同位素稀释液相色谱串联质谱法测定血清肌酐

目的 建立一种使用同位素稀释液相色谱串联质谱法(ID-LC/MS/MS)测定血清肌酐的候选参考方法.方法 以[2H3]肌酐为内标,用无水乙醇沉淀血清中的蛋白质,用氯仿纯化上清液,用液相色谱串联质谱分离测定,以包括法定量.结果 血清肌酐测定的批内、批间和总变异系数的平均值分别为0.57%(范围0.52%～0.61%)、0.43%(范围0.11%～0.59%)和0.73%(范围0.62%～0.83%).加样回收试验的回收率范围为99.09%～101.13%.分析两种参考物质SRM909b和SRM 967b,测定结果与认定值的偏差小于0.4%.结论 建立了ID-LC/MS/MS法测定血清肌酐的方法,方法准确、精密、简便,可望作为血清肌酐测定的参考方法.     

同位素稀释液相色谱串联质谱法测定血清睾酮

目的建立一种用同位素稀释液相色谱串联质谱法(ID-LC/MS/MS)测定血清睾酮的候选参考方法。方法以[16,17,17-d3]睾酮为内标,用重量法准确地与血清混合,用乙酸乙酯-正己烷混合溶剂提取,以羟丙基-β-环糊精水溶液对提取液作净化处理,用液相色谱串联质谱分析,质谱选择离子监测模式检测睾酮与内标的特定碎片离子,用包括法定量。结果血清睾酮测定的批内、批间和总变异系数(CV)的均值(范围)为0.84%(0.22%~2.00%)、1.01%(0.48%~2.37%)和1.37%(0.53%~3.09%)。参考物质ERM DA-345a和NIST SRM 971测定结果与认定值的平均偏差范围为-2.0%~+1.8%。结论用ID-LC/MS/MS建立了血清睾酮的测定方法,方法准确、精密、简便,有望作为血清睾酮测定的参考方法。     

同位素稀释液相色谱串联质谱法测定人血清尿酸

目的建立一种使用同位素稀释液相色谱串联质谱（ID-LC/MS/MS）测定人血清尿酸的候选参考方法。方法用[1,3]1-5N2尿酸作内标,与一定量的血清充分混匀,加入等量乙腈沉淀血清蛋白并提取尿酸,氯仿纯化上清液后用液相色谱串联质谱（LC/MS/MS）分离测定。优化LC/MS/MS的色谱条件,评价该法的精密度、回收率和偏倚,并计算不确定度。结果对3个浓度水平的室间质量评价用质控血清测定3批,批内、批间和总变异系数（CV）的均值（范围）分别为0.54%（0.44%-0.69%）、0.66%（0.45%-0.79%）和0.86%（0.66%-1.02%）。加样回收试验回收率范围为98.38%-102.64%。美国国家标准与技术研究所（NIST）标准物质SRM 909b-Ⅰ、Ⅱ的测定均值与靶值的偏倚分别为0.04%和0.25%。3种质控血清的相对扩展不确定度分别为1.80%、2.19%和2.04%。结论建立的ID-LC/MS/MS测定血清尿酸的方法精密、准确,有望作为血清尿酸测定的参考方法。     

血清醛固酮候选参考测量程序的建立及性能评估

目的建立基于同位素稀释液相色谱-串联质谱(ID-LC-MS/MS)的血清醛固酮候选参考方法。方法以甲基叔丁基醚为萃取剂,采用液液萃取方式进行样本前处理。以醛固酮-2H7为内标,采用电喷雾离子源(ESI)负离子模式建立检测血清醛固酮的ID-LC-MS/MS方法,并对方法的准确度、精密度、灵敏度、线性等基本分析性能进行验证。结果 ID-LC-MS/MS测定血清醛固酮的线性范围为0.08～3.55 nmol/L,检测限和定量限(LOQ)分别为0.012 nmol/L和0.045 nmol/L。批内和批间变异系数(CV)分别为5.0%和4.1%。平均加标回收率为98.52%～100.14%。测定国际临床化学和检验医学联合会参考实验室外部质量评价计划(RELA)样本的结果偏移1.6%。结论建立的测定血清醛固酮的ID-LC-MS/MS方法准确、精密,有望作为测定血清醛固酮的参考方法。     

同位素稀释液相色谱串联质谱法测定血清总胆固醇

目的建立同位素稀释液相色谱串联质谱（LC／MS／MS）测定血清总胆固醇的方法。方法血清样品中加入[3，4-^13 C2]-胆固醇作内标，用氢氧化钠水解血清胆固醇酯为胆固醇，用三氧化铬—硫酸氧化胆固醇为胆甾-4-烯-3，6-二酮，用LC／MS／MS分析胆固醇氧化产物，采用大气压化学电离源，用多反应监测（MRM）模式和选择离子监测（SIR）模式检测，用修正标准曲线法对血清样品进行定量。结果两种检测模式的峰面积比与胆固醇浓度的线性相关系数均大于0．9999。MRM模式测定血清总胆固醇的平均批内变异系数（CV）为0．95％（范围0．92％～0．99％），平均总CV为0．86％（0．82％～0．89％）；SIR模式平均批内CV为0．64％（0．54％～0．77％），平均总CV为0．69％（0．62％～0．81％）。测定国际或国家标准物质结果与靶值的平均偏差在MRM模式下为0．23％（0．14％～1．00％），SIR模式为0．24％（0．07％～1．27％）。结论成功建立了LC／MS／MS测定血清总胆固醇的方法，方法特异、精密、简便，可望用作血清胆固醇测定的参考方法。     

同位素稀释液相色谱串联质谱法测定血清葡萄糖

目的 建立一种使用同位素稀释液相色谱串联质谱法(ID-LC/MS/MS)测定血清葡萄糖的候选参考方法.方法 以[~(13)C_6]葡萄糖为内标,用重量法准确地与血清混合,除去蛋白后在碱性条件下与1-苯基-3-甲基-5-吡唑酮反应,用LC/MS/MS测定葡萄糖和内标衍生产物,以包括法定量.结果 血清葡萄糖测定的批内、批间和总变异系数的平均值分别为0.36%(范围0.28%-0.42%)、0.47%(范围0.20%-0.67%)和0.61%(范围0.42%-0.76%).加样回收试验的回收率范围为99.0%-100.9%.分析参考物质SRM 965a,测定结果与认定值的平均偏差为-0.20%(范围-0.39%-+0.11%).结论 建立了ID-LC/MS/MS法测定血清葡萄糖的方法,方法准确、精密、简便,可望作为血清葡萄糖测定的参考方法.     

人血浆中血管紧张素Ⅱ候选参考方法的建立

目的建立用同位素稀释液相色谱串联质谱(ID-LC/MS/MS)测定人血浆中血管紧张素Ⅱ的候选参考方法, 并对方法性能进行评价。方法以[13C6-15N]-血管紧张素Ⅱ为内标, 重量法准确称取血浆及一定量内标混合, 同时加入酶抑制剂, 经硫酸锌溶液蛋白沉淀、反相固相萃取板处理, 用液相色谱串联质谱分析, 质谱选择多反应离子监测模式检测血管紧张素Ⅱ及内标的特定离子碎片。按照ISO15193要求对所建方法进行线性、灵敏度、精密度、回收率等性能评估及不确定度的评价。结果血管紧张素Ⅱ在10～1 000 pg/g范围内线性良好(r=0.999 5), 检测下限7.68 pg/g, 加标回收率范围为97.14%～102.85%, 批内不精密度≤3.21%, 批间不精密度≤2.96%, 总不精密度≤3.67%。结论用同位素稀释液相色谱串联质谱建立了血浆血管紧张素Ⅱ的检测方法, 该方法准确可靠, 有望成为血浆中血管紧张素Ⅱ测定的参考方法。     

同位素稀释质谱法在美国CDC-CRMLN计划中的比对结果分析

目的总结并回顾性分析同位素稀释质谱法在美国疾病预防控制中心(CDC)胆固醇参考方法实验室网络(CRMLN)中的比对结果,为我国血脂测定提供质量保证。方法采用我国建立的同位素稀释液相色谱串联质谱(ID-LC/MS/MS)测定血清总胆固醇(TC)和三酰甘油(TG)的方法参加CRMLN比对。2016年之前每3个月1次,每次4种样品,测定2批。2016年之后每半年比对1次,每次4种样品,测定2批。每次测定中至少同时测定2个有证标准物质作为质控品。结果 15次TC比对结果显示,本血脂参考实验室(以下简称"本室")平均CV为0.43%,CDC各参加实验室间CV为0.42%,本室与实验室间总体均值的偏移为0.22%,与CDC靶值的偏移为0.58%。15次TG比对结果显示,本室平均CV为0.62%,本室测定TG的结果与实验室间均值的偏移为-0.98%,与CDC靶值的偏移为-0.80%。TC和TG各60个比对结果中,98%(59/60)的TC测定CV满足CDC的精密度要求,70%(42/60)的测定满足TC准确度要求(TC:CV≤1%,偏移≤1%);92%(55/60)的TG测定准确度满足CDC的要求(TG:偏移≤2.55%)。结论 ID-LC/MS/MS测定血清TC和TG的方法在CRMLN比对中数据良好,与CDC及各网络实验室测定结果一致,有望在我国血脂标准化中发挥重要作用并为参考测量比对计划提供经验和技术支持。     

同位素稀释液相色谱串联质谱法测定血清可替宁

目的 建立一种同位素稀释液相色谱串联质谱(ID-LC/MS/MS)测定血清可替宁的方法,以评价不同吸烟状况健康人的吸烟暴露水平分布状况.方法 以[D3]-可替宁作内标,乙腈沉淀蛋白、离心后吸取上清液、氮气挥干、流动相重组,液相分离后进人串联质谱分析;然后,采用多离子反应监测模式,以标准品制作标准曲线,结合同位素内标法定量建立同位素稀释液相色谱串联质谱法.用以对0 68、48.42、94.34、250.95、287.04 μg/L 5个水平血清样本进行5次重复分析,每次每种血清重复分析3份,以考察方法的精密度;同时测定与评价血清样本添加不同浓度标准品的加样回收率和样本在常温、4℃、-80℃保存的稳定性,以及2010年10月至12月期间94名健康志愿者在不同吸烟状况下的血清可替宁分布情况.并用Mann-Whitney U检验分析60名非吸烟、14名戒烟与20名吸烟健康志愿者血清可替宁含量的差异.结果 用ID-LC/MS/MS检测血清可替宁在本试验条件下分离良好,无内源性物质的干扰,具有较好的特异性;血清可替宁、内标峰面积比与可替宁浓度的线性相关系数≥0.9993;测定5个水平血清样本的总变异系数(CV)分别为4.71％、1.40％、1.98％、1.10％和1.03％;批内CV分别为2.19％、0.78％、0.75％、0.65％和0.67％,ID-LC/MS/MS的检测限(LOD)和定量限(LOQ)分别为0.013和0.050 μg/L,具有较高的灵敏度;3次试验的加样回收率范围为99.22％ ～ 102.67％;样本在常温条件下放置2d、4 ℃放置7d以及-80℃冻存保存3个月测定结果的准确度为99.28％～ 100.87％,批间CV均＜5％.检测94名健康人血清可替宁水平呈偏态和尖态分布(偏度2.71,峰度6.65),其中,20名吸烟者的可替宁浓度为116.40 (63.17 ～241.12) μg/L,14名已成烟者为0.67 (0.15～0.95) μg/L,60名非吸烟者为0.22 (0.15 ～0.42) μg/L;已戒烟者(Z=-2.12,P＜0.05)和吸烟者(Z=-6.67,P＜0.001)血清可替宁浓度分别显著高于非吸烟者.结论 建立的ID-LC/MS/MS测定血清可替宁方法操作简便、特异、灵敏,可望在吸烟暴露水平评价及暴露与疾病发生危险的研究中提供有效技术平台.     

同位素稀释液相色谱串联质谱法测定人血清中5-甲基四氢叶酸

目的建立测定人血清中5-甲基四氢叶酸的同位素稀释液相色谱串联质谱法(ID-LC/MS/MS)。方法对5-甲基四氢叶酸纯品定性分析后,用两种不同原理(质量平衡法和定量核磁共振法)的定值方法测定纯品纯度,再以5-甲基四氢叶酸同位素标记物(~(13)C_5-5-甲基四氢叶酸)为内标物,用电喷雾三重四级杆串联质谱多重反应监测模式对6例相同水平浓度的血清进行定值及不确定度评定,并对方法的精密度、正确度、检测限、定量限进行考察。结果定性分析确认样品主成分后,质量平衡法与定量核磁共振法测定5-甲基四氢叶酸纯品的纯度为76.65%;人血清5-甲基四氢叶酸定值结果为8.22 ng/m L,扩展不确定度为0.54 ng/m L;方法检测限为0.05 ng/m L,定量限为0.50 ng/m L,重复性与期间精密度的变异系数(CV)均在5.0%以内,用国际标准物质NIST SRM 1955进行正确度验证,3个水平测量结果均在认定值±扩展不确定度范围内。结论建立了测定人血清中5-甲基四氢叶酸的ID-LC/MS/MS法,该法特异性好,灵敏度高,可准确测定人血清中5-甲基四氢叶酸的含量。     

高效液相色谱测定血清甘油三酯的研究——一种参考方法的建议

目的　建立特异、精密的血清总甘油和游离甘油测定方法 ,以便甘油三酯测定标准化。方法　以 1,2 ,4 丁三醇作内标 ,用柱前衍生高效液相色谱技术分析血清皂化前后的甘油含量 (两者分别代表血清游离甘油和总甘油浓度 )。结果　测定总甘油相对不精密度小于 2 % ,游离甘油小于 4% ;总甘油平均回收率 10 0 0 % ,游离甘油 99 7% ,与同位素稀释 /质谱法的相对偏差不大于± 2 %。结论方法特异、精密、简单 ,可望用作血清甘油三酯测定参考方法。     

血清尿素同位素稀释气相色谱质谱法的建立和研究

目的 建立一种基于同位素稀释/气相色谱/质谱技术(isotope dilution/gas chromatography/mass spectrometry,ID/GC/MS)的血清尿素候选参考方法.方法 以[13C,15N2]尿素为内标,用无水乙醇沉淀、去除血清中的蛋白类物质,依次使用丙二醛-二甲基缩醛和N-甲基-(三甲基硅烷基)-三氟乙酰胺(MSTFA)将尿素衍生成为三甲基硅烷氧基嘧啶,用气相色谱/质谱(GC/MS)分析衍生产物,以包括法定量.结果 血清尿素测定的批内、批间和总变异系数的平均值分别为0.38%(范围0.12%～0.47%)、0.62%(范围0.49%～0.87%)和0.73%(范围0.51%～0.93%),回收率范围为99.37%～100.95%,分析美国国家标准和技术研究院(NIST)2个水平的血清标准物质SRM 909b,测定结果与靶值的偏差小于0.2%.结论 建立了ID/GC/MS技术测定血清尿素的方法,方法准确、精密、简便,可望作为血清尿素测定的参考方法.     

Precision of glucose measurements in control sera by isotope dilution/mass spectrometry: proposed definitive method compared with a reference method

This improved isotope-dilution gas chromatographic/mass spectrometric (GC/MS) method, in which [13C]glucose is the internal standard, meets the requirements of a Definitive Method. In a first study with five reconstituted lyophilized sera, a nested analysis of variance of GC/MS values indicated considerable among-vial variation. The CV for 32 measurements per serum ranged from 0.5 to 0.9%. However, concentration and uncertainty values (mmol/L per gram of serum) assigned to one serum by the NBS Definitive Method (7.56 +/- 0.28) were practically identical to those obtained with the proposed method (7.57 +/- 0.20). In the second study, we used twice more [13C]glucose diluent to assay four serum pools and two lyophilized sera. The CV ranged from 0.26 to 0.5% for the serum pools and from 0.28 to 0.59% for the lyophilized sera. In comparison, results by the hexokinase/glucose-6-phosphate dehydrogenase reference method agreed within acceptable limits with those by the Definitive Method but tended to be slightly higher (up to 3%) for lyophilized serum samples or slightly lower (up to 2.5%) for serum pools.     

反相高效液相色谱紫外法检测人血清尿酸

目的探讨日本临床化学会(JSCC)推荐的检测人血清尿酸(UA)的反相高效液相色谱紫外(HPLC-UV)法是否可作为候选参考方法来验证同位素稀释质谱法、评价常规方法。方法对反相HPLC-UV法进行复现并进行方法学评价。观察尿酸酶处理人血清样本后的色谱以评价其特异性;检测系列标准液的UA水平并绘制标准曲线,观察线性范围;用朗道公司质控品评价精密度;用UA标准液评价回收率;分别用有证参考物SRM 909b(Ⅰ和Ⅱ)、国家一级标准物质GBW 09176、GBW 09175、GBW 09174评价正确度,并与2008年国际临床化学与检验医学联合会(IFCC)参考实验室RELA(ring trials for reference labora-tories)结果进行比对;用改良Bland-Altman图评价5种常规检测系统与反相HPLC-UV法间的偏差。结果尿酸酶处理后UA色谱峰消失;本法的线性范围为2.08～1 785μmol/L;批内变异系数(CV)均<0.3%,批间CV均<0.4%,日间CV均<2.3%,总CV均<2.7%;平均相对回收率为96.0%～100.6%;与SRM909bⅠ和Ⅱ靶值的偏移分别为-2.5%、-2.3%;与GBW09176、GBW 09174、GBW 09175靶值的偏移分别为0.29%,-0.74%和0.06%;与参加RELA比对的另3家实验室的平均值进行比较,水平1偏移为0.35%,水平2为-0.69%;Hitachi、Beckman Coulter、Roche、Dade、Vitros常规检测系统检测人血清UA与反相HPLC-UA法的相关系数分别为0.998 9、0.996 5、0.999 2、0.999 2和0.998 7,与反相HPLC-UA法的偏差均小于5%的生物学变异。结论本法特异、简便、快速,精密度好,正确度高,与具有良好溯源的常规测定系统具有良好的相关性和一致性,可推荐作为人血清UA测定的候选参考方法。     

Determination of folate vitamers in human serum by stable-isotope-dilution tandem mass spectrometry and comparison with radioassay and microbiologic assay

BACKGROUND: Current clinical methods for folate give different results and cannot measure the various forms of folate. We developed an isotope-dilution tandem mass spectrometric method coupled to liquid chromatography (LC/MS/MS) as a candidate reference method for 5-methyltetrahydrofolic acid (5MeTHF), 5-formyltetrahydrofolic acid (5FoTHF), and folic acid (FA) in human serum. METHODS: We quantitatively isolated folates from 275 microL of serum with a phenyl solid-phase extraction cartridge, then detected and quantified them in stabilized serum extracts by positive-ion electrospray ionization LC/MS/MS. We used an isocratic mobile phase of acetic acid in organic solvent on a C(8) analytical column. (13)C-labeled folates were used as internal standards. RESULTS: Limits of detection in serum were 0.13 (5MeTHF), 0.05 (5FoTHF), and 0.07 (FA) nmol/L. Within- and between-run imprecision (CV) was <7% for 5MeTHF and <10% for 5FoTHF at concentrations >0.5 nmol/L, and <10% for FA at concentrations >2.0 nmol/L. Total folate (TFOL) concentrations determined by competitive protein binding radioassay were approximately 9% lower than results obtained with LC/MS/MS. The microbiologic assay gave approximately 15% higher TFOL results with FA calibrator and no difference with 5MeTHF calibrator. The mean (SD) [range] TFOL in 42 sera was 35.5 (17.8) [6.5-75.6] nmol/L. Thirty-two samples with TFOL <50 nmol/L had, on average, 93.3% 5MeTHF, 2.3% FA, and 4.4% 5FoTHF. Ten samples with TFOL >50 nmol/L had, on average, 81.7% 5MeTHF, 15.7% FA, and 2.5% 5FoTHF. CONCLUSIONS: This stable-isotope-dilution LC/MS/MS method can quantify 5MeTHF, 5FoTHF, and FA in serum. Currently used clinical assays agree with this candidate reference method.     

International Standard for serum vitamin B(12) and serum folate: international collaborative study to evaluate a batch of lyophilised serum for B(12) and folate content.

BACKGROUND: Vitamin B(12) and folate measurements in serum show wide inter-methodology variability. This variability appears to be due in part to the lack of standardisation against internationally accepted reference materials. Pooled human serum, lyophilised in ampoules and designated 03/178, was therefore evaluated by 24 laboratories in seven countries for its suitability to serve as an International Standard (IS) for B(12) and folate. METHODS: IS 03/178 was assayed using a range of commercial analysers, microbiological assays and, for folate, candidate reference methods based on liquid chromatography coupled to isotope-dilution tandem mass spectrometry (LC/MS/MS). RESULTS: Mean vitamin B(12) and folate values for reconstituted 03/178 across all laboratories and methods were 480 pg/mL [coefficient of variation (CV) 12.8%] and 5.52 ng/mL (CV 17.1%), respectively. The total folate content of reconstituted 03/178, determined using LC/MS/MS, was 12.1 nmol/L (equivalent to 5.33 ng/mL), made up of 9.75 nmol/L 5-methyl tetrahydrofolic acid (5MeTHF; CV 5.5%), 1.59 nmol/L 5-formyl tetrahydrofolic acid (5FoTHF; CV 4.2%) and 0.74 nmol/L folic acid (FA; CV 31.6%). The inclusion of three serum samples in the study with different B(12) and folate levels demonstrated a considerable reduction in inter-laboratory variability when the B(12) and folate content of the samples was determined relative to the IS 03/178 rather than to the analyser calibration. IS 03/178 demonstrated satisfactory long-term stability in accelerated degradation studies. CONCLUSIONS: Use of IS 03/178 to standardise serum B(12) and folate assays reduced inter-laboratory variability. The World Health Organization (WHO) Expert Committee on Biological Standardisation established 03/178 as the first IS for serum vitamin B(12) and serum folate, with assigned values of 480 pg/mL of vitamin B(12) and 12.1 nmol/L folate when the lyophilised contents of the ampoule are reconstituted with 1 mL of water.     

How to make things work again--troubleshooting using the GC-IDMS determination of triacylglycerols as an example

This article describes the process of "repairing" a method which has gone out of control, using the gas-chromatographic isotope-dilution mass spectrometric (GC-IDMS) determination of total glycerides in serum, measured as glycerol. The original method used 13C2-glycerol as aqueous internal standard and 12C-tripalmitin dissolved in toluene as external standard. The modified method used tripalmitin as internal and external standard, the former being labelled uniformly on the glycerol moiety of tripalmitin (13C3-tripalmitin). In addition, glycerol-free human serum albumin was added to the external standards to "trap" the glycerol physically during evaporation of the extraction solvent after alkaline hydrolysis. The modified method was more stable than the original one and the intensity of the MS-signal in the modified method was at least 100 times stronger in the external standards than in the original method. The precision of the modified method in measuring total glycerides in serum samples (as total glycerol) was better than in the original method, the coefficients of variation being under 1.5% at concentrations between 0.8 and 3.5 mmol/l.