroxyvitamin D₃ (25(OH)D₃) as the metabolite of vitamin D, is connected with various of diseases, and important to people with limited sunshine. Thus, the investigation of serum 25-hydroxyvitamin D and its variation in these people is necessary. In this study, a simple, precise, and accurate method for serum 25(OH)D₃ determination by LC/MS/MS was developed. Serum samples were obtained monthly for one year from 11 male and 11 female indoor workers in Sapporo, Japan, and the overall 25(OH)D₃ concentration was 12.9 ± 4.7 ng/mL. The 25(OH)D₃ in females was significantly lower than that in males (14.0 ± 5.0 vs. 11.9 ± 4.3 ng/mL). The serum 25(OH)D₃ concentration in males and females were both strongly correlated to UV-B radiation (r² = 0.8477 and 0.7384, respectively), with a two-month’s lag. Also the monthly change in 25(OH)D₃ in males was more significant than that in females.

Glycans, which are widespread in nature, consist of a large number of monosaccharides linked via glycosidic bonds. Due to the complex nature of glycan structures on glycoproteins, assessing the configuration and positions of the glycosidic linkages of a glycan is a subject of considerable interest. In this study, a method for accomplishing this using partially O-methylated alditols (PMAs) from glycans combined with LC-MS analysis is reported. N-Glycans were first per-methylated with methyl iodide, and the levels of methylation were further confirmed by MALDI-TOF. PMAs were then produced via complete hydrolysis and reduction. PMAs derived from Fetuin N-glycan and Lewis^a antigen carbohydrates were successfully detected by LC-MS analysis. This analysis can be performed without the need for an additional derivatization step for GC analysis, and should be suitable for use in conjunction with a LC-MS-based analysis platform.

Drosophila melanogaster is a model organism in neurodegenerative disease research. In neurodegenerative study, the direct spatial information of neurotransmitters such as γ-aminobutyric acid (GABA) in the brain of Drosophila melanogaster is important to understand the role of GABA. Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is an attractive method for direct visualization of neurotransmitters. In this paper, we describe methods to visualize GABA in the brain and head of Drosophila melanogaster using MALDI-IMS.

The third-phase formation behavior in ionic liquid (IL) extraction system using trioctylphosphine oxide (TOPO) was investigated. In the use of a relatively less-lipophilic IL, such as 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C₄mimTf₂N), the third phase was formed between the aqueous phase and the IL phase. The third phase seems to have a relatively high lipophilicity compared to the IL phase. The main components of the third phase were suggested as being (H₃O)TOPO⁺, IL anion (Tf₂N⁻), IL cation (C₄mim⁺) and free TOPO. In addition, the third phase showed an extraction concentration ability for the Fe(III)-thiocyanato complex.

Human sputum, a typical highly viscous biosample, was directly characterized at the molecular level using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without multi-step sample pretreatment, in an attempt to provide a method for constructing the pattern recognition of rapid diagnosis of lung cancer. Under the optimal experiment conditions, glucose, amino acids, phosphoric lipids and other typical analytes in the sputum sample could be used to conduct qualitative or quantitative (in arginine) analysis. More interestingly, the full scan mass spectra from 50 patients of non-small cell lung cancer, recording the mass spectral fingerprints of sputum samples, were differentiated from the control group (50 healthy individuals) through principal component analysis (PCA). These findings suggest that valuable molecular information concealed in human sputum could be easily revealed and applied for conducting qualitative or quantitative analysis by direct ND-EESI-MS analysis.

We have developed a microfluidic bioassay system that mimics glomerular filtration and tubular secretion in the kidney. The system consists of a peristaltic micropump (heart), a dialysis component (renal corpuscle), and a secretion component (renal proximal tubule). Analytes were separated by size using a dialysis membrane in the dialysis component. Model cells were cultured on a membrane in the secretion component, and active transport mediated by P-glycoprotein (P-gp) was confirmed using the P-gp substrate rhodamine 123 with or without the P-gp inhibitor quinidine sulfate. The system achieved both size separation and selective transport by P-gp on a single microchip. This proof-of-concept model may find applications in drug excretion assays, including studies of drug-drug interactions during tubular secretion.

A new Cr³⁺ probe was synthesized using simple Schiff base reaction, which showed prominent fluorescence increasing switch before and after addition Cr³⁺. The probe proved to have excellent properties, based on both UV-vis absorption and fluorescence spectra. Those properties included high switching performance, good selectivity, and small interference with other metal ions. The fluorescent change mechanism of the probe was attributed to the combined action between the restricted C=N isomerization and the suppression of highly efficient photo-induced electron transfer (PET) process. Moreover, this fluorescence probe for Cr³⁺ detection also has great potential for bioimaging of cancer cells.

A gold (Au)-deposited surface plasmon resonance (SPR)-based glass rod sensor that is coated with an α-mercaptoethyl-ω-methoxy polyoxyethylene (PEG thiol) layer (approximately 13 nm thick) and a Teflon AF2400 overlayer (12 μm thick) was used to detect the hydrocarbon and gasoline contents of automotive engine oil. Hydrocarbons and gasoline present in the engine oil penetrate through the porous Teflon layer and accumulate in the PEG thiol layer, and are then detected using the SPR sensor. The refractivities of the selective layers that contain a hydrocarbon on the Au-deposited glass rod sensor were estimated from the sensor responses when using light-emitting diodes (LEDs) with various operating wavelengths as light sources. Gasoline concentrations up to 10%, w/w in commercial engine oil can be measured directly using this sensor when it is coated with the selective layers. The responses of an SPR-based optical waveguide sensing system using Au films coated with identical selective layers were also measured. The results demonstrate the value of the Au-deposited SPR glass rod sensor coated with the selective layers for the detection of the gasoline content and fuel dilution of automotive engine oil.

Quantitative nuclear magnetic resonance (qNMR) has emerged as an easy, rapid and reproducible method for various pharmaceuticals. In the current study, a general qNMR approach for calibrating the purity of the thiopeptcin reference standard (also known as nocathiacin I) was developed using sulfadoxine as an internal standard. Experimental conditions, such as the relaxation delay time and number of scans, were systematically optimized, and the method was validated with different analytical parameters, including selectivity, stability, linearity, precision and robustness. To examine the reliability and feasibility of the present qNMR method, there was no significant difference in the quantification of this complex cyclic peptide compared to the mass balance method. The present study further exemplified that qNMR is a reliable and valuable approach for the assessing of absolute purity of small-molecule pharmaceuticals, which provides a useful tool for drug discovery and development.

A previously reported emulsion flow (EF) extraction system does not equip the refining device for any used organic phase. Therefore, the processing of large quantities of wastewater by using the EF extractor alone could lead to the accumulation of extracted components into the organic phase, and a lowering of the extraction performance. In the present study, we developed an organic phase-refining-type EF system, which is equipped with a column for refining a used organic phase to prevent accumulation, and successfully applied it for treating uranium-containing wastewater.