Quantification of SARS-CoV-2 spike and nucleocapsid proteins using isotope dilution tandem mass spectrometry

The emergence and subsequent global outbreak of the novel coronavirus SARS-CoV-2 prompted our laboratory to launch efforts to develop methods for SARS-CoV-2 antigen detection and quantification. We present an isotope dilution mass spectrometry method (IDMS) for rapid and accurate quantification of the primary antigens, spike and nucleocapsid proteins. This IDMS method utilizes liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze sample tryptic digests for detection and quantification of selected conserved peptides of SARS-CoV-2 spike and nucleocapsid proteins. The IDMS method has the necessary attributes to be successfully utilized for accurate quantification in SARS-CoV-2 protein-based vaccines and as targets of rapid diagnostic tests. Absolute quantification was achieved by quantifying and averaging 5 peptides for spike protein (3 peptides in the S1 subunit and 2 peptides in the S2 subunit) and 4 peptides for nucleocapsid protein. The overall relative standard deviation of the method was 3.67% for spike protein and 5.11% for nucleocapsid protein. IDMS offers speed (5 h total analysis time), sensitivity (LOQ; 10 fmol/µL) and precision for quantification of SARS-CoV-2 spike and nucleocapsid proteins.     

超高效液相色谱-串联质谱法同时检测消毒产品中13种抗生素

目的采用超高效液相色谱-串联质谱技术,建立消毒产品中8类13种抗生素的检测方法。方法样品经甲醇或乙腈提取后,经Waters HSS T3色谱柱(100 mm×2.1 mm,1.8μm)分离,三重四级杆串联质谱仪检测。结果13种选定的抗生素在4~100μg/L范围内线性关系良好,相关系数均大于0.991,检出限为2~25μg/kg。在3种不同剂型的消毒产品中,低、中、高3个浓度加标水平的回收率为71.2%~130.4%,相对标准偏差均小于11.3%,满足消毒产品中抗生素违法添加的检测要求。运用建立的方法,在一份膏霜剂型的消毒产品中检测出氧氟沙星,含量为21.1 mg/kg,其余样品中均未检出相关物质。结论该方法简单、可靠、重现性好,覆盖的抗生素种类多。     

同位素稀释-气相色谱串联质谱法测定啤酒中4种亚硝胺类化合物

目的 建立啤酒中4种N-亚硝胺类化合物（N-亚硝基二甲胺、N-亚硝基二乙胺、N-亚硝基二丙胺、N-亚硝基二苯胺）的同位素稀释固相萃取-气相色谱串联质谱测定方法。 方法 样品经活性炭固相萃取小柱富集、二氯甲烷洗脱,洗脱液经氮吹浓缩定容后,采用INNOWAX毛细管色谱柱分离,多反应监测（MRM）模式检测,同位素稀释内标法定量。 结果 各物质在5 μg/L~200 μg/L范围内线性关系良好,相关系数均大于0.9995。方法的检出限为0.03-0.10 μg/L,定量限为0.10~0.33 μg/L。不同水平的加标回收率为72.1%~100.3%,相对标准偏差为1.5%~9.5%（n=6）。 结论 该方法操作简单,灵敏度和准确度高,适用于啤酒中4种N-亚硝胺类化合物的测定。     

串联质谱技术在脂肪酸氧化代谢病诊断中的应用研究

目的探讨利用串联质谱技术检测干血滤纸片中酰基肉碱水平,诊断脂肪酸氧化代谢病。方法对象为2941例临床遗传性代谢病高危儿童,利用串联质谱技术检测患儿干血滤纸片中酰基肉碱水平,结合临床资料和常规生化结果,进行脂肪酸氧化代谢病诊断。结果诊断了14例脂肪酸氧化代谢病(0.5%),其中肉碱棕榈酰转移酶Ⅰ缺乏症1例,肉碱棕榈酰转移酶Ⅱ缺乏症1例,短链酰基辅酶A脱氢酶缺乏症1例,中链酰基辅酶A脱氢酶缺乏症7例,极长链酰基辅酶A脱氢酶缺乏症2例,多种酰基辅酶A脱氢酶缺乏症2例。结论通过串联质谱技术检测干血滤纸片中酰基肉碱水平,可对部分脂肪酸氧化代谢病进行诊断。     

Immunoaffinity chromatography for purification of Salbutamol and Clenbuterol followed screening and confirmation by ELISA and GC-MS

Screening and confirmatory methods for the determination of Salbutamol (SAL) and Clenbuterol (CL) in swine urine were established. The polyclonal antibody against SAL was prepared, which was used to develop the indirect competitive enzyme-linked immunosorbent assay (ELISA) with the limit of detection of 0.5 ng/ml, and to prepare the immunoaffinity chromatography column. The immunoaffinity column could extract and purify SAL and CL simultaneously, with a binding capacity of 400 ng for SAL and 416 ng for CL. After purification, the swine urine samples were screened by ELISA for the presence of SAL and/or CL, and the positive samples were further confirmed and quantified by gas chromatography-mass spectrometry (GC-MS). The results showed that 95% of the positive samples were confirmed by GC-MS with various levels of SAL (1.1-4.6 ng/ml) and/or CL (1.9-229.1 ng/ml) residues in the incurred samples, and all the negative samples were confirmed with no SAL and/or CL residues.     

液相色谱质谱联用(LC-MS/MS)在天然化学成分分析中的应用Ⅰ.音喷离子化(SSI)与大气压化学离子化(APCI)对利血平的比较分析

报道应用 L C- MS/ MS,采用音喷离子化 (SSI)与大气压化学离子化 (APCI)对利血平的比较分析 ,应用这两种离子化方法比较所得的利血平的标准质谱 (MS)和二级质谱 (MS2 ) ,实验证明两种离子化方法所得结果完全一致     

Evaluation of Genetic Stability of Recombinant Human Factor VIII by Peptide Mapping and On-line Mass Spectrometric Analysis

Purpose. The genetic stability of a recombinant human factor VIII (rhFVIII) product expressed in Chinese hamster ovary cells (Recombinate) has been evaluated through comparisons of the protein produced at the beginning, middle and end of a typical production campaign. Methods. Recombinant human factor VIII was incubated with thrombin, the resulting four polypeptides were isolated by RP-HPLC, subjected to proteolysis with trypsin, and the peptide mixtures were resolved by RP-HPLC. Tryptic peptide mixtures were subjected to online mass spectrometric analysis using an electrospray ionization source interfaced to a quadrupole mass analyzer scanning from 1950–200 amu, and the peptide ion data were compared for three lots produced from the beginning, middle and end of a production campaign. Results. The UV elution profiles for each of the rhFVIIIa polypeptides were highly similar for factor VIII isolated from the beginning, middle and end of production. Total ion data from the peptide maps derived from three lots of rhFVIII were compared by MH¹⁺ values as a function of scan range. A total of 918 ions were analyzed for the four polypeptides of rhFVIII produced at the beginning, middle and end of a production campaign. The ions were detected at the same relative retention times, as indicated by the similar scan numbers for the three lots. Conclusions. These observations support that rhFVIII preparations produced from the beginning, middle and end of a production campaign were highly similar, and demonstrate genetic stability in the manufacturing process of Recombinate.     

Use of Stable Isotopes for Evaluation of Drug Delivery Systems: Comparison of Ibuprofen Release in Vivo and in Vitro from Two Biphasic Release Formulations Utilizing Different Rate-Controlling Polymers

Certain delivery systems are intended to release the active ingredient in different phases to obtain the desired therapeutic effect. For these formulations, such as a bilayer tablet, it is desirable to distinguish and measure the release of drug from the different phases simultaneously. Mass spectrometric methods were developed to measure three ibuprofen isotopomers in serum and two in dissolution fluid. The analytical methods were linear (r 0.992) over the concentration range of interest and recovery was greater than 99.2% for all isotopomers. Coadministration of [²H₀]ibuprofen, [²H₄]ibuprofen, and [²H₇]ibuprofen to male beagles demonstrated that the isotopomers were bioequivalent and verified the absence of any kinetic isotope effect due to deuterium incorporation (p = 0.286). These methods were then used to evaluate a bilayer tablet formulation composed of an immediate release layer of 100 mg [²H₄]ibuprofen and a sustained release layer with a drug load of 300 mg [²H₀]ibuprofen. Two different rate-controlling polymer matrices that provided similar in vitro dissolution profiles were compared in the sustained release phase, while the immediate release formulation remained the same. In male beagles, the HPMC matrix delivered a significantly greater amount of ibuprofen (p < 0.05). The AUC was threefold greater for HPMC (1067 ± 437 nmole * h/ml) versus EUDRAGIT^® (320 ± 51), and C_max was nearly four times greater (145 ± 62.1 nmole/ml for HPMC versus 37.9 ± 14.4 for EUDRAGIT^®). Although T_max for HPMC (3.4 ± 1.9 h) lagged behind EUDRAGIT^® (2.0 ± 0.82 h), the difference was not significant (p > 0.05). The immediate release layer was absorbed to the same extent as an oral solution (containing [²H₇]ibuprofen) that was administered concomitantly with the bilayer tablet. Using the stable isotope markers also demonstrated that the release rates of the two layers were independent of each other, both in vivo and in vitro. Stable isotope techniques are a useful tool in the development of biphasic release formulations since they can be used to determine proper drug load of each phase as well as the appropriate rate of release.     

Intrapulmonary gas mixing and dead space in artificially ventilated dogs

In this study we have investigated the effects of breath holding and of the physical properties of gases on four different respiratory dead spaces (V _D): the Fowler, the physiological, the washout and the inert gas dead space. The experiments were performed with dogs which were ventilated artifically with breathing patterns with different post-inspiratory breath holding times (t _a) of 0, 0.5, 1.0 and 2.0 s. Tracer amounts of acetone, ether and enflurane were infused continuously into a peripheral vein and a bolus of a mixture of krypton, Freon12 and SF₆ was introduced into the peritoneal cavity. After reaching steady state, samples of arterial blood, mixed venous blood and mixed expired air were taken simultaneously. From the partial pressures (P _a, P _¯V and P respectively) we determined the excretion (=P/P_¯V), retention (R=P_a/P_¯V) and the physiological dead space fraction (V _D,phys/V _T=(1 P/P_a) for each gas, where V _T is tidal volume. Further, we recorded the expirograms of the six tracer gases and of CO₂ from which the Fowler dead space fractions (V _D,Fowler/V _T) of the different gases were determined. Also the washout dead space fractions (V _D,washout/V _T) for He and SF₆ were determined as well as the inert gas dead space fraction (V _D,MIGET/V _T) with the use of the multiple inert gas elimination technique (MIGET).With the exception of V _D,phys/V _T for SF₆, all dead space fractions decreased with increasing t _a. V _D,phys/V _T for the poorly soluble gas SF₆ was considerably larger than V _D,phys/V _T for the remaining gases. For the highly soluble acetone V _Fowler/V _T was considerably smaller than V _D,Fowler/V _T for the other gases. V _{D,washout,SF6}/V _T was always larger than V _D,washout,He/V _T and V _D,Fowler,SF6/V _T. Further, V _D,phys/V _T was larger than V _D,Fowler/V _T for SF₆ and acetone. However, for gases with intermediate solubility in blood V _D,phys/V _T tended to be smaller than V _D,Fowler/V _T. We conclude that the respiratory dead spaces are affected by the breathing pattern and by the physical properties of gases, i.e. their diffusivity in alveolar gas and their solubility in blood or lung tissue.     

UV spectrometric and DC polarographic studies on apigenin and luteolin

Remarks on polyphenolic compounds has been arisen since past few years. The flavonoids appears to be the important groups of compounds with their capability to inhibit DNA damage, lipid peroxidation, to quench free radicals and, at least, anticarcinogenic and antiproliferative effects. On the other hand, their mechanism of action is still unexplained. Apigenin and luteolin are the most wide-spread flavones and they exhibited to be useful in chemoprevention. UV spectrometric and DC polarographic studies on these two compounds have been carried out with regard to changing pH. The most significant changes were observed at basic pH. These results could aid to elucidation of their mechanism of action as pH is one of the important factors for bioprocesses passing in living organisms.