Introducing Doolittle multivariate calibration algorithm for infrared spectrometric determination of STTP, SS, and SC in Iranian washing powder

Figures & data

Figure 1.  ATR-FTIR spectra of standard samples with water background (obtained in 750–2000 cm⁻¹).

Figure 2.  ATR-FTIR spectra of 25 different three components standard solutions with concentration range of 0.25– 2.89, 0.20–2.49, and 0.2912–1.2010 g/100 g for STPP, SC, and SS, respectively (water as the reference).

Table 1. Composition of the calibration (sample 1–25) and predication sample (26–35).

Sample	STPP (g per 100 g)	SS (g per 100 g)	SC (g per 100 g)
1	2.890	2.490	1.200
2	2.670	2.410	1.050
3	2.540	2.090	0.970
4	2.440	2.110	0.950
5	2.160	1.950	0.920
6	2.120	1.710	0.890
7	1.940	1.700	0.870
8	1.710	1.580	0.840
9	1.480	1.170	0.800
10	1.150	0.980	0.600
11	0.690	0.720	0.0410
12	0.440	0.290	0.200
13	0.250	0.200	0.270
14	0.830	0.800	0.500
15	2.300	0.200	0.500
16	1.320	0.200	1.100
17	0.790	0.210	1.400
18	1.310	0.310	1.420
19	1.320	0.610	0.810
20	1.760	0.600	0.290
21	1.300	1.100	0.500
22	0.820	1.140	0.520
23	0.810	1.100	0.290
24	1.810	1.510	0.300
25	1.820	1.500	0.800
26	0.330	1.510	1.100
27	0.330	2.000	0.800
28	0.310	2.010	1.410
29	2.350	2.000	1.110
30	0.560	0.930	1.320
31	1.550	1.300	1.070
32	2.080	1.030	1.120
33	1.050	1.280	0.710
34	1.280	1.120	0.800
35	1.710	0.980	1.400
Note: STPP, Sodium tripolyphosphate; SS, sodium sulfate; SC, sodium carbonate.

Table 2. Quantitative analysis of STTP, SS, and SC applied in predication (samples no. 26–35) set by DMCA and KM models (g per 100 g).

	Method	STPP	SS	SC
1	KM	0.344	1.460	0.982
	DMCA	0.335	1.497	1.084
	References	0.330	1.510	1.100
2	KM	0.350	1.749	0.9574
	DMCA	0.327	1.945	0.792
	References	0.330	2.000	0.800
3	KM	0.332	1.979	0.8150
	DMCA	0.312	1.997	0.786
	References	0.310	2.010	0.800
4	KM	2.406	1.825	0.876
	DMCA	2.210	2.041	1.162
	References	2.350	2.000	1.110
5	KM	0.516	0.916	1.188
	DMCA	0.567	0.935	1.356
	References	0.560	0.930	1.320
6	KM	1.514	1.322	1.017
	DMCA	1.476	1.293	0.979
	References	1.550	1.300	1.070
7	KM	2.008	0.999	1.022
	DMCA	2.068	1.027	1.102
	References	2.080	1.030	1.120
8	KM	1.104	1.333	0.655
	DMCA	1.041	1.278	0.690
	References	1.050	1.280	0.710
9	KM	1.204	1.089	0.817
	DMCA	1.331	1.118	0.804
	References	1.280	1.120	0.800
10	KM	1.671	1.006	1.586
	DMCA	1.647	0.960	1.322
	References	1.710	0.98	1.400
Note: STPP, Sodium tripolyphosphate; SS, sodium sulfate; SC, sodium carbonate; DMCA, Doolittle multivariate calibration algorithm; KM, K-Matrix.

Table 3. Statistical parameters of the applied models.

Calibration model		R^2	RMSEP
KM	STPP	0.962	0.118
	SC	0.835	0.110
	SS	0.873	0.011
DMCA	STPP	0.947	0. 141
	SC	0.967	0.035
	SS	0.992	0.009
Note: R^2, correlation coefficient; STPP, sodium tripolyphosphate; SS, sodium sulfate; SC, sodium carbonate; DMCA, Doolittle multivariate calibration algorithm; RMSEP, root mean square error of prediction; KM, K-Matrix.

Table 4. Recovery study results.

	Added			Found			Recovery
Sample	STPP (g/100 g)	SS (g/100 g)	SC (g/100 g)	STPP (g/100 g)	SS (g/100 g)	SC (g/100 g)	STPP	SS	SC
1*	0.490	0.500	0.880	0.506	0.536	0.828	103.265	107.200	94.090
2	1.480	0.510	1.200	1.515	0.488	1.242	102.364	97.568	103.500
3*	0.500	1.510	1.220	0.521	1.472	1.227	110.200	106.262	105.000
4	0.500	0.990	0.580	0.551	1.052	0.609	95.306	99.117	102.623
5	0.980	1.020	1.220	0.934	1.011	1.252	95.408	99.019	104.754
6	1.000	0.520	0.900	1.089	0.574	0.881	108.900	110.307	97.888
7*	1.02	1.510	0.910	1.020	1.532	0.960	100.000	101.457	105.494
8	1.510	1.500	0.610	1.472	1.471	0.580	97.483	98.066	95.081
9*	1.490	1.010	0.610	1.478	1.009	0.622	99.194	99.900	101.967
Note: STPP, Sodium tripolyphosphate; SS, sodium sulfate; SC, sodium carbonate. * Mean of three measurements.

Table 5. Precision for synthetic mixtures (n=3).

	STPP		SS		SC
Sample	SD	Percentage of RSD	SD	Percentage of RSD	SD	Percentage of RSD
1	0.005	1.009	0.008	0.771	0.006	0.982
3	0.003	0.592	0.004	0.275	0.006	0.491
7	0.008	0.782	0.006	0.389	0.010	1.039
9	0.006	0.363	0.005	0.493	0.004	0.630
Note: STPP, Sodium tripolyphosphate; SS, sodium sulfate; SC, sodium carbonate; SD, standard deviation; RSD, relative standard deviation.