Metals in Sewage Sludge

APPLICATION NOTE

SUMMARY

The application note summarizes the digestion of SQC001S, a sewage sludge Certified Reference Material using ColdBlock Digestion Pro Series Technology.

Instrument:	ColdBlock CBM sample digester, chiller, ICP-OES, ICP-MS (with CRC technology)
Published:	December 2024
Digestion Time:	45 minutes
Acid Used:	HNO₃, HCl & H₂O₂
Average ColdBlock Recovery vs. CRM:	103% Arsenic 96% Mercury 98% Lead

METHODOLOGY

Chiller temperature was set to -5°C
5g of each sample was weighed and placed into a ColdBlock™ Digestion vessel
10mL of 1:1 HNO₃ + 5mL 1:1 HCl was added, and the samples were digested at 70% power for 5 minutes
10mL HNO₃ was added and digested again at 60% power for 20 minutes (repeat this step if fuming continues)
3mL of 30% H₂O₂ was added slowly, and digested again at 60% for 10 minutes
Add 5mL HCl and digest a final time at 60% power for 10 minutes
Samples were cooled and bulked to 50mL using ultrapure water

DISCUSSION

This method yielded data comparable to EPA 3050b standards (with improved recovery of antimony) in just 45
The addition of HCl in the final step of the digestion helps keep certain elements such as antimony and silver solubilized
This method is not appropriate for standard ICP-MS instruments that are not equipped with Collision/Reaction Cell technology, for more detailed information please contact ColdBlock at info@coldblock.ca

Metals in Sewage Sludge, CRM, SQC001S, after bulk up to 50mL

Results

Metals in Sewage Sludge
Method:	0.5g	10mL 1:1 HNO3 + 5mL 1:1 HCl, digest at 70% for 5 minutes, then add 10mL HNO3 and digest at 60% for 20 minutes (repeat this step if fuming continues) Add 3mL of 30% H₂O₂, slowly and digest again @ 60% for 10 minutes, then add 5mL HCl and digest again @ 60% for 10 minutes 5.Cool and bulk to 50mL with 2% HNO₃
Element	Certified Value	+/-	Sample A	Sample B	Sample C	Sample D	Sample E	Average (ppm)	Stdev	% RSD	% Recovery vs certified value
Ag (ppm)	42.3	5.5	37.2	38.4	37.4	41.2	44.2	39.7	2.99	7.5%	94%
Al (ppm)	18800	3120	17907	19519	18208	17571	18164	18274	741	4.1%	97%
As (ppm)	282	35.9	284	294	293	271	316	292	16.5	5.6%	103%
Ba (ppm)	430	40.7	425	449	435	389	412	422	22.9	5.4%	98%
Be (ppm)	45.1	4.8	48.9	48.5	48.8	48.8	48.1	48.6	0.327	0.7%	108%
Ca (ppm)	66200	8280	68389	71253	65949	67212	67194	67999	2013	3.0%	103%
Cd (ppm)	64.4	5.2	59	60.5	62.9	62.9	65.6	62.2	2.53	4.1%	97%
Co (ppm)	49.3	4.39	48.4	47.4	45.9	48.6	53	48.7	2.65	5.4%	99%
Cr (ppm)	116	14.6	121	119	121	123	137	124	7.29	5.9%	107%
Cu (ppm)	416	33.8	416	391	396	423	485	422	37.6	8.9%	101%
Fe (ppm)	33900	5630	31232	32641	32119	31724	36715	32886	2202	6.7%	97%
Hg (ppm)	6.06	1.44	5.91	5.62	5.91	5.77	5.96	5.83	0.139	2.4%	96%
K (ppm)	4330	161	3991	3968	4447	4062	4484	4190	254	6.1%	97%
Mg (ppm)	13200	1110	14243	14001	13618	13184	14129	13835	433	3.1%	105%
Mn (ppm)	1310	350	1130	1550	1191	1340	1246	1291	164	12.7%	99%
Mo (ppm)	102	17	95.2	96.6	103.6	107.5	107.6	102	5.91	5.8%	100%
Na (ppm)	3100	304	2895	2967	2783	2995	3066	2941	107.6	3.7%	95%
Ni (ppm)	106	6.42	103.2	108.5	106.4	104	109.7	106	2.80	2.6%	100%
Pb (ppm)	126	10.5	121	121	125	119	130	123	4.38	3.6%	98%
Sb (ppm)	70.8	24	66.3	66.8	69.1	69.0	75.9	69.4	3.84	5.5%	98%
Se (ppm)	146	18.6	137	144	151	154	145	146	6.61	4.5%	100%
Tl (ppm)	40.9	10.9	38.2	39.1	38	37.7	44.1	39.4	2.67	6.8%	96%
V (ppm)	105	15.8	104	104	96.8	92.8	107	101	5.89	5.8%	96%
Zn (ppm)	913	82.8	905	885	863	881	1002	907	55.1	6.1%	99%

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