Random-access Immunoassay Research Articles

Elevated B-type natriuretic peptide level expression associated with acute myocardial infarction patients in Jammu population (India)

B-type natriuretic peptide (BNP) is a highly sensitive and specific indicator of the size of myocardial infarction, which can help in assessing the degree of cardiovascular risk. Elevated BNP levels in patients hospitalized for acute myocardial infarction (AMI) are associated with heart failure and mortality, and the measurements of BNP in a short-term period could be helpful to predict the future events. The role of short-term follow-up BNP level has not been established in the patients with AMI. This retrospective study was conducted on the patients admitted to the Government Medical College, Jammu (India). The analysis of blood EDTA sample was analysed for BNP and this test was performed by using a fully automated random access immunoassay analyser whose principle is based on micro-particle enzyme immunoassay (MEIA). The reference range of BNP is 0-100 pg mL-1. The study revealed a 90% BNP increase in AMI patients in comparison to the 10% increase in normal healthy ones. However, BNP showed elevated levels in healthy individuals suffering from renal insufficiency. The BNP was > 100 pg mL-1 in the majority of AMI patients while in controls BNP is <100 pg mL-1.

A 24-Hour Extended Calibration Strategy for Quantitating Tacrolimus Concentrations by Liquid Chromatography-Tandem Mass Spectrometry.

Tacrolimus has a low therapeutic index requiring strict control of whole blood concentrations. Although random access immunoassay platforms exist that rapidly provide quantitative values for tacrolimus, LC-MS/MS may provide more accurate quantitation. However, batch testing in many LC-MS/MS assays is not efficient, particularly when testing patients suspected of having tacrolimus toxicity. Extending calibration curve stability beyond the traditionally accepted single batch may facilitate improved turnaround time and reduce testing costs. A 24-h extended calibration of LC-MS/MS tacrolimus was designed and validated to reduce calibrator usage, improve turnaround time, and provide a more efficient workflow for urgent requests. Patient samples included in the study were extracted and assayed with coextracted calibrators and quality control in real time. The same patient samples were extracted again 24 h later without coextracted calibrators. The data acquired from the second patient sample extraction was applied to the original calibration curve acquired 24 h prior and compared to the data for the same samples coextracted with calibrators, creating a value set utilizing extended curve stability. A linear regression compared the results using the extended curve to the results of the coextracted acquisitions. This yielded a strong correlation between the 2 data populations, with a slope of 1.0061 and a correlation coefficient of >0.95. The average bias between original patient values and patient values 24 h later was 3.4% across all patient samples. Patient tacrolimus values were comparable when extracted within 24 h of calibration versus values coextracted with calibrators. Demonstrating comparability within 24 h of calibration allows the laboratory to provide rapid turnaround time for urgent samples without the need for an entirely new calibration curve.

Serum pregnancy-associated plasma protein A levels in the first, second and third trimester of pregnancy: relation to newborn anthropometric parameters and maternal tobacco smoking.

IntroductionThe purpose of this study was to evaluate the associations of the first, second and third trimester serum pregnancy-associated plasma protein A (PAPP-A) concentrations with neonatal anthropometric parameters. The effect of tobacco smoking during pregnancy on PAPP-A level was also studied.Material and methodsOne hundred and fifty healthy pregnant women were divided into smoking and tobacco-abstinent groups. Serum PAPP-A level was measured with the KRYPTOR rapid random-access immunoassay analyzer. The relationship between PAPP-A and newborn related outcome as well as markers of estimated intensity of cigarette smoking was evaluated by univariate and multivariate linear regression.ResultsPregnancy-associated plasma protein A concentration was positively correlated with birth weight in the first (β = 31.6; p < 0.001), second (β = 10.6; p < 0.05), and third (β = 4.6; p < 0.001) trimester of gestation. A significant association between PAPP-A and birth body length and head circumference in the second (β = 0.02; p < 0.05) and third trimester (β = 0.01; p < 0.01) was also found. The serum PAPP-A levels were significantly lower in the smoking than in the tobacco-abstinent group in each trimester of pregnancy (p < 0.001). The largest impact of the number of cigarettes smoked per day on PAPP-A level was found in the second (β = –1.2; p = 0.004) and third trimester (β = –2.6; p = 0.001).ConclusionsMaternal serum PAPP-A levels during gestation might be significant predictors for birth weight. Increased PAPP-A concentrations in the second and third trimester appeared to also be predictive for newborn body length and head circumference. Smoking alters maternal PAPP-A levels in all trimesters, with the greatest impact related to the number of cigarettes smoked per day.

Identification of respiratory viruses with a novel point-of-care multianalyte antigen detection test in children with acute respiratory tract infection

BackgroundRapid etiological diagnosis of a respiratory virus infection may have impact on antiviral and antibiotic therapy, patient cohorting, and prediction of the clinical course. Most point-of-care tests for detection of respiratory viruses have limitations in diagnostic performance and clinical usability. A novel, multianalyte point-of-care antigen detection test system (mariPOC®; ArcDia International Oy Ltd., Turku, Finland) detects eight respiratory viruses (influenza A and B viruses, respiratory syncytial virus (RSV), adenovirus, human metapneumovirus, and parainfluenza type 1, 2, and 3 viruses) from a single nasopharyngeal swab specimen by a fully automated, random-access immunoassay method. ObjectivesTo evaluate mariPOC® point-of-care test system in comparison with reverse transcription polymerase chain reaction (RT-PCR) in a pediatric emergency department setting. Study designProspectively collected samples from 158 children (mean age, 1.8 years) with respiratory symptoms and/or fever were analyzed both by mariPOC® and by multiplex RT-PCR. ResultsThe sensitivities and specificities (95% confidence intervals) of the mariPOC® test were for influenza A (n=7), 71% (38–100) and 100%; influenza B (n=22), 86% (72–100) and 98% (95–100); RSV (n=35), 89% (78–99) and 100%; adenovirus (n=12), 25% (1–50) and 97% (95–99); and for human metapneumovirus (n=8), 50% (15–85) and 100%, respectively. Parainfluenzaviruses were detected only in five patients. ConclusionsThis novel point-of-care test system is a rapid, practical, and specific method for simultaneous detection of eight respiratory viruses. Compared with RT-PCR, its sensitivity is moderately high for detection of RSV and influenza viruses, and low for adenovirus.

Fit-for-purpose evaluation of architect i1000SR immunoassay analyzer

BackgroundLast year Abbott Laboratories introduced the Architect i1000SR modular chemiluminescent immunoassay analyzer for laboratories performing <200test/day. The analyzer has a diverse menu of most routinely tested assays for the low to mid volume hospital laboratory. We evaluated the analytical performance, productivity and efficiency of this system for a 1-y period. MethodThe analytical performance was ascertained by i) determining functional sensitivity in serum matrix for cTnI and measuring precision for other assays. ii) Accuracy was determined by performing patient correlations for TSH, cTnI and FT4 assays. iii) Analyzer productivity and efficiency were evaluated by determining the expected annual throughput and impact of routine workload on STAT TATs, respectively. ResultsCoefficient of variation ranging from 3.6 to 8.2% was achieved for all assays evaluated. Functional sensitivity for cTnI was found to be 0.05ng/ml. Patient correlation gave regression coefficients ranging from 0.875–0.998. An average hourly throughput ranged from 41–48 tests per hour (tph). ConclusionsWe find the Architect i1000SR random access immunoassay analyzer met all of the requirements desired in a low to mid volume instrument. Stat turn around times (TAT) are maintained to <20min.

‘Ferritin as an indicator of suspected iron deficiency in children with autism spectrum disorder: prevalence of low serum ferritin concentration’

‘Ferritin as an indicator of suspected iron deficiency in children with autism spectrum disorder: prevalence of low serum ferritin concentration’

Maternal serum biochemistry at 11-13+6 weeks in relation to the presence or absence of the fetal nasal bone on ultrasonography in chromosomally abnormal fetuses: an updated analysis of integrated ultrasound and biochemical screening

Screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-hCG and pregnancy associated plasma protein-A (PAPP-A) at 11-13(+6) weeks of gestation is associated with a detection rate of 90%, for a false-positive rate of 5%. Recent evidence suggests that in about 70% of fetuses with trisomy 21 the nasal bone is not visible at the 11-13(+6) week scan and that the frequency of absence of nasal bone differs in different ethnic groups. In addition, there is a relationship between absent nasal bone and nuchal translucency thickness. In a preliminary study we showed that while PAPP-A levels were lower and free beta-hCG levels were higher in trisomy 21 fetuses with an absent nasal bone, this difference was not statistically different. In fetuses with trisomy 13 and trisomy 18, there is also a high (57 and 67%) incidence of an absent nasal bone. The aim of this present study was to extend our examination of whether the level of maternal serum biochemical markers is independent of the presence or absence of the nasal bone in cases with trisomy 21 and to ascertain if any differences exist in cases with trisomies 13 and 18. This study data comprised 100 trisomy 21 singleton pregnancies at 11-13(+6) weeks of gestation from our previous study and an additional 42 cases analysed as part of routine OSCAR screening. A total of 34 cases with trisomy 18 and 12 cases with trisomy 13 were also available. Ultrasound examination was carried out for measurement of fetal NT and assessment of the presence or absence of the fetal nasal bone. Maternal serum free beta-hCG and PAPP-A were measured using the Kryptor rapid random access immunoassay analyser (Brahms Diagnostica AG, Berlin). The distribution of maternal serum free beta-hCG and PAPP-A in chromosomally abnormal fetuses with absent and present nasal bone was examined. The nasal bone was absent in 29 and present in 13 of the new trisomy 21 cases and in 98 (69%) and 44 respectively in the combined series. For the trisomy 18 cases, the nasal bone was absent in 19 (55.9%) cases and in 3 (25%) of cases of trisomy 13. There were no significant differences in median maternal age, median gestational age, NT delta, free beta-hCG MoM and PAPP-A MoM in trisomy 21 fetuses with and without a visible nasal bone, and similarly for those with trisomies 13 or 18. For a false-positive rate of 5%, it was estimated that screening with the four markers in combination with maternal age would be associated with a detection rate of 96% of cases with trisomy 21. For a false-positive rate of 0.5%, the detection rate was 88%. There is no relationship between an absent fetal nasal bone and the levels of maternal serum PAPP-A or free beta-hCG in cases with trisomies 13, 18 or 21. An integrated sonographic and biochemical test at 11-13(+6) weeks can potentially identify about 88% of trisomy 21 fetuses for a false-positive rate of 0.5%.

Performance characteristics of the IMMULITE 2000 erythropoietin assay

Background: Erythropoietin (EPO) is a glycoprotein hormone produced by specialized cells in the kidney that acts as the primary regulator of erythropoiesis. Serum EPO measurements are useful for diagnostic evaluations of anemia and polycythemia. Methods: The IMMULITE 2000 is an automated random access immunoassay analyzer for the central laboratory. The limit of detection (LOD), linearity, imprecision, comparison to another commercially available assay, and reference interval of a new EPO assay for this analyzer were assessed. Results: The LOD was 0.2 U/l. The assay was linear within an allowable systematic error of 10% over the range tested (2–178 U/l). The total imprecision of the new assay was <7% for concentrations from 15.8 to 68.4 U/l. Comparison with the Advantage EPO assay method showed comparable results. Deming regression analysis gave a slope of 1.13±0.02, an intercept of −1.09±0.97, and a S y/ x of 7.1 ( r=0.99) over the range tested (2–200 U/l). Conclusions: The IMMULITE 2000 EPO assay shows acceptable performance and is suitable for routine clinical use.

Integrated ultrasound and biochemical screening for trisomy 21 using fetal nuchal translucency, absent fetal nasal bone, free beta-hCG and PAPP-A at 11 to 14 weeks.

Screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) at 11 to 14 weeks of gestation is associated with a detection rate of 90% for a false-positive rate of 5%. Recent evidence suggests that in about 70% of fetuses with trisomy 21, the nasal bone is not visible at the 11th- to 14th-week scan (Cicero et al., 2001). The aim of this study was to examine whether fetal NT thickness and the level of maternal serum biochemical markers is independent of the presence or absence of the nasal bone, and to estimate the performance of a screening test that integrates the two sonographic and the two biochemical markers. This was a retrospective case-control study comprising 100 trisomy 21 and 400 chromosomally normal singleton pregnancies at 11 to 14 weeks of gestation. Ultrasound examination was carried out for measurement of fetal NT and assessment of the presence or absence of the fetal nasal bone. Maternal serum free beta-hCG and PAPP-A were measured using the Kryptor rapid random-access immunoassay analyser (Brahms Diagnostica GmbH, Berlin). The distribution of fetal NT, maternal serum free beta-hCG and PAPP-A in trisomy 21 fetuses with absent and present nasal bone was examined. The nasal bone was absent in 69 and present in 31 of the trisomy 21 fetuses. There were no significant differences in median maternal age, median gestational age, NT delta, free beta-hCG MoM and PAPP-A MoM in trisomy 21 fetuses with and without a visible nasal bone. For a false-positive rate of 5%, it was estimated that screening with the four markers in combination with maternal age would be associated with a detection rate of 97%. For a false-positive rate of 0.5%, the detection rate was 90.5%. An integrated sonographic and biochemical test at 11 to 14 weeks can potentially identify about 90% of trisomy 21 fetuses for a false-positive rate of 0.5%.

Interference From Digitoxin-like Immunoreactive Factors Reduced in a New Monoclonal Chemiluminescent Digitoxin Assay

Endogenous digoxin-like immunoreactive factors (DLIF) can interfere with some digoxin immunoassays. We looked for similar interference, called digitoxin-like immunoreactive factors (DTLIF) in two digitoxin immunoassays: A new chemiluminescent assay (CLIA), processed on the automated random access immunoassay system ACS:180, and a fluorescent polarization assay (FPIA), processed on the semiautomated TDx batch analyzer. One hundred thirty-seven samples of sera were tested from nondigitalized pregnant women, patients with liver or kidney diseases, and cord blood. The CLIA digitoxin assay uses a murine monoclonal antibody and requires no sample pretreatment; the FPIA digitoxin assay uses a polyclonal rabbit antibody and requires sample precipitation. Both assays have a similar dynamic range and sensitivity and give comparable results with commercial controls and external quality control survey samples. Although the CLIA detected no digitoxin in any sample tested, the FPIA showed apparent digitoxin concentrations of more than 2.0 ng/ml for 100% and 44% among cord blood and liver disease specimens, respectively. The highest DTLIF concentration was found in serum from a patient with liver disease (18.1 ng/ml). When spiked with 32 ng/ml digitoxin, six of the samples containing DTLIF generated FPIA digitoxin values of 6% to 27.5% more than the expected digitoxin levels. Two specimens with no detectable DTLIF activity were run as controls, and when spiked with digitoxin, showed target digitoxin concentrations in the FPIA. The CLIA recovered near the target digitoxin values (32 ng/ml) in all spiked samples. It was concluded that the polyclonal FPIA digitoxin assay may give discordant digitoxin concentrations in some patient groups because of interference from digitoxin-like immunoreactive factors. The CLIA digitoxin assay is not affected by DTLIF interference.

Follicle-stimulating hormone measured in unextracted urine: a reliable tool for easy assessment of ovarian capacity

Objective: To determine the presence of FSH in unextracted urine of perimenopausal women using a microparticle enzyme immunoassay kit on an AxSYM random access immunoassay analyzer. Design: Controlled descriptive study. Setting: A large teaching hospital and infertility clinic. Patient(s): Forty perimenopausal women aged 32–55 years admitted to our clinic for a gynecological operation. Intervention(s): None. Main Outcome Measure(s): Mean serum FSH level and urinary FSH in early-morning urine, in a random void urine sample, and in 24-hour urine on the same day. FSH in urine on the day of excretion and 1 and 4 weeks thereafter, stored under various conditions. FSH in urine before and after extraction. Result(s): The Pearson’s correlation coefficient between mean serum FSH levels and urinary FSH in early morning urine was 0.904, in a random void 0.915, and in 24-hour urine 0.857. Determination of optimal storage conditions revealed that urine was best kept at 4°C without any additive. The correlation between FSH in extracted and unextracted urine was 98.9%. Conclusion(s): In perimenopausal women, FSH can be reliably measured in unextracted urine. The correlation between urinary FSH and a random void urine sample and mean FSH from a serial serum sample is very high. Urine can be stored for 4 weeks at 4°C without loss of FSH immunoreactivity.

Rapid, automated assay for progesterone on the Abbott AxSYM™ analyzer

We describe an automated assay for progesterone (P4) in human serum and plasma with the Abbott AxSYM random-access immunoassay analyzer. In this one-step competitive assay, P4 immobilized onto latex microparticles competes with sample P4 for binding to a conjugate of alkaline phosphatase (AP) and anti-P4 antibody. Total CVs ranged from 3.4% to 8.2% in multiple precision studies conducted according to the 20-day NCCLS EP5-T protocol. The detection limit (zero calibrator + 2 SD) was 0.10 microg/L across 36 experiments. Values for diluted samples were 83-116% of expected. Recovery of P4 added to serum specimens was 92-115%. Cross-reactivities with 43 natural and synthetic steroids were 0-6.3%. No significant interference was detected from bilirubin, protein, erythrocytes, hemoglobin, triglycerides, or cholesterol. In a multisite correlation study, AxSYM P4 results compared well with results from a commercial RIA method (n = 1156; r = 0.976; slope = 1.03; y-intercept = 0.04). Assay throughput is >80 tests per hour in batch mode, 60 tests per hour with mixed load list configurations.

Immunoassay Automation: an Updated Guide to Systems. D.W. Chan, ed. San Diego: Academic Press, Inc., 1996, 312 pp. $59.95. ISBN 0-12-167640-4.

A balanced mix of academic and commercial scientists have compiled the essential information necessary for a critical comparison of automated immunoassay systems. This text focuses on systems that are fully automated, dedicated analyzers for immunodiagnostics, combining continuous access, primary tube sampling, bar-code reading, sophisticated information processing, and a diverse menu of available analytes to provide for workstation consolidation. The book begins with an excellent overview of the role of random-access immunoassay analyzers in addressing the challenges to today’s hospital laboratories and guiding …

One-step all-in-one dry reagent immunoassays with fluorescent europium chelate label and time-resolved fluorometry

The availability of an intrinsically fluorescent, inert, and stable Eu chelate label made it feasible to design one-step all-in-one immunoassays with time-resolved fluorometry for detection. Both competitive and noncompetitive immunoassays are performed in microtitration wells containing all assay-specific components in a stable dry form. Only the sample and one assay buffer common for all analytes need to be added. Model assays for human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), and progesterone all reached equilibrium in 15 min or less without compromising the performance characteristics of the measurements, all of which perform at least equivalent to state-of-the-art assays. The detection limits for hCG, AFP, and progesterone were 0.3 IU/L, 0.1 microgram/L, and 0.5 nmol/L, respectively. The assay ranges for hCG and AFP were linear to 5000 IU/L and 1200 micrograms/L, respectively. The immunoassay format can be readily implemented in a fully automated random-access immunoassay system with optimal performance characteristics and no handling of analyte-specific assay components.

Evaluation of the technicon immuno I® random access immunoassay analyzer and calculation of pediatric reference ranges for endocrine tests, T-uptake, and ferritin

Objectives: Evaluation of the precision, accuracy, and user-friendliness of the Technician Immuno I. Calculation of pediatric reference ranges for ferritin and endocrine tests run on Immuno I. Methods: Precision and accuracy were measured using controls and method comparison studies. Pediatric reference ranges were calculated by comparing the Immuno I results for 100 patients with those of the Abbott IMx and TDx. The regression equation obtained was then used to convert the [Mx and TDx reference ranges to reference ranges for the Immuno I. Results: The Immuno I provided both accurate and precise measurement of drugs and endocrine hormones. Pediatric reference ranges were obtained for ferritin and all endocrine tests. Conclusion: The Immuno I is user-friendly and provides reliable measurement of both the drugs tested and endocrine tests on a micro-sample. Reagent and curve stability are excellent.

Rapid, automated quantification of total human chorionic gonadotropin in serum by a chemiluminescent enzyme immunometric assay

Total human chorionic gonadotropin (hCG-hCG beta) in serum was assayed with the immulite system, a fully automated random-access immunoassay analyzer that has a unique centrifugal procedure for solid-phase washing and a chemiluminescent detection system. The broad range of the hCG calibration curve (up to 5000 IU/L) is achieved by using a small serum sample size (5 microL), which provides sufficient volume for low-end sensitivity and prevents the possible high-dose hook effect in the working range of the assay. Within-run imprecision (CV) ranged from 3.9% to 5.9% for hCG between 10.5 and 2908 IU/L. Between-run imprecision ranged from 8.8% to 12.7% for hCG mean concentrations from 11.4 to 88.4 IU/L. The antibodies used in the immulite hCG assay system gave little or no interferences when high amounts of follitropin, lutropin, and thyrotropin were added. A complete recognition of the free beta-subunit of hCG was obtained (+/- 180%). In sera from women with molar pregnancies, we observed no high-dose hook effect at hCG concentrations up to 3000 kIU/L. The broad range of hCG concentrations encountered throughout normal pregnancy (up to 200 kIU/L) requires an extended working range to avoid high dilutions. In early pregnancy, accuracy in the range of 1000-5000 IU/L is enhanced by avoiding dilutions.

Impact of Random-access Automation on the Immunoassay Laboratory

To raise productivity without sacrificing quality or increasing costs at North Memorial Medical Center, Robbinsdale, Minn, various random-access immunoassay analyzers (RAIAs) were evaluated. The analyzers were compared for their ability to perform immunoassay tests throughout the day, and provide expedient turnaround time for certain analytes without sacrificing result quality. The RAIA ACS: 180 analyzer (Ciba-Corning Diagnostics Corp, Medfield, Mass) was chosen and phased in at the medical center’s immunoassay section. The labor savings from using this analyzer have increased productivity enough to absorb a 15% greater work load, and the medical center now offers several additional immunoassay tests previously referred to other laboratories.

Abbott AxSYM random and continuous access immunoassay system for improved workflow in the clinical laboratory

We describe a new clinical laboratory instrument, the Abbott AxSYM, which provides random- and continuous-access testing for immunoassays, 20 onboard reagents, primary tube sampling, and a throughput of 80 to 120 tests per hour. The AxSYM incorporates three separate analytical technologies for processing immunoassays: microparticle enzyme immunoassay, fluorescence polarization immunoassay, and a novel technology known as ion-capture immunoassay. The system incorporates both common and technology-specific subsystems controlled by a real-time software scheduling processor. Tests can be processed in one- or two-step sandwich or competitive formats, with variable pipetting steps, incubation periods, optical read formats, and wash sequences. Menu capabilities include tests for hepatitis, retrovirus, tumor markers, fertility markers, thyroid functions, and therapeutic drugs. The time to first result is approximately 15-25 min for most routine assays and < or = 15 min for stat assays (i.e., creatine kinase MB isoenzyme, human chorionic gonadotropin beta subunit, and therapeutic drugs). AxSYM assay performance for 23 assays was comparable with that of the Abbott IMx and TDx analyzers; specimen correlation data had correlation coefficients ranging from 0.97 to 0.99 and slopes ranging from 0.99 to 1.10. Within-run imprecision (CV) was 1.5% to 11.4%, with most assays (19 of 23) demonstrating CVs < or = 8.0%.

Performance characteristics of the ACS:180™ automated chemiluminescence system

The Ciba.Corning ACS: 180™ is a benchtop random-access Immunoassay analyser, operating with a time-to-first result of 15 minutes and a throughput of 180 tests/hour. The system can accommodate both competitive and sandwich-format chemiluminescence assays, using paramagnetic particles as solid phase and acridinium ester as label. Up to thirteen assays can reside on-board at one time from a total menu of twenty-five assays, including thyroid, anaemia, fertility, cancer, cardiac analysis and therapeutic drug monitoring applications. User interaction is limited to loading primary tubes or sample cups onto a carousel, loading on-board supplies, entering patient information, and designating which tests will be run on each sample. An automated process track is used to move disposable test cuvettes through preheating, sample addition, reagent addition, incubation, separation and measurement steps. Robotic sample and reagent probes perform all fluid transfer actions; dispense precision of both is 1% over their delivery volume ranges (10 to 200-μL and 50-500μL respectively). Magnetic separation yields a recovery variation of less than 1% at a concentration level of 200 μg/500μL, and less than 3% of 20μg/500μL Following separation and washing of the particles, reagents are added to initiate the chemiluminescence reaction. The lumlnometer accumulates this signal over 5 seconds, with a precision of 2% at 350,000 photon counts. Data reduction is accomplished through either spline or four/five parameter logistic curve-fitting methods and is pre-programmed for each assay. Data demonstrating the performance of the ACS:180™ will be shown.