A method optimization study for atomic absorption spectrophotometric determination of total zinc in insulin using direct aspiration technique

Peer review under responsibility of Alexandria University Faculty of Medicine.

Available online 24 April 2014

Figures & data

Table 1 Evaluation for system suitability of zinc analysis in insulin using AAS.

Sr. No	Zinc standard (μg/mL)	Five absorbance reading					Relative standard deviation (%)
01	0.20	0.030	0.029	0.030	0.029	0.029	1.86
02	0.40	0.061	0.060	0.061	0.060	0.061	0.61
03	0.60	0.090	0.090	0.091	0.090	0.091	0.91
04	0.80	0.119	0.122	0.122	0.121	0.122	1.08
05	1.00	0.149	0.147	0.148	0.146	0.146	0.89
06	1.20	0.172	0.175	0.175	0.176	0.176	0.94

Acceptance criteria = The % relative standard deviation for zinc absorbance reading should not be more than 2.0%.

Figure 1 The linearity verification for total Zn determination through flame atomic absorption spectrometry.

Table 2 Linearity data for analysis of zinc in insulin using AAS.

Sr. No	Concentration of zinc standard (μg/mL)	Mean absorbance	Relative standard deviation (%)	R^2	Slop	Intercept	Linear regression equation
1	0.20	0.037	1.53	0.996	0.144	0.010	y = 0.144x + 0.010
2	0.40	0.069	1.45
3	0.60	0.099	1.02
4	0.80	0.128	1.20
5	1.00	0.159	0.65
6	1.20	0.179	0.97

Table 3 Repeatability (intra-day) data for zinc analysis.

Sample	Theoretical zinc concentration (μg/mL)	Measured zinc concentration (μg/mL)	Relative standard deviation (%)
1	0.80	0.822	0.6380
2	0.80	0.818	0.1847
3	0.80	0.822	1.6900
4	0.80	0.818	1.0278
5	0.80	0.833	0.3602

Table 4 Intermediate precision (inter-day) data for zinc analysis.

Sample	Day	Theoretical zinc concentration (μg/mL)	Measured zinc concentration (μg/mL)	Relative standard deviation (%)
01	1st	0.80	0.859	0.9994
	2nd	0.80	0.837	0.7292
	3rd	0.80	0.848	0.4732
02	1st	1.00	1.020	0.7264
	2nd	1.00	1.034	1.2735
	3rd	1.00	1.050	1.1735

Table 5 Percentage recovery of zinc in spiked sample, using spiking levels of 0.100, 0.200 and 0.400 μg/mL.

Solution	Concentration (μg/mL)	Total Concentration (μg/mL)	Concentration obtained (μg/mL)	Concentration recovered (μg/mL)	Recovery (%)	Relative standard deviation (%)	LOD (μg/mL)	LOQ (μg/mL)
Real sample + Amount added	0.228	0.328	0.326	0.098	98.00	1.8217	0.0032	0.012
	0.100
Real sample + Amount added	0.228	0.428	0.430	0.202	101.00	1.3652
	0.200
Real sample + Amount added	0.228	0.628	0.631	0.403	100.75	0.1970
	0.400

Acceptance criteria = 95% ⩽ Recovery ⩽ 115%, Results 98% ⩽ Recovery ⩽ 101%.

Table 6 Robustness data for zinc analysis.

Parameters change		Zn Standard (μg/mL)	Five absorbance reading					Relative standard deviation (%)
Integration time (s)	Bandwidth (nm)
3.0 to 2.0	0.4 to 0.2	0.20	0.039	0.038	0.039	0.038	0.039	1.42
		0.40	0.078	0.080	0.079	0.080	0.079	1.06
		0.80	0.107	0.109	0.107	0.107	0.107	0.83
		1.00	0.141	0.141	0.140	0.141	0.140	0.39
		1.20	0.171	0.171	0.173	0.171	0.173	0.64
		1.60	0.199	0.204	0.202	0.201	0.201	0.90

Acceptance criteria = The % relative standard deviation for zinc absorbance reading should not be more than 2.0%.