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4438 J. Med. Plants Res.
Figure 1. Comparison of sulfate and chloride levels in the herbal tea samples.
Table 2. Fluoride, chloride, and sulfate set standard limits.
Organization
Anions (mg/L)
Fluoride Chloride Sulfate
US EPA 2.0* and 4.0** 250.0** 250.0**
US FDA 1.7 250.0 250.0
WHO 1.5 - -
EC 1.5 250.0 250.0
* US EPA permissible level, under the NPDWR; ** US EPA permissible level, under the NSDWR.
de-ionized water, and then homogenized, filtered through a 0.2 μm
membrane filter (Schleicher & Schuell, Germany), and degassed by
sonication. A 50 μL injection volume was used for the standards,
and depending on the concentration of the anions in the samples, a
5 to 100 μL injection volume was used for the samples. A 1.0
mL/min IC flow rate was used.
A standard stock solution was prepared from a multi-ion
standard (Seven Anion Standard II Standard, Dionex, USA) and
was used for preparing the different calibration curves (correlation
coefficient ≥ 0.99) for all of the measured anions. The calibration
curves were prepared with a concentration range of 0 - 10 mg/L
fluoride; 0 - 50 mg/L chloride; and 0 - 50 mg/L sulphate. The limit of
detection (LOD) and limit of quantitation (LOQ) for the measured
anions are as follows, for fluoride 0.10 and 0.35 mg/L, for chloride
0.39 and 1.29 mg/L, and for sulfate 1.16 and 3.88 mg/L, respectively.
For the measured anions, the recovery of the applied
method of analysis was accomplished by spiking the prepared
herbal tea samples with aliquots of the anion standard, and then
analyzed. Recovery of fluoride was 108.05 – 127.67%, chloride was
93.75 – 94.46%, and sulfate was 91.92 – 92.77%; with a standard
deviation ranging from 0.000 - 0.014 for fluoride, 0.004 - 0.010 for
chloride, and 0.086 - 0.199 for sulfate.
RESULTS AND DISCUSSION
SO4
The fluoride, chloride and sulfate levels were measured
for all the herbal tea brands (Table 1 and Figure 1). The
US EPA, US FDA and European Commission (EC) have
set standard limits or suggested values for fluoride,
chloride and sulfate in drinking water (Table 2) based on
the probable effects that they may have (EC, 1998; US
EPA, 2009; US FDA, 2009). Unlike the other organizations,
the WHO provides no guideline value for
chloride and sulfate, but only for fluoride (Table 2) (WHO,
2011). Some of the contaminants that are in drinking
water are considered under the National Primary Drinking
Water Regulations (NPDWR) standards and cause