. 2025 Aug 20;63(9):e00471-25. doi: 10.1128/jcm.00471-25

TABLE 2.

Magnesium, calcium, and zinc cation concentrations before and after adjustment in different brands of Mueller–Hinton broth after 0, 2, and 6 h of chelation, as measured using inductively coupled plasma mass spectrometry (ICP-MS)^a^,^d

			Cation concentration (µg/mL) at baseline and after chelation
			Mg²⁺			Ca²⁺			Zn²⁺
Broth manufacturer/details^b			0 h	2 h^c	6 h^c	0 h	2 h^c	6 h^c	0 h	2 h^c	6 h^c
BD-BBL	MHIIB	Before CA	NA	0.04	0.03	NA	0.15	0.15	NA	<0.02	<0.02
Lot no.	0252334	After CA	10	12	11	22	26	24	0.98	0.58	0.57
BD-Difco	MHB	Before CA	4.1	0.01	0.01	3.0	0.08	0.08	0.29	<0.02	<0.02
Lot no.	1123327	After CA	NA	11	11	NA	24	24	NA	0.57	0.56
Oxoid	MHB	Before CA	5.6	0.02	0.02	6.5	0.09	0.09	0.27	<0.02	<0.02
Lot no.	3000775	After CA	NA	11	11	NA	23	24	NA	0.56	0.56
Merck	MHB	Before CA	2.1	0.01	0.01	7.6	0.07	0.07	0.70	<0.02	<0.02
Lot no.	BCCF7733	After CA	NA	11	11	NA	23	23	NA	0.58	0.58

^{^a}

CA, cation adjustment; MHB, Mueller–Hinton broth; MHIIB, Mueller–Hinton II broth; NA, not applicable.

^{^b}

Each cation-adjusted Mueller–Hinton broth (CAMHB) or iron-depleted CAMHB (ID-CAMHB) was prepared from MHB or MHIIB from four different manufacturers: BD-BBL, BD-Difco, Oxoid, Merck.

^{^c}

ID-CAMHB was treated with Chelex for 2 or 6 h, followed by cation (magnesium, calcium, and zinc) adjustment.

^{^d}

ICP-MS values for iron and other cations are the average of two measurements.