Dispersive Liquid-Liquid Microextraction in the Analysis of Milk and Dairy Products: A Review

Table 1

Modes of DLLME used in dairy analysis.

Sample	Sample preparation	Extraction/dispersive solvent	Analytes extracted	Enrichment factor	Analytical method	LOD (μg/L)	Reference
DLLME
Infant formula, fermented milk	Acid hydrolysis, enzymatic hydrolysis and derivatisation	Tetrachloroethene (90 μL)/acetonitrile (0.5 mL)	Thiamine	Not specified	Reversed phase HPLC (RP-HPLC)	0.09	[13]
Soybean milk	Liquid-liquid extraction	Carbon tetrachloride (40 μL)/acetonitrile (1 mL)	Phthalate acid esters	200–260	GC-MS	0.57–0.79 ng/g	[14]
Full fat milk, half fat milk, skimmed milk, follow-on formula	Dilution, protein precipitation by TCA	Chloroform (200 μL)/acetonitrile (2 mL)	Macrocyclic lactones	65–200	HPLC-DAD coupled to APCI-IT-MS/MS	HPLC-DAD: 0.3–1.4 ng/g; LC-MS/MS: 0.03–0.72 ng/g	[15]
Milk	Protein precipitation by TCA, pH adjustment, derivatisation by fluorescamine	Chloroform (1 mL)/ACN (1.9 mL)	Sulfonamides	2.2	RP-HPLC-FL	0.6–1.03	[16]
Milk, white cheese, yogurt, unpasteurised milk	Milks: protein precipitation, removal of fat; yogurt and cheese: dilution, removal of fat	Chloroform (150 μL)/ACN (2 mL)	Nonsteroidal anti-inflammatory drugs	Milk: 81.1–141, yogurt: 45.9–81 cheese: 145–229	Field amplified sample stacking in CE (FASS)	Milk (μg/kg): 4.8–13; Yogurt (μg/kg): 3.0–9.7; Cheese (μg/kg): 6.1–7.7	[17]
Whole milk, skimmed milk, powdered milk	Whole milk: centrifugation, powdered milk: reconstitution with ultrapure water; Protein precipitation by ACN and NaCl	Chloroform (1.5 mL)/ACN (2.4 mL)	Aflatoxin M1	33	UHPLC-MS/MS	0.6 ng/kg	[18]
Milk	Centrifugation, protein precipitation by ACN	Carbon tetrachloride (35 μL)/ethanol (800 μL)	Cholesterol	Not specified	HPLC-UV	0.01	[19]
Milk	Protein precipitation by ACN and NaCl	Chloroform (40 μL)/ACN (1 mL)	Pesticides	176–435	GC-FID, GC-MS	4–58	[20]
Milk	Protein precipitation by ACN and NaCl	1,2-Dibromoethane (20 μL)/ACN (800 μL)	Phthalates	397–499	GC-FID, GC-MS	1.0–3.0	[21]
Milk	Saponification, in-tube LLE	1,1,2,2-Tetrachloroethane (22 μL)/ACN (1 mL)	Polybrominated diphenyl ethers	271–307	GC-MS	0.012–0.29	[22]
Milk	QuEChERS	Chloroform (200 μL)/10% acetic acid-ACN (1 mL)	Fluoroquinolones	Not specified	RP-HPLC-UV	0.8–5.0 μg/kg	[23]
Milk	Protein precipitation and fat removal by NaOH and acetone, SPE	Chlorobenzene (19 μL)/acetone (1 mL)	Polychlorinated biphenyls, polybrominated diphenyl ethers	Not specified	GC-MS	Polychlorinated biphenyls: 0.01–0.04 polybrominated biphenyls: 0.2–0.4	[24]
Infant formula	Protein precipitation by TCA, pH adjustment	Tetrachloroethylene (30 μL)/ACN (440 μL)	BPA, BPB	BPA: 237, BPB: 220	GC-MS	BPA: 0.06, BPB: 0.03	[25]
Ultrasound assisted DLLME
Bottled milk	Protein precipitation by TCA and lead acetate	Carbon tetrachloride (40 μL)/methanol (0.8 μL)	Phthalate acid esters (PAEs), butyl benzyl ester (BBP), di-isooctyl phthalate (DIOP)	PAEs: 226–258, BBP: 270,; DIOP: 220–229	GC-FID	0.75–0.79 ng/g, 0.66 ng/g 0.64–0.76 ng/g	[26]
Skimmed milk	Protein precipitation by ACN, derivatisation by HFBI	Chloroform (100 μL)/ACN (2 mL)	Chloropropanols	Not specified	GC-MS/MS	0.9–3.6	[27]
Milk, cheese	QuEChERS	Chloroform (500 μL)/ACN (3 mL)	Alfatoxins: B1, M1	B1: 30, M1: 30	RP-HPLC-FL	B1: 0.1 μg/kg; M1: 0.01 μg/kg	[28]
UA-IL/IL-DLLME
Infant formula	Dilution	[C6MIM][PF6] (70 μL)/[C4MIM][BF4] (100 μL)	Sulfonamides	Not specified	RP-HPLC-PDA	2.94–16.7 μg/kg	[29]
DLLME with back extraction
Breast milk, ice cream	Protein precipitation by salting out with NaCl, phosphoric acid, ACN	Chloroform (200 μL)/ACN (1 mL)	Parabens	4.6–9.2	CE-DAD	300	[30]
USA-RM-DLLME
Butter	Melting for 5 min at 40°C	Triton X-100 (1.25% w/v)/water (400 μL)	Acetoin	245	RP-HPLC-UV	200,000	[31]
USA-IL-DLLME
Milk	Microwave digestion with HNO3 and H2O2, chelation with 1-Phenylthiosemicarbazide	[C6MIM][Tf2N] (100 μL)	Selenium	150	Graphite furnace atomic absorption spectrometry (GFAAS)	12	[32]
LDS-DLLME
Cheese	Protein precipitation, filtration	1-octanol (60 μL)/acetone (475 μL)	Sorbic and benzoic acids	Cheese: sorbate (143), benzoate (170)	GC-FID	Cheese sorbate 150 ng/g, benzoate: 140 ng/g	[33]
Milk	Fat removal by centrifugation	1-Heptanol (320 μL)/MeOH : water (80 : 20) (3 mL)	Aflatoxin M1	Not specified	Fluorescence spectrophotometer	0.013	[34]
Yoghurt drinks	Protein precipitation, filtration	1-Octanol (60 μL)/ethanol (450 μL)	Benzoate, sorbate	Benzoate: 162, sorbate: 181	RP-HPLC-UV	Benzoate: 0.2, sorbate: 0.5	[35]
VA-DLLME
Whole milk, skimmed milk, semiskimmed goat milk, yogurt	Protein precipitation by ACN and acetic acid, fat removal by hexane and centrifugation	Chloroform (110 μL)/ACN (500 μL)	Estrogenic compounds	Not specified	MEKC-MS	Whole milk: 6–71, skimmed milk: 3–64, semiskimmed goat milk: 4–220, yogurt: 12–140	[36]
IL-DLLME
Breast milk	Protein precipitation by HClO4, H3PO4, MeOH	NFX: [C8C1im][PF6] (42 μL)/MeOH (80 μL); BNZ: [C8C1im][PF6] (42 μL)/MeOH (101 μL)	NFX, BNZ	NFX: 33.8, BNZ: 28.8	RP-HPLC-UV	NFX: 90, BNZ: 60	[37]