Table 7 Comparison of the present method with data obtained in two previously described methods

Analytical apparatus

LC-MS/MS (ESI)

LC-MS/MS (ESI)

LC-MS/MS (ESI)

Mass spectrometer

API5500 (ABSciex)

API3200 (ABSciex)

6430 (Agilent)

Analytical column

Cation-H

30 mm × 4.6 mm

(Bio-Rad)

Zorbax SB-C3

150 × 4.6 mm 5 μm

(Agilent)

Scherzo SM-C18 MF

100 × 2 mm 3 μm silica (Imtakt)

Sample preparation

Dilution

Solid-phase extraction (SAX)

Solid-phase extraction (SCX + NH2)

Internal standard

Glyphosate-¹³C₃, ¹⁵N

Glyphosate-2-¹³C, ¹⁵N

Glyphosate-¹³C₂, ¹⁵N

Amount of sample (μL)

600

500

ca. 100 (depend on the creatinine concentration)

Average recovery (%)

92-102 (0.1-800 μg/L, n = 6)

91.0-99.6 (0.33-1.33 μg/L, n = 3)

Intra-day precision (%RSD)

2.0-11.6 (0.1-800 μg/L, n = 6)

3.54 (n = 10)

5.6-11.4 (0.33-1.33 μg/L, n = 6)

Inter-day precision (%RSD)

9.96 (n = 40 over 4 runs)

6.8-14.0 (0.33-1.33 μg/L, n = 10 over 5 runs respectively)

LLOQ (μg/L)

0.10

0.3

LOD (μg/L)

0.023

0.5

0.1

Analytical stability

86 or more injection

Verification of matrix effect

Confirmed with pool urine

Confirmed with 10 individual urine

Prepared sample stability

72 h

Freeze-thaw sample stability

3 cycles^a (only human milk)

3 cycles

Long-term sample stability

5 °C (24 h)^a

−20 °C (3 months)^a

25 °C (1 week)

4 °C (1 month)

−80 °C (1 month)

Application of methods to urine samples

n = 31, detection rate 45%, max 10.66 μg/L

n = 54, detection rate 59%, max 1.99 μg/L