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ANALES
RANF

www.analesranf.com

Table 1. Sources of drinking water used to prepare bleach dilutions in this Table 3. Drinking water analysis
study.

Name Sampling region Water source Water purification plant Water sample Conductivity (µS/cm) pH COD (mg/L)
I 296 7.40 ? 15
I North San Roque Lake Suquía (Agua Cordobesas) II 301 7.93 ? 15
III 143.5 6.93 ? 15
II Eastern San Roque Lake Barrio Patricios Cooperative IV 120.7 7.73 ? 15
V 295 8.04 130
III South Los Molinos Lake Los Molinos (Agua Cordobesas)
The WHO has proposed the use of 1 g/L bleach solutions
IV West Rio Icho Cruz Dam Coopi-Carlos Paz Cooperative for disinfection in institutional settings since it provides a large mar-
gin of safety regarding the effective concentration necessary to in-
V Central San Roque Lake Suquia (Agua Cordobesas) activate the majority of microorganisms on inert surfaces.

The diluted solutions were transferred to disinfected plastic Bleach solutions are usually prepared based on standard
bottles, tightly closed and stored at room-controlled temperature procedures that consider the labeled available chlorine of the con-
(20-25 ºC) under the conditions described in table 2. In addition, a centrated bleach, which is known to decrease with time. Thus, the
solution obtained with drinking water number V was transferred to confirmation that nominal concentration is maintained within the
a transparent container and exposed to room light. accepted range during the shelf-life period is an additional warranty
that the expected concentrations can be obtained after dilution, pro-
Table 2. Conditions of preparing and storage of diluted bleach solutions vided that correct procedures are followed.

Sample number Drinking water used for dilution Type of container Table 4 shows the available chlorine of the assayed con-
centrated solutions. As can be seen there, the values obtained are
1 I Opaque in agreement with those declared in their respective labels and also
with the concentration decrease permitted for the time elapsed from
2 II Opaque the date of elaboration (Argentinian regulation 7355/2019) (10).

3 III Opaque Table 4. Available chlorine concentration in several trademark bleaches
as determined by iodometric titration.
4 IV Opaque

5 V Opaque

6 V Transparent

To determine chlorine concentrations, 1 mL of each 1 g/L Brand Labeled Experimental Timea Allowed Requirement
solution was titrated (in triplicate) at 0, 1, 12 hours and 1, 2, 3, 5, concentration (g/L) concentration compliance
7, 10 and 14 days, using the experimental procedure described for (g/L) declining (%)b
the concentrated bleach solutions. The BUD of the diluted solutions
were considered achieved when the average chlorine dropped below 25 27.01 29 to 3 Yes
90 % of its initial concentration. The normal chlorine amount con-
tained in the different drinking water sources was considered negli- AA 25 27.01 78 up to 7 Yes
gible. 25 27.38 92 up to 9 Yes
49.58 14 up to 3 Yes
46 52.17 116 up to 20 Yes
24.79 59 up to 5 Yes
6. RESULTS AND DISCUSSION 58 52.17 138 up to 25 Yes

B 25

The pH, conductivity and COD values of drinking water C 60
samples were within the limits established by international recom-
mendations (18). However, sample Nº 5 has a COD value higher aTime elapsed from the manufacturing date and the day of titration
than expected (table 3). bAllowed reduction of available chlorine concentration considering the time elap-
sed from the date of elaboration (Argentinian regulation 7355/2019).

Compliance of commercial bleaches and stability of 1 g/L-dilutions

234 using different sources of drinking water
María E. Gavelli, Laura C. Luciani , Carolina Bustos, María E. Olivera
An. Real Acad. Farm. Vol. 86. Nº4 (2020) · pp. 231 - 236