Page 70 - Application Notebook - Solution for Food Safety

LAAN-A-LM-E076

Application Liquid Chromatography Mass Spectrometry

News Analysis of Sulfamic Acid in Fertilizers Using LC/MS

(LCMS-2020)
No.C105

Sulfamic acid, due to its plant growth inhibiting effects,
is subject to maximum limits in fertilizers as specified in 4500 95.90(-)
the official standard for ordinary fertilizers according to
1)
the Japanese Fertilizers Regulation Act. According to the
2)
Testing Methods for Fertilizers supervised by Japan's 4000
Food and Agricultural Materials Inspection Center
(FAMIC), the ion chromatography (IC) method is
specified as the test method for sulfamic acid in 3500
ammonium sulfate. It has been reported, however, that
when applying this IC method with byproduct
compound fertilizer (fertilizer produced by concentrating 3000
and drying liquid byproducts obtained from fermentation
plants involved in amino acid production, etc.) samples
that contain large amounts of organic matter, it is 2500
difficult to separate the sulfamic acid peaks from
contaminant peaks generated from sample matrix. 3)
In this application, we investigated the analytical 0.0 2.5 5.0 7.5 min
conditions for LC/MS that would permit acquisition of
mass information and provide high selectivity in order to
eliminate the effects of contaminating components. The Fig. 1 Mass Chromatogram (SIM) of Sulfamic Acid (0.1 mg/L)
LCMS-2020 single quadrupole mass spectrometer was
used for the analysis.
Good quantitative results were obtained, confirming the Area
applicability of this method using byproduct compound
fertilizer as the actual sample. 27500
25000
n Analysis of Standard Solution 22500
Table 1 shows the analytical conditions, and Fig. 1 shows 20000
chromatogram obtained using a standard solution 17500
(0.1 mg/L aqueous solution) of sulfamic acid.
As retention of a zwitterionic compound such as 15000
sulfamic acid is difficult using reversed phase conditions, 12500
we adopted conditions using a HILIC column. Isocratic 10000
analysis was conducted using a mobile phase consisting 7500 R = 0.9991732
of acetonitrile / ammonium formate + formic acid R = 0.9983472
2
(pH 3.2). 5000
Applying the LC/MS method (ESI-Negative), we 2500 Area % RSD (0.001 mg/L, n=5) 2.72 %
conducted selected ion monitoring (SIM) analysis using 0
the deprotonated molecule at m/z 95.9. Fig. 2 shows the 0.0 25.0 50.0 75.0 Concentration
calibration curve. Excellent linearity was obtained over
the entire concentration range of 0.001 to 0.1 mg/L,
with a correlation coefficient greater than 0.999. Fig. 2 Calibration Curve (0.001 – 0.1 mg/L)

Table 1 Analytical Conditions
Column : Phenomenex Luna HILIC 20A (100 mm L. × 2.0 mm I.D., 5 μm)
Mobile Phases : Acetonitrile/100 mmol/L Ammonium Formate+ Formic Acid (pH 3.2) = 90:10, v/v
Flowrate : 0.2 mL/min
Column Temperature : 40 ˚C
Injection Volume : 1 μL
Probe Voltage : -3.5 kV (ESI-negative mode)
DL Temperature : 250 ˚C
Block Heater Temperature : 400 ˚C
Nebulizing Gas Flow : 1.5 L/min
Drying Gas Flow : 15 L/min
Monitoring Ion (SIM) : m/z 95.9