# Overview of the different dilution steps on the cobas mira plus

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Overview of the different dilution steps on the COBAS MIRA Plus

1. Dilution of the samples

The dilution of the samples is activated by the REACTION MODES D-R-S, D-R-S-SR1 and D-R-S-SR1-SR2.
The diluent and factor are entered in the parameter setting as following:

A N A L Y S I S
DILUTION NAME : NACL  Diluent (enter name in P62)
FACTOR : 41  Factor

The following dilution factorsare available: 4.0 to 150.0
These dilutions need one predilution cuvette.

Pipetted sample volumes to perform these dilutions:

Dilution 1:4.00 ...... 1:150.00
Sample volume (S) 75.0 l 300/factor 2.0 l
Diluent volume (Dil) 15.0 l 90 - S but maximum 50 l * 50.0 l
Reagent volume (R) 210 l 300 - S - Dil * 248 l
Total volume 300 l 300 l * 300 l

* These formulas aretheoretical. When the sample volume is a number with more than 1 decimal, it will be rounded to a number with 1 decimal. The diluent and reagent volumes are adapted in order to have the best dilution factor and a total volume in the cuvette that is near to 300 l.

Example: Dilution = 1:41

Theoretical values:

S = 300 / 41= 7.32 l
Dil = 90 - 7.32 = 82.68 l Maximal volume is 50 l ==>Dil = 50 l
R = 300 - 7.32 - 50 = 242.68 l

S = 7.3 l
Total volume in the cuvette = 7.3 x 41 = 299.3
Dil = 90 - 7.3 = 82.7 l Maximal volume is 50 l ==> Dil = 50 l
R = 299.3 - 7.3 - 50 = 242 l
2. Dilution of standards

The dilution of the standards is activated by the REACTION MODES D-R-S, D-R-S-SR1 and D-R-S-SR1-SR2 and the CALIBRATION MODE > SLOPE AVERAGE.The standards dilution can be performed by 2 different ways:
- Factor: the standards are placed in several cups and they are diluted like the samples.
- Main: the instrument makes several dilutions from a main standard placed in one cup.

2.1 Factor

The diluent and factor are entered in the parameter setting as following:

A N A L Y S I S
DILUTION NAME : NACL  Diluent (enter namein P62)
FACTOR : 41  Factor
TIME: NO
STD: FACTOR

The standards are diluted like the samples (see chapter 1.). They are pipetted from several cups (1 standard / cup).

2.2 Main direct

A N A L Y S I S
DILUTION NAME : NACL  Diluent (enter name in P62)
FACTOR : 41  Factor
TIME: NO
STD: MAIN DIRECT
Main STD: 41 x Ass. value  conc. of the main std.POS: 1  position of the main std.
FACT.STD - 1: 6 2: 8
3: 12 4: 24
4: 48 6: 96
7: NO 8: NO

The concentration of the standards is automatically calculated by the instrument.

The main direct dilution is performed as below:

Up to 8 standards ca be prepared by diluting a main standard with the factors 1:0, 1:1 and 1:1.5 to 1:30000.

Followingconditions must be fulfilled (dilution 1:0 and 1:1 are not taken in account)

- Dfmax / Dfmin  100
- If Dfmin < 9, then Dfmax must be < 150
- If Dfmax > 150, then Dfmin must be > 9 .

Where Dfmin = lowest dilution factor of the serie and
Dfmax = highest dilution factor of the serie
If one dilution is greater than 1:150, an intermediate predilution by 1:6 to 1:200 is performed from the mainstandard. This intermediate predilution factor (Dfint) is calculated as following:

Dfmin = lowest dilution factor of the serie
Dfmax = highest dilution factor of the serie
Dfint.min = lowest intermediate dilution = Dfmax /150 (If Dfint.min < 6 then Dfint.min = 6)
Dfint.max = highest intermediate dilution = Dfmin /1.5 (If Dfint.max >200 then Dfint.max = 200)

Dfint.max - Dfint.min
Dfint =Dfint.min + ---------------------------- x10
100
All the standards are then prepared from this intermediate predilution. The dilution factors are recalculated by dividing them by the intermediate dilution factor.

Pipetted sample volumes to perform the dilutions that do not request a predilution cuvette:

. Dilution 1:0: the standard is replaced with diluent.

. Dilution 1:1: the...