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.     

串联质谱分析干血滤纸片中酰基肉碱质控

目的：串联质谱技术是近几年应用于临床检验的新技术，具有特异性强、灵敏度高，一次试验可检测数十种物质的优点。本文通过对近4年的质控结果进行分析，探讨影响检测结果的因素及应对措施。方法：美国CDC每年提供4批酰基肉碱质控干血滤纸片，酰基肉碱检测方法为取直径为3mm的质控干血滤纸片放入96孔聚丙烯板，经含酰基肉碱内标的甲醇萃取，盐酸正丁醇衍生后，进行串联质谱检测。分析本实验室质控结果与美国CDC检测结果的偏差及其他实验室质控结果（169个实验室的均值）与美国CDC检测结果的偏差之间的差异。结果：本实验室每次质控结果所有酰基肉碱均在美国CDC检测结果95％可信区间内，且每一批结果的临床评价与美国CDC质控临床评价完全一致。本实验室质控结果与美国CDC检测结果的偏差与其他实验室质控结果与美国CDC检测结果的偏差比较，无显著差异，丙酰基肉碱差异显著（Z=-2．638，P〈0．005），戊二酰基肉碱差异亦显著（Z=-2．482，P〈0．005）。结论：本实验室酰基肉碱质控结果，达到美国CDC的质控要求，丙酰基肉碱检测值偏高，其阳性判断切割值设定也相应增高，而戊二酰基肉碱检测值偏低，其阳性判断切割值设定也相应降低。     

Comparison between radial bone mineral density measured by single photon absorptiometry and histomorphometric bone mass parameters measured on iliac crest biopsies

Summary Bone mineral density (BMD) measured by single photon absorptiometry (SPA) with a Moolsgard 1100^® device on the distal and proximal part of the radius was compared with histomorphometric parameters measured on iliac crest biopsies in 37 patients suffering from various bone disorders. In the whole population, a good correlation was observed between the cancellous bone volume (Cn-BV/TV) measured on iliac crest biopsies and BMD from both the proximal part of the radius (r=0.76, p < 0.001) and the distal part of the radius (r=0.73, p < 0.001). Significant, although weaker correlations, were also found between the cortical width and the BMD from the distal part (r=0.37, p < 0.001) and the proximal part (r=0.44, p < 0.001) of the radius. In the 14 untreated osteoporotic patients, only a significant Spearman correlation was observed between the iliac Cn-BV/TV and the proximal radial BMD (r=0.69, p < 0.05). It is thus not clear, whether radial proximal BMD correctly indicates cortical bone density in osteoporotic patients or not. The large internal variability of each of the two investigated methods and the small group of osteoporotic patients might explain the lack of correlation between the two methods in this group.     

Comparisons of interval breast cancers with other breast cancers detected through mass screening and in outpatient clinics in Japan

In a nation-wide collaborative study on mass screening for breast cancer, we collected 152 cases of interval breast cancer diagnosed at 35 hospitals or clinics distributed throughout Japan. The definition of interval breast cancer used in the present study is "breast cancer cases which were diagnosed as having 'no malignant findings' in a previous screening for breast cancer but subsequently diagnosed as 'breast cancer' at a hospital or medical clinic within two years of the previous screening." The clinical stages and prognoses of these interval cancer were analyzed and compared with those of other breast cancers detected through mass screening and in outpatient clinics. In the clinical staging of interval breast cancer, Tis (non infiltrating cancer) accounted for only 2.1%, compared to 8.0% in cases detected through mass screening. At stage I 43.4% were interval breast cancers compared to 32.9% breast cancers detected through mass screening and 25.4% diagnosed in outpatient clinics. The stage differences between interval breast cancers and breast cancers detected through mass screening were not statistically significant. Five-year survival rates were 85.6% for interval breast cancers, 91.7% for breast cancers detected through mass screening and 84.7% for breast cancers diagnosed in outpatient clinics. Ten-year survival rates were 75.9, 80.5 and 78.1%, respectively, suggesting the interval breast cancer cases to show a similar prognosis to that of breast cancer cases diagnosed in outpatient clinics. The differences in five- and 10-year survival rates among the three groups were not statistically significant. From the present study we were not able to confirm the general belief of interval cancer being more aggressive in nature and showing a poorer prognosis than cancer detected through periodic screening. The reasons for this are discussed.     

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.