Download 210 nm. Development of the CE separation

報告者:黃俊強
2010/11/17
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
INTRODUCTION

N-Methylcarbamates (NMCs) first introduction into the
agrochemical market in the1950s. They are used world-wide as
insecticides,acaricides, nematocides and molluscicides on a large
number of crops.

NMCs currently constitute a class of chemicals widely used in agriculture
to combat a large number of pests in a great variety of crops, and their
residues may be encountered in fruits and vegetables.
3
INTRODUCTION

High solubility and low sorption causes aldicarb and carbofuran
to be mobile in groundwater, and their toxic degradation products
aldicarb sulfoxide and aldicarb sulfone and 3-hydroxy-carbofuran
are also soluble in water.

Gas chromatography (GC) has provided good results, but
problems sometimes arise because of the thermal lability of the
analytes.
INTRODUCTION

Since the 1970s, high-performance liquid chromatography (HPLC) has
become the preferred choice for the determination of NMCs, because, in
this case, the thermal lability problem is obviated.

Although normal-phase separations have been implemented successfully
in many cases, reversed-phase HPLC (RP-HPLC) has been much more
popular, due mainly to its operational simplicity and better performance.
INTRODUCTION

Capillary electrophoresis (CE) has achieved recognition as a
separation technique for use in the separation of inorganic and
organic compounds,and has also been reported as a novel
approach for the determination of pesticides
 INTRODUCTION
2.1 Chemicals and samples
 MATERIALS
AND
METHODS
2.2 Instrumental
set-up
2.3 Solid-phase extraction
 RESULTS AND DISCUSSION
 CONCLUSIONS
Chemicals and samples
Chemicals and samples

Acetonitrile and ethyl acetate were obtained from Scharlau

Sodium dodecyl sulfate (SDS) was obtained from Riedel–de Ha¨en

The solid-phase extraction (SPE) cartridges were 500mg of
graphite carbon obtained from Supelco

The pesticide standards were obtained from Riedel–de Ha¨en
Instrumental set-up

All CE experiments were performed with P/ACE model 5500 (Beckman
Instruments) equipped with a Beckman diode-array detector.

Beckman System Gold Software was used for system control, and for
data collection and processing.

A fused-silica capillary with 75-μm internal diameter (ID) and total length
(LT) of 57cm (50 cm to the detector, (LD)), 375 μm outer diameter (OD)
were chosen.
P/ACE 5500
Instrumental set-up
Sodium hydroxide (0.1M)for 5 min
1min with Milli-Q water
Background electrolyte solution for 4 min
sample injection
Instrumental set-up
Sodium hydroxide(0.1M) for 1min
Milli-Q water for 1min
 20.0 psi presure for each run
Solid-phase extraction
1.Ethyl acetate 10ml
5.Dried 10min
2.Acetonitrile 15ml
6.Elute with ACN
(2ml)
3. Milli-Q water 10ml
7.Dry
4.water sample 250ml
(flow rate of 5mlmin−1)
8.250ml buffer
 INTRODUCTION
3.1 Development of the CE separation
 MATERIALS AND METHODS
3.2 Application to environmental samples
 RESULTS AND DISCUSSION
 CONCLUSIONS
Development of the CE separation
 The pH of the buffer systems tested
pH: 7~11
(1)Phosphate
(2)Carbonate
(3)Borate
pH:8
Borate
Development of the CE separation
 Different voltages tests:
20~27kv
23 kv
 Different injection time tests:
4~12s
12s
Development of the CE separation

Figure 1. Migration time versus concentration of SDS. Conditions:20mM borax/HCl
running buffer, pH 8; separation voltage: 23 kV;detection: 210 nm.
Development of the CE separation

Figure 2. Electropherogram of the five compounds (30 ng ml−1)under optimal
conditions. Experimental and instrumental conditionsas in Fig 1. SDS: 140mM.
Development of the CE separation
 Separation were made using a sodoum
borate/Hcl(20mM;pH:8)buffer solution and140mM
sodium dodecyl sulfate at 23 kv.
 Th sample were injected for 12 S and detector was
conduced by UV diode-array absorption at 210nm in
less than 17min.
Application to environmental samples
77~97%
CONCLUSIONS
 The present data confirm the viability of MEKC in the
detection and quantification of a family of well-known
pesticides
 These results demonstrated that the analysis are more
economical than current methods due to the low
solvent consumption , analysis times and resolutions.
Summery

2004年Carretero團隊以MEKC-DAD偵測得滅克、得滅克亞風、得滅克
風、加保扶、3-羥基加保扶等五種農藥，並藉由MEKC的方法可在20分
鐘內將這些農藥分離出來。所探討的最佳條件為20 mM硼酸鈉/鹽酸 緩
衝溶液(pH8) 並添加 140 mM SDS。LOD分別為2.3、3.8、2.01、7.47、
5.11 (μg litre−1)其中以3-羥基加保扶的偵測極限可達最低2.01 (μg
litre−1)。MEKC的方法應用在真實樣品上以簡單的固相萃取處理方式減
少干擾並加以淨化、濃縮達到分析的效果，得到平均回收率為77~97%
(n=5) RSD值為2~7%