Oil and Grease
1
Without calibration transfer Added(ppm) Found (ppm) %* 5.83 4.77 81.8 11.7 9.18 78.5 17.5 14.9 85.1 5.83 4.89 83.9 11.7 9.41 80.4 17.5 14.0 80.0 5.83 4.84 83.0 11.7 9.41 80.4 17.5 13.7 78.3 UHQ water samples River water samples Tap water samples Signal (E+06) m/z 84 124 0 40 80 120 Signals: gasoline in water samples Error analysis SEP 1.238 r 0.997 Slope 0.915 Intercept 0.242 Error analysis SEP 1.330 r 0.993 Slope 0.935 Intercept 0.109 5 15 25 5 15 25 5 0 10 20 0 10 20 5 Found (ppm) Added (ppm) Found (ppm) Added (ppm) PLS Prediction (tap water samples) PLS Prediction (river water samples) PLS Calibration (UHQ water samples) 5 15 25 5 15 25 5 Found (ppm) Added (ppm) 84 124 0 20 40 60 80 44 84 124 0 20 40 60 80 44 Signal(E+06) m/z Calibration samples Universidad de Salamanca GERSTEL ChemSensor 4440 (Headspace-Mass Spectrometer) Different analytical procedures have been proposed for the determination of the conventional pollutant oil and grease, related with hydrocarbons, vegetable oils, animal fats, waxes, soaps, greases and related matter in waters. As a result of the complexity of the samples the definition of oil and grease is based on the procedure used, which can alter the amount and composition of the material extracted. Standard protocols in polluted waters propose gravimetric or infrared spectrometric procedures, with previous liquid-liquid extraction or solid-phase extraction. In this work we propose the use of Headspace-Mass Spectrometry, which has a series of advantages because the sample preparation steps are eliminated and no solvent is needed. A three component synthetic oil (n-hexadecane, isooctane and benzene) has been used as the calibration standard. Introduction A method based on Headspace-Mass Spectrometry has been developed for the determination of oil and grease in water, involving minimum sample treatment. The analytical signals were the sum of the intensities of the ions measured at m/z: 57, 71, 78, 85 and 99. A Box Behnken design for screening/optimising the significant variables was applied. A multivariate PLS calibration model built in UHQ water was used to predict oil in tap and river waters with satisfactory results. Additionally, samples spiked with three different spike levels of gasoline were analysed using the three component synthetic oil mixture as the calibration standard and the oil content was correctly predicted. Conclusions DETERMINATION OF OIL AND GREASE IN WATER BY HEADSPACE-MASS SPECTROMETRY María Esther Fernández Laespada, Yolanda González Martín, José Luis Pérez Pavón, Carmelo García Pinto and Bernardo Moreno Cordero Departamento de Química Analítica, Nutrición y Bromatología; Universidad de Salamanca. 37008 Salamanca. ESPAÑA. HEADSPACE SAMPLER Temperatures Oven 80 ºC Loop 120 ºC Transfer line 130 ºC Time Head space generation 40 min Injection 1 min MASS SPECTROMETER Data acquisition time 1.0 min Mass range 49-150 da Experimental conditions Statistical Packages ü The Unscrambler ® v7.6 SR-1 ü Pirouette v 3.0 Box-Behnken experimental design Variable Level Low High HS generation time (min) (A) 10 40 HS generation temp. (ºC) (B) 50 80 Salt content (g/L NaCl) (C) 2 30 Experiment* Var. A Var. B Var. C 1 10 50 16 2 40 50 16 3 25 50 2 4 25 50 30 5 10 80 16 6 40 80 16 7 25 80 30 8 25 80 2 9 10 65 30 10 10 65 2 11 40 65 2 12 40 65 30 Centre 25 65 16 * All experiments were made in triplicate Experimental plan Regression coefficients and P-values Term m/z=57 m/z=78 Coefficient P-value Coefficient P-value Intercept 7.78e+6 0.000* 2.93e+6 0.000* A 1.87e+4 0.024* 1.87e+4 0.000* B 7.02e+4 0.000* 1.52e+4 0.000* C 9.51e+3 0.268 2.04e+3 0.342 A x B 1.57e+5 0.147 4.88e+4 0.074 A x C -4.67e+4 0.661 -1.96e+4 0.464 B x C 1.70e+4 0.873 7.52e+3 0.778 A x A -1.17e+4 0.934 -5.03e+4 0.160 B x B -1.71e+5 0.230 -6.49e+4 0.073 C x C -3.73e+5 0.012* -1.34e+5 0.001* m/z Lack of fit 57 0.584 71 0.236 78 0.832 85 0.216 99 0.608 * Most significant variables and interaction effects (P-value <0.05) Quantification: Oil and grease in water by PLS Quantification: Gasoline in water by PLS With calibration transfer Added(ppm) Found (ppm) %* 5.83 5.43 93.1 11.7 9.89 84.5 17.5 15.7 89.7 5.83 5.18 88.8 11.7 9.85 84.2 17.5 14.7 84.0 5.83 5.14 88.2 11.7 9.80 83.8 17.5 14.3 81.7 UHQ water samples River water samples Tap water samples Recovery in gasoline spiked water samples *Results obtained as a mean of three determinations Future Research Determination of different types of oils Diesel fuel, Kerosene Crude oil, Engine oil 50 65 80 10 25 40 Response Time (min) Temperature (ºC) m/z = 57 50 65 80 10 25 40 Response Time (min) Temperature (ºC) m/z = 78 Response surfaces Determination in different water matrices Sea water Waste water Study of other calibration standard mixtures n-Hexadecane, isooctane and chlorobenzene n-Hexadecane, pristane and toluene n-Hexadecane and stearic acid Samples spiked with the synthetic oil mixture The prediction of the gasoline spiked samples was carried out with the model built with the synthetic oil mixture Signals obtained Error analysis SEC 0.648 SEV 0.767 rCal 0.997 rVal 0.995 ®
Transcript of Oil and Grease
Without calibration transfer
Added(ppm) Found (ppm) %*
5.83 4.77 81.811.7 9.18 78.517.5 14.9 85.1
5.83 4.89 83.911.7 9.41 80.417.5 14.0 80.0
5.83 4.84 83.011.7 9.41 80.417.5 13.7 78.3
UHQ water samples
River water samples
Tap water samples
Sig
nal (
E+
06)
m/z84 124
0
40
80
120
Signals: gasoline in water samples
Error analysis
SEP 1.238
r 0.997
Slope 0.915
Intercept 0.242
Error analysis
SEP 1.330
r 0.993
Slope 0.935
Intercept 0.109
5 15 25
5
15
25
5
0 10 200
10
20
5
Fou
nd (
ppm
)
Added (ppm)
Fou
nd (
ppm
)
Added (ppm)
PLS Prediction (tap water samples)
PLS Prediction (river water samples)
PLS Calibration (UHQ water samples)
5 15 25
5
15
25
5
Fou
nd (
ppm
)
Added (ppm)
84 124
0
20
40
60
80
44 84 124
0
20
40
60
80
44
Sig
nal(E
+06
)
m/z
Calibration samples
Universidad de Salamanca
GERSTEL ChemSensor 4440(Headspace-Mass Spectrometer)
Different analytical procedures have been proposed for the determination of the conventional pollutant oil and
grease, related with hydrocarbons, vegetable oils, animal fats, waxes, soaps, greases and related matter in
waters. As a result of the complexity of the samples the definition of oil and grease is based on the procedure
used, which can alter the amount and composition of the material extracted.
Standard protocols in polluted waters propose gravimetric or infrared spectrometric procedures, with previous
liquid-liquid extraction or solid-phase extraction.
In this work we propose the use of Headspace-Mass Spectrometry, which has a series of advantages because
the sample preparation steps are eliminated and no solvent is needed.
A three component synthetic oil (n-hexadecane, isooctane and benzene) has been used as the calibration
standard.
Introduction
A method based on Headspace-Mass Spectrometry has been developed for the determination of oil and grease in water, involving minimum sample treatment.The analytical signals were the sum of the intensities of the ions measured at m/z: 57, 71, 78, 85 and 99. A Box Behnken design for screening/optimising thesignificant variables was applied.A multivariate PLS calibration model built in UHQ water was used to predict oil in tap and river waters with satisfactory results. Additionally, samples spiked withthree different spike levels of gasoline were analysed using the three component synthetic oil mixture as the calibration standard and the oil content wascorrectly predicted.
Conclusions
DETERMINATION OF OIL AND GREASE IN WATER BYHEADSPACE-MASS SPECTROMETRY
María Esther Fernández Laespada, Yolanda González Martín, José Luis PérezPavón, Carmelo García Pinto and Bernardo Moreno Cordero
Departamento de Química Analítica, Nutrición y Bromatología; Universidad de Salamanca. 37008 Salamanca. ESPAÑA.
HEADSPACE SAMPLER
Temperatures Oven 80 ºC
Loop 120 ºC
Transfer line 130 ºC
Time Head space generation 40 min
Injection 1 min
MASS SPECTROMETER
Data acquisition time 1.0 min
Mass range 49-150 da
Experimental conditions
Statistical Packagesü The Unscrambler® v7.6 SR-1
ü Pirouette v 3.0
Box-Behnken experimental design
Variable Level
Low High
HS generation time (min) (A) 10 40
HS generation temp. (ºC) (B) 50 80
Salt content (g/L NaCl) (C) 2 30
Experiment* Var. A Var. B Var. C
1 10 50 162 40 50 163 25 50 24 25 50 305 10 80 166 40 80 167 25 80 308 25 80 29 10 65 30
10 10 65 211 40 65 212 40 65 30
Centre 25 65 16
* All experiments were made in triplicate
Experimental plan Regression coefficients and P-values
Term m/z=57 m/z=78
Coefficient P-value Coefficient P-value
Intercept 7.78e+6 0.000* 2.93e+6 0.000*A 1.87e+4 0.024* 1.87e+4 0.000*B 7.02e+4 0.000* 1.52e+4 0.000*C 9.51e+3 0.268 2.04e+3 0.342
A x B 1.57e+5 0.147 4.88e+4 0.074A x C -4.67e+4 0.661 -1.96e+4 0.464B x C 1.70e+4 0.873 7.52e+3 0.778A x A -1.17e+4 0.934 -5.03e+4 0.160B x B -1.71e+5 0.230 -6.49e+4 0.073C x C -3.73e+5 0.012* -1.34e+5 0.001*
m/z Lack of fit
57 0.58471 0.23678 0.83285 0.21699 0.608
* Most significant variables and interaction effects (P-value <0.05)
Quantification: Oil and grease in water by PLS
Quantification: Gasoline in water by PLS
With calibration transfer
Added(ppm) Found (ppm) %*
5.83 5.43 93.111.7 9.89 84.517.5 15.7 89.7
5.83 5.18 88.811.7 9.85 84.217.5 14.7 84.0
5.83 5.14 88.211.7 9.80 83.817.5 14.3 81.7
UHQ water samples
River water samples
Tap water samples
Recovery in gasoline spiked water samples
*Results obtained as a mean of three determinations
Future Research
Determination of different types of oils
Diesel fuel, KeroseneCrude oil, Engine oil
5065
80
10
25
40
Res
pons
e
Time (m
in) Temperature (ºC)
m/z = 57
50
65
80
10
25
40
Res
pons
e
Time (m
in) Temperature (ºC)
m/z = 78
Response surfaces
Determination in different water matrices
Sea waterWaste water
Study of other calibration standard mixtures
n-Hexadecane, isooctane and chlorobenzenen-Hexadecane, pristane and toluenen-Hexadecane and stearic acid
Samples spiked with the synthetic oil mixture
The prediction of the gasoline spiked samples was carried out with the model built with the synthetic oil mixture
Signals obtained
Error analysis
SEC 0.648 SEV 0.767
rCal 0.997 rVal 0.995
®
