Hach ISENH4181, User Manual

Page: 14 / 18

Table 3 Standard solution volumes and concentrations
Measured sample
concentration
Volume of standard to
add
Concentration of standard solution
1 to 2 mg/L 0.5 mL 100 mg/L NH
3
—N
3 to 6 mg/L 1.0 mL 100 mg/L NH
3
—N
7 to 15 mg/L 0.3 mL 1000 mg/L NH
3
—N
15 to 30 mg/L 0.5 mL 1000 mg/L NH
3
—N
30 to 60 mg/L 1.0 mL 1000 mg/L NH
3
—N
3. Measure the concentration of the spiked sample.
4. Calculate the expected (theoretical) concentration of the spiked sample:
C
E
= (C
S
x V
S
/V
T
) + (C
SS
x V
SS
/V
T
)
Where:
• C
E
= expected (theoretical) concentration of the spiked sample
• C
S
= concentration of the sample (mg/L) before the standard solution was added
• C
SS
= concentration of the standard solution (mg/L)
• V
S
= sample volume (mL) before the standard solution was added
• V
SS
= volume of the standard solution (mL)
• V
T
= total volume (standard solution volume (mL) + sample volume)
5. Calculate the percent recovery of the standard addition. A percent recovery of 100 (±5)% is an
indication that the sample measurements are accurate.
Percent recovery = C
M
/C
E
x 100
Where:
• C
M
= measured concentration of the sample after the addition of the standard solution
• C
E
= expected (theoretical) concentration of the sample after the addition of the standard
solution
Section 10 Consumables
Note: Product and Article numbers may vary for some selling regions. Contact the appropriate distributor or refer to
the company website for contact information.
Description Quantity Item no.
Ammonium Ionic Strength Adjustor (ISA) Powder Pillows 100/pkg 2980699
Ammonia standard solution, 1 mg/L as NH
3
–N 500 mL 189149
Ammonia standard solution, 10 mg/L as NH
3
–N 500 mL 15349
Ammonia standard solution, 100 mg/L as NH
3
–N 500 mL 2406549
Ammonia standard solution, 1000 mg/L as NH
3
–N 1 L 2354153
Wash bottle, polyethylene, 500 mL 1 62011
Disposable wipes, 11 x 22 cm 280/pkg 2097000
Beaker, 30 mL, plastic, colorless 80/pkg SM5010
Beaker, 100 mL, polypropylene 1 108042
Probe stand for standard Intellical probes 1 8508850
12 English