to caffeine For example -Instrumax CAD Performance inspection
Instrumax (Tianjin) Co., Ltd.Instrumax (Tianjin) Co., Ltd.- Experiment purpose:caffeine-Inspection Instrumax CAD Performance
- Experimental conditions:
Instruments: INSTRUMAX Charged Aerosol Detector (CAD)(CADetector a1)
INSTRUMAX Nitrogen Generator g15)
Agilent liquid chromatograph(HPLC-1200)
Column: InfinityLab Poroshell 120 EC-C18 3.0*100mm 2.7μm
Reagent: methanol (Merck HPLC grade) distilled water (Watson's)
Sample: water caffeine Solution standard material
（5μg/mL，25μg/mL，125μg/mL，250μg/mL，500μg/mL）
(with certificate)
1, experimental process
3.1 Experimental conditions
Mobile phase: methanol: water =20:80
Column: InfinityLab Poroshell 120 EC-C18 3.0×100mm 2.7μm
Column temperature:50℃
Flow rate:0.5mL/min
Instrumax (Tianjin) Co., Ltd.CAD Conditions
Drift tube temperature:35℃
Atomized air flow:3L/min
Charging airflow:1L/min
Charging current:1μA
Gain：0.05
RF：2.0
Inspection items
Noise Drift: Acquisition 21min, evaluation 1~21min noise drift
Signal to noise ratio:5μg/mL caffeine Standards, injection 10μL, evaluate the signal-to-noise ratio
Injection precision:25 µg/mL caffeine Standard solution (5 µL),5 µg/mL caffeine Standard solution (10µL),5 µg/mL caffeine Standard solution (20 µL), evaluate retention time, peak height RSD%
Response linearity: use include 5 traceable standards at different concentrations to confirm the linear response of the system. Calculate the correlation coefficient (r) between peak area and sample concentration, i.e. response linearity.
3.2 Experimental results
3.2.1 Baseline noise and baseline drift
noise (ASTM) | drift | |
Test results | 25.14fA | 2.534fA |
Instrumax (Tianjin) Co., Ltd.3.2.2 signal-to-noise ratio
Sample:5.0μg/mL caffeine, injection 10μL
signal-to-noise ratio (50ng caffeine) | |
Test results | S/N=209.3 |
3.2.3 Injection precision
25 µg/mL caffeine Standard solution (5 µL),5 µg/mL caffeine Standard solution (10µL),5 µg/mL caffeine Standard solution (20 µL), evaluate retention time, peak height RSD%, the results are as follows:
5µg/mL caffeine Standard solution (10µL) | 5µg/mL caffeine Standard solution (20 µL) | 25µg/mL caffeine Standard solution (5 µL) | ||||||||
serial number | retention time | Peak height | serial number | retention time | Peak height | serial number | retention time | Peak height | ||
1 | 3.338 | 0.732 | 1 | 3.375 | 2.552 | 1 | 3.325 | 3.650 | ||
2 | 3.355 | 0.747 | 2 | 3.37 | 2.562 | 2 | 3.332 | 3.569 | ||
3 | 3.344 | 0.732 | 3 | 3.375 | 2.503 | 3 | 3.334 | 3.608 | ||
4 | 3.357 | 0.749 | 4 | 3.361 | 2.508 | 4 | 3.329 | 3.635 | ||
5 | 3.339 | 0.748 | 5 | 3.362 | 2.483 | 5 | 3.326 | 3.692 | ||
6 | 3.342 | 0.735 | 6 | 3.376 | 2.525 | 6 | 3.331 | 3.619 | ||
RSD% | 0.245 | 1.123 | RSD% | 0.202 | 1.201 | RSD% | 0.105 | 1.142 | ||
Instrumax (Tianjin) Co., Ltd.3.2.4 Response linearity
Use include 5 traceable standards at different concentrations to confirm the linear response of the system. Calculate the correlation coefficient (R) between peak area and sample concentration, that is, response linearity.
Concentration (μg/mL) | Peak area |
5 | 3.638 |
25 | 43.116 |
125 | 258.658 |
250 | 525.608 |
500 | 997.079 |
Response linearity | |
Test results | R2=0.9989 R=0.9995 |
2, summary and discussion
Summary of results
Project | result | Suggested reference requirements |
baseline noise | 25.14fA | ≤40fA |
Baseline drift | 2.534fA | ≤40fA/20min |
signal-to-noise ratio | S/N=209.3 | ≥10 |
Precision | 1.142%（5μL） 1.123%（10μL） 1.201%（20μL） | ≤5.0% |
Response linearity | R=0.9995 | ≥0.991 |
Discussion of results:It can be seen from the results of noise drift, signal-to-noise ratio, precision, response linearity, etc.,Instrumax Charged Aerosol Detector (CAD) It has small noise drift, high sensitivity, good precision and good linearity. It is a powerful tool for detecting semi-volatile and non-volatile substances.