QuEChERS Sample Preparation in the Simultaneous ... - Springer Link

14 downloads 21276 Views 325KB Size Report
performed by bulk adsorbents Bondesil PSA, C18, ... e mail: amelinvg@mail.ru .... is sulfamethazine, SMTZ is sulfamethizole, SMTP is sulfamethoxypyridazine, ...
ISSN 10619348, Journal of Analytical Chemistry, 2015, Vol. 70, No. 9, pp. 1076–1084. © Pleiades Publishing, Ltd., 2015. Original Russian Text © V.G. Amelin, N.M. Volkova, A.A. Timofeev, A.V. Tret’yakov, 2015, published in Zhurnal Analiticheskoi Khimii, 2015, Vol. 70, No. 9, pp. 948–956.

ARTICLES

QuEChERS Sample Preparation in the Simultaneous Determination of Residual Amounts of Quinolones, Sulfanilamides, and Amphenicols in Food Using HPLC with a DiodeArray Detector V. G. Amelina, N. M. Volkovaa, b, A. A. Timofeeva, b, and A. V. Tret’yakovb a

Vladimir State University, ul. Gor’kogo 87, Vladimir, 600000 Russia Center for Animals Health, District of Yur’evets, Vladimir, 600901 Russia email: [email protected]

b Federal

Received March 1, 2014; in final form, July 10, 2014

Abstract—A method is proposed for the simultaneous determination of antibiotics of quinolone series (enox acin, danofloxacin, lomefloxacin, enrofloxacin, difloxacin, and oxolinic acid), sulfanilamides (sulfanil amide, sulfadiazine, sulfapyridine, sulfamerazine, sulfachloropyridazine, sulfadimethoxine, and sulfaqui noxaline), and amphenicols (chloramphenicol, florfenicol, and thiamphenicol) in foodstuffs by HPLC with diodearray detection at 228 and 280 nm from single weighed portion using a simplified, rapid, and safe QuEChERS sample preparation. The analytical range is 0.01–2 mg/kg for quinolones and 0.002–1 mg/kg for sulfanilamides and amphenicols at a sample weight of 5 g. The relative standard deviation of the results of analysis does not exceed 0.1. The time of analysis is 1–1.5 h. Keywords: antibiotics of quinolone series, sulfanilamides, amphenicols, food, HPLC, diodearray detector DOI: 10.1134/S1061934815090026

Antibiotics are used for the treatment of infectious diseases in humans and animals, and as growth addi tives in livestock breeding; therefore, their residual amounts can be present in the food of animal origin [1]. The main classes of antibiotics used in veterinary are quinolones, amphenicols, and sulfanilamides. The consumption of food containing residual amounts of antibiotics negatively affects the human body; there fore, their concentrations in food are regulated [2]. At present, numerous methods are known for the determination of sulfanilamides and amphenicols, including methods of capillary electrophoresis and HPLC [3–6], in which the extract is purified by solid phase extraction [7, 8], and chromatographic–mass spectrometric methods of the simultaneous determi nation of residual amounts of antibiotics of various classes [9–11]. The first group of methods presumes use of a large quantity of toxic organic solvents, the second one uses expensive sophisticated equipment. A method for the determination of five quinolones (mar bofloxacin, difloxacin, norfloxacin, enrofloxacin, and ciprofloxacin) with HPLC and a diodearray detector (HPLCDAD) in meet and eggs was proposed. For extraction of antibiotics from samples acetonitrile, purification of the extracts, and concentration using solidphase extraction were used [12]. Determination of 13 quinolones in feed using HPLC with DAD and fluorometric detectors and sample preparation using solidphase extraction was also proposed [13]. The

above methods are time consuming and laborious, which prevents their use for analyzing large numbers of samples in a short time. The method of dispersion solidphase extraction QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) known from 2003 was initially used for the isolation of pesticides and now is also used for the extraction of residual amounts of antibiotics. The extraction of target components is performed with acetonitrile in the presence of buffer salts. The purifi cation of the extracts from lipids, fats, and proteins is performed by bulk adsorbents BondesilPSA, C18, graphitized carbon black, ionexchange resins, and their combinations. QuEChERS ensures a significant reduction of the time of sample preparation, there is no need in using additional methods of sample prepa ration and purification, the method is characterized by high recovery of a wide range of antibiotics. The sim plicity of the method ensures the high reliability and reproducibility and the reduction of the consumption of organic solvents. However, at present this method of the extraction of target components and subsequent analysis is used mainly when HPLC and mass spec trometry (MS) are combined (Table 1). In the present work, a combination of QuEChERS and HPLCDAD is studied for the simultaneous determination of sulfanilamides, amphenicols, and quinolones in foodstuffs from a single weighed portion of sample.

1076

QuEChERS SAMPLE PREPARATION IN THE SIMULTANEOUS DETERMINATION

1077

Table 1. Data on the determination of residual amounts of antibiotics in foodstuffs using QuEChERS sample preparation Antibiotic

Matrix

Method of determina tion; column

R, %

LOD, µg/kg

Sulfanilamides: Shrimps SDZ, SDM, SMZ, SMTZ; SAM, SPD, STZ

58–133 HPLC–MS; (50 × 4.6 mm) RR Zor bax Eclipse XDBC18 (1.8 µm)

Sulfanilamides: Meat SDZ, SDM, SPD, SMO, STZ, SQX; SMZ, SMT, SCPZ

25–50

Sulfanilamides: SQX, SDM, STZ, SMT, STZ, SCPD

10–100 UHPLC–MS/MS; 1.9 mm (2.1 × 50 mm), Hypersil Gold AQ



Sulfanilamides: Feed SCPD, STZ, SDM, SDX, SMT, SMO, SMTP, SAM, SQX, STZ, SSZ

86–106 HPLC–MS/MS; (4.6 ×150 mm) Zorbax Eclipse XDB C18 (5 µm)



Amphenicols: CAP, FLO, TAP

86–110 HPLC–DAD; (150 × 4.6 mm) KINETEXTM (2.6 µm)

Milk, meat, liver, silage

Milk

HPLC–MS, HPLC/MS/MS; (75 × 4.6 mm), Symmetry C18 (3.5 µm)

LOQ, µg/kg

Refer ences

0.06–0.7



[15]



25–50

[16]

7–12

1–100

[17]

0.9–7

[18]

20–46

[19]

SAM is sulfanilamide, SDZ is sulfadiazine; SDX is sulfadoxine; SDM is sulfadimethoxine; SMZ is sulfamezazine; SMO is sul famethoxazole, SMR is sulfamerazine, SMT is sulfamethazine, SMTZ is sulfamethizole, SMTP is sulfamethoxypyridazine, SPD is sul fapyridine, SSZ is sulfisoxazole, STZ is sulfathiazole, SQX is sulfaquinoxaline, SCPD is sulfachloropyridazine, CAP is chlorampheni col, TAP is thiamphenicol, FLO is florfenicol, UHPLC is ultrahigh performance liquid chromatography.

EXPERIMENTAL Equipment. A Flexar DAD liquid chromatograph with a DAD detector (PerkinElmer, United States) was used in the work. Separation was performed on a Supelcosil LC18 column (250 × 4.6 mm, 5 µm) (SigmaAldrich, United States) in the gradient elution mode. Reagents. Standard samples of antibiotics, sulfa nilamide, danofloxacin, oxolinic acid (Dr. Ehrenstor fer GmbH, Germany), sulfadiazine, sulfapyridine, sulfamerazine, sulfachloropyridazine, sulfadimethox ine, sulfaquinoxaline, difloxacin (Fluka, Germany), chloramphenicol, florfenicol, thiamphenicol (Sigma, Germany), enoxacin, lomefloxacin, enrofloxacin (Sigma, China) were used. Standard solutions with the concentration 10 µg/mL were prepared in acetoni trile. Acetonitrile for chromatography, potassium dihydrophosphate (Merck, Germany), magnesium sulfate of cp grade, sodium chloride of cp grade, triso dium citrate dihydrate of cp grade, disodium citrate sesquihydrate of cp grade, adsorbents Bondesil PSA (Varian, United States) and C18 (Supelco, United States), and sodium acetate (Dudley Chemical, Rus sia) were used. Sample preparation. The studied samples were ground in a mixer. A weighed portion (5 g) of analyzed test sample was placed in a 50 mL centrifuge tube and 10.0 mL of acetonitrile, and 0.1 mL of concentrated HCOOH were added; the tube was capped and vigor ously shaken for 1 min. Then a mixture of 4.0 g of JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

MgSO4, 1.0 g of NaCl, 1.0 g of Na3C6H5O7 · 2H2O, and 0.5 g of Na2С6Н6О7 · 1.5Н2О was added. The con tents of the tube were shaken for 1 min (to avoid lumps formation) and centrifuged for 5 min at 4500 rpm. A portion of the extract supernatant (5 mL) was taken and transferred into a 15mL centrifuge tube which contained a mixture of adsorbent BondesilPSA (0.15 g), С18 (0.15 g), and MgSO4 (0.9 g). The tube was vigorously shaken for 1 min and centrifuged for 5 min at 2700 rpm; 1 mL of the extract was taken and transferred into a microvial and evaporated to dryness under a nitrogen flow; the residue was dissolved in 100 µL of mobile phase; and chromatography was per formed. The conditions of the determination of qui nolones and chloramphenicol were as follows: tem perature of column thermostat 35°C, mobile phase 20 mM of potassium dihydrophosphate, 1.2 g/L of 1sodium heptanesulfonate (pH 2.2), and acetoni trile; concentration of acetonitrile, vol %: 20 (0– 3 min), 17 (3–7 min), 40 (7–10 min), and 20 (10– 15 min); detection wavelength 280 nm. The condi tions of the determination of sulfanilamides and amphenicols were as follows: temperature of column thermostat 30°C, mobile phase 20 mM of sodium ace tate (pH 5 adjusted with СН3СООН); content of ace tonitrile, vol %: 15 (0–5 min), 5 (5–7 min), 10 (7– 10 min), 25 (10–15 min), 40 (15–17 min), 15 (17– 19 min), and 10 (19–25 min); detection wavelength 280 nm for sulfanilamides and 228 nm for ampheni No. 9

2015

1078

AMELIN et al. mAU

4

70 3

1 60

2

50

7

40 5

6

30 20 10 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Time, min

Fig. 1. Chromatogram of model mixture of antibiotics solutions (10 µg/mL): 1, enoxacin; 2, danofloxacin; 3, lomefloxacin; 4, enrofloxacin; 5, oxolinic acid; 6, chloramphenicol; 7, difloxacin.

cols. In both cases, the mobile phase flow rate was 1 mL/min and sample injection volume was 20 µL. Sample preparation time 30–40 min. To character ize the efficiency of sample preparation, recovery (R) was calculated using the equation

ckVk × 100, c0V0 where ck and c0 are the concentrations of analyte in the resulting test solution concentrate and the initial con centration of analyte in the initial sample, Vk and V0 are the volumes of the concentrate and sample, respectively. R=

RESULTS AND DISCUSSION Fluoroquinolones, quinolones, and chloram phenicol are of acidic character (Table 2); therefore, phosphoric acid was added to the mobile phase to obtain pH 2.2, and separation was performed in the presence of micelles of sodium 1heptanesulfonate. The concentrations of acetonitrile and surfactants were varied, and gradient was created for the better separation of quinolones and chloramphenicol (CAP). A chromatogram of a mixture of six quinolo nes and CAP obtained under optimum conditions at the wavelength 280 nm is presented in Fig. 1. Under these conditions, we could not completely separate the pairs danofloxacin–lomefloxacin and oxolinic acid– chloramphenicol.

In the determination of sulfanilamides and amphenicols, the mobile phase consisting of acetoni trile and an acetate buffer solution with pH 5 appeared to be the optimal. Figure 2 presents a chromatogram of a mixture of seven sulfanilamides and three amphenicols obtained under the optimum conditions. Peaks of sulfanilamide, sulfadiazine, sulfapyridine, sulfamerazine, sulfachloropyridazine, chlorampheni col, sulfadimethoxine, and sulfaquinoxaline were recorded at 280 nm and peaks of thiamphenicol and florfenicol, at 228 nm. The selection of amounts of magnesium sulfate and BondesilPSA and C18 adsorbents for the purification of the extract from lipids, fats, and proteins was per formed by the maximum recovery of antibiotics from real objects. In the analysis of 5 g of sample 0.9 g of magnesium sulfate and 0.15 g of each of BondesilPSA and С18 are necessary. Tables 3 and 4 present the recov eries of antibiotics from various matrices using the QuEChERS method under optimum conditions with the introduction of additives at 0.05 and 0.5 mg/kg levels. It was found that the recovery varied from 62 to 100% for quinolones and from 54 to 120% for sulfanil amides and amphenicols depending on the matrix. Table 5 contains analytical characteristics of meth ods for the determination of antibiotics. The calibra tion characteristics are linear in the range 0.05– 10 µg/mL in the simultaneous determination of qui nolones and CAP, and 0.01–5 µg/mL in the simulta neous determination of sulfanilamides and ampheni

JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

No. 9

2015

QuEChERS SAMPLE PREPARATION IN THE SIMULTANEOUS DETERMINATION Table 2. Studied antibiotics Name

Structural formula

pKa

Quinolones

O

O

F

OH 6.2

Enoxaxin (ENO)

N

N

N

HN

CH3 O

Danofloxacin (DANO)

O

F

H3C N

OH 6.2

N

N

O

O

F Lomefloxacin (LOME)

H3C

OH

N

⋅ HCl

N F

HN

2.4

CH3

O

O

F

OH 6.2

Enrofloxacin (ENRO)

N

N

N

H3C

O

O

F

OH

N

Difloxacin (DI)

N

6.1

N

F O Oxolinic acid (OX)

O O

HO

6.9

N

N

O

Sulfanilamides

Sulfanilamide

JOURNAL OF ANALYTICAL CHEMISTRY

O O S NH2

H2N

Vol. 70

No. 9

2015

3.2

1079

1080

AMELIN et al.

Table 2. (Contd.) Name

Structural formula

pKa

O N

O S

Sulfadiazine

N H

N

6.5

N

8.4

H2N O O S N H

Sulfapyridine

H2N O O N S N N H

Sulfamerazine

7.0

H2N

N

O O N S N H

Sulfachloropyridazine

Cl 5.5

H2N O O

Sulfadimethoxine

N

O N H

N

6.2

O

H2N

N Sulfaquinoxaline

H N

O S

5.5

O N

NH2

Amphenicols

OH Chloramphenicol

O

+

Cl

5.5

O

HO

N

Cl

H N

O− OH Thiamphenicol

H3C S O2 O

Florfenicol (FLOR)

H3C

Cl

H N

Cl

7.2

O

HO

O S

F

OH

N H

O

8.6

Cl Cl

JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

No. 9

2015

QuEChERS SAMPLE PREPARATION IN THE SIMULTANEOUS DETERMINATION

1081

Table 3. Recoveries (%) and RSD values (indicated in brackets) of quinolones and CAP from various matrices (n = 3, P = 0.95) Matrix

ENO

DANO

LOME

ENRO

OX

DI

CAP

Chicken meat

95 ± 1 (0.01) 62 ± 7 (0.12) 73 ± 4 (0.06) 87 ± 6 (0.07) 93 ± 7 (0.08) 96 ± 4 (0.04) 85 ± 4 (0.06)

Pork

77 ± 9 (0.12) 53 ± 5 (0.09) 69 ± 6 (0.09) 86 ± 6 (0.07) 96 ± 5 (0.05) 99 ± 2 (0.02) 79 ± 2 (0.03)

Beef

91 ± 10 (0.10) 69 ± 5 (0.05) 82 ± 5 (0.06) 95 ± 3 (0.03) 94 ± 5 (0.06) 97 ± 3 (0.03) 97 ± 3 (0.03)

Cheese

93 ± 2 (0.02) 71 ± 5 (0.05) 85 ± 6 (0.07) 85 ± 3 (0.04) 69 ± 1 (0.02) 99 ± 1 (0.01) 85 ± 1 (0.03)

Ham

68 ± 4 (0.05) 77 ± 2 (0.03) 69 ± 1 (0.02) 95 ± 5 (0.05) 70 ± 7 (0.10) 99 ± 1 (0.01) 77 ± 5 (0.09)

Beef liver

72 ± 2 (0.03) 65 ± 5 (0.08) 65 ± 4 (0.06) 86 ± 2 (0.02) 64 ± 4 (0.06) 100 ± 1 (0.01) 87 ± 7 (0.06)

Milk

85 ± 3 (0.04) 98 ± 3 (0.04) 83 ± 3 (0.04) 93 ± 2 (0.03) 68 ± 3 (0.05) 100 ± 1 (0.01) 89 ± 6 (0.07)

Honey

99 ± 1 (0.01) 65 ± 5 (0.08) 83 ± 5 (0.06) 99 ± 4 (0.04) 75 ± 3 (0.04) 99 ± 1 (0.01) 91 ± 1 (0.02)

Chicken egg

91 ± 1 (0.01) 76 ± 2 (0.03) 85 ± 1 (0.01) 96 ± 5 (0.06) 96 ± 7 (0.07) 99 ± 1 (0.01) 69 ± 5 (0.06)

cols (R 2 ≥ 0.99). The limits of detection (LOD) and lowest limits of quantification (LOQ) were calculated at signaltonoise ratios 3 and 10, respectively. The limits of detection of antibiotics at the sample weight 5 g were 0.002–0.1 mg/kg depending on the analyte. The ana lytical ranges for quinolones were 0.01–2 mg/kg and

mAU 100 90 80 70 60 50 40 30

(а) 10 6

1

0

9 8

3 4 2 5

7

10

5 mAU 100 90 80 70 60 50 40 30

those for sulfanilamides and amphenicols were 0.002– 1 mg/kg at the sample weight 5 g and the degree of extract preconcentration 10. It was found that, under the selected conditions of sample preparation and purification of extracts, the components of matrices of food and feed (proteins,

20

15

25

Time, min (b)

9

6 2

1

5

3 4 5

7

10

15

8 10

20

25

Time, min Fig. 2. Chromatogram of model mixture of sulfanilamides and amphenicols (5 mg/mL): 1, sulfanilamide; 2, sulfadiazine; 3, sul fapyridine; 4, sulfamerazine; 5, thiamphenicol; 6, sulfachloropyridazine; 7, florfenicol; 8, chloramphenicol; 9, sulfadimethox ine; 10, sulfaquinoxaline. (a) 228 nm; (b) 280 nm. JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

No. 9

2015

1082

AMELIN et al.

Table 4. Recoveries (%) of sulfanilamides and amphenicols from various matrices (n = 3, P = 0.95) Antibiotic SAM SDZ SPD SMP SCPD SDM SQX TAP FLO

Pork

Milk

Chicken egg

64 ± 4 (0.06)* 115 ± 8 (0.06) 64 ± 7 (0.09) 56 ± 5 (0.09) 65 ± 6 (0.09) 67 ± 5 (0.07) 73 ± 2 (0.03) 56 ± 5 (0.09) 54 ± 5 (0.09)

72 ± 7 (0.09) 67 ± 6 (0.08) 68 ± 4 (0.06) 71 ± 1 (0.02) 71 ± 4 (0.06) 43 ± 3 (0.07) 120 ± 8 (0.06) 68 ± 4 (0.06) 64 ± 7 (0.09)

91 ± 8 (0.09) 96 ± 6 (0.07) 84 ± 4 (0.05) 88 ± 4 (0.05) 84 ± 4 (0.05) 81 ± 2 (0.03) 85 ± 2 (0.03) 84 ± 4 (0.05) 81 ± 2 (0.03)

* RSD values are indicated in brackets.

fats, lipids, etc.) did not affect the results of determi nation of the studied antibiotics (Fig. 3). The results of analysis of foodstuffs show an appropriately high accu racy of the developed method, as the relative standard deviation of the results of analysis did not exceed 0.09 (Table 6). It was found that, in the most of the ana lyzed products, the residual amounts of fluoroquinio lones were in excess, and CAP and DI were not found (Table 6). An excess of sulfanilamides was found in the samples of cheese (MRL 0.025 mg/kg). Sulfadiazine was found in the Dvaro cheese (0.11 ± 0.03 mg/kg) (RSD = 0.08), and 0.052 ± 0.008 mg/kg (RSD = 0.10) of sulfadimethoxine was found in the Rossiiskii cheese

Table 5. Analytical characteristics of the methods of determination of antibiotics (n = 3, P = 0.95, sample weight 5 g) Antibiotic

tR, min

Equation of calibration characteristic

R2

LOD µg/mL

LOQ mg/kg

µg/mL

mg/kg

Quinolones and chloramphenicol ENO DANO LOME ENRO OX CAP DI

3.38 4.53 4.87 5.37 6.26 6.65 8.86

y = –5992 + 40106x y = –1357 + 42621x y = – 9619 + 60674x y = –15848 + 89105x y = –6780 + 32167x y = –5992 + 40105x y = –24759 + 66095x

0.9928 0.9904 0.9983 0.9974 0.9946 0.9928 0.9915

0.02 0.01 0.04 0.01 0.2 0.1 0.2

0.004 0.002 0.008 0.002 0.04 0.02 0.04

0.05 0.04 0.1 0.04 0.5 0.5 0.6

0.01 0.008 0.02 0.008 0.1 0.1 0.1

0.007 0.1 0.07 0.07 0.1 0.01 0.07 0.01 0.007 0.01

0.01 0.2 0.1 0.1 0.2 0.02 0.1 0.02 0.01 0.02

0.02 0.4 0.2 0.2 0.4 0.04 0.2 0.04 0.02 0.04

Sulfanilamides and amphenicols SAM SDZ SPD SMP TAP SCPD FLO SDM SQX CAP

4.12 6.48 8.04 8.79 9.50 16.89 19.07 21.16 21.36 20.46

y = 46512x y = 29849x y = 55460x y = 55536x y = 29851x y = 74708x y = 54537x y = 90904x y = 55409x y = 38258x

0.9996 0.9944 0.9999 0.9945 0.9944 0.9999 0.9945 0.9959 0.9844 0.9999

0.005 0.01 0.01 0.01 0.01 0.007 0.01 0.008 0.005 0.008

Table 6. Results of determination of antibiotics (mg/kg) in real objects (n = 3, P = 0.95) Matrix Chicken meat Pork Milk Fishfood Kippered herring Ravioli

ENO –* – – 0.13 ± 0.02 (0.06) 1.84 ± 0.07 (0.08) –

DANO LOME ENRO OX – – 0.018 ± 0.005 (0.08)** – – – – – 0.044 ± 0.003 (0.09) – – – 0.19 ± 0.03 (0.05) – 0.12 ± 0.03 (0.07) – 0.14 ± 0.01 (0.07) 1.44 ± 0.06(0.09) – 0.21 ± 0.04 (0.08) 0.22 ± 0.03 (0.07) – 0.51 ± 0.04 (0.04) –

* Not found. ** RSD values are indicated in brackets. JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

No. 9

2015

QuEChERS SAMPLE PREPARATION IN THE SIMULTANEOUS DETERMINATION mAU 45 40 35 30 25 20 15 10 5 0 1.0 mAU 45 40 35 30 25 20 15 10 5 0 1.0 mAU 45 40 35 30 25 20 15 10 5 0 1.0 mAU 45 40 35 30 25 20 15 10 5 0 1.0

1083

(а)

2.0

3.0

5.0

4.0

6.0

7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Time, min (b)

6.0

7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Time, min (c)

6.0

7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Time, min (d)

2 4

1

2.0

3.0

5.0

4.0

4 2

2.0

3.0

4.0

5.0

3

1 2

2.0

3.0

4.0

5

5.0

6.0

7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 Time, min

Fig. 3. Chromatogram of extracts from: (a) beef; (b) fishfood; (c) ravioli; (d) herring. 1, Enoxacin; 2, danofloxacin; 3, lomefloxacin; 4, enrofloxacin; 5, oxolinic acid.

(Fig. 5). None of the studied antibiotics was found in the samples of pork, beef, and chicken eggs. REFERENCES 1. Mashkovskii, M.D., Lekarstvennye sredstva (Pharma ceutical Preparations), Moscow: Novaya Volna, 2005. 2. SanPiN (Sanitary Regulations and Standards) 2.3.2.280410: Additions and Changes no. 22 to SanPin JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

(Sanitary Regulations and Standards) 2.3.2.107801: Hygienic Requirements for Safety and Nutritional Value of Food Products, Moscow, 2010. 3. Ricci, M.C. and Cross, R.F., J. Microcolumn Sep., 1993, vol. 5, no. 3, p. 207. 4. Kowalski, P., Plenis, A., Oledzka, I., and Konieczna, L., J. Pharm. Biomed. Anal., 2011, vol. 54, p. 160. 5. Hillaert, S. and Bossche, W., J. Pharm. Biomed. Anal., 2004, vol. 36, p. 437. No. 9

2015

1084

AMELIN et al.

6. Schenck, F.J. and Callery, P.S., J. Chromatogr. A, 1998, vol. 812, p. 99. 7. Malintan, N.T. and Mohd, M.A., J. Chromatogr. A, 2006, vol. 1127, p. 154. 8. Snegocki, T., Posyniak, A., and Zmudzki, J., Bull. Vet. Inst. Pulawy, 2007, vol. 51, p. 59. 9. Weiwei, B., Zhimin, Q., Craig, A., Heqing, Z., and Liping, C., J. Chromatogr. A, 2008, vol. 1202, p. 173. 10. WenLin, L., RenJye, L., and MawRong, L., Food Chem., 2010, vol. 121, p. 797. 11. Lin, C., Lin, W., Chen, Y., and Wang, S., J. Chromatogr. A, 1997, vol. 792, p. 37. 12. Gigosos, P.G., Revesado, P.R., Cadahia, O., Fente, C.A., and Vazquez, B.I., J. Chromatogr. A, 2000, vol. 871, p. 31. 13. Pecorelli, I., Galarini, R., Bibi, R., Floridi, A.J., Cas ciarri, E., and Floridi, A., Anal. Chim. Acta, 2003, vol. 483, p. 81.

14. Anastassiades, M., Lehotay, S.J., Stajnbaher, D., and Schenck, F.J., J. AOAC Int., 2003, vol. 86, no. 2, p. 412. 15. VillarPulido, M., GilbertLopez, B., Garcia Reyes, J.F., Ramos Martos, N., and MolinaDiaz, A., Talanta, 2011, vol. 85, p. 1419. 16. Bittencourt, M.S., Martinsa, M.T., de Albuquer que, F.G.S., Barreto, F., and Hoff, R., Food Addit. Con tam., 2012, vol. 29, no. 4, p. 508. 17. Filigenzi, M.S., Ehrke, N., Aston, L.S., and Poppen ga, R.H., Food Addit. Contam., 2011, vol. 28, p. 1324. 18. Lopes, R.P., Eustaquia de Freitas Passos, E., Fabiano de Alkimim Filho, J.,Vargas, E.A., Augusti, D.V., and Augusti, R., Food Control, 2012, vol. 28, p. 192. 19. Karageorgou, E.G. and Samanidou, V.F., J. Sep. Sci., 2011, vol. 34, p. 1893. 20. Fuh, M.R.S. and Chan, S.A., Talanta, 2011, vol. 55, p. 1127. Translated by I. Duchovni

JOURNAL OF ANALYTICAL CHEMISTRY

Vol. 70

No. 9

2015