Statistical analysis of trace metals content of cocaine using inductively coupled plasma-mass spectrometry calibrations

Figures & data

Table 1. Sample plan employed for the cocaine samples

Sample Code (Cocaine seizures)	A B	C
6	6x, 6y	-
18	183, 184	-
7	71, 76	-
29	291, 298	-
14	141, 148	-
23	232, 235	-
13	131, 136	-
24	244, 246	-
28	− 282, 283	-
32	321, 324	-
10	− 10A6, 10A10	-
26	− 263A, 265B	-
9	9A, 9B	-
15	15A6, 15A10	-
19	195, 198	-
25	252, 258	-
4	-	4
12	-	12
20	-	20
21	-	21
31	-	31

Total number of samples—37,‘–‘ Signifies no sample

Figure 1. Levels of relationship for different kinds of cocaine samples seized (Kar-Weng et al., 2016).

Table 2. ICP-MS operational parameters used

Parameters	Conditions
RF Power	1 kW
Radio frequency	40 mHz
Carrier gas flow rate	0.64L/min
Plasma gas flow rate	15 L/min
Plasma observation	Radial
Pump uptake	1.5 ml/min

Table 3. Statistical analysis of samples

Sample 6
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Rows	1079.104	9	119.9004	6.402736	0.005392	3.178893
Columns	20.43838	1	20.43838	1.091419	0.323404	5.117355
Error	168.5379	9	18.72643
Total	1268.08	19
Sample 18
Rows	22,964.43	9	2551.604	684.9746	1.14E-11	3.178893
Columns	2.355038	1	2.355038	0.632207	0.447008	5.117355
Error	33.52597	9	3.725107
Total	23,000.32	19
Sample 7
Rows	7681.983	9	853.5536	7.101859	0.003727	3.178893
Columns	118.4871	1	118.4871	0.985854	0.346701	5.117355
Error	1081.686	9	120.1873
Total	8882.156	19
Sample 29
Rows	418.0879	9	46.45421	63.12959	4.67E-07	3.178893
Columns	0.453306	1	0.453306	0.616026	0.452692	5.117355
Error	6.622693	9	0.735855
Total	425.1639	19
Sample 14
Rows	298.4433	9	33.16037	82.57644	1.43E-07	3.178893
Columns	0.335405	1	0.335405	0.835231	0.384594	5.117355
Error	3.614146	9	0.401572
Total	302.3929	19
Sample 23
Rows	4695.235	9	521.6928	3.02482	0.057351	3.178893
Columns	268.6005	1	268.6005	1.557369	0.243541	5.117355
Error	1552.236	9	172.4707
Total	6516.072	19
Sample 13
Rows	341.8538	9	37.98375	173.1062	5.37E-09	3.178893
Columns	0.225569	1	0.225569	1.028002	0.337109	5.117355
Error	1.974821	9	0.219425
Total	344.0541	19
Sample 24
Rows	514.701	9	57.189	145.2892	1.17E-08	3.178893
Columns	0.172608	1	0.172608	0.438513	0.524433	5.117355
Error	3.542597	9	0.393622
Total	518.4162	19
Sample 28
Rows	906.9165	9	100.7685	324.8468	3.23E-10	3.178893
Columns	2.755789	1	2.755789	8.88382	0.015435	5.117355
Error	2.791828	9	0.310203
Total	912.4641	19
Sample 32
Rows	415.886	9	46.20955	285.0302	5.79E-10	3.178893
Columns	0.655582	1	0.655582	4.043767	0.075217	5.117355
Error	1.459094	9	0.162122
Total	418.0007	19
Sample 9
Rows	5171.554	9	574.6171	841.538	4.51E-12	3.178893
Columns	0.775786	1	0.775786	1.136154	0.314225	5.117355
Error	6.145359	9	0.682818
Total	5178.475	19
Sample 15
Rows	210,176.5	9	23,352.94	256.7125	9.25E-10	3.178893
Columns	52.8125	1	52.8125	0.580553	0.465593	5.117355
Error	818.7233	9	90.96926
Total	211,048	19
Sample 19
Rows	1748.343	9	194.2603	2.011651	0.156257	3.178893
Columns	156.8224	1	156.8224	1.623965	0.234459	5.117355
Error	869.1082	9	96.56758
Total	2774.273	19
Sample 25
Rows	1919.497	9	213.2775	2574.384	2.96E-14	3.178893
Columns	0.083722	1	0.083722	1.010571	0.341027	5.117355
Error	0.745614	9	0.082846
Total	1920.327	19
Sample 10
Rows	2913.373	9	323.7081	2.332019	0.111584	3.178893
Columns	242.8278	1	242.8278	1.749352	0.218579	5.117355
Error	1249.292	9	138.8102
Total	4405.492	19
Sample 26
Rows	2105.408	9	233.9342	396.9403	1.31E-10	3.178893
Columns	7.041284	1	7.041284	11.94767	0.0072	5.117355
Error	5.304092	9	0.589344
Total	2117.753	19

Table 4. Descriptive data of 10 elements in 37 cocaine samples

Element	Mean	SD	Minimum	Q1	Median	Q3	Maximum
Ca	61.94	54.60	13.13	17.39	30.94	34.87	960.43
As	0.32	0.13	0	0.26	0.34	0.42	0.52
Cr	1.66	0.55	0	1.57	1.81	1.99	2.21
Fe	2.65	2.41	0	1.65	2.11	3.42	11.54
Mg	24.35	78.06	0	0.84	1.73	3.04	352.42
Ni	0.09	0.09	0	0.03	0.07	0.13	0.35
Zn	6.25	14.12	0	0	0.59	4.70	54.23
Cu	0.52	0.65	0	0.16	0.30	0.57	2.52
Mn	0.54	0.72	0	0.06	0.27	0.61	2.58
Pb	0.52	2.55	0	0	0.06	0.17	15.60

Q1–;1^st Quartile

Q3–3^rd Quartile

Table 5. Within-seizure presentation of some metals in cocaine samples at 95% confidence level

Code	Ca	As	Cr	Fe	Mg	Ni	Zn	Cu	Mn	Pb	P-values
6y	34.52	0.21	1.88	ND	0.83	ND	0.59	0.28	0.04	0.07	0.3234
6x	15.09	0.24	1.89	ND	0.64	ND	ND	0.24	0.03	0.06
183	118.64	0.12	1.41	1.70	13.91	0.06	1.93	0.12	0.38	0.23	0.4470
184	110.23	0.16	1.27	2.37	14.42	0.32	2.29	0.16	0.37	0.05
71	88.77	0.25	1.53	1.78	28.23	0.13	6.10	0.45	0.32	0.13	0.3467
76	40.16	0.26	1.58	6.68	24.82	0.09	4.70	0.31	0.22	0.18
291	14.24	0.40	1.98	2.74	1.73	0.07	ND	0.07	0.63	ND	0.4527
298	17.39	0.29	1.74	1.22	3.04	0.06	ND	0.38	0.58	0.17
141	13.53	0.32	1.57	2.39	0.38	0.06	ND	0.54	0.09	0.06	0.3846
148	13.13	0.51	1.99	2.45	3.11	0.03	ND	0.26	0.06	ND
232	82.31	0.29	1.64	4.56	2.63	0.15	9.62	0.67	2.05	0.18	0.2435
235	22.56	0.33	2.05	2.05	1.26	0.05	1.98	0.41	0.07	0.07
131	13.18	0.35	1.71	1.65	0.62	0.03	ND	0.53	0.09	0.06	0.3371
136	15.17	0.42	1.91	1.91	0.84	0.03	ND	ND	0.06	ND
244	18.59	0.36	2.13	4.88	1.51	0.09	ND	0.16	0.09	0.95	0.5244
246	16.12	0.51	2.04	5.29	1.75	0.06	ND	0.86	0.06	0.19
282	23.22	0.46	2.07	2.11	0.90	0.05	ND	0.94	0.05	0.12	0.0154
283	22.36	0.05	0.05	ND	ND	ND	ND	ND	ND	ND
321	15.07	0.28	1.31	0.52	ND	ND	1.01	0.26	0.02	0.02	0.0752
324	16.18	0.35	1.83	2.03	0.42	0.05	0.59	0.57	0.10	ND
10A6	33.23	ND	ND	ND	ND	ND	ND	ND	ND	ND	0.2186
10A10	35.33	0.42	2.04	4.82	1.68	0.18	54.23	2.46	1.52	0.24
263A	34.77	ND	ND	ND	ND	ND	ND	ND	0.01	ND	0.0072
265B	34.87	0.39	2.21	3	0.96	0.25	1.82	0.59	2.46	0.10
9A	34.81	0.41	1.78	1.83	47.11	0.07	1.19	0.18	0.27	ND	0.3142
9B	31.37	0.42	1.81	2.59	47.04	0.09	ND	0.09	0.30	ND
15A6	77.08	0.36	1.92	3.42	352.42	0.10	10.15	0.73	1.40	ND	0.4656
15A10	111.83	0.52	2.14	7.93	332.82	0.35	21.52	0.17	2.58	0.20
195	29.42	0.31	1.67	4.05	1.56	0.15	44.94	2.31	1.30	0.11	0.2345
198	22.74	0.42	2.09	2.29	1.54	0.03	0.24	0.08	0.39	ND
252	33.94	0.30	1.90	1.81	2.50	0.17	5.80	0.30	0.78	ND	0.3410
258	33.44	0.34	1.89	2.61	1.93	0.13	5.19	0.08	0.61	ND

ND-Not Detected

Table 6. Metal data of selected cocaine samples from different seizures

Metals	Ca	As	Cr	Fe	Mg	Ni	Zn	Cu	Mn	Pb
4	22.08	0.47	1.48	ND	1.28	ND	ND	0.35	0.08	0.08
12	960.43	0.50	2.05	2.05	2.02	0.08	53.45	2.52	0.19	0.25
20	33.35	0.28	1.80	3.89	2.70	0.34	3.44	1.38	1.83	15.60
21	21.78	0.34	1.79	11.54	1.99	0.07	0.21	0.48	0.41	ND
31	30.94	0.17	1.35	ND	2.42	0.11	0.20	0.28	0.48	0.06

ND-Not Detected

Table 7. Heavy metal content in cocaine compared to natural mineral water, animal fats, and edible fats and oils

Elements	Cocaine	Natural Mineral water	Animal fats	Edible fats and oils
Lead (Pb)	0.52	0.01	0.1	0.1
Arsenic (As)	0.32	0.01	0.1	0.1
Chromium (Cr)	1.66	0.003	0.05	0.05

Table 8. Metal profile of cocaine sample x and y

	Ca	As	Cr	Fe	Mg	Ni	Zn	Cu	Mn	Pb
Sample x (First seized)	18.59	0.36	2.13	4.88	1.51	0.09	0	0.16	0.09	0.95
Sample y (Found missing sample)	16.12	0.51	2.04	5.29	1.75	0.06	0	0.86	0.06	0.19

Sample x and y represent samples 24₄ and 24₆ respectively

Kar-Weng, C., Zulkfeli, M., Leethavani, B., Muhammad-Hafis, Z., & Md-Pauzi, A. (2016). Street-Level classification of illicit heroin using inorganic elements coupled with pattern monitoring. Egyptian Journal of Forensic Sciences, 6, 275–279. doi:10.1016/j.ejfs.2015.05.004

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