BD CrystalSpec Guía Para La Utilizacion página 2

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2. For ease of calibrating, press the Calibration Button using a finger of your left hand and press
the Test Button using a finger of your right hand.
3. The sequence of button press and release is important for the proper calibration and accurate
functioning of the CrystalSpec.
4. If during calibration the expected displays do not show, after the display clears, re-start the cali-
bration procedure with step 1.
5. If a calibration reading (step 8) of other than "2.0" is returned, remove the Calibration Standard
and wipe the outside of the tube with a Kimwipe or clean cloth to remove any smudges, finger
prints, etc. and re-calibrate.
6. Calibration between sample readings is not necessary; however, the CrystalSpec Calibration
Standard (S) should be read as a sample on a daily basis. If the standard reads 1.9, 2.0 or 2.1, the
instrument is calibrated and does not need re-calibration.
7. The calibration should be stable if ambient conditions of temperature and light remain relative-
ly constant. If these conditions change, re-calibration is recommended.
8. Do not press the Test Button until the calibration procedure has been successfully completed (steps
1 - 8 are completed successfully) or the CrystalSpec will not be properly calibrated and readings
will not be valid.
TESTING PROCEDURES – Clear, flat bottomed glass tubes, 16 – 17 mm diameter must be used for sam-
ples. Organisms may be suspended in water, saline or clear growth medium of yellow to pale brown
color (e.g., Mueller-Hinton Broth, TSB, or BHI Broth). Use of other colored liquids as a suspending
medium is not recommended. A minimum of 2.0 mL of liquid is required.
1. If the sample volume is between 2.0 mL and 4.0 mL, insert the Low Volume Sample Adapter. If
the volume is greater than 4.0 mL, the Low Volume Sample Adapter is not needed.
2. Vortex the test sample and set aside briefly if bubbles are present. Gently tapping on the tube may
aid in eliminating bubbles. Insert the test tube sample tube into the nephelometer. Make sure the
tube is inserted as far as possible into the instrument.
3. Depress and release the test button [test tube graphic]. The result will be displayed along with the
battery status readout.
EXAMPLE: For a sample of McFarland 1.0 and a battery that requires changing, the display will
read:
"1.0 MCFARLAND
4. Adjust the sample preparation with more organisms if the readout is lower than expected, or with
sterile diluent if the reading is higher than expected. Vortex the sample and reread.
5. Repeat step 4 until the desired turbidity is achieved.
6. Repeat steps 2 – 5 (above) for additional samples.
RESULTS
The CrystalSpec Nephelometer displays the measurement in McFarland units. These readings repre-
sent the density of the suspension and can be used to estimate the CFU/mL of the suspension tested.
LIMITATIONS OF THE PROCEDURE
The meter must be calibrated with the supplied CrystalSpec Calibration Blank (B) and CrystalSpec
Calibration Standard (S). The use of other standards will result in miscalibration of the instrument.
The CrystalSpec Standard is to be used only for calibration of this instrument and not as a visual, i.e.
manual approximation to a barium sulfate McFarland standard.
Do not use the CrystalSpec Nephelometer for measurements outside the range of McFarland stan-
dards 0.5 – 4.0.
Volumes below 2.0 mL cannot be measured in the instrument.
Clear, flat bottomed glass tubes, 16 – 17 mm diameter must be used for samples.
For best results we recommend 9 V Alkaline batteries.
Do not use in direct sunlight.
PERFORMANCE CHARACTERISTICS
The reproducibility of the instrument was measured over time with standards at concentrations equiv-
alent to McFarland 0.5, 1, 2, 3, and 4 turbidity standards. The error for any estimate was determined
to be ± 0.1 McFarland unit.
To determine the accuracy of the CrystalSpec Nephelometer, colony counts were performed on sus-
pensions of E. coli ATCC™ 25922 prepared in saline. Each test was performed in replicates of five and the
average of the plate counts is given in Table 1.
Table 1
McFarland Expected CFU/mL x 10
0.5 1.5
1.0 3.0
2.0 6.0
3.0 9.0
4**0 12.0
* Because of difficulty in achieving the exact target McFarland density, these results were obtained by
using the CrystalSpec readings and adjusting the observed CFU/mL as if each dilution had been the
target McFarland.
**Four replicators were used to calculate the adjusted CFU/mL and % CV.
WARRANTY: The CrystalSpec Nephelometer is warranted to be free from defects for one year from the
date of purchase.
MAINTENANCE AND TROUBLESHOOTING: No maintenance is required except for battery replacement
when the battery indicator reads "B0", or "E" is displayed, indicating a low battery.
If the "E" is displayed, the internal error checking has detected a problem due to improper use, dis-
charged battery, or an electronic failure. If calibration and/or replacement of the battery does not cor-
rect the problem, (in the United States) contact Becton Dickinson, Technical Services, toll free
(800) 638-8663.
AVAILABILITY
Cat. No. Description
245009 CrystalSpec™ Nephelometer, including a CrystalSpec™ Calibration Blank and CrystalSpec™
Calibration Standard, Low Volume Sample Adapter, and battery.
245015 CrystalSpec™ Calibration Blank and CrystalSpec™ Calibration Standard, carton of one
each.
REFERENCES
1. McFarland, J. 1907. The nephelometer: an instrument for estimating the number of bacteria in
suspensions used for calculating the opsonic index for vaccines. JAMA 49:1176-1178.
2. Roessler, W.G., and C.R. Brewer. 1967. Permanent turbidity standards. Appl. Microbiol. 15:1114-
1121.
3. Pugh, T.L., and W. Heller. 1957. Density of polystyrene and polyvinyl toluene latex particles. J.
Colloid Sci. 12:173-180.
4. Mallette, M.F. 1969. XV. Evaluation of growth by physical and chemical means, p. 521-566. In J.R.
Norris and D.W. Ribbons (ed.). Methods in microbiology, vol. 1. Academic Press Inc., New York.
1:34 PM Page 2
B0".
8 Adjusted* CFU/mL x 10 8
1.7
3.3
6.5
10.4
13.0
2
%CV
11.6
10.7
14.8
8.2
9.9