Table 2. Phosphorus quotas (mol P cell⁻¹) of Thalassiosira pseudonana as measured on individual cells with SXRF and on bulk samples by colorimetry and radioisotopes.

The quotas are means (± SD) of 48 cells for SXRF and three filters for the colorimetric analyses. The range of quotas measured by Sunda & Huntsman (1995 ▶) were calculated from C measured over a range of Fe concentrations assuming the Redfield ratio of 106:1 C:P. The range of quotas measured by Thompson et al. (1992 ▶) was calculated from measurements of cellular C and N using the Redfield ratio of 106C:16N:1P.

SXRF	3.8 × 10−15 ± 1.4 × 10−15
Spectrophotometric	3.0 × 10−15 ± 7.0 × 10−17
Sunda & Huntsman (1995 ▶)	2.8 × 10−15–6.1 × 10−15
Thompson et al. (1992 ▶)	6.2 × 10−15–7.8 × 10−15