Cartridge Column Research Articles

Pullusurfactans A–E, new biosurfactants produced by Aureobasidium pullulans A11211-4-57 from a fleabane, Erigeron annus (L.) pers.

Yeast biosurfactants have potent applications in medical, cosmeceutical, and food industries due to their specific modes of action, low toxicity, and applicability. In this study, biosurfactant-producing yeasts were screened for various industrial applications. Among them, Aureobasidium pullulans strain A11211-4-57 with potent surfactant activity from fleabane flower, Erigeron annus (L.) pers., was selected. From culture supernatant of strain A11211-4-57, five new low-surface-tension chemicals designated as pullusurfactans A-E were identified through consecutive chromatography steps, involving ODS, silica gel, Sephadex LH-20, and ODS Sep-pak cartridge columns. Based on mass and NMR measurements, structures of pullusurfactans A-E were determined as myo-inositol lipids with molecular formulae of C20H35O9, C18H32O8, C20H35O9, C24H42O9, and C18H32O8, respectively. These compounds exhibited potent biosurfactant activities (22.90, 22.40, 32.28, 25.28, and 22.44 mN/m, respectively). These results suggest that these novel biosurfactants have potential use as biosurfactants in industrial aspect.

Evaluation of reversed-phase nano liquid chromatography conditions by using reversed-phase thin layer chromatography based on Hansen solubility parameters for the analysis of amphiphilic glycosylsphingolipid transformations

Pulse chase analysis is often used in investigating dynamics of cellular substances. Fluorescently labeled lactosyl sphingosine molecule is useful in chasing its transformation, however the analysis of such metabolites in attomole level is of extreme difficult due to the presence of large amount of endogenous amphiphilic molecules such as glycosphingolipids, sphingomyerin, and glycerophospholipids. Nano LC suites for analyzing the attomole scale metabolites, therefore removal of endogenous substances prior to nano LC and finding appropriate nano LC conditions are necessary. Thus, we focused on the solubility of fluorescent BODIPY-labeled lactosylsphingosine (Lac-Sph-BODIPY) to identify suitable solvents to remove endogenous compounds. In this study, we evaluated solvents by using C18 thin layer chromatography (RP TLC). The mobility (Rf) of Lac-Sph-BODIPY against several solvent mixtures on RP TLC were plotted against polarity and hydrogen bonding capability followed by Hansen solubility parameters (HSPs). The optimum solvent mixture with Rf = 0.3 ± 0.1 was chosen for elimination of endogenous phospholipids on a ZrO2-SiO2 cartridge column and subsequent separation by nano LC. Efficient removal of endogenous phospholipids was demonstrated, and good resolution in nano LC analysis of Lac-Sph-BODIPY extracted from Chinese hamster ovary (CHO)-K1 cells was achieved. It was also shown that the amount of exogenously added compound was important in the investigation of metabolites using cultured cells.

On-line coupling of molecularly imprinted solid phase extraction with liquid chromatography for the fast determination of coumarins from complex samples

In this work, an on-line SPE-HPLC method with spectrophotometric detection was developed for the determination of coumarins in complex samples. For the on-line cleanup of samples, a molecularly imprinted polymer was packed into the column cartridge and coupled directly with HPLC (MISPE-HPLC) using a column switching system. The separation of coumarins was performed on a C18 core-shell column (100×4.6mm, 5μm) with a mobile phase consisting of 0.3% acetic acid/acetonitrile with gradient elution at a flow-rate of 1mLmin−1. The total time of the whole analytical run, including the extraction step, was 13.25min. The on-line MISPE-HPLC method was optimized and validated. The results showed good linearity (0.10–100μgmL−1) with correlation coefficients higher than 0.99. The LOD values were from 0.03 to 0.15μgmL−1. The proposed method was successfully applied for analysis of real samples (Cassia cinnamon, chamomile tea, and Tokaj specialty wines) and obtained recoveries varied from 78.7% to 112.2% with an RSD less than 9%.

Dose-on-demand production of diverse 18F-radiotracers for preclinical applications using a continuous flow microfluidic system

IntroductionThe production of 18F-radiotracers using continuous flow microfluidics is under-utilized due to perceived equipment limitations. We describe the dose-on-demand principle, whereby the back-to-back production of multiple, diverse 18F-radiotracers can be prepared on the same day, on the same microfluidic system using the same batch of [18F]fluoride, the same microreactor, the same HPLC column and SPE cartridge to obtain a useful production yield. Methods[18F]MEL050, [18F]Fallypride and [18F]PBR111 were radiolabeled with [18F]fluoride using the Advion NanoTek Microfluidic Synthesis System. The outlet of the microreactor was connected to an automated HPLC injector and following the collection of the product, SPE reformulation produced the 18F-radiotracer in <10% ethanolic saline. A thorough automated cleaning procedure was implemented to ensure no cross-contamination between radiotracer synthesis. ResultsThe complete productions for [18F]MEL050 and [18F]Fallypride were performed at total flow rates of 20μL/min, resulting in 40±13% and 25±13% RCY respectively. [18F]PBR111 was performed at 200μL/min to obtain 27±8% RCY. Molar activities for each 18F-radiotracer were >100GBq/μmol and radiochemical purities were >97%, implying that the cleaning procedure was effective. ConclusionsUsing the same initial solution of [18F]fluoride, microreactor, HPLC column and SPE cartridge, three diverse 18F-radiotracers could be produced in yields sufficient for preclinical studies in a back-to-back fashion using a microfluidic system with no detectable cross-contamination.

봉독으로부터 Phospholipase A₂ 성분 분리

PLA₂ is the second highest content of bee venom components next to the melittin. However, unlike melittin has various pharmacological effects, PLA₂ has been known as an allergen and thus most researches on PLA₂ were focused on removing it or inhibiting its activity. Recently, PLA₂ is effective in the treatment of liver damage and cancer cell suppression. PLA₂ is in the spotlight as an active ingredient of pharmaceuticals. In this study, we developed a method for effective isolation of PLA₂ from bee venom. Sep-pak cartridge column was used to separate pure PLA₂ from the TFA / MeCN mobile phase after 6 steps including column stabilization and bee venom injection. The purity was 99.7±0.03% and the yield was 37.5±3.6%, proving that PLA₂ of high purity can be effectively separated by this method. Purified PLA₂ activity, as well as standard PLA₂ activity had the growth inhibitions against hepatocellular carcinoma cells. This study will be useful for the research on physiological activity of PLA₂ and the development of various pharmaceuticals containing PLA₂.

Screening of over 100 drugs in horse urine using automated on-line solid-phase extraction coupled to liquid chromatography-high resolution mass spectrometry for doping control

A fast method for the direct analysis of enzyme-hydrolysed horse urine using an automated on-line solid-phase extraction (SPE) coupled to a liquid-chromatography/high resolution mass spectrometer was developed. Over 100 drugs of diverse drug classes could be simultaneously detected in horse urine at sub to low parts per billion levels. Urine sample was first hydrolysed by β-glucuronidase to release conjugated drugs, followed by centrifugal filtration. The filtrate (1mL) was directly injected into an on-line SPE system consisting of a pre-column filter and a SPE cartridge column for the separation of analytes from matrix components. Through valves-switching, the interfering matrix components were flushed to waste, and the analytes were eluted to a C18 analytical column for refocusing and chromatographic separation. Detections were achieved by full-scan HRMS in alternating positive and negative electrospray ionisation modes within a turn-around time of 16min, inclusive of on-line sample clean-up and post-run mobile phase equilibration. No significant matrix interference was observed at the expected retention times of the targeted masses. Over 90% of the drugs studied gave estimated limits of detection (LoDs) at or below 5ng/mL, with some LoDs reaching down to 0.05ng/mL. Data-dependent acquisition (DDA) was included to provide additional product-ion scan data to substantiate the presence of detected analytes. The resulting product-ion spectra can be searched against an in-house MS/MS library for identity verification. The applicability of the method has been demonstrated by the detection of drugs in doping control samples.

Analytical Method for Nitroimidazoles and Their Major Metabolites in Livestock and Fishery Products Using LC-MS/MS.

A sensitive and reliable method for the simultaneous determination of four nitroimidazoles (ipronidazole (IPZ), dimetridazole (DMZ), metronidazole (MNZ) and ronidazole (RNZ)) and three metabolites (IPZ-OH, MNZ-OH and 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI)) in livestock and fishery products was developed. The analytes were extracted from samples with acetone containing acetic acid. The crude extracts were defatted by liquid-liquid partition using acetonitrile and n-hexane followed by solid-phase extraction using a cartridge column packed with divinylbenzene-N-vinylpyrolidone copolymer bearing sulfo groups. The analytes in the eluate from the cartridge column were extracted with ethyl acetate after addition of ammonium sulfate. The solvent was removed from the extract, and the residue was dissolved in 0.1 vol% formic acid. The HPLC separation was performed on a C18 column with a gradient formed from water containing 0.1 vol% formic acid and acetonitrile containing 0.1 vol% formic acid. For detection of the analytes, tandem mass spectrometry with positive ion electrospray ionization was used. The recovery tests were performed on 10 livestock and fishery products. The truenesse ranged from 74.6 to 111.1%, with repeatability of 0.5-8.3 RSD% for the entire procedure. The limit of quantification was 0.0001 mg/kg for IPZ, IPZ-OH, MNZ and MNZ-OH, and 0.0002 mg/mg for DMZ, RNZ and HMMNI.

Determination of Diniconazole in Agricultural Products, Livestock and Marine Products by LC-MS/MS.

An LC-MS/MS method for the determination of diniconazole in agricultural products, livestock and marine products was developed. Diniconazole in agricultural products was extracted with acetone. The extract was concentrated and partitioned with n-hexane and 10% sodium chloride solution. Agricultural products such as grains and beans were defatted using n-hexane-acetonitrile. Livestock and marine products were extracted with a mixture of acetone and n-hexane, and the organic layer was evaporated to dryness. The residue was defatted using n-hexane-acetonitrile. Cleanup was carried out using a Florisil cartridge column and a graphitized carbon cartridge column for these samples. The LC separation was carried out on an Inertsil ODS-3 column with a linear gradient of 0.1% formic acid and acetonitrile containing 0.1% formic acid. MS was carried out in the positive ion electrospray ionization mode. The calibration curve was linear between 0.00125 to 0.00750 mg/L. Average recoveries (n=5) of diniconazole from 16 kinds of agricultural products, livestock and marine products fortified at the MRLs (0.01 ppm) were 88.3-108%, and the relative standard deviations were 0.5-5.1%. The limits of quantitation were 0.01 mg/kg.

Optimized Multiresidue Analysis of Organic Contaminants of Priority Concern in a Daily Consumed Fish (Grass Carp).

The organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), are of priority concern because of their persistence, toxicity, and long-distance transportation in global environment. Their residues in a daily consumed fish (grass carp) pose potential threat to human health and aquatic ecosystems. The present study optimized an analytical protocol of microwave-assisted extraction (MAE), lip-removal by gel permeation chromatography (GPC), cleanup by solid phase cartridge (SC) or adsorption chromatography column (CC), and gas chromatography-mass spectrometry (GC/MS). Besides traditional statistical parameters, some indicators were calculated to judge the performances of extraction by various methods. The optimization experiment showed that n-hexane/acetone was the best MEA extraction solvent; an optimal fraction time of 10–39 min could simultaneously elute all the target chemicals in a single GPC run. Both CC and SC showed good recoveries. However, CC performed better than SC (p < 0.05) for OCPs, and SC performed better than CC for PBDEs (p < 0.05). We also emphasized the limitations and advantages of SC and CC and finally proposed SC as the promising cleanup method because of its low-cost materials, time-saving steps, being free of manual filling, and operation by automated SPE system.

Estimation of residual antibiotics in soil and underground water of areas affected by pharmaceutical wastewater in Lahore

Drinking water is most essential thing for life on earth. Due to environmental pollution day by day the quality and quantity of drinking water is lowering. Ground water tables are becoming contaminated due industrial pollution. Contamination level of antibiotics namely ofloxacin (OFL), ciprofloxacin (CIP), levofloxacin (LEV), oxytetracycline (OTC), doxycycline (DOX) were quantified in soil and underground water of surrounding areas of pharmaceutical industry in Lahore. HPLC with DAD detector, C-18 column and solid phase cartridges were used to analyze antibiotic residues. In groundwater DOX has highest mean level of contamination and OFL was determined as highest contaminating pollutant in soil. Highest detected value in groundwater of OFL was 0.50, CIP and LEV 0.20, DOX 0.80, OTC 0.40 ng/L. Ground water have residual level of CIP 0.01–0.20 ng/L, LEV 0.02–0.20 ng/L, OFL 0.01–0.50 ng/L, OTC 0.02–0.40 ng/L, and DOX 0.04–0.80 ng/L. Ground water was contaminated by these residues is very important as it is source of accumulation of antibiotics to human and animal body as well as to plants.

GPC-HPLC-MS/MS测定植物组织中IAA与ABA的方法

植物激素检测的有效性和高效性是开展植物研究的前提。本试验采用净化-定量-浓缩多联机系统(GPC)纯化样品、利用HPLC-MS/MS检测以及内标法定量测定植物组织内源IAA和ABA含量。通过正交试验设计优化适于激素提取和纯化的条件，结果表明：取样量0.5 g、80%甲醇提取液、浓缩温度35℃和C18 SPE柱为最优组合。IAA和ABA的含量分别为20.34 ng/g和789.93 ng/g；最低检出限分别为2.36 ng/g和31.95 ng/g；回收率为70.43%和80.17%；变异系数分别为1.87%和2.26%。 The effectiveness and efficiency of the plant hormone detection is a prerequisite for plant research. The sample was purified with the GPC system, and the method employed HPLC-MS/MS for multiple reaction monitoring of concentrations of IAA, ABA, and deuterated IAA and ABA analogs. The condition of extraction and purification of hormones were optimized by orthogonal design. The results show that the composite of 0.5 g samples, 80% methanol extraction solvent, concentration temperature 35˚C and C18 cartridge column for solid-phase extraction (SPE), were optimal extraction procedure for each type of plant tissue. The contents of IAA and ABA as high as 20.34 ng/g and 789.3 ng/g were achieved by this method, respectively; the detectable limits were 2.36 ng/g and 31.95 ng/g; the recoveries were 70.43% and 80.17%; the RSD were 1.87% and 2.26%.

前駆イオンスキャンと精密質量分析を組み合わせたLC/MS/MS によるヒト尿中のパラベン抱合体の分離と同定

A precursor ion scanning method in liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed to identify metabolites of 4-hydroxybenzoic acid esters (parabens) in urine as a first step of paraben-metabolites determination in urine. The identification was confirmed by analyzing elemental compositions of conjugation group ions and those fragment ions with LC/Q-ToF MS/MS. Two milliliters of urine diluted with the same volume of acetonitrile was passed through an ODS cartridge column. After the urine sample passed through the ODS cartridge, the cartridge was added with 6mL of methanol elute, which was concentrated to 4mL. The concentrate was filtrated with a polytetrafluoroethylene (PTFE) filter of 0.45 mm pore size. Then the filtrates with PTFE was prepared to a sample for LC/MS/MS and LC/Q-ToF/MS after being concentrated to 1mL. Precursor ion scan by monitoring product ions of [M-H]－ of paraben molecules was applied for finding paraben conjugates. Precursor ions of m/z245 and 341 were found as candidate ions that produce [M-H]－ ion of ethyl-4-hydroxybenzoate (ethyl paraben). In order to confirm elemental compositions of the candidates, accurate masses of the m/z245 and 341 were respectively determined to be m/z245.0138 and 341.0875 in the mass error within 1.5ppm by LC/MS/MS. The elemental compositions of C9H9SO6 and C15H17O9 were respectively confirmed from the accurate masses of m/z245.0138 and 341.0875 within mass error of 1.5ppm. If the ions of C9H9SO6－ and C15H17O9－ are conjugates of ethylparaben, those would be respectively produced by esterization with chemicals of H2SO4 and C6H10O7 in elemental composition. From the compositions of H2SO4 and C6H10O7, sulfuric acid and glucuronic acid were retrieved as a top scored chemicals in a database(ChemSpider). The retrieved chemicals are well known as conjugating chemicals to parabens, and the retention times of the C9H9SO6 and C15H17O9 peaks were respectively agreed with those estimated from the logKow values of ethylparaben conjugates of sulfuric acid and glucuronic acid. Then we concluded that the ions of C9H9SO6－ and C15H17O9－ were [M-H]－ of ethylparaben conjugates of sulfuric acid and glucuronic acid, respectively. With the similar manner, some of other conjugating chemicals were estimated.

Detection of Histamine in Fish and Fishery Products in Osaka Prefecture (Fiscal 2015 Report).

Histamine food poisoning is caused by ingestion of spoiled fish containing high levels of histamine. This paper reports cases in which histamine was detected in Osaka prefecture in fiscal year 2015 in a survey of fish and fishery products on the market and the food poisoning. A suspected case of histamine food poisoning was also evaluated to investigate the cause and minimize further problems. Histamine in food was separated on SPE cartridge columns, and analyzed after derivatization with fluorescamine by means of HPLC-FL. Histamine was detected in some fishery products on the market and in food that had caused poisoning. The samples in which histamine was detected were semi-dried whole round herring (Urumeiwashi-maruboshi), mackerel (Saba) and sardine dumpling (Iwashi-tsumire). These foods were the main causes of histamine food poisoning according to the report of the Ministry of Health, Labour and Welfare, Government of Japan.

Rapid and highly sensitive analysis of benzodiazepines and tandospirone in human plasma by automated on-line column-switching UFLC-MS/MS.

A high-throughput method was developed for the detection of 31 benzodiazepine drugs and tandospirone in human plasma by on-line column-switching ultra-fast liquid chromatography-tandem mass spectrometry. Plasma samples (100μl) spiked with the 32 drugs and oxazepam-d5 (internal standard) were diluted with 300μl of 13.3mM ammonium acetate/acetonitrile (33:67, v/v). After centrifugation and filtration, the clear supernatant was injected directly onto the extraction column (Oasis HLB cartridge column). The following procedure was fully automated. The analytes retained on the extraction column were eluted by backflushing of the extraction column and introduced into an analytical column (SUMIPAX ODS D-Swifter column, 30mm×3.0mm i.d.; particle size 2μm) by column switching. Quantification was performed by multiple reaction monitoring with positive-ion electrospray ionization. Distinct peaks appeared for each drug and the internal standard on each channel within 7min, including the extraction time. All drugs spiked into plasma showed recoveries of 83-95%. The regression equations for the 32 drugs showed excellent linearities in the range of 50-2000pg/ml of plasma and the limits of detection ranged from 20 to 50pg/ml. The lower and upper limits of quantitation were 50-100ng/ml and 2000pg/ml, respectively. Intra- and interday coefficients of variation for none of the drugs were greater than 13.6%. The accuracies of quantitation were 87-112%. The multiple reaction monitoring information-dependent acquisition of enhanced product ions method enabled the quantification and confirmation of diazepam, triazolam, and lorazepam obtained from actual plasma.

Purification of Flavonoids from Chinese Bayberry (Morella rubra Sieb. et Zucc.) Fruit Extracts and α-Glucosidase Inhibitory Activities of Different Fractionations.

Chinese bayberry (Morella rubra Sieb. et Zucc.) fruit have a diverse flavonoid composition responsible for the various medicinal activities, including anti-diabetes. In the present study, efficient simultaneous purification of four flavonoid glycosides, i.e., cyanidin-3-O-glucoside (1), myricetin-3-O-rhamnoside (2), quercetin-3-O-galactoside (3), quercetin-3-O-rhamnoside (4), from Chinese bayberry pulp was established by the combination of solid phase extract (SPE) by C18 Sep-Pak® cartridge column chromatography and semi-preparative HPLC (Prep-HPLC), which was followed by HPLC and LC-MS identification. The purified flavonoid glycosides, as well as different fractions of fruit extracts of six bayberry cultivars, were investigated for α-glucosidase inhibitory activities. The flavonol extracts (50% methanol elution fraction) of six cultivars showed strong α-glucosidase inhibitory activities (IC50 = 15.4–69.5 μg/mL), which were higher than that of positive control acarbose (IC50 = 383.2 μg/mL). Four purified compounds 1–4 exerted α-glucosidase inhibitory activities, with IC50 values of 1444.3 μg/mL, 418.8 μg/mL, 556.4 μg/mL, and 491.8 μg/mL, respectively. Such results may provide important evidence for the potential anti-diabetic activity of different cultivars of Chinese bayberry fruit and the possible bioactive compounds involved.

Matrix solid-phase dispersion followed by liquid chromatography tandem mass spectrometry for the determination of selective ciclooxygenase-2 inhibitors in sewage sludge samples

A straightforward single-step extraction method based on matrix solid-phase dispersion (MSPD), followed by high-performance liquid chromatography with hybrid quadrupole time of flight mass spectrometry (LC–QTOF-MS), was developed and optimized to determine five non-steroidal anti-inflammatory drugs (Valdecoxib, Etoricoxib, Parecoxib, Celecoxib and 2,5-Dimethylcelecoxib) in sewage sludge samples. The influence of different operational parameters on the extraction efficiency a well as in the matrix effects of the produced extracts was evaluated in detail. Under final working conditions, freeze dried samples (0.2g) were first soaked with 100μL of aqueous potassium hydroxide solution (60%, w/v), mixed with 1g of anhydrous sodium sulfate and dispersed with 1g of Florisil. This blend was transferred to the top of a polypropylene column cartridge containing 3g of silica. Analytes were recovered using 15mL of hexane/acetone (1:2, v/v) mixture. The extracts were concentrated by evaporation and reconstituted with 1mL of methanol/water (1:1, v/v), filtered and injected in the LC system. Quantification limits from 0.005 and 0.05ngg−1 and absolute recoveries between 86 and 105% were achieved. Results indicated the presence of two of the targeted COXIBs in real samples of sewage sludge, the highest average concentration (22ngg−1) corresponding to celecoxib. Moreover, the screening capabilities of the LC–QTOF-MS system demonstrated that the developed MSPD extraction procedure might be useful for the selective extraction of some other pharmaceuticals (e.g. amiodarone and their metabolite N-desethylamiodarone, miconazole, clotrimazole and ketoprofen) from sludge samples.

Purification of Pyridylaminated Oligosaccharides Using 1,2-Dichloroethane Extraction

Fluorescence derivatization of the oligosaccharides released from glycoconjugates is widely used for precise structural characterization. To ensure labeling of the oligosaccharides, a large excess of fluorescence reagents is usually added to the reaction tube. Therefore, any excess reagents and by-products of the labeling reaction should be removed by several column chromatographies, including using a cellulose cartridge or spin columns. However, these purification steps are often time-consuming, expensive, and laborious. In this study, we found that 1,2-dichloroethane extraction could effectively and easily purify pyridylaminated oligosaccharides with a high recovery rate.

Determination of Diphenylamine in Agricultural Products by HPLC-FL.

A method for the determination of diphenylamine in agricultural products was developed. Diphenylamine was extracted with acetonitrile from a sample under an acidic condition, passed through a C18 cartridge column, re-extracted with n-hexane, cleaned up on a PSA cartridge column, determined by HPLC with fluorescence detector and confirmed by liquid chromatography with tandem mass spectrometry. Average recoveries (n=5) from brown rice, corn, soybeans, potato, cabbage, eggplant, spinach, orange, apple and green tea were in the range from 76.7 to 94.9%, and the relative standard deviations were from 0.6 to 5.8% at concentrations equal to the maximum residue limits (MRLs). The quantification limits were 0.01 mg/kg, which is the uniform limit in the positive list system for agricultural chemical residues in food in Japan.

GC-대용량 주입장치와 SPE를 적용한 QuEChERS 잔류농약 분석법의 효율성 비교

본 연구는 STQ 분석법의 정확성(accuracy)과 재현성(reproducibility) 및 정제효과(efficiency)를 판별하고자 식품공전 다성분 동시 분석법 제 1법, QuEChERS 분석법과 회수율 시험 및 matrix effect의 조사를 실시하여 비교 분석하였다. 시험에 사용한 시료 및 장비는 국내 생산 대표 작물인 감자, 사과, 고추, 현미, 대두 5가지 작물을 대상으로 45종의 농약 성분을 기체 크로마토그래프(Gas chromatograph)로 분석하였다. 3가지 분석 방법에 대한 다종 혼합 농약의 정밀성을 판단하기 위해 표준검량곡선을 작성한 결과 <TEX>$R^2$</TEX> 값은 0.990 이상으로 높은 직선성을 보였고 분석 장비의 최소검출량은 0.1 ng이었다. 각각의 분석법에 따른 회수율 시험의 상대표준편차(Relative standard deviation, RSD)는 30% 이내로 요구 조건을 충족하였으며 다성분 동시 분석법 제 1법 89.13%, QuEChERS 분석법 92.45%, STQ 분석법 85.28%의 평균 회수율을 보였다. 또한 5가지 시료에 대한 45종 농약성분의 평균 matrix effect는 다성분 동시 분석법 24.61%, QuEChERS 분석법 23.98%, STQ분석법 11.24%로 나타났다. 특히 STQ 분석법은 QuEChERS 분석법으로 추출한 시료 용액을 고상의 <TEX>$C_{18}$</TEX>, PLS, PSA cartridge column을 차례로 통과하여 용출 정제하는 방법으로 전처리 소요 시간이 짧고 용이하며 높은 정제효과를 보였다. 그러나 전처리 과정에서 농축과정의 생략으로 소량의 추출용매를 분취하여 분석하기 때문에 분석방법의 검출한계(method detection limit, MDL)가 높아지는 문제가 발생하는데, 이를 보완하기 위해 시료의 대량 주입으로 검출한계를 낮추고자 하였다. 대용량 주입장치(large volume injector, LVI)를 이용하여 STQ 분석법을 적용한 분석 결과 표준검량곡선은 0.990 이상의 <TEX>$R^2$</TEX> 값으로 높은 직선성을 보였고, 검출한계는 0.01 mg/kg 수준이었다. 회수율 시험 결과 91.84%의 평균 회수율을 보였으며 2수준 3회 반복 처리에 따른 상대표준편차는 30% 미만이었고 평균 matrix effect는 17.90%으로 높은 재현성과 정확성, 정제 효과를 나타내었다. This study was conducted to compare STQ method, multi-residue method in Korean food code and QuEChERS method for validated selected and accuracy, reproducibility and efficiency. A total of 45 selected and targeted pesticides were the analyzed by GC and 5 of them were crops (apple, potato, green pepper, rice, soy bean). <TEX>$R^2$</TEX> values were calculated in the standard calibration curve was over 0.990. Recovery tests were performed by three replications in two levels and the relative standard deviation of the repeated experiments was less than 30%. The average percentage of recoveries in the multi-residue method in Korean food code was 89.13%, QuEChERS method was 92.45% and STQ method was 85.28%. In addition, matrix effects in multi-residue method in Korean food code was 24.61%, QuEChERS method was 23.98% and STQ method showed 11.24%. The STQ method is easy and showed high clean-up effect in extracting the sample solution than the QuEChERS method and clean-up with C18, PLS, PSA cartridge columns. A large volume of the sample was injected in order to compensable for the problem, that occurred due to high detection limit in the analyser. When the STQ method was applied using a large volume injector, the standard calibration curve showed a higher linearity <TEX>$R^2=0.990$</TEX>, and method detection limit was 0.01 mg/kg. It showed an average recovery of 91.84% and the relative standard deviations of three replications repeated in two level process was less than 30% and had an average matrix effect of 17.90%.

Development of a Ga-68 labeled triptorelin analog for GnRH receptor imaging

Abstract Optimized total synthesis, radiolabeling and quality control of [68Ga]-DOTA-Hyd-TRP as an efficient and possible PET radiotracer for GnRH receptor imaging in various tumors is of great interest. DOTA-Hyd-TRP was synthesized using solid phase peptide synthesis followed by conjugation to DOTA using pSCN-Bn-DOTA. [68Ga]-DOTA-Hyd-TRP was prepared using generator-based [68Ga]GaCl3 and DOTA-Hyd-TRP under optimized conditions for time, temperature, ligand amount, gallium content and column cartridge purification followed by proper formulation. The biodistribution of the tracer in rats was studied using tissue counting up to 120 min. [68Ga]-DOTA-Hyd-TRP was prepared at optimized conditions in 5–7 min at 95 ℃ followed by separation using C18 cartridge (radiochemical purity ≈ 99 ± 0.88% ITLC, &gt; 99% HPLC, specific activity: 300 ± 15 MBq/nM). The biodistribution of the tracer demonstrated high kidney uptake of the tracer in 10–20 min as well as significant testicular uptake consistent with reported GnRH receptor mappings. Block test studies by triptorelin pretreatment of the animals prior to tracer administration demonstrated significant specific uptake in receptor rich organs including testes and stomach.