Metals in Soil, ERA 540

APPLICATION NOTE

SUMMARY

The application note summarizes the digestion of ERA 540, a Metals in Soil certified reference material using ColdBlock Digestion Pro Series Technology.

Instrument:	ColdBlock CBM, chiller, ICP-OES, ICP-MS (with CRC technology)
Published:	March 2025
Digestion Time:	45 Minutes
Acid Used:	HNO₃, HCl & H₂O₂
Average ColdBlock Recovery vs. CRM:	95% Antimony 100% Mercury 102% Silver

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METHODOLOGY

Chiller temperature was set to -5°C
0.5g of each sample was weighed and placed into a ColdBlock Digestion vessel
10mL of 1:1 HNO₃ + 5mL 1:1 HCl were 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
5mL HCl was added and digested 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 in just 45 minutes
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

15 samples of ERA 540 after bulk up to 50mL

Results

ERA #540 Metals in Soil (lot:D125-540)
Method:	0.5g – Add 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. Cool and bulk to 50mL with ultrapure water
Element	Reference Value* (mg/kg) n=5	ColdBlock Average (mg/kg) n=16	ColdBlock Stdev	ColdBlock % RSD	ColdBlock % Recovery vs SW-846 3050B
Aluminum	7165	7236	549.4	7.6%	101%
Antimony	129	123	9.66	7.9%	95%
Arsenic	139	152	5.52	3.6%	110%
Barium	196	208	19.6	9.4%	106%
Beryllium	223	245	31.7	13.0%	110%
Cadmium	181	194	14.6	7.6%	107%
Calcium	4421	4323	307.5	7.1%	98%
Chromium	136	131	8.08	6.2%	96%
Cobalt	129	137	10.1	7.3%	107%
Copper	235	259	21.8	8.4%	111%
Iron	6782	7012	353.2	5.0%	103%
Lead	89	100	6.2	6.2%	113%
Magnesium	1809	2033	92.67	4.6%	112%
Manganese	245	254	20.9	8.2%	103%
Mercury	27	27	1.9	7.1%	100%
Molybdenum	94	97	5.2	5.3%	102%
Nickel	154	163	11.5	7.0%	106%
Potassium	2069	2198	158.0	7.2%	106%
Selenium	129	136	7.54	5.5%	105%
Silver	54	55	2.7	4.8%	102%
Sodium	271	290	26.6	9.2%	107%
Thallium	166	179	14.0	7.8%	108%
Vanadium	139	135	8.09	6.0%	97%
Zinc	336	340	18.7	5.5%	101%

Click here to download the Application Note in PDF format.

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