How to Calculate Reading Points on EM-200Plus Chemistry Analyzer | Step-by-Step Guide

Step-by-Step Guide to Calculate Reading Points on the EM-200Plus Instrument

1. Understand Key Parameters

• Test Cycle: 18 seconds per point.
• R2 Addition Point: 18 (fixed for all methods).
• Total Reaction Points: 34 (maximum).

2. Calculation Methods

A. 1 Point End Method

• Purpose: Measure absorbance at the end of the reaction.
• Formula:

End Point=⌈Total Reaction Time (seconds)18⌉End Point=⌈18Total Reaction Time (seconds)​⌉

• Example (Total Protein):
  • Reaction Time = 10 minutes = 600 seconds.
  • End Point = 60018≈33.33→Round up to 3418600​≈33.33→Round up to 34.

B. 2 Point End Method

• Purpose: Measure absorbance before and after R2 addition.
  • Start Point: 1 point before R2 addition (17) or 1 point after (19), depending on the test.
  • End Point:

End Point=R2 Point+⌊Reaction Time After R2 (seconds)18⌋End Point=R2 Point+⌊18Reaction Time After R2 (seconds)​⌋

• Example 1 (Total Bilirubin):
  • Start Point = 18−1=1718−1=17.
  • Reaction Time After R2 = 5 minutes = 300 seconds.
  • End Point = 18+⌊30018⌋=18+16=3418+⌊18300​⌋=18+16=34.
• Example 2 (HDL-C):
  • Start Point = 18+1=1918+1=19.
  • End Point = 34 (same calculation as above).

C. Kinetic/Fixed-Time Method

• Purpose: Measure absorbance during stabilized reaction intervals.
  • Start Point:

Start Point=R2 Point+⌈Delay Time (seconds)18⌉Start Point=R2 Point+⌈18Delay Time (seconds)​⌉

• End Point:

End Point=Start Point+⌊Measurement Time (seconds)18⌋End Point=Start Point+⌊18Measurement Time (seconds)​⌋

• Example 1 (ALT - Double Reagent):
  • Delay Time = 1 minute = 60 seconds.
    Start Point = 18+⌈6018⌉=18+4=2218+⌈1860​⌉=18+4=22.
  • Measurement Time = 3 minutes = 180 seconds.
    End Point = 22+⌊18018⌋=22+10=3222+⌊18180​⌋=22+10=32.
• Example 2 (AMY - Single Reagent):
  • Start Point = ⌈12018⌉=7⌈18120​⌉=7.
  • End Point = 7+⌊18018⌋=7+10=177+⌊18180​⌋=7+10=17.

3. Key Notes

• Rounding: Always round up for delay times and down for measurement times to ensure points fit within the 34-point limit.
• R2 Handling: For methods without R2 (e.g., AMY), calculate points directly from the start of the reaction.

Summary Table

By following these steps, you can accurately configure reading points for precise and efficient testing on the EM-200Plus.

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