Bayer HealthCare Rapidlab 800 User Manual

Water quality is an important consider-
ation in the laboratory because it can
significantly affect the outcome of
laboratory procedures and the measure-
ment of patient samples.

This bulletin provides an overview of
reagent water quality guidelines as
specified by the National Committee
for Clinical Laboratory Standards
(NCCLS).

1

Use these guidelines to

evaluate the reagent water quality in
your laboratory and to determine the
best method for obtaining the water
quality you need.

Good laboratory practices suggest that
you establish a protocol that supports
the manufacturer’s requirements for the
instrument to:

• ensure optimum performance of 

automated laboratory instruments

• eliminate water quality as a source of

problems when troubleshooting

• help you to meet requirements for

state and federal laboratory 
certification

Reagent water is laboratory water that
meets specifications for clinical 
laboratory use.

2,3

The NCCLS has defined three grades
of reagent water: 

• Type I, the highest grade 

• Type II, the intermediate grade

• Type III, the lowest grade

Table 1 lists the NCCLS specifications for the three types of reagent water. Use
this information to determine the water quality in your laboratory. Refer to the
NCCLS guidelines for common laboratory uses of Type I, Type II, and Type III
reagent water.

Maximum bacterial content 

10 (preferably bacteria 

1000

not applicable

colony forming units per 

free)

mL (CFU/mL) *

pH

not applicable

not applicable

5.0 – 8.0

Minimum resistivity 

10 (inline measurement 

1.0

0.1

(megohm/centimeter at 

by sensor or resistor)

25°C) †

Maximum silicate (mg/L) ‡

0.05 

0.1

1.0

Particulate matter (µm) §

smaller than 0.22 µm

not applicable

not applicable

(water is passed through
a 0.22 µm filter)

Organic compounds **

pretreat with activated 

not applicable

not applicable

carbon 

* Bacterial content: The number of colony forming units in water. Bacterial content is a water contam-

inant you measure to determine water quality.

† Resistivity: The ability of water to resist electrical conduction due to the ion content. Resistivity is the

standard test measurement for determining water quality. The higher the resistivity, the lower the ion
content and the better the water quality.

‡ Silicates: Compounds you remove to produce Type I reagent water.

§ Particulate matter: Undissolved (insoluble) substances larger than 0.22 µm are removed by the filter.

** Organic compounds: Compounds you remove to produce Type I reagent water.

As with all diagnostic testing procedures, good laboratory practices suggest that
you establish a protocol that supports the manufacturer’s requirements for
selecting the appropriate type of reagent water. You can then produce reagent
water in your laboratory by setting up and maintaining a water purification system
which uses the purification methods described in Table 2.

Table 2 describes some of the typical laboratory water purification methods.

Distillation

Changes water from liquid to vapor and leaves behind 
impurities such as particulates and bacteria

Deionization

Uses synthetic resins to remove ionized impurities by ion exchange

Reverse Osmosis

Forces water under pressure through a semipermeable membrane 
to remove dissolved solids and organic impurities

Adsorption 

Uses activated carbon, clays, silicates or metal oxides to remove
organic impurities

Filtration

Forces water through a semipermeable membrane to remove 
insoluble matter, emulsified solids, pyrogens, and microorganisms