輪邊減速器外文文獻_圖文

1、 16001440 1280 1120 ±#247 I I I too 640 1. 1 41 480 320 160 I 1 I 2 3 I I 4 I 5 I 6 I 7 I ?1 I 9 I 10 I 11 I 12 I 1 I 14 I 15 I 16 I 17 I 1$ I 1920 I Fig. 8. Daily variation (mean ± 1 SD in the probe colorimeter over 20 days at three different absorbance values by measuring each well in si

2、x different plates (576 readings, with a test solution of 0.90 A (Table 2. The mean CV for all the plates was 1.46% (range, 0.42-2.09%. The day-to-day variation of the instrument was assessed by measuring three solutions of differing absorbance values on 20 different days. A complete plate of 96 wel

3、ls was used for the measurement of each standard. Standards were obtained by diluting a stock solution of the reaction products of the peroxidase assay system and checked daily in the spectrophotometer (450 mm. Figure 8 summarizes the results and the overall statistical estimates are given in Table

4、3. We measured the sensitivity of the instrument to stray and ambient light by suspending a 100-W light-bulb 1 m above the reading head. This had no measurable effect on the readings, because the probes can only accept light from directly underneath, as a result of their opaque coating. Contaminatio

5、n due to carryover from row to row was measured by radioisotope transfer and found to be <1%, with less than 2 L solution being transferred. No interaction between adjacent wells could be detected when highand low-absorbance solutions were placed in neighboring wells. Similarly, no optical edge e

6、ffects were observed in wells along the periphery of the plate. Discussion The instrument described here fulfills the need for a multi-channel instrument capable of reading large numbers of micro-scale ELISA tests carried out in microtiter plates. By reading through the bottom of the plates, the nee

7、d to transfer solutions to cuvets has been eliminated, and this combined with the ability to read 12 wells in sequence has considerably improved reading speed. Such problems as nonuniformity of meniscus and bubbles trapped under the probes have been overcome by careful design of the reading head, pa

8、rticularly the dipping probes, so that the final reproducibility of the instrument depends mainly on the optical quality of the microtiter plates used. The colorimeter described can be used with various enzyme substrates and is being used successfully in this laboratory with both peroxidase and alka

9、line phosphatase substrates, at 460 and 410 nm. Table 3. Summary of Day-to-Day Nominal absorbance Mean Instrument reading Replicates 0.60 613 Single Triplicate Variation 1.10 1.50 1553 1113 Single Tripilcate Single Tripilcat. Analysis over al/points n SD CV % Analysis after position averaging n SD C

10、V, % 1920 29 640 21 1920 35 3.14 640 24 2.16 1920 37 640 28 4.73 96 13 2.19 3.42 32 9 1.40 2.38 96 15 0.95 1.80 32 10 0.62 96 17 1.53 32 11 0.97 Pooledstatistics are given of the day-to-day instrument variation based on either analysis of individual readings, or triplicate means. Triplicates were ob

11、tained by averaging across a row of wells to give four readings per row,thusgiving 32 readings per plate. Statistics are also given of(a analysis based on all the measurements or (b analysis after each identical well on the plate had been averaged. CLINICAL CHEMISTRY, Vol. 25, No. 4, 1979 575 The pl

12、ates used for calibrating and testing the instrument were standard flat-bottom microtiter plates, which were not intended for optical measurements but were found to be of sufficient uniformity to give reasonably reproducible results (see Table 2. However, the largest component in the variation betwe

13、en readings is associated with the plates themselves, so an improvement in the optical quality of the well bottoms would substantially improve test accuracy (i.e., might reduce the CV by twofold. The variability of the technique has been tested above by using each well as a single estimation. Test v

14、ariation can be further reduced by using replicates. The number of replicates chosen would depend not only on the reproducibility instrument, but on the reproducibility of the ELISA self. of the test it- References 1. Engvall, E., and Perlmann, P., Enzyme linked immunosorbent assay, ELISA, J. Immuno

15、l. 109, 129 (1972. 2. Voller, A.,Bedwell, D. E., Huldt, G., and Engvall, E., A microplate method of enzyme-linked immunosorbent assay and its application to malaria. Bull. WHO 51, 209 (1974. 3. Scharpe, S. L., G. M., Quantitative enzyme Chem. 22,733 (1976. 4. Wisdom, (1976. Coorman, W. M., Blomme, immunoassay: W. J., and Laekeman, Current status. Clin. Clin. Chem. G. B., Enzyme-immunoassay. 22, 1243 5. Ruitenberg, E. J., Brosi, B. J. M., and Steerenberg, P. A. I., Direct measurement of microplates and its application to enzyme-linked immun