Development and evaluation of LC-MS/MS method for determining concentration of serum vancomycin / 临床检验杂志

Objective To establish a liquid chromatography-tandem mass chromatography ( LC-MS/MS) method for determination of vancomycin concentration in human serum and compare its methodological performance with chemiluminescence microparticle immuno-assay (CMIA). Methods The proteins in serum sample were precipitated by methanol and then vancomycin was eluted and separated on Agilent Poroshell 120EC C18 column (2.1 mm×50 mm, 2.7 μm) with mobile phase of methanol and water in a gradient percentage. Both phases of methanol and water contained 0.1% formic acid. The flow rate was 0.5 mL/min. Norvancomycin was applied as internal standard. Electrospray ionization source was applied and operated in positive ion mode of multiple reaction monitoring (MRM). A total of 112 serum samples collected from the patients taking vancomycin in our hospital, and the results were compared with those of CMIA. Results The method exhibited good linearty within the concentration range of 1 to 100 μg/mL (r2＝ 0.9964).The intra-and inter-day accuracy and precision were all satisfactory for the requirements of quantitative drug testing. No matrix effect and carry-over effect were observed. The results of Wilcoxon symbol rank test showed a difference with statistical significance was found between the serum con-centrations of vancomycin determined by LC-MS/MS and CMIA (P＜0.05), but strong positive correlation and good linear regression were shown between the two methods (Y＝1.06X－0.37, r＝0.986). Conclusion LC-MS/MS should be a cost-saving method superior to CMIA. Its results highly correlated with those of CMIA method. The advantages of LC-MS/MS on accuracy and precision obviously outperformed those of CMIA. Since all the results of LC-MS/MS are comparable to CMIA, this method should be promising to use in determining concentration of vancomycin in serum samples with high clinical value.

Comparison of HPLC and CMIA Method in Monitoring Concentration of Phenytoin in Epileptic Patients' Plasma / 医药导报

Objective To establish a high performance liquid chromatography (HPLC) method for determining phenytoin concentration in epilepsy patients' plasma,and compare this method with chemiluminescence microparticle immunoassay (CMIA),and to evaluate the consistency of the two methods.Methods HPLC and CMIA methods were applied to determine the plasma concentration of phenytoin in 60 epileptic patients,respectively.The difference of results was analyzed by two-side paired t-test,and then the correlation and consistency of the two methods were investigated with Passing-Bablok regression and Bland-Altman method.Results There was no significant difference between the results of the two methods (P ＞0.05).The regression equation of the determination results by HPLC (Y) and CMIA (X) was Y=0.992 9X +0.143 7 (R2 =0.992 6,n =60),which indicated the correlation of the two methods was good.Bland-Altman analysis showed that the consistency of the two methods for determining was good.Conclusion HPLC and CMIA method in monitoring plasma concentration of phenytoin have good correlation and consistency.Both methods can be used for therapeutic drug monitoring of phenytoin.

Application value of CMIA in HCV infection validation in low risk population / 国际检验医学杂志

Objective To detect the reactive samples of enzyme-linked immunosorbent assay (ELISA1) by chemiluminescence microparticle immunoassay (CMIA),and to analyze the application value of CMIA in HCV infection validation of blood donors.Methods Nucleic acid 3-item combined testing (NAT),another ELISA2,HCV antibody supplementary test(Western Blot test,WB) and CMIA test supplemented in blood samples of 102 ELISA1 anti-HCV reactive blood donors were retrospectively analysed.Results Among 102 blood donors of anti-HCV positive,32 cases (31.37%,32/102) were HCV RNA reactive samples,50 cases (49.02%,50/102) were ELISA2/WB reactive simultaneously.With CMIA NAT results as the reference standard,CMIA was poorly correlated with HCV RNA (Spearman correlation coefficient rs=0.395,P<0.01),and the consistency between them was weak by Kappa test (Kappa=0.270,P<0.01).With ELISA2/WB detection results as the reference standard,CMIA was highly correlated with the results(Spearman correlation coefficient rs=0.713,P<0.01),and which showed high consistency by Kappa test (Kappa=0.674,P<0.01).Conclusion CMIA as a detection method of protein label after HCV infection has great value in the HCV infection confirmation in low-risk population.

Falsely Elevated Tacrolimus Concentrations Using Chemiluminescence Microparticle Immunoassay in Kidney Transplant Patient / 대한이식학회지

Tacrolimus is one of the effective immunosuppressive drugs used after an organ transplant procedure. However, due to its narrow therapeutic range, its usefulness in preventing transplant rejection and minimizing nephrotoxicity is dependent on the monitoring of whole blood trough levels of tacrolimus. A 49-year-old kidney transplant recipient presenting with cough and general weakness was admitted to the hospital. Due to the patient's deeply compromised clinical condition, an immunosuppressive therapy was discontinued. Tacrolimus concentrations in the patient's whole blood samples were measured, using an automated chemiluminescent microparticle immunoassay (CMIA) instrument. Interference was suspected because tacrolimus concentrations after the discontinuation of tacrolimus dose were 20.9 and 18.2 ng/mL at day 2 and 3, respectively. Tacrolimus concentrations were 11.1 and 12.6 ng/mL, respectively, when re-tested using an antibody-conjugated magnetic immunoassay (ACMIA). We evaluated the relationship between the CMIA and ACMIA results, and calculated the expected values from the regression equation. Residuals were –8.4 and –4 ng/mL, respectively. There have been several cases with false detection of elevated tacrolimus concentrations using ACMIA; however, such falsely detected elevations using CMIA have rarely been reported. When unexpectedly high concentrations of tacrolimus are detected by CMIA in transplant patients, an immediate re-test using another technique might be necessary to rule out falsely elevated results.

Comparison and bias evaluation of two methods for detection of pepsinogen / 国际检验医学杂志

Objective To explore the consistency of chemiluminescence microparticle immunoassay(CMIA)reagent and particle‐enhanced turbidimetric immunoassay(PETIA) reagent for detecting pepsinogen(PG) ,so as to provide laboratory references for en‐suring the reliability of PETIA reagent in detecting PG .Methods According to the requirement of EP9‐A2 file made by the Nation‐al Committee for Clinical Laboratory Standards(NCCLS) ,taking PETIA as evaluating method and CMIA as reference method ,a to‐tal of 92 specimens collected from patients with various degrees of gastric atrophy were selected ,PETIA and CMIA reagents were utilized for bidirectional detection of PG .Then recorded test results of pepsinogenⅠ(PGⅠ) ,and PGⅠ /pepsinogenⅡ(PG Ⅱ) rati‐o ,and carried out method comparison and bias evaluation for the two kinds of reagents .Results The expected relative bias of detec‐tion results of PGⅠ and PGⅠ /PG Ⅱ ratio by using PETIA and CMIA reagents were acceptable within linear range of methods . Conclusion The results of PGⅠ and PG Ⅱ detected by using PETIA reagent could be accepted .

Performance evaluation of paramagnetic particles chemiluminescence micro-particle immunoassay for determination of serum vitamin B12 / 中国免疫学杂志

Objective:To evaluate the performance of paramagnetic particles chemiluminescence microparticle immunoassay ( CMIA) for detection of serum Vitamin B12 ( VitB12 ).Methods: Analysed CMIA system precision, accuracy, anti-interference, analytical measuring range( AMR) ,clinical reportable range ( CRR) and biological reference interval were evaluated,according to the clinical and laboratory standards institude ( CLSI) EP5-A2,EP15-A2,EP7-A2,EP6-A,C28-A3c guidelines.To assess the accuracy,we used the reference material SRM 1955 from national institute of standards and technology ( NIST ) and external quality assessment ( EQA) samples ( LN5-B and K-C) from CAP.Results:The precisions of within-run and between-run were less than standard of manu-facturer when the concentration of VitB12 was 108.84-874.43 pmol/L.The results of SRM1955 met the allowable range of the target val-ue.The results of EQA samples( K-C and LN5-B) also up to the CAP calibration and validation/linear evaluation error limits stipulated standards,and the results through linear verification when the concentration of VitB12 was 89-1 057 pmol/L.The 95% verification interval contains the specified value also.The relative deviation was less than external quality assessment standard from national center for clinical laboratory ( TEa:target value ±25%).Anti-interference evaluation showed without significant interferenc when TG ≤20 mmol/L,Bil ≤300 μmol/L VitC≤1.5 g/L to the VitB12 detection system ( CMIA).AMR validation showed determines the best fit equation was linear equation polynomial.There was the linear relationship when the concentration of VitB12 was 0-1 107 pmol/L.The upper limit of CRR was 110 700 pmol/L,the maximum dilution was 100 times.Biological reference interval validation showed that the overall level of VitB12 in this study reference individuals conform to the standard of manufacturer statement for the population,the overall level of VitB12 in female little higher than male,but no significant differences.Conclusion:Performance of CMIA for detection of serum VitB12 basically met needs of laboratory,which can provide reliable results of VitB12 for laboratory,provide information for the VitB12 status of population in the laboratory evaluation.