Question

ICP-MS.

Samples 1-4 are are standard solutions for Fe and Cu at 5,10,25,50 ppb stock solution.

Samples 5 to 9 are tap water run multiple times.

Construct calibration lines for Fe and Cu then calculate concentration of the chosen ions in tap water (use the ratio data) using concentration vs. ratio.

You should have 5 results for each ion, determine the mean and 95% confidence.

Answer 1

1) for Fe

Based on the data of Iron, the calibration data was obtained.

Standard (ppb)	Fe (ppb)	RSD	CPS	Ratio
50	27.05436	0.756911	440537.6	1.424524
25	11.75415	1.700481	231846.4	0.774779
10	3.634464	4.002003	132754.5	0.429965
5	-0.53245		78119.99	0.253011

Fe Ratio = 0.029*[Fe] RP = 0.958 Ratio • Fe - Linear (Fe) 10 20 40 50 60 30 [Fe], ppb

From the calibration data, concentration of Fe (ppb) was estimated.

Test (Fe)	Ratio	[Fe]=Ratio/0.029
Tap water	0.841586	29.02
Tap water	0.889633	30.68
Tap water	0.784022	27.04
Tap water	0.814529	28.09
Tap water	0.8144	28.08
	mean	28.58
	stdev	1.37
	95% confidence	1.20

Mean [Fe], ppb in tap water = 28.58

95% confidence level for Fe in tap water = 1.2

2) For Cu,

Based on the standard data available, the following calibration graph was plotted.

Standard (ppb)	Cu (ppb)	RSD	CPS	Ratio
50	24.57213	1.356854	515047.5	2.868376
25	11.68233	1.086254	274253.2	1.557164
10	4.474696	1.524023	147228.8	0.824069
5	1.117383	2.619541	86256.58	0.482445

Cu Ratio = 0.059*[Cu] R? = 0.969 Ratio - Linear (Cu) 0 10 20 40 50 60 30 [Cu], ppb

Test (Cu)	Ratio	[Cu]=Ratio/0.059
Tap water	2.154371	36.51
Tap water	2.072295	35.12
Tap water	2.102923	35.64
Tap water	2.108276	35.73
Tap water	2.09726	35.55
	mean	35.71
	stdev	0.51
	95% confidence	0.45

Mean [Cu] in tap water, ppb = 35.71

95% confidence interval = 0.45