Biological Evidence 2018, Vol.8, No.2, 6-20
9
Table 2 Working conditions of the FAAS
Metals Slit width
(nm)
Noise Wavelength
(nm)
Lamp current
(mA)
Calibration
range (µg/ml)
Flame composition
Characteristic
concentration
(mg/L)
Concentration
of Check
(mg/L)
Acetylene
(L/min)
Air
(L/min)
Cd
0.50
1.0
228.80
3.00
0.01-1.8
2.00
10.00
0.001
0.5
Ni
0.20
1.0
232.00
4.00
0.18-8.0
2.00
10.00
0.018
1.0
Co
0.20
1.0
240.70
6.00
0.08-9.0
2.00
10.00
0.008
1.0
Cu
0.50
1.0
324.70
3.00
0.02-5.0
2.00
10.00
0.002
0.5
Zn
0.50
1.0
213.90
5.00
0.01-1.5
2.00
10.00
0.001
1.0
Cr
0.20
1.0
357.90
6.00
0.06-15.0
2.00
10.00
0.006
1.0
Pb
1.00
0.92 217.00
5.00
0.20-20.0
2.00
10.00
0.020
1.0
Mn
0.20
1.0
279.50
5.00
0.03-3.6
2.00
10.00
0.003
1.0
1.5 Quality control/assurance
The quality assurance and quality control involves procedural blanks, replicate sampling and analysis and spike
recovery method. The recovery was calculated based on equation 1. The spike recovery was carried out by adding
a known analyte concentrations and reanalyzing the samples (Iwegbue et al., 2015a). The blanks were carried out
for the respective metals under study using analytical method without the sample. The recovery values obtained
ranged from 90.91% to 96.87% which is acceptable. Black was analyzed after the analysis of 7 samples of the
seasonings and culinary condiments that have been dry-ashed and acid digested. The detection and quantification
limits were assessed based on noise generated during the blank samples analysis. The limit of detection (LOD)
and limit of quantification (LOQ) were the level of analyte that provide a signal-to-noise ratio of 3 and 10
respectively. The LOD, LOQ, percentage spike recoveries of the various metals under study is presented in Table
3.
% recovery =
( )
( )
x100
Equation 1
Table 3 Spike recovery, limits for the heavy metals analysis
Metals LOD (mg/kg) LOQ (mg/kg) Quantity of standard
added (mg/kg)
Quantity determined
(mg/kg)
Sample concentration
(mg/kg)
Percentage
recovery (%)
Cd
0.0003
0.001
0.50
1.18
0.74
95.16
Ni
0.004
0.01
0.70
2.14
1.51
96.83
Co
0.002
0.01
0.50
1.08
0.68
91.53
Cu
0.001
0.004
0.20
0.40
0.24
90.91
Zn
0.0003
0.001
0.40
0.89
0.54
94.68
Cr
0.002
0.01
0.70
2.14
1.52
96.40
Pb
0.004
0.01
1.00
3.40
2.51
96.87
Mn
0.001
0.004
0.60
1.75
1.21
96.69
1.6 Health risk assessment
Health risk assessment has been widely applied in studies related to human health. The notable indices used for
health risk assessment include total hazard quotients, health risk index and daily intake of metal. In this study, the
health risk index were calculated in 4 criteria including adult (22-55 years with average body weight of 70 kg),
under graduate (16-25 years with average body weight of 65 kg), school children (6-15 years with average body
weight of 35 kg) (Ihedioha et al., 2014; Abubakar et al., 2014; Kigigha et al., 2017) and infants (1 - <6 years with
average body weight of 15 kg) (Iwegbue et al., 2015a).
1.6.1 Estimated daily intake of metals
Estimated daily intake of metals has been widely calculated by authors (Orisakwe et al., 2012; Iwegbue et al.,
2013a; 2015a).
